E21B1/00	7	Percussion drilling<br><br><u>NOTE</u><br><br>When classifying in groups E21B1/12 - E21B1/38, a symbol from one of the following main groups of B25D should also be given:<br>B25D9/00 Portable percussive tools with fluid-pressure drives<br>B25D11/00 Portable percussive tools with motor drive<br>B25D16/00 Portable percussive machines with superimposed rotation<br>B25D17/00 Details of, or accessories for, portable power-driven percussive tools	E21B1/00	E21B1/00		441
E21B1/02	8	Surface drives for drop hammers {or percussion drilling}, e.g. with a cable	E21B1/02	E21B1/02		489
E21B1/04	9	Devices for reversing the movement of the rod or cable at the surface	E21B1/04	E21B1/04		447
E21B1/12	8	with a reciprocating impulse member (E21B1/02, E21B1/38 take precedence)	E21B1/12	E21B1/12		47
E21B1/14	9	driven by a rotating mechanism	E21B1/14	E21B1/14		30
E21B1/16	10	with spring-mounted reciprocating masses, e.g. with air cushion	E21B1/16	E21B1/16		2
E21B1/18	11	with elastic joining of the drive to the push-rod by double buffer springs	E21B1/18	E21B1/18		2
E21B1/20	10	formed as centrifugal hammers	E21B1/20	E21B1/20		1
E21B1/22	9	driven by electromagnets	E21B1/22	E21B1/22		40
E21B1/24	9	the impulse member being a piston driven directly by fluid pressure	E21B1/24	E21B1/24		26
E21B1/26	10	by liquid pressure	E21B1/26	E21B1/26		151
E21B1/28	11	working with pulses	E21B1/28	E21B1/28		10
E21B1/30	10	by air, steam or gas pressure	E21B1/30	E21B1/30		304
E21B1/32	11	working with pulses	E21B1/32	E21B1/32		20
E21B1/34	12	the impulse member being a piston of an internal-combustion engine	E21B1/34	E21B1/34		94
E21B1/36	8	Tool-carrier piston type, i.e. in which the tool is connected to an impulse member	E21B1/36	E21B1/36		50
E21B1/38	8	Hammer piston type, i.e. in which the tool bit or anvil is hit by an impulse member	E21B1/38	E21B1/38		181
E21B3/00	7	Rotary drilling	E21B3/00	E21B3/00		716
E21B3/02	8	Surface drives for rotary drilling	E21B3/02	E21B3/02		3340
E21B3/022	9	{Top drives}	E21B3/02	E21B3/02		1322
E21B3/025	9	with a to-and-fro rotation of the tool	E21B3/025	E21B3/025		210
E21B3/03	9	with an intermittent unidirectional rotation of the tool	E21B3/03	E21B3/03		34
E21B3/035	9	with slipping or elastic transmission	E21B3/035	E21B3/035		51
E21B3/04	9	Rotary tables	E21B3/04	E21B3/04		746
E21B3/045	10	{movably mounted on the drilling structure or platform (derricks adapted to be moved on their substructure E21B15/003)}	E21B3/04	E21B3/04		82
E21B3/06	10	Adaptation of rotary draw works to drive rotary tables	E21B3/06	E21B3/06		222
E21B4/00	7	Drives for drilling, used in the borehole	E21B4/00	E21B4/00		393
E21B4/003	8	{Bearing, sealing, lubricating details (for roller bits E21B10/22)}	E21B4/00	E21B4/00		780
E21B4/006	8	{Mechanical motion converting means, e.g. reduction gearings (E21B4/10 takes precedence)}	E21B4/00	E21B4/00		518
E21B4/02	8	Fluid rotary type drives	E21B4/02	E21B4/02		2321
E21B4/04	8	Electric drives (E21B4/12 takes precedence)	E21B4/04	E21B4/04		728
E21B4/06	8	Down-hole impacting means, e.g. hammers (boring rams E21B11/02)	E21B4/06	E21B4/06		460
E21B4/08	9	impact being obtained by gravity only, e.g. with lost-motion connection	E21B4/08	E21B4/08		144
E21B4/10	9	continuous unidirectional rotary motion of shaft or drilling pipe effecting consecutive impacts	E21B4/10	E21B4/10		171
E21B4/12	9	Electrically operated hammers	E21B4/12	E21B4/12		72
E21B4/14	9	Fluid operated hammers	E21B4/14	E21B4/14		1745
E21B4/145	10	{of the self propelled-type, e.g. with a reverse mode to retract the device from the hole}	E21B4/14	E21B4/14		288
E21B4/16	8	Plural down-hole drives, e.g. for combined percussion and rotary drilling (E21B4/10 takes precedence); Drives for multi-bit drilling units	E21B4/16	E21B4/16		2339
E21B4/18	8	Anchoring or feeding in the borehole	E21B4/18	E21B4/18		620
E21B4/20	8	combined with surface drive (E21B4/10 takes precedence)	E21B4/20	E21B4/20		251
E21B6/00	7	Drives for drilling with combined rotary and percussive action	E21B6/00	E21B6/00		832
E21B6/02	8	the rotation being continuous	E21B6/02	E21B6/02		166
E21B6/04	9	Separate drives for percussion and rotation	E21B6/04	E21B6/04		203
E21B6/06	8	the rotation being intermittent, e.g. obtained by ratchet device	E21B6/06	E21B6/06		421
E21B6/08	9	Separate drives for percussion and rotation	E21B6/08	E21B6/08		134
E21B7/00	7	Special methods or apparatus for drilling	E21B7/00	E21B7/00		2687
E21B7/001	8	{Drilling a non circular hole (excavating trenches E02F5/02; cutting machines for slitting E21C25/00)}	E21B7/00	E21B7/00		1677
E21B7/002	8	{Drilling with diversely driven shafts extending into the borehole (⁠ E21B7/001 takes precedence)}	E21B7/00	E21B7/00		391
E21B7/003	8	{Drilling with mechanical conveying means}	E21B7/00	E21B7/00		388
E21B7/005	9	{with helical conveying means (E21B7/201 takes precedence; augers E21B10/44; drilling rods or pipes with helical structure E21B17/22)}	E21B7/00	E21B7/00		642
E21B7/006	10	{combined with a bucket-type container}	E21B7/00	E21B7/00		112
E21B7/007	8	{Drilling by use of explosives (underwater drilling using explosives E21B7/1245)}	E21B7/00	E21B7/00		215
E21B7/008	8	{Drilling ice or a formation covered by ice}	E21B7/00	E21B7/00		325
E21B7/02	8	Drilling rigs characterised by means for land transport {with their own drive}, e.g. skid mounting or wheel mounting	E21B7/02	E21B7/02		4467
E21B7/021	9	{With a rotary table, i.e. a fixed rotary drive for a relatively advancing tool}	E21B7/02	E21B7/02		517
E21B7/022	9	{Control of the drilling operation; Hydraulic or pneumatic means for activation or operation (control circuits for drilling masts E21B15/045)}	E21B7/02	E21B7/02		1149
E21B7/023	9	{the mast being foldable or telescopically retractable}	E21B7/02	E21B7/02		473
E21B7/024	9	{having means for adapting to inclined terrain; having means for stabilizing the vehicle while drilling}	E21B7/02	E21B7/02		802
E21B7/025	9	{Rock drills, i.e. jumbo drills}	E21B7/02	E21B7/02		1307
E21B7/026	9	{having auxiliary platforms, e.g. for observation purposes}	E21B7/02	E21B7/02		243
E21B7/027	9	{Drills for drilling shallow holes, e.g. for taking soil samples or for drilling postholes}	E21B7/02	E21B7/02		835
E21B7/028	10	{the drilling apparatus being detachable from the vehicle, e.g. hand portable drills}	E21B7/02	E21B7/02		299
E21B7/04	8	Directional drilling	E21B7/04	E21B7/04		4964
E21B7/043	9	{for underwater installations}	E21B7/04	E21B7/04		186
E21B7/046	9	{horizontal drilling (drilling with mechanical conveying means E21B7/003)}	E21B7/04	E21B7/04		2587
E21B7/06	9	Deflecting the direction of boreholes	E21B7/06	E21B7/06		1576
E21B7/061	10	{the tool shaft advancing relative to a guide, e.g. a curved tube or a whipstock}	E21B7/06	E21B7/06		1262
E21B7/062	10	{the tool shaft rotating inside a non-rotating guide travelling with the shaft (E21B7/067 and E21B7/068 take precedence)}	E21B7/06	E21B7/06		540
E21B7/064	10	{specially adapted drill bits therefor}	E21B7/06	E21B7/06		385
E21B7/065	10	{using oriented fluid jets}	E21B7/06	E21B7/06		180
E21B7/067	10	{with means for locking sections of a pipe or of a guide for a shaft in angular relation, e.g. adjustable bent sub}	E21B7/06	E21B7/06		685
E21B7/068	10	{drilled by a down-hole drilling motor (down-hole drives per seE21B4/00, E21B7/067 takes precedence)}	E21B7/06	E21B7/06		805
E21B7/10	9	Correction of deflected boreholes	E21B7/10	E21B7/10		597
E21B7/12	8	Underwater drilling (using heave compensators E21B19/09)	E21B7/12	E21B7/12		949
E21B7/122	9	{with submersible vertically movable guide}	E21B7/12	E21B7/12		120
E21B7/124	9	with underwater tool drive prime mover, e.g. portable drilling rigs for use on underwater floors	E21B7/124	E21B7/124		373
E21B7/1245	10	{using explosive means (anchors driven in by explosive charges B63B21/28)}	E21B7/124	E21B7/124		27
E21B7/128	9	from floating support with independent underwater anchored guide base	E21B7/128	E21B7/128		462
E21B7/132	9	from underwater buoyant support	E21B7/132	E21B7/132		68
E21B7/136	9	from non-buoyant support (E21B7/124 takes precedence)	E21B7/136	E21B7/136		125
E21B7/14	8	Drilling by use of heat, e.g. flame drilling	E21B7/14	E21B7/14		424
E21B7/143	9	{underwater}	E21B7/14	E21B7/14		28
E21B7/146	9	{Thermal lances}	E21B7/14	E21B7/14		195
E21B7/15	9	of electrically generated heat	E21B7/15	E21B7/15		473
E21B7/16	8	Applying separate balls or pellets by the pressure of the drill, so-called shot-drilling	E21B7/16	E21B7/16		104
E21B7/18	8	Drilling by liquid or gas jets, with or without entrained pellets (E21B7/14 takes precedence)	E21B7/18	E21B7/18		1997
E21B7/185	9	{underwater}	E21B7/18	E21B7/18		132
E21B7/20	8	Driving or forcing casings or pipes into boreholes, e.g. sinking; Simultaneously drilling and casing boreholes	E21B7/20	E21B7/20		2339
