E
SECTION E — FIXED CONSTRUCTIONS
  
EARTH DRILLING; MINING
 E21
EARTH DRILLING; MINING
 E21

Note(s)

In this class, the following term is used with the meaning indicated:

  • "drilling" covers boring and vice versa.

 E21B
EARTH DRILLING, e.g. DEEP DRILLING (mining, quarrying E21C; making shafts, driving galleries or tunnels E21D); OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS  [5]
 E21B 1/00 - 
E21B 7/00
Methods or apparatus for drilling
 E21B 1/00
Percussion drilling (drives used in the borehole E21B 4/00)  [3]
 E21B 1/02
·  Surface drives for percussion drilling
 E21B 1/04
·  ·  Devices for reversing the movement of the rod or cable at the surface
 E21B 3/00
Rotary drilling (drives used in the borehole E21B 4/00; rotary drilling machines in general B23B)  [3]
 E21B 3/02
·  Surface drives for rotary drilling
 E21B 3/04
·  ·  Rotary tables
 E21B 3/06
·  ·  ·  Adaptation of rotary draw works to drive rotary tables (connecting or disconnecting couplings or joints E21B 19/16; rope, cable, or chain winding mechanisms, capstans B66