E21B7/201	9	{with helical conveying means}	E21B7/20	E21B7/20		317
E21B7/203	10	{using down-hole drives}	E21B7/20	E21B7/20		84
E21B7/205	9	{without earth removal (E21B7/30 takes precedence)}<br><br><u>NOTE</u><br><br>Special methods or apparatus for drilling without earth removal E21B7/26	E21B7/20	E21B7/20		274
E21B7/206	10	{using down-hole drives}	E21B7/20	E21B7/20		96
E21B7/208	9	{using down-hole drives (E21B7/203 and E21B7/206 take precedence)}	E21B7/20	E21B7/20		364
E21B7/24	8	Drilling using vibrating or oscillating means, e.g. out-of-balance masses (percussion drilling E21B1/00)	E21B7/24	E21B7/24		1148
E21B7/26	8	Drilling without earth removal, e.g. with self-propelled burrowing devices (E21B7/30 takes precedence)	E21B7/26	E21B7/26		326
E21B7/265	9	{Combined with earth removal}	E21B7/26	E21B7/26		42
E21B7/267	9	{Drilling devices with senders, e.g. radio-transmitters for position of drilling tool}	E21B7/26	E21B7/26		87
E21B7/28	8	Enlarging drilled holes, e.g. by counterboring	E21B7/28	E21B7/28		2219
E21B7/30	9	without earth removal	E21B7/30	E21B7/30		387
E21B10/00	7	Drill bits (specially adapted for deflecting the direction of boring {E21B7/064}; with means for collecting substances E21B27/00)	E21B10/00	E21B10/00		1265
E21B10/003	8	{with cutting edges facing in opposite axial directions}	E21B10/00	E21B10/00		142
E21B10/006	8	{providing a cutting edge which is self-renewable during drilling}	E21B10/00	E21B10/00		96
E21B10/02	8	Core bits (characterised by wear resisting parts E21B10/48)	E21B10/02	E21B10/02		671
E21B10/04	9	with core destroying means	E21B10/04	E21B10/04		305
E21B10/06	9	Roller core bits	E21B10/06	E21B10/06		153
E21B10/08	8	Roller bits (E21B10/26 takes precedence; roller core bits E21B10/06; characterised by wear resisting parts E21B10/50)	E21B10/08	E21B10/08		545
E21B10/083	9	{with longitudinal axis, e.g. wobbling or nutating roller bit (longitudinal axis roller reamers E21B10/30)}	E21B10/08	E21B10/08		99
E21B10/086	9	{with excentric movement}	E21B10/08	E21B10/08		31
E21B10/10	9	with roller axle supported at both ends	E21B10/10	E21B10/10		371
E21B10/12	9	with discs cutters	E21B10/12	E21B10/12		418
E21B10/14	9	combined with non-rolling cutters other than of leading-portion type	E21B10/14	E21B10/14		193
E21B10/16	9	characterised by tooth form or arrangement	E21B10/16	E21B10/16		754
E21B10/18	9	characterised by conduits or nozzles for drilling fluids	E21B10/18	E21B10/18		672
E21B10/20	9	characterised by detachable or adjustable parts, e.g. legs or axles	E21B10/20	E21B10/20		534
E21B10/22	9	characterised by bearing, lubrication or sealing details	E21B10/22	E21B10/22		690
E21B10/23	10	with drilling fluid supply to the bearings	E21B10/23	E21B10/23		86
E21B10/24	10	characterised by lubricating details (E21B10/23 takes precedence)	E21B10/24	E21B10/24		450
E21B10/246	11	{with pumping means for feeding lubricant}	E21B10/24	E21B10/24		116
E21B10/25	10	characterised by sealing details	E21B10/25	E21B10/25		452
E21B10/26	8	Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers (percussion drill bits with leading portion E21B10/40)	E21B10/26	E21B10/26		1177
E21B10/265	9	{Bi-center drill bits, i.e. an integral bit and eccentric reamer used to simultaneously drill and underream the hole}	E21B10/26	E21B10/26		134
E21B10/28	9	with non-expansible roller cutters	E21B10/28	E21B10/28		358
E21B10/30	10	Longitudinal axis roller reamers, e.g. reamer stabilisers	E21B10/30	E21B10/30		237
E21B10/32	9	with expansible cutting tools	E21B10/32	E21B10/32		1067
E21B10/322	10	{cutter shifted by fluid pressure (E21B10/345 takes precedence)}	E21B10/32	E21B10/32		723
E21B10/325	10	{the cutter being shifted by a spring mechanism}	E21B10/32	E21B10/32		385
E21B10/327	10	{the cutter being pivoted about a longitudinal axis (E21B10/34 takes precedence)}	E21B10/32	E21B10/32		177
E21B10/34	10	of roller-cutter type	E21B10/34	E21B10/34		229
E21B10/345	11	{cutter shifted by fluid pressure}	E21B10/34	E21B10/34		143
E21B10/36	8	Percussion drill bits ({with helical conveying portion E21B10/445;} characterised by wear resisting parts E21B10/46)	E21B10/36	E21B10/36		1024
E21B10/38	9	characterised by conduits or nozzles for drilling fluids	E21B10/38	E21B10/38		708
E21B10/40	9	with leading portion	E21B10/40	E21B10/40		458
E21B10/42	8	Rotary drag type drill bits with teeth, blades or like cutting elements, e.g. fork-type bits, fish tail bits (characterised by wear resisting parts E21B10/46; by conduits or nozzles for drilling fluid E21B10/60; by detachable or adjustable parts E21B10/62)	E21B10/42	E21B10/42		1065
E21B10/43	9	characterised by the arrangement of teeth or other cutting elements	E21B10/43	E21B10/43		1915
E21B10/44	8	Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts (E21B10/42 takes precedence)	E21B10/44	E21B10/44		1644
E21B10/445	9	{percussion type, e.g. for masonry}	E21B10/44	E21B10/44		347
E21B10/46	8	characterised by wear resisting parts, e.g. diamond inserts	E21B10/46	E21B10/46		1474
E21B10/48	9	the bit being of core type	E21B10/48	E21B10/48		431
E21B10/485	10	{with inserts in form of chisels, blades or the like}	E21B10/48	E21B10/48		79
E21B10/50	9	the bit being of roller type	E21B10/50	E21B10/50		424
E21B10/52	10	with chisel- or button-type inserts	E21B10/52	E21B10/52		513
E21B10/54	9	the bit being of the rotary drag type, e.g. fork-type bits	E21B10/54	E21B10/54		963
E21B10/55	10	with preformed cutting elements	E21B10/55	E21B10/55		783
E21B10/56	9	Button-type inserts (E21B10/52 takes precedence)	E21B10/56	E21B10/56		713
E21B10/567	10	with preformed cutting elements mounted on a distinct support, e.g. polycrystalline inserts	E21B10/567	E21B10/567		849
E21B10/5671	11	{with chip breaking arrangements}	E21B10/567	E21B10/567		74
E21B10/5673	11	{having a non planar or non circular cutting face}	E21B10/567	E21B10/567		448
E21B10/5676	11	{having a cutting face with different segments, e.g. mosaic-type inserts}	E21B10/567	E21B10/567		223
E21B10/573	11	characterised by support details, e.g. the substrate construction or the interface between the substrate and the cutting element	E21B10/573	E21B10/573		349
E21B10/5735	12	{Interface between the substrate and the cutting element}	E21B10/573	E21B10/573		526
E21B10/58	9	Chisel-type inserts ({E21B10/485,}E21B10/52 take precedence)	E21B10/58	E21B10/58		702
E21B10/60	8	characterised by conduits or nozzles for drilling fluids (for roller bits E21B10/18; for percussion drill bits E21B10/38)	E21B10/60	E21B10/60		1436
E21B10/602	9	{the bit being a rotary drag type bit with blades}	E21B10/60	E21B10/60		887
E21B10/605	9	{the bit being a core-bit}	E21B10/60	E21B10/60		152
E21B10/61	9	characterised by the nozzle structure	E21B10/61	E21B10/61		578
E21B10/62	8	characterised by parts, e.g. cutting elements, which are detachable or adjustable (E21B10/64 takes precedence; for roller bits E21B10/20; for augers E21B10/44)	E21B10/62	E21B10/62		1574
E21B10/627	9	with plural detachable cutting elements	E21B10/627	E21B10/627		208
E21B10/633	10	independently detachable	E21B10/633	E21B10/633		457
E21B10/64	8	characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe	E21B10/64	E21B10/64		260
E21B10/66	9	the cutting element movable through the drilling pipe and laterally shiftable	E21B10/66	E21B10/66		334
E21B11/00	7	Other drilling tools	E21B11/00	E21B11/00		115
E21B11/005	8	{Hand operated drilling tools}	E21B11/00	E21B11/00		663
E21B11/02	8	Boring rams	E21B11/02	E21B11/02		98
E21B11/04	8	Boring grabs	E21B11/04	E21B11/04		106
E21B11/06	8	with driven cutting chains or similarly driven tools	E21B11/06	E21B11/06		106
E21B12/00	7	Accessories for drilling tools	E21B12/00	E21B12/00		2051
E21B12/02	8	Wear indicators	E21B12/02	E21B12/02		318
E21B12/04	8	Drill bit protectors	E21B12/04	E21B12/04		246
E21B12/06	8	Mechanical cleaning devices	E21B12/06	E21B12/06		885
E21B15/00	7	Supports for the drilling machine, e.g. derricks or masts	E21B15/00	E21B15/00		4353
E21B15/003	8	{adapted to be moved on their substructure, e.g. with skidding means; adapted to drill a plurality of wells}	E21B15/00	E21B15/00		2236
E21B15/006	8	{Means for anchoring the drilling machine to the ground}	E21B15/00	E21B15/00		1471
E21B15/02	8	specially adapted for underwater drilling (E21B15/04 takes precedence)	E21B15/02	E21B15/02		1136
E21B15/04	8	specially adapted for directional drilling, e.g. slant hole rigs	E21B15/04	E21B15/04		1647
E21B15/045	9	{Hydraulic, pneumatic or electric circuits for their positioning}	E21B15/04	E21B15/04		337
E21B17/00	7	Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; {Cables;} Casings; Tubings	E21B17/00	E21B17/00		4436
E21B17/003	8	{with electrically conducting or insulating means (E21B17/028 and E21B17/023 take precedence)}	E21B17/00	E21B17/00		1008
E21B17/006	8	{Accessories for drilling pipes, e.g. cleaners (wear protectors E21B17/10; handling drilling pipes E21B19/00; thread protectors B65D59/00)}	E21B17/00	E21B17/00		905
E21B17/01	8	Risers	E21B17/01	E21B17/01		1556
E21B17/012	9	{with buoyancy elements (E21B17/015 takes precedence)}	E21B17/01	E21B17/01		494
E21B17/015	9	{Non-vertical risers, e.g. articulated or catenary-type}	E21B17/01	E21B17/01		430
E21B17/017	9	{Bend restrictors for limiting stress on risers}	E21B17/01	E21B17/01		257
E21B17/02	8	Couplings; joints {(expandable couplings or joints E21B43/106)}	E21B17/02	E21B17/02		1508
E21B17/021	9	{Devices for subsurface connecting or disconnecting by rotation}	E21B17/02	E21B17/02		274
E21B17/023	9	{Arrangements for connecting cables or wirelines to downhole devices}	E21B17/02	E21B17/02		646
E21B17/025	10	{Side entry subs}	E21B17/02	E21B17/02		116
E21B17/026	10	{Arrangements for fixing cables or wirelines to the outside of downhole devices}	E21B17/02	E21B17/02		273
E21B17/028	9	{Electrical or electro-magnetic connections}	E21B17/02	E21B17/02		798
E21B17/0283	10	{characterised by the coupling being contactless, e.g. inductive}	E21B17/02	E21B17/02		269
E21B17/0285	10	{characterised by electrically insulating elements}	E21B17/02	E21B17/02		403
E21B17/03	9	between drilling rod or pipe and drill motor {or surface drive}, e.g. between drilling rod and hammer	E21B17/03	E21B17/03		567
E21B17/04	9	between rod {or the like} and bit or between rod and rod {or the like}	E21B17/04	E21B17/04		1278
E21B17/041	10	{specially adapted for coiled tubing}	E21B17/04	E21B17/04		83
E21B17/042	10	Threaded	E21B17/042	E21B17/042		2789
E21B17/0423	11	{with plural threaded sections, e.g. with two-step threads}	E21B17/042	E21B17/042		311
E21B17/0426	11	{with a threaded cylindrical portion, e.g. for percussion rods}	E21B17/042	E21B17/042		568
E21B17/043	11	with locking means	E21B17/043	E21B17/043		606
E21B17/046	10	with ribs, pins, or jaws, and complementary grooves or the like, e.g. bayonet catches	E21B17/046	E21B17/046		1508
E21B17/0465	11	{characterised by radially inserted locking elements}	E21B17/046	E21B17/046		341
E21B17/05	10	Swivel joints	E21B17/05	E21B17/05		544
E21B17/06	10	Releasing-joints, e.g. safety joints	E21B17/06	E21B17/06		954
E21B17/07	10	Telescoping joints for varying drill string lengths; Shock absorbers	E21B17/07	E21B17/07		1367
E21B17/073	11	{with axial rotation}	E21B17/07	E21B17/07		209
E21B17/076	11	{between rod or pipe and drill bit}	E21B17/07	E21B17/07		312
E21B17/08	9	Casing joints	E21B17/08	E21B17/08		1223
E21B17/085	10	{Riser connections (connectors for wellhead E21B33/038)}	E21B17/08	E21B17/08		379
E21B17/0853	11	{Connections between sections of riser provided with auxiliary lines, e.g. kill and choke lines}	E21B17/08	E21B17/08		159
E21B17/10	8	Wear protectors; Centralising devices {, e.g. stabilisers}	E21B17/10	E21B17/10		1041
E21B17/1007	9	{for the internal surface of a pipe, e.g. wear bushings for underwater well-heads}	E21B17/10	E21B17/10		242
E21B17/1014	9	{Flexible or expansible centering means, e.g. with pistons pressing against the wall of the well (E21B17/1042 takes precedence)}	E21B17/10	E21B17/10		692
E21B17/1021	10	{with articulated arms or arcuate springs}	E21B17/10	E21B17/10		386
E21B17/1028	11	{with arcuate springs only, e.g. baskets with outwardly bowed strips for cementing operations}	E21B17/10	E21B17/10		379
E21B17/1035	9	{for plural rods, pipes or lines, e.g. for control lines}	E21B17/10	E21B17/10		388
E21B17/1042	9	{Elastomer protector or centering means}	E21B17/10	E21B17/10		454
E21B17/105	10	{split type}	E21B17/10	E21B17/10		217
E21B17/1057	9	{Centralising devices with rollers or with a relatively rotating sleeve (E21B17/1014 takes precedence)}	E21B17/10	E21B17/10		501
E21B17/1064	10	{Pipes or rods with a relatively rotating sleeve}	E21B17/10	E21B17/10		248
E21B17/1071	9	{specially adapted for pump rods, e.g. sucker rods}	E21B17/10	E21B17/10		485
E21B17/1078	9	{Stabilisers or centralisers for casing, tubing or drill pipes (E21B17/1007 - E21B17/1064 take precedence)}	E21B17/10	E21B17/10		2022
E21B17/1085	9	{Wear protectors; Blast joints; Hard facing}	E21B17/10	E21B17/10		820
E21B17/1092	9	{Gauge section of drill bits}	E21B17/10	E21B17/10		245
E21B17/12	9	Devices for placing or drawing out wear protectors	E21B17/12	E21B17/12		144
E21B17/14	8	Casing shoes {for the protection of the bottom of the casing}	E21B17/14	E21B17/14		377
E21B17/16	8	Drill collars	E21B17/16	E21B17/16		454
E21B17/18	8	Pipes provided with plural fluid passages {(E21B17/203 takes precedence)}	E21B17/18	E21B17/18		1104
E21B17/20	8	Flexible or articulated drilling pipes {, e.g. flexible or articulated rods, pipes or cables}	E21B17/20	E21B17/20		1027
E21B17/203	9	{with plural fluid passages}	E21B17/20	E21B17/20		187
E21B17/206	9	{with conductors, e.g. electrical, optical}	E21B17/20	E21B17/20		472
E21B17/22	8	Rods or pipes with helical structure	E21B17/22	E21B17/22		1435
E21B19/00	7	Handling rods, casings, tubes or the like outside the borehole, e.g. in the derrick; Apparatus for feeding the rods or cables	E21B19/00	E21B19/00		1614
E21B19/002	8	{specially adapted for underwater drilling (E21B19/09, E21B19/143 take precedence)}	E21B19/00	E21B19/00		871
E21B19/004	9	{supporting a riser from a drilling or production platform}	E21B19/00	E21B19/00		491
E21B19/006	10	{including heave compensators}	E21B19/00	E21B19/00		457
E21B19/008	8	{Winding units, specially adapted for drilling operations}	E21B19/00	E21B19/00		760
E21B19/02	8	Rod or cable suspensions	E21B19/02	E21B19/02		1001
E21B19/04	9	Hooks	E21B19/04	E21B19/04		209
E21B19/06	9	Elevators, i.e. rod- or tube-gripping devices	E21B19/06	E21B19/06		1316
E21B19/07	10	Slip-type elevators	E21B19/07	E21B19/07		515
E21B19/08	8	Apparatus for feeding the rods or cables (E21B19/22 takes precedence; automatic feed E21B44/02); Apparatus for increasing or decreasing the pressure on the drilling tool; Apparatus for counterbalancing the weight of the rods	E21B19/08	E21B19/08		852
E21B19/081	9	Screw-and-nut feed mechanisms	E21B19/081	E21B19/081		855
E21B19/083	9	Cam, rack or like feed mechanisms	E21B19/083	E21B19/083		294
E21B19/084	9	with flexible drawing means, e.g. cables	E21B19/084	E21B19/084		1245
E21B19/086	9	with a fluid-actuated cylinder (E21B19/084, E21B19/087, E21B19/09 take precedence)	E21B19/086	E21B19/086		1502
E21B19/087	9	by means of a swinging arm	E21B19/087	E21B19/087		361
E21B19/089	9	with a spring or an additional weight	E21B19/089	E21B19/089		71
E21B19/09	9	specially adapted for drilling underwater formations from a floating support using heave compensators supporting the drill string	E21B19/09	E21B19/09		501
E21B19/10	8	Slips; Spiders {; Catching devices (rotary tables with master bushing or kelly bushing E21B3/04)}	E21B19/10	E21B19/10		1966
E21B19/102	9	{using rollers or spherical balls as load gripping elements}	E21B19/10	E21B19/10		69
E21B19/12	8	Rope clamps {; Rod, casings or tube clamps not secured to elevators}	E21B19/12	E21B19/12		292
E21B19/14	8	Racks, ramps, troughs or bins, for holding the lengths of rod singly or connected; Handling between storage place and borehole (E21B19/20, E21B19/22 take precedence)	E21B19/14	E21B19/14		2183
E21B19/143	9	{specially adapted for underwater drilling}	E21B19/14	E21B19/14		276
E21B19/146	9	{Carousel systems, i.e. rotating rack systems}	E21B19/14	E21B19/14		325
E21B19/15	9	Racking of rods in horizontal position; Handling between horizontal and vertical position	E21B19/15	E21B19/15		653
E21B19/155	10	{Handling between horizontal and vertical position}	E21B19/15	E21B19/15		924
E21B19/16	8	Connecting or disconnecting pipe couplings or joints (E21B19/20 takes precedence)	E21B19/16	E21B19/16		2159
E21B19/161	9	{using a wrench or a spinner adapted to engage a circular section of pipe (E21B19/168 takes precedence)}	E21B19/16	E21B19/16		787
E21B19/162	10	{cathead actuated}	E21B19/16	E21B19/16		98
E21B19/163	10	{piston-cylinder actuated}	E21B19/16	E21B19/16		364
E21B19/164	10	{motor actuated (E21B19/162 and E21B19/163 take precedence)}	E21B19/16	E21B19/16		519
E21B19/165	9	{Control or monitoring arrangements therefor}	E21B19/16	E21B19/16		570
E21B19/166	10	{Arrangements of torque limiters or torque indicators}	E21B19/16	E21B19/16		207
E21B19/167	9	{using a wrench adapted to engage a non circular section of pipe, e.g. a section with flats or splines}	E21B19/16	E21B19/16		147
E21B19/168	9	{using a spinner with rollers or a belt adapted to engage a well pipe}	E21B19/16	E21B19/16		154
E21B19/18	8	Connecting or disconnecting drill bit and drilling pipe	E21B19/18	E21B19/18		712
E21B19/20	8	Combined feeding from rack and connecting, e.g. automatically	E21B19/20	E21B19/20		586
E21B19/22	8	Handling reeled pipe or rod units, e.g. flexible drilling pipes {(lifting or hauling appliances using two or more cooperating endless chains B66D3/003)}	E21B19/22	E21B19/22		1668
E21B19/24	8	Guiding or centralising devices for drilling rods or pipes	E21B19/24	E21B19/24		1468
E21B21/00	7	Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor (freeing objects stuck in boreholes by flushing E21B31/03)	E21B21/00	E21B21/00		3242
E21B21/001	8	{specially adapted for underwater drilling (dual gradient drilling E21B21/082)}	E21B21/00	E21B21/00		510
E21B21/002	8	{Down-hole drilling fluid separation systems (containers comprising collecting means with a strainer E21B27/005; subsoil filtering E21B43/02; down-hole production separators E21B43/38)}	E21B21/00	E21B21/00		340
E21B21/003	8	{Means for stopping loss of drilling fluid (plastering the borehole wall E21B33/138)}	E21B21/00	E21B21/00		958
E21B21/01	8	Arrangements for handling drilling fluids or cuttings outside the borehole, e.g. mud boxes	E21B21/01	E21B21/01		1946
E21B21/011	9	{Dust eliminating or dust removing while drilling}	E21B21/01	E21B21/01		250
E21B21/012	10	{using exhaust air from the drilling motor for blowing off the dust at the borehole entrance}	E21B21/01	E21B21/01		47
E21B21/013	10	{by liquids}	E21B21/01	E21B21/01		155
E21B21/0135	11	{Liquid flushing installations}	E21B21/01	E21B21/01		135
E21B21/014	10	{Preventing exhaust air from the drill motor from blowing-off towards the working face}	E21B21/01	E21B21/01		2
E21B21/015	9	Means engaging the bore entrance, e.g. hoods for collecting dust	E21B21/015	E21B21/015		919
E21B21/019	9	{Arrangements for maintaining circulation of drilling fluid while connecting or disconnecting tubular joints}	E21B21/01	E21B21/01		128
E21B21/02	8	Swivel joints in hose-lines	E21B21/02	E21B21/02		472
E21B21/06	8	Arrangements for treating drilling fluids outside the borehole	E21B21/06	E21B21/06		900
E21B21/062	9	{by mixing components}	E21B21/06	E21B21/06		770
E21B21/063	9	{by separating components}	E21B21/06	E21B21/06		386
E21B21/065	10	{Separating solids from drilling fluids}	E21B21/06	E21B21/06		1619
E21B21/066	11	{with further treatment of the solids, e.g. for disposal}	E21B21/06	E21B21/06		802
E21B21/067	10	{Separating gases from drilling fluids}	E21B21/06	E21B21/06		457
E21B21/068	9	{using chemical treatment}	E21B21/06	E21B21/06		383
E21B21/07	9	for treating dust-laden gaseous fluids	E21B21/07	E21B21/07		244
E21B21/08	8	Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure (valve arrangements therefor E21B21/10)	E21B21/08	E21B21/08		2575
E21B21/082	9	{Dual gradient systems, i.e. using two hydrostatic gradients or drilling fluid densities}	E21B21/08	E21B21/08		66
E21B21/085	9	{Underbalanced techniques, i.e. where borehole fluid pressure is below formation pressure}	E21B21/08	E21B21/08		356
E21B21/10	8	Valve arrangements in drilling-fluid circulation systems	E21B21/10	E21B21/10		2131
E21B21/103	9	{Down-hole by-pass valve arrangements, i.e. between the inside of the drill string and the annulus (valves specifically for maintaining circulation of drilling fluid while connecting or disconnecting tubular joints E21B21/019)}	E21B21/10	E21B21/10		872
E21B21/106	9	{Valve arrangements outside the borehole, e.g. kelly valves (valves specifically for maintaining circulation of drilling fluid while connecting or disconnecting tubular joints E21B21/019)}	E21B21/10	E21B21/10		697
E21B21/12	8	using drilling pipes with plural fluid passages, e.g. closed circulation systems	E21B21/12	E21B21/12		943
E21B21/14	8	using liquids and gases, e.g. foams	E21B21/14	E21B21/14		645
E21B21/16	8	using gaseous fluids (E21B21/14 takes precedence)	E21B21/16	E21B21/16		1012
E21B21/18	8	Preventing exhaust air from the drill motor from blowing-off towards the working face	E21B21/18	E21B21/18		5
E21B23/00	7	Apparatus for displacing, setting, locking, releasing or removing tools, packers or the like in boreholes or wells (setting of casings, screens or liners E21B43/10)	E21B23/00	E21B23/00		2336
E21B23/001	8	{Self-propelling systems or apparatus, e.g. for moving tools within the horizontal portion of a borehole}	E21B23/00	E21B23/00		601
E21B23/004	8	{Indexing systems for guiding relative movement between telescoping parts of downhole tools}	E21B23/00	E21B23/00		134
E21B23/006	9	{"J-slot" systems, i.e. lug and slot indexing mechanisms}	E21B23/00	E21B23/00		811
E21B23/01	8	for anchoring the tools or the like (E21B23/02&#160;-&#160;E21B23/06 take precedence; anchoring of drives in the borehole E21B4/18)	E21B23/01	E21B23/01		2436
E21B23/02	8	for locking the tools or the like in landing nipples or in recesses between adjacent sections of tubing (E21B23/03&#160;-&#160;E21B23/06 take precedence)	E21B23/02	E21B23/02		1175
E21B23/03	8	for setting the tools into, or removing the tools from, laterally offset landing nipples or pockets	E21B23/03	E21B23/03		342
E21B23/04	8	operated by fluid means, e.g. actuated by explosion (E21B23/08 takes precedence)	E21B23/04	E21B23/04		569
E21B23/0411	9	{specially adapted for anchoring tools or the like to the borehole wall or to well tube}	E21B23/04	E21B23/04		457
E21B23/04115	10	{using radial pistons}	E21B23/04	E21B23/04		140
E21B23/0412	9	{characterised by pressure chambers, e.g. vacuum chambers}	E21B23/04	E21B23/04		232
E21B23/0413	9	{using means for blocking fluid flow, e.g. drop balls or darts (using balls or the like for actuating downhole valves E21B34/142)}	E21B23/04	E21B23/04		212
E21B23/0414	9	{using explosives}	E21B23/04	E21B23/04		166
E21B23/0415	9	{using particular fluids, e.g. electro-active liquids}	E21B23/04	E21B23/04		76
E21B23/0416	9	{characterised by force amplification arrangements}	E21B23/04	E21B23/04		54
E21B23/0417	9	{Down-hole non-explosive gas generating means, e.g. by chemical reaction}	E21B23/04	E21B23/04		58
E21B23/0418	9	{specially adapted for locking the tools in landing nipples or recesses}	E21B23/04	E21B23/04		82
E21B23/0419	9	{using down-hole motor and pump arrangements for generating hydraulic pressure}	E21B23/04	E21B23/04		214
E21B23/042	9	{using a single piston or multiple mechanically interconnected pistons}	E21B23/04	E21B23/04		699
E21B23/0421	9	{using multiple hydraulically interconnected pistons}	E21B23/04	E21B23/04		64
E21B23/0422	9	{characterised by radial pistons (using radial pistons for anchoring E21B23/04115)}	E21B23/04	E21B23/04		50
E21B23/0423	9	{using step motors}	E21B23/04	E21B23/04		13
E21B23/06	8	for setting packers	E21B23/06	E21B23/06		2001
E21B23/065	9	{setting tool actuated by explosion or gas generating means}	E21B23/06	E21B23/06		214
E21B23/08	8	Introducing or running tools by fluid pressure, e.g. through-the-flow-line tool systems	E21B23/08	E21B23/08		776
E21B23/10	9	Tools specially adapted therefor	E21B23/10	E21B23/10		326
E21B23/12	9	Tool diverters	E21B23/12	E21B23/12		274
E21B23/14	8	for displacing a cable or a cable-operated tool, e.g. for logging or perforating operations in deviated wells	E21B23/14	E21B23/14		1008
E21B25/00	7	Apparatus for obtaining or removing undisturbed cores, e.g. core barrels or core extractors (core bits E21B10/02)	E21B25/00	E21B25/00		1964
E21B25/005	8	{Above ground means for handling the core, e.g. for extracting the core from the core barrel}	E21B25/00	E21B25/00		269
E21B25/02	8	the core receiver being insertable into, or removable from, the borehole without withdrawing the drilling pipe	E21B25/02	E21B25/02		553
E21B25/04	9	the core receiver having a core forming cutting edge or element, e.g. punch type core barrels	E21B25/04	E21B25/04		176
E21B25/06	8	the core receiver having a flexible liner or inflatable retaining means	E21B25/06	E21B25/06		161
E21B25/08	8	Coating, freezing, consolidating cores (E21B25/06 takes precedence); Recovering uncontaminated cores or cores at formation pressure	E21B25/08	E21B25/08		344
E21B25/10	8	Formed core retaining or severing means (E21B25/06, E21B25/08 take precedence)	E21B25/10	E21B25/10		605
E21B25/12	9	of the sliding wedge type	E21B25/12	E21B25/12		87
E21B25/14	9	mounted on pivot transverse to core axis	E21B25/14	E21B25/14		122
E21B25/16	8	for obtaining oriented cores	E21B25/16	E21B25/16		380
E21B25/18	8	the core receiver being specially adapted for operation under water	E21B25/18	E21B25/18		362
E21B27/00	7	Containers for collecting or depositing substances in boreholes or wells, e.g. bailers, {baskets or buckets} for collecting mud or sand; Drill bits with means for collecting substances, e.g. valve drill bits	E21B27/00	E21B27/00		1186
E21B27/005	8	{Collecting means with a strainer}	E21B27/00	E21B27/00		235
E21B27/02	8	Dump bailers, i.e. containers for depositing substances, e.g. cement or acids	E21B27/02	E21B27/02		469
E21B27/04	8	where the collecting or depositing means include helical conveying means	E21B27/04	E21B27/04		172
E21B28/00	7	Vibration generating arrangements for boreholes or wells, e.g. for stimulating production ({for fishing for or freeing objects E21B31/005;} for transmitting measuring-signals E21B47/14; for geophysical measurements G01V1/02)	E21B28/00	E21B28/00		1163
E21B29/00	7	Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground	E21B29/00	E21B29/00		1101
E21B29/002	8	{Cutting, e.g. milling, a pipe with a cutter rotating along the circumference of the pipe}	E21B29/00	E21B29/00		486
E21B29/005	9	{with a radially-expansible cutter rotating inside the pipe, e.g. for cutting an annular window}	E21B29/00	E21B29/00		719
E21B29/007	9	{with a radially-retracting cutter rotating outside the pipe}	E21B29/00	E21B29/00		93
E21B29/02	8	by explosives or by thermal or chemical means {(freeing stuck objects by explosives E21B31/002)}	E21B29/02	E21B29/02		723
E21B29/04	8	Cutting of wire lines or the like (E21B29/02 takes precedence)	E21B29/04	E21B29/04		217
E21B29/06	8	Cutting windows, e.g. directional window cutters for whipstock operations ({E21B29/005 and}E21B29/08 take precedence)	E21B29/06	E21B29/06		769
E21B29/08	8	Cutting or deforming pipes to control fluid flow	E21B29/08	E21B29/08		369
E21B29/10	8	Reconditioning of well casings, e.g. straightening	E21B29/10	E21B29/10		868
E21B29/12	8	specially adapted for underwater installations (E21B29/08 takes precedence)	E21B29/12	E21B29/12		207
E21B31/00	7	Fishing for or freeing objects in boreholes or wells	E21B31/00	E21B31/00		476
E21B31/002	8	{Destroying the objects to be fished, e.g. by explosive means}	E21B31/00	E21B31/00		99
E21B31/005	8	{using vibrating or oscillating means}	E21B31/00	E21B31/00		298
E21B31/007	8	{fishing tools with means for attaching comprising fusing or sticking}	E21B31/00	E21B31/00		36
E21B31/03	8	Freeing by flushing	E21B31/03	E21B31/03		211
E21B31/035	8	{controlling differential pipe sticking}	E21B31/00	E21B31/03		122
E21B31/06	8	using magnetic means	E21B31/06	E21B31/06		254
E21B31/08	8	using junk baskets or the like	E21B31/08	E21B31/08		146
E21B31/107	8	using impact means for releasing stuck parts, e.g. jars	E21B31/107	E21B31/107		643
E21B31/1075	9	{using explosives}	E21B31/107	E21B31/107		52
E21B31/113	9	hydraulically-operated	E21B31/113	E21B31/113		381
E21B31/1135	10	{Jars with a hydraulic impedance mechanism, i.e. a restriction, for initially delaying escape of a restraining fluid}	E21B31/113	E21B31/113		95
E21B31/12	8	Grappling tools, e.g. tongs or grabs	E21B31/12	E21B31/12		412
E21B31/125	9	{specially adapted for parted wire line or ropes}	E21B31/12	E21B31/12		103
E21B31/14	9	with means deflecting the direction of the tool, e.g. by use of knuckle joints	E21B31/14	E21B31/14		61
E21B31/16	9	combined with cutting or destroying means	E21B31/16	E21B31/16		287
E21B31/18	9	gripping externally, e.g. overshot	E21B31/18	E21B31/18		1332
E21B31/20	9	gripping internally, e.g. fishing spears	E21B31/20	E21B31/20		938
E21B33/00	7	Sealing or packing boreholes or wells	E21B33/00	E21B33/00		192
E21B33/02	8	Surface sealing or packing	E21B33/02	E21B33/02		407
E21B33/03	9	Well heads; Setting-up thereof	E21B33/03	E21B33/03		2648
E21B33/035	10	specially adapted for underwater installations (E21B33/043, E21B33/064, E21B33/076 take precedence)	E21B33/035	E21B33/035		1062
E21B33/0353	11	{Horizontal or spool trees, i.e. without production valves in the vertical main bore}	E21B33/035	E21B33/035		141
E21B33/0355	11	{Control systems, e.g. hydraulic, pneumatic, electric, acoustic, for submerged well heads}	E21B33/035	E21B33/035		879
E21B33/037	11	Protective housings therefor	E21B33/037	E21B33/037		276
E21B33/0375	12	{Corrosion protection means}	E21B33/037	E21B33/037		36
E21B33/038	11	Connectors used on well heads, e.g. for connecting blow-out preventer and riser	E21B33/038	E21B33/038		1121
E21B33/0385	12	{electrical connectors}	E21B33/038	E21B33/038		208
E21B33/0387	11	{Hydraulic stab connectors}	E21B33/035	E21B33/038		184
E21B33/04	10	Casing heads; Suspending casings or tubings in well heads	E21B33/04	E21B33/04		1799
E21B33/0407	11	{with a suspended electrical cable}	E21B33/04	E21B33/04		187
E21B33/0415	11	{rotating or floating support for tubing or casing hanger}	E21B33/04	E21B33/04		214
E21B33/0422	11	{a suspended tubing or casing being gripped by a slip or an internally serrated member}	E21B33/04	E21B33/04		455
E21B33/043	11	specially adapted for underwater well heads ({E21B33/0407,}E21B33/047 take precedence)	E21B33/043	E21B33/043		827
E21B33/047	11	for plural tubing strings	E21B33/047	E21B33/047		503
E21B33/05	11	Cementing-heads, e.g. having provision for introducing cementing plugs	E21B33/05	E21B33/05		339
E21B33/06	10	Blow-out preventers {, i.e. apparatus closing around a drill pipe, e.g. annular blow-out preventers (rotating blow-out preventers E21B33/085)}	E21B33/06	E21B33/06		2153
E21B33/061	11	{Ram-type blow-out preventers, e.g. with pivoting rams}	E21B33/06	E21B33/06		228
E21B33/062	12	{with sliding rams}	E21B33/06	E21B33/06		622
E21B33/063	13	{for shearing drill pipes (cutting of wireline E21B29/04)}	E21B33/06	E21B33/06		405
E21B33/064	11	specially adapted for underwater well heads	E21B33/064	E21B33/064		844
E21B33/068	10	having provision for introducing objects or fluids into, or removing objects from, wells (cementing-heads E21B33/05)	E21B33/068	E21B33/068		1112
E21B33/072	11	for cable-operated tools (E21B33/076 takes precedence)	E21B33/072	E21B33/072		422
E21B33/076	11	specially adapted for underwater installations	E21B33/076	E21B33/076		501
E21B33/08	9	Wipers; Oil savers	E21B33/08	E21B33/08		917
E21B33/085	10	{Rotatable packing means, e.g. rotating blow-out preventers}	E21B33/08	E21B33/08		604
E21B33/10	8	in the borehole {(sealing the junction between main bore and laterals E21B41/0042)}	E21B33/10	E21B33/10		624
E21B33/12	9	Packers; Plugs (used for cementing E21B33/134, E21B33/16)	E21B33/12	E21B33/12		3420
E21B33/1204	10	{permanent; drillable}	E21B33/12	E21B33/12		306
E21B33/1208	10	{characterised by the construction of the sealing or packing means (E21B33/1277 takes precedence)}	E21B33/12	E21B33/12		2576
E21B33/1212	11	{including a metal-to-metal seal element}	E21B33/12	E21B33/12		286
E21B33/1216	11	{Anti-extrusion means, e.g. means to prevent cold flow of rubber packing}	E21B33/12	E21B33/12		511
E21B33/122	10	Multiple string packers	E21B33/122	E21B33/122		652
E21B33/124	10	Units with longitudinally-spaced plugs for isolating the intermediate space	E21B33/124	E21B33/124		830
E21B33/1243	11	{with inflatable sleeves}	E21B33/124	E21B33/124		421
E21B33/1246	12	{inflated by down-hole pumping means operated by a pipe string}	E21B33/124	E21B33/124		58
E21B33/126	10	with fluid-pressure-operated elastic cup or skirt (E21B33/122, E21B33/124 take precedence)	E21B33/126	E21B33/126		855
E21B33/1265	11	{with mechanical slips}	E21B33/126	E21B33/126		208
E21B33/127	10	with inflatable sleeve (E21B33/122, E21B33/124 take precedence)	E21B33/127	E21B33/127		1663
E21B33/1272	11	{inflated by down-hole pumping means operated by a pipe string}	E21B33/127	E21B33/127		54
E21B33/1275	11	{inflated by down-hole pumping means operated by a down-hole drive}	E21B33/127	E21B33/127		119
E21B33/1277	11	{characterised by the construction or fixation of the sleeve}	E21B33/127	E21B33/127		605
E21B33/128	10	with a member expanded radially by axial pressure (E21B33/122, E21B33/124 take precedence)	E21B33/128	E21B33/128		1412
E21B33/1285	11	{by fluid pressure}	E21B33/128	E21B33/128		563
E21B33/129	10	with mechanical slips for hooking into the casing (E21B33/122, E21B33/124 take precedence)	E21B33/129	E21B33/129		875
E21B33/1291	11	{anchor set by wedge or cam in combination with frictional effect, using so-called drag-blocks (E21B33/1295 takes precedence)}	E21B33/129	E21B33/129		373
E21B33/1292	12	{with means for anchoring against downward and upward movement}	E21B33/129	E21B33/129		291
E21B33/1293	11	{with means for anchoring against downward and upward movement (E21B33/1291, E21B33/1295 take precedence)}	E21B33/129	E21B33/129		535
E21B33/1294	11	{characterised by a valve, e.g. a by-pass valve}	E21B33/129	E21B33/129		448
E21B33/1295	11	actuated by fluid pressure	E21B33/1295	E21B33/1295		665
E21B33/12955	12	{using drag blocks frictionally engaging the inner wall of the well}	E21B33/1295	E21B33/1295		117
E21B33/13	9	Methods or devices for cementing, for plugging holes, crevices or the like	E21B33/13	E21B33/13		6465
E21B33/134	10	Bridging plugs	E21B33/134	E21B33/134		1994
E21B33/136	10	Baskets, e.g. of umbrella type	E21B33/136	E21B33/136		123
E21B33/138	10	Plastering the borehole wall; Injecting into the formation	E21B33/138	E21B33/138		2442
E21B33/14	10	for cementing casings into boreholes	E21B33/14	E21B33/14		2144
E21B33/143	11	{for underwater installations}	E21B33/14	E21B33/14		138
E21B33/146	11	{Stage cementing, i.e. discharging cement from casing at different levels}	E21B33/14	E21B33/14		264
E21B33/16	11	using plugs for isolating cement charge; Plugs therefor {(stage cementing E21B33/146; spacer compositions C09K8/424)}	E21B33/16	E21B33/16		555
E21B33/165	12	{Cementing plugs specially adapted for being released down-hole (cementing heads E21B33/05)}	E21B33/16	E21B33/16		230
E21B33/167	12	{Cementing plugs provided with anti-rotation mechanisms, e.g. for easier drill-out}	E21B33/16	E21B33/16		77
E21B34/00	7	Valve arrangements for boreholes or wells	E21B34/00	E21B34/00		407
E21B34/02	8	in well heads	E21B34/02	E21B34/02		1908
E21B34/025	9	{Chokes or valves in wellheads and sub-sea wellheads for variably regulating fluid flow}	E21B34/02	E21B34/02		510
E21B34/04	9	in underwater well heads	E21B34/04	E21B34/04		610
E21B34/045	10	{adapted to be lowered on a tubular string into position within a blow-out preventer stack, e.g. so-called test trees}	E21B34/04	E21B34/04		144
E21B34/06	8	in wells	E21B34/06	E21B34/06		2895
E21B34/063	9	{Valve or closure with destructible element, e.g. frangible disc (E21B34/103 takes precedence)}	E21B34/06	E21B34/06		1340
E21B34/066	9	{electrically actuated}	E21B34/06	E21B34/06		1053
E21B34/08	9	responsive to flow or pressure of the fluid obtained (E21B34/10 takes precedence)	E21B34/08	E21B34/08		1981
E21B34/085	10	{with time-delay systems, e.g. hydraulic impedance mechanisms}	E21B34/08	E21B34/08		61
E21B34/10	9	operated by control fluid supplied from outside the borehole	E21B34/10	E21B34/10		2183
E21B34/101	10	{with means for equalizing fluid pressure above and below the valve}	E21B34/10	E21B34/10		255
E21B34/102	10	{with means for locking the closing element in open or closed position (E21B34/105 and E21B34/108 take precedence)}	E21B34/10	E21B34/10		498
E21B34/103	11	{with a shear pin}	E21B34/10	E21B34/10		350
E21B34/105	10	{retrievable, e.g. wire line retrievable, i.e. with an element which can be landed into a landing-nipple provided with a passage for control fluid}	E21B34/10	E21B34/10		254
E21B34/106	11	{the retrievable element being a secondary control fluid actuated valve landed into the bore of a first inoperative control fluid actuated valve}	E21B34/10	E21B34/10		85
E21B34/107	11	{the retrievable element being an operating or controlling means retrievable separately from the closure member, e.g. pilot valve landed into a side pocket (E21B34/106 takes precedence)}	E21B34/10	E21B34/10		48
E21B34/108	10	{with time delay systems, e.g. hydraulic impedance mechanisms}	E21B34/10	E21B34/10		155
E21B34/12	9	operated by movement of casings or tubings	E21B34/12	E21B34/12		908
E21B34/125	10	{with time delay systems, e.g. hydraulic impedance mechanisms}	E21B34/12	E21B34/12		46
E21B34/14	9	operated by movement of tools, e.g. sleeve valves operated by pistons or wire line tools {(E21B34/066 takes precedence)}	E21B34/14	E21B34/14		2304
E21B34/142	10	{unsupported or free-falling elements, e.g. balls, plugs, darts or pistons}	E21B34/14	E21B34/14		1288
E21B34/16	8	Control means therefor being outside the borehole {(control systems for submerged well heads E21B33/0355)}	E21B34/16	E21B34/16		1152
E21B35/00	7	Methods or apparatus for preventing or extinguishing fires	E21B35/00	E21B35/00		414
E21B36/00	7	Heating, cooling or insulating arrangements for boreholes or wells, e.g. for use in permafrost zones	E21B36/00	E21B36/00		1015
E21B36/001	8	{Cooling arrangements}	E21B36/00	E21B36/00		588
E21B36/003	8	{Insulating arrangements}	E21B36/00	E21B36/00		587
E21B36/005	8	{Heater surrounding production tube}	E21B36/00	E21B36/00		209
E21B36/006	8	{Combined heating and pumping means}	E21B36/00	E21B36/00		192
E21B36/008	8	{using chemical heat generating means}	E21B36/00	E21B36/00		197
E21B36/02	8	using burners	E21B36/02	E21B36/02		337
E21B36/025	9	{the burners being above ground or outside the bore hole}	E21B36/02	E21B36/02		76
E21B36/04	8	using electrical heaters	E21B36/04	E21B36/04		1238
E21B37/00	7	Methods or apparatus for cleaning boreholes or wells (E21B21/00 takes precedence)	E21B37/00	E21B37/00		2645
E21B37/02	8	Scrapers specially adapted therefor	E21B37/02	E21B37/02		1392
E21B37/04	9	operated by fluid pressure, e.g. free-piston scrapers	E21B37/04	E21B37/04		253
E21B37/045	10	{Free-piston scrapers}	E21B37/04	E21B37/04		55
E21B37/06	8	using chemical means for preventing or limiting {, e.g. eliminating,} the deposition of paraffins or like substances	E21B37/06	E21B37/06		1868
E21B37/08	8	cleaning in situ of down-hole filters, screens, {e.g. casing perforations,} or gravel packs (E21B37/06 takes precedence)	E21B37/08	E21B37/08		755
E21B37/10	8	Well swabs	E21B37/10	E21B37/10		348
E21B40/00	7	Tubing catchers, automatically arresting the fall of oil-well tubing {(preventing small objects from falling into the borehole E21B41/0021)}	E21B40/00	E21B40/00		49
E21B40/001	8	{in the borehole (anchoring tools in the borehole E21B23/01)}	E21B40/00	E21B40/00		108
E21B41/00	7	Equipment or details not covered by groups E21B15/00&#160;-&#160;E21B40/00	E21B41/00	E21B41/00		4515
E21B41/0007	8	{for underwater installations (E21B41/005, E21B41/04, E21B41/06, E21B41/08, E21B41/10 take precedence)}	E21B41/00	E21B41/00		1035
E21B41/0014	9	{Underwater well locating or reentry systems}	E21B41/00	E21B41/00		175
E21B41/0021	8	{Safety devices, e.g. for preventing small objects from falling into the borehole}	E21B41/00	E21B41/00		714
E21B41/0035	8	{Apparatus or methods for multilateral well technology, e.g. for the completion of or workover on wells with one or more lateral branches}	E21B41/00	E21B41/00		657
E21B41/0042	9	{characterised by sealing the junction between a lateral and a main bore}	E21B41/00	E21B41/00		302
E21B41/005	8	{Waste disposal systems}	E21B41/00	E21B41/00		554
E21B41/0057	9	{Disposal of a fluid by injection into a subterranean formation}	E21B41/00	E21B41/00		346
E21B41/0064	10	{Carbon dioxide sequestration (storing fluids in porous layers B65G5/005)}	E21B41/00	E21B41/00		667
E21B41/0071	9	{Adaptation of flares, e.g. arrangements of flares in offshore installations (flares of waste gases or noxious gases F23G7/08)}	E21B41/00	E21B41/00		222
E21B41/0078	8	{Nozzles used in boreholes (drilling by liquid or gas jets E21B7/18; drill bits with nozzles E21B10/60; perforators using direct fluid action E21B43/114; obtaining a slurry of minerals using nozzles E21B43/29)}	E21B41/00	E21B41/00		527
E21B41/0085	8	{Adaptations of electric power generating means for use in boreholes}	E21B41/00	E21B41/00		1206
E21B41/0099	8	{specially adapted for drilling for or production of natural hydrate or clathrate gas reservoirs; Drilling through or monitoring of formations containing gas hydrates or clathrates}	E21B41/00	E21B41/00		801
E21B41/02	8	in situ inhibition of corrosion in boreholes or wells	E21B41/02	E21B41/02		1064
E21B41/04	8	Manipulators for underwater operations, e.g. temporarily connected to well heads	E21B41/04	E21B41/04		506
E21B41/06	8	Work chambers for underwater operations, e.g. temporarily connected to well heads	E21B41/06	E21B41/06		129
E21B41/08	8	Underwater guide bases, e.g. drilling templates; Levelling thereof	E21B41/08	E21B41/08		388
E21B41/10	8	Guide posts, e.g. releasable; Attaching guide lines to underwater guide bases	E21B41/10	E21B41/10		270
E21B43/00	7	Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells (applicable only to water E03B)	E21B43/00	E21B43/00		3494
E21B43/003	8	{Vibrating earth formations}	E21B43/00	E21B43/00		564
E21B43/006	8	{Production of coal-bed methane (E21B43/243 takes precedence)}	E21B43/00	E21B43/00		1785
E21B43/01	8	specially adapted for obtaining from underwater installations	E21B43/01	E21B43/01		2098
E21B43/0107	9	{Connecting of flow lines to offshore structures (E21B43/013 takes precedence)}	E21B43/01	E21B43/01		460
E21B43/0122	9	{Collecting oil or the like from a submerged leakage (cleaning or keeping clear the surface of open water from oil or the like E02B15/04)}	E21B43/01	E21B43/01		551
E21B43/013	9	Connecting a production flow line to an underwater well head	E21B43/013	E21B43/013		559
E21B43/0135	10	{using a pulling cable}	E21B43/013	E21B43/013		193
E21B43/017	9	Production satellite stations, i.e. underwater installations comprising a plurality of satellite well heads connected to a central station	E21B43/017	E21B43/017		432
E21B43/0175	10	{Hydraulic schemes for production manifolds}	E21B43/017	E21B43/017		145
E21B43/02	8	Subsoil filtering	E21B43/02	E21B43/02		266
E21B43/025	9	{Consolidation of loose sand or the like round the wells without excessively decreasing the permeability thereof}	E21B43/02	E21B43/02		371
E21B43/04	9	Gravelling of wells	E21B43/04	E21B43/04		1617
E21B43/045	10	{Crossover tools}	E21B43/04	E21B43/04		362
E21B43/08	9	Screens or liners {(expandable screens or liners E21B43/108)}	E21B43/08	E21B43/08		1488
E21B43/082	10	{Screens comprising porous materials, e.g. prepacked screens}	E21B43/08	E21B43/08		427
E21B43/084	10	{Screens comprising woven materials, e.g. mesh or cloth}	E21B43/08	E21B43/08		340
E21B43/086	10	{Screens with preformed openings, e.g. slotted liners (comprising porous materials E21B43/082)}	E21B43/08	E21B43/08		1377
E21B43/088	10	{Wire screens (comprising porous materials E21B43/082; comprising woven materials E21B43/084)}	E21B43/08	E21B43/08		591
E21B43/10	9	Setting of casings, screens, liners {or the like} in wells	E21B43/10	E21B43/10		1805
E21B43/101	10	{for underwater installations}	E21B43/10	E21B43/10		80
E21B43/103	10	{of expandable casings, screens, liners, or the like}	E21B43/10	E21B43/10		1212
E21B43/105	11	{Expanding tools specially adapted therefor}	E21B43/10	E21B43/10		766
E21B43/106	11	{Couplings or joints therefor}	E21B43/10	E21B43/10		365
E21B43/108	11	{Expandable screens or perforated liners}	E21B43/10	E21B43/10		384
E21B43/11	8	Perforators; Permeators	E21B43/11	E21B43/11		828
E21B43/112	9	Perforators with extendable perforating members, e.g. actuated by fluid means	E21B43/112	E21B43/112		379
E21B43/114	9	Perforators using direct fluid action {on the wall to be perforated}, e.g. abrasive jets	E21B43/114	E21B43/114		676
E21B43/116	9	Gun or shaped-charge perforators	E21B43/116	E21B43/116		1391
E21B43/117	10	Shaped-charge perforators (E21B43/118 takes precedence)	E21B43/117	E21B43/117		1105
E21B43/118	10	characterised by lowering in vertical position and subsequent tilting to operating position	E21B43/118	E21B43/118		78
E21B43/1185	10	Ignition systems	E21B43/1185	E21B43/1185		787
E21B43/11852	11	{hydraulically actuated}	E21B43/1185	E21B43/1185		198
E21B43/11855	11	{mechanically actuated, e.g. by movement of a wireline or a drop-bar (E21B43/11852 takes precedence)}	E21B43/1185	E21B43/1185		123
E21B43/11857	11	{firing indication systems}	E21B43/1185	E21B43/1185		77
E21B43/119	9	Details, e.g. for locating perforating place or direction	E21B43/119	E21B43/119		1236
E21B43/1193	10	{Dropping perforation guns after gun actuation}	E21B43/119	E21B43/119		67
E21B43/1195	10	{Replacement of drilling mud; decrease of undesirable shock waves}	E21B43/119	E21B43/119		146
E21B43/12	8	Methods or apparatus for controlling the flow of the obtained fluid to or in wells (E21B43/25 takes precedence; valve arrangements E21B34/00)	E21B43/12	E21B43/12		3506
E21B43/121	9	{Lifting well fluids (monitoring of down-hole pump systems E21B47/008)}	E21B43/12	E21B43/12		2417
E21B43/122	10	{Gas lift}	E21B43/12	E21B43/12		1060
E21B43/123	11	{Gas lift valves}	E21B43/12	E21B43/12		857
E21B43/1235	12	{characterised by electromagnetic actuation}	E21B43/12	E21B43/12		43
E21B43/124	10	{Adaptation of jet-pump systems}	E21B43/12	E21B43/12		247
E21B43/126	10	{Adaptations of down-hole pump systems powered by drives outside the borehole, e.g. by a rotary or oscillating drive (powered by fluid E21B43/129)}	E21B43/12	E21B43/12		1057
E21B43/127	11	{Adaptations of walking-beam pump systems}	E21B43/12	E21B43/12		1109
E21B43/128	10	{Adaptation of pump systems with down-hole electric drives}	E21B43/12	E21B43/12		2125
E21B43/129	10	{Adaptations of down-hole pump systems powered by fluid supplied from outside the borehole (gas-lift E21B43/122; jet pumps E21B43/124)}	E21B43/12	E21B43/12		421
E21B43/13	10	{specially adapted to dewatering of wells of gas producing reservoirs, e.g. methane producing coal beds}	E21B43/12	E21B43/13		458
E21B43/14	8	Obtaining from a multiple-zone well	E21B43/14	E21B43/14		2657
E21B43/16	8	Enhanced recovery methods for obtaining hydrocarbons	E21B43/16	E21B43/16		5525
E21B43/162	9	{Injecting fluid from longitudinally spaced locations in injection well}	E21B43/16	E21B43/16		316
E21B43/164	9	{Injecting CO2 or carbonated water (in combination with organic material C09K8/594)}	E21B43/16	E21B43/16		2162
E21B43/166	9	{Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium (CO2 injection  E21B43/164; steam injection E21B43/24)}	E21B43/16	E21B43/16		550
E21B43/168	10	{Injecting a gaseous medium}	E21B43/16	E21B43/16		1320
E21B43/17	9	Interconnecting two or more wells by fracturing or otherwise attacking the formation ({E21B43/2405,}E21B43/247 take precedence)	E21B43/17	E21B43/17		299
E21B43/18	9	Repressuring or vacuum methods	E21B43/18	E21B43/18		437
E21B43/20	9	Displacing by water	E21B43/20	E21B43/20		3813
E21B43/24	9	using heat, e.g. steam injection	E21B43/24	E21B43/24		3626
E21B43/2401	10	{by means of electricity}	E21B43/24	E21B43/24		1125
E21B43/2403	10	{by means of nuclear energy}	E21B43/24	E21B43/24		84
E21B43/2405	10	{in association with fracturing or crevice forming processes (E21B43/247 takes precedence)}	E21B43/24	E21B43/24		386
E21B43/2406	10	{Steam assisted gravity drainage [SAGD]}	E21B43/24	E21B43/24		790
E21B43/2408	11	{SAGD in combination with other methods}	E21B43/24	E21B43/24		475
E21B43/241	10	combined with solution mining of non-hydrocarbon minerals, e.g. solvent pyrolysis of oil shale	E21B43/241	E21B43/241		175
E21B43/243	10	Combustion in situ	E21B43/243	E21B43/243		1359
E21B43/247	11	in association with fracturing processes {or crevice forming processes}	E21B43/247	E21B43/247		488
E21B43/248	12	using explosives	E21B43/248	E21B43/248		126
E21B43/25	8	Methods for stimulating production {(by vibrating earth formations E21B43/003)}	E21B43/25	E21B43/25		1342
E21B43/255	9	{including the injection of a gaseous medium as treatment fluid into the formation}	E21B43/25	E21B43/25		189
E21B43/26	9	by forming crevices or fractures	E21B43/26	E21B43/26		10096
E21B43/2605	10	{using gas or liquefied gas}	E21B43/26	E21B43/26		643
E21B43/2607	10	{Surface equipment specially adapted for fracturing operations}	E21B43/26	E21B43/26		2139
E21B43/261	10	{Separate steps of (1) cementing, plugging or consolidating and (2) fracturing or attacking the formation}	E21B43/26	E21B43/26		1036
E21B43/263	10	using explosives	E21B43/263	E21B43/263		812
E21B43/2635	11	{by means of nuclear energy}	E21B43/263	E21B43/263		42
E21B43/267	10	reinforcing fractures by propping	E21B43/267	E21B43/267		4251
E21B43/27	10	by use of eroding chemicals, e.g. acids	E21B43/27	E21B43/27		791
E21B43/28	8	Dissolving minerals other than hydrocarbons, e.g. by an alkaline or acid leaching agent (E21B43/241 takes precedence)	E21B43/28	E21B43/28		880
E21B43/281	9	{using heat}	E21B43/28	E21B43/28		140
E21B43/283	9	{in association with a fracturing process}	E21B43/28	E21B43/28		180
E21B43/285	8	Melting minerals, e.g. sulfur (E21B43/24 takes precedence)	E21B43/285	E21B43/285		110
E21B43/29	8	Obtaining a slurry of minerals, e.g. by using nozzles	E21B43/29	E21B43/29		225
E21B43/292	9	{using steerable or laterally extendable nozzles}	E21B43/29	E21B43/29		51
E21B43/295	8	Gasification of minerals, e.g. for producing mixtures of combustible gases (E21B43/243 takes precedence)	E21B43/295	E21B43/295		704
E21B43/30	8	Specific pattern of wells, e.g. optimising the spacing of wells	E21B43/30	E21B43/30		1427
E21B43/305	9	{comprising at least one inclined or horizontal well}	E21B43/30	E21B43/30		1739
E21B43/32	8	Preventing gas- or water-coning phenomena, i.e. the formation of a conical column of gas or water around wells	E21B43/32	E21B43/32		426
E21B43/34	8	Arrangements for separating materials produced by the well	E21B43/34	E21B43/34		2491
E21B43/35	9	{specially adapted for separating solids (down-hole drilling fluid separation systems E21B21/002; separating solids from drilling fluids E21B21/065)}	E21B43/34	E21B43/35		1119
E21B43/36	9	Underwater separating arrangements (E21B43/38 takes precedence)	E21B43/36	E21B43/36		588
E21B43/38	9	in the well	E21B43/38	E21B43/38		1404
E21B43/385	10	{by reinjecting the separated materials into an earth formation in the same well}	E21B43/38	E21B43/38		333
E21B43/40	9	Separation associated with re-injection of separated materials {(E21B43/385 takes precedence)}	E21B43/40	E21B43/40		935
E21B44/00	7	Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions	E21B44/00	E21B44/00		5582
E21B44/005	8	{Below-ground automatic control systems}	E21B44/00	E21B44/00		727
E21B44/02	8	Automatic control of the tool feed ({E21B44/005,}E21B44/10 take precedence)	E21B44/02	E21B44/02		911
E21B44/04	9	in response to the torque of the drive {; Measuring drilling torque (E21B44/06 takes precedence; measuring stresses in a well bore pipe E21B47/007)}	E21B44/04	E21B44/04		461
E21B44/06	9	in response to the flow or pressure of the motive fluid of the drive	E21B44/06	E21B44/06		327
E21B44/08	9	in response to the amplitude of the movement of the percussion tool, e.g. jump or recoil	E21B44/08	E21B44/08		120
E21B44/10	8	Arrangements for automatic stopping when the tool is lifted from the working face	E21B44/10	E21B44/10		25
E21B45/00	7	Measuring the drilling time or rate of penetration	E21B45/00	E21B45/00		783
E21B47/00	7	Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08)	E21B47/00	E21B47/00		11293
E21B47/001	8	for underwater installation	E21B47/001	E21B47/001		519
E21B47/002	8	by visual inspection	E21B47/002	E21B47/002		1514
E21B47/0025	9	{generating an image of the borehole wall using down-hole measurements, e.g. acoustic or electric}	E21B47/002	E21B47/002		626
E21B47/003	8	Determining well or borehole volumes	E21B47/003	E21B47/003		213
E21B47/005	8	Monitoring or checking of cementation quality or level	E21B47/005	E21B47/005		1211
E21B47/006	8	{Detection of corrosion or deposition of substances}	E21B47/00	E21B47/00		385
E21B47/007	8	Measuring stresses in a pipe string or casing (for locating blocked portions of pipes E21B47/09)	E21B47/007	E21B47/007		865
E21B47/008	8	Monitoring of down-hole pump systems, e.g. for the detection of "pumped-off" conditions	E21B47/008	E21B47/008		888
E21B47/009	9	Monitoring of walking-beam pump systems	E21B47/009	E21B47/009		406
E21B47/01	8	Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like<br><br><u>NOTE</u><br><br>Devices for both supporting and protecting measuring instruments are only classified in E21B47/017	E21B47/01	E21B47/01		1794
E21B47/013	9	Devices specially adapted for supporting measuring instruments on drill bits	E21B47/013	E21B47/013		390
E21B47/017	9	Protecting measuring instruments	E21B47/017	E21B47/017		1788
E21B47/0175	10	{Cooling arrangements}	E21B47/017	E21B47/017		254
E21B47/02	8	Determining slope or direction	E21B47/02	E21B47/02		595
E21B47/022	9	of the borehole, e.g. using geomagnetism	E21B47/022	E21B47/022		2182
E21B47/0224	10	using seismic or acoustic means	E21B47/0224	E21B47/0224		194
E21B47/0228	10	using electromagnetic energy or detectors therefor	E21B47/0228	E21B47/0228		456
E21B47/0232	11	at least one of the energy sources or one of the detectors being located on or above the ground surface	E21B47/0232	E21B47/0232		205
E21B47/0236	10	using a pendulum	E21B47/0236	E21B47/0236		324
E21B47/024	9	of devices in the borehole (determining slope or direction of the borehole E21B47/022)	E21B47/024	E21B47/024		1417
E21B47/026	9	of penetrated ground layers	E21B47/026	E21B47/026		355
E21B47/04	8	Measuring depth or liquid level	E21B47/04	E21B47/04		1706
E21B47/047	9	Liquid level (measuring depth or liquid level using radioactive markers E21B47/053)	E21B47/047	E21B47/047		896
E21B47/053	9	using radioactive markers	E21B47/053	E21B47/053		80
E21B47/06	8	Measuring temperature or pressure	E21B47/06	E21B47/06		6992
E21B47/07	9	Temperature	E21B47/07	E21B47/07		2634
E21B47/08	8	Measuring diameters or related dimensions at the borehole	E21B47/08	E21B47/08		757
E21B47/085	9	using radiant means, e.g. acoustic, radioactive or electromagnetic	E21B47/085	E21B47/085		484
E21B47/09	8	Locating or determining the position of objects in boreholes or wells {, e.g. the position of an extending arm}; Identifying the free or blocked portions of pipes	E21B47/09	E21B47/09		1497
E21B47/092	9	by detecting magnetic anomalies	E21B47/092	E21B47/092		678
E21B47/095	9	by detecting an acoustic anomalies, e.g. using mud-pressure pulses	E21B47/095	E21B47/095		371
E21B47/098	9	using impression packers, e.g. to detect recesses or perforations	E21B47/098	E21B47/098		82
E21B47/10	8	Locating fluid leaks, intrusions or movements	E21B47/10	E21B47/10		2040
E21B47/103	9	using thermal measurements	E21B47/103	E21B47/103		278
E21B47/107	9	using acoustic means	E21B47/107	E21B47/107		746
E21B47/11	9	using tracers; using radioactivity	E21B47/11	E21B47/11		1325
E21B47/111	10	{using radioactivity}	E21B47/11	E21B47/11		244
E21B47/113	9	using electrical indications; using light radiations	E21B47/113	E21B47/113		682
E21B47/114	10	{using light radiation}	E21B47/113	E21B47/11		153
E21B47/117	9	Detecting leaks, e.g. from tubing, by pressure testing	E21B47/117	E21B47/117		844
E21B47/12	8	Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling	E21B47/12	E21B47/12		4037
E21B47/125	9	using earth as an electrical conductor (by electromagnetic energy E21B47/13)	E21B47/125	E21B47/125		154
E21B47/13	9	by electromagnetic energy, e.g. radio frequency	E21B47/13	E21B47/13		2349
E21B47/135	10	using light waves, e.g. infrared or ultraviolet waves	E21B47/135	E21B47/135		1131
E21B47/138	9	{Devices entrained in the flow of well-bore fluid for transmitting data, control or actuation signals}	E21B47/12	E21B47/13		383
E21B47/14	9	using acoustic waves	E21B47/14	E21B47/14		1061
E21B47/16	10	through the drill string or casing {, e.g. by torsional acoustic waves}	E21B47/16	E21B47/16		559
E21B47/18	10	through the well fluid {, e.g. mud pressure pulse telemetry}	E21B47/18	E21B47/18		1488
E21B47/20	11	by modulation of mud waves, e.g. by continuous modulation	E21B47/20	E21B47/20		362
E21B47/22	11	by negative mud pulses using a pressure relieve valve between drill pipe and annulus	E21B47/22	E21B47/22		135
E21B47/24	11	by positive mud pulses using a flow restricting valve within the drill pipe	E21B47/24	E21B47/24		383
E21B47/26	8	Storing data down-hole, e.g. in a memory or on a record carrier	E21B47/26	E21B47/26		677
E21B49/00	7	Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells	E21B49/00	E21B49/00		10634
E21B49/001	8	{specially adapted for underwater installations}	E21B49/00	E21B49/00		254
E21B49/003	8	{by analysing drilling variables or conditions (E21B49/005 takes precedence; systems specially adapted for monitoring a plurality of drilling variables or conditions E21B44/00)}	E21B49/00	E21B49/00		750
E21B49/005	8	{Testing the nature of borehole walls or the formation by using drilling mud or cutting data}	E21B49/00	E21B49/00		1242
E21B49/006	8	{Measuring wall stresses in the borehole}	E21B49/00	E21B49/00		697
E21B49/008	8	{by injection test; by analysing pressure variations in an injection or production test, e.g. for estimating the skin factor (measuring pressure E21B47/06)}	E21B49/00	E21B49/00		811
E21B49/02	8	by mechanically taking samples of the soil	E21B49/02	E21B49/02		1651
E21B49/025	9	{of underwater soil, e.g. with grab devices}	E21B49/02	E21B49/02		121
E21B49/04	9	using explosives in boreholes; using projectiles penetrating the wall	E21B49/04	E21B49/04		106
E21B49/06	9	using side-wall drilling tools {pressing} or scrapers	E21B49/06	E21B49/06		412
E21B49/08	8	Obtaining fluid samples or testing fluids, in boreholes or wells	E21B49/08	E21B49/08		2120
E21B49/081	9	{with down-hole means for trapping a fluid sample (E21B49/10 takes precedence)}	E21B49/08	E21B49/08		719
E21B49/0813	10	{Sampling valve actuated by annulus pressure changes}	E21B49/08	E21B49/08		70
E21B49/0815	10	{Sampling valve actuated by tubing pressure changes}	E21B49/08	E21B49/08		69
E21B49/082	10	{Wire-line fluid samplers (E21B49/083 takes precedence)}	E21B49/08	E21B49/08		326
E21B49/083	10	{Samplers adapted to be lowered into or retrieved from a landing nipple, e.g. for testing a well without removing the drill string}	E21B49/08	E21B49/08		81
E21B49/084	9	{with means for conveying samples through pipe to surface}	E21B49/08	E21B49/08		319
E21B49/086	9	{Withdrawing samples at the surface}	E21B49/08	E21B49/08		362
E21B49/087	9	{Well testing, e.g. testing for reservoir productivity or formation parameters}	E21B49/08	E21B49/08		669
E21B49/0875	10	{determining specific fluid parameters}	E21B49/08	E21B49/08		1095
E21B49/088	10	{combined with sampling}	E21B49/08	E21B49/08		520
E21B49/10	9	using side-wall fluid samplers or testers	E21B49/10	E21B49/10		996
E21B2200/00	7	Special features related to earth drilling for obtaining oil, gas or water	CPCONLY	E21B2200/00		15
E21B2200/01	8	Sealings characterised by their shape	CPCONLY	E21B2200/01		708
E21B2200/02	8	Down-hole chokes or valves for variably regulating fluid flow	CPCONLY	E21B2200/02		478
E21B2200/03	8	Valves operated by gear mechanisms, e.g. rack and pinion mechanisms	CPCONLY	E21B2200/03		81
E21B2200/04	8	Ball valves	CPCONLY	E21B2200/04		1311
E21B2200/05	8	Flapper valves	CPCONLY	E21B2200/05		1175
E21B2200/06	8	Sleeve valves	CPCONLY	E21B2200/06		1727
E21B2200/08	8	Down-hole devices using materials which decompose under well-bore conditions	CPCONLY	E21B2200/08		815
E21B2200/09	8	Detecting, eliminating, preventing liquid slugs in production pipes	CPCONLY	E21B2200/09		102
E21B2200/20	8	Computer models or simulations, e.g. for reservoirs under production, drill bits	CPCONLY	E21B2200/20		3098
E21B2200/22	8	Fuzzy logic, artificial intelligence, neural networks or the like	CPCONLY	E21B2200/22		1521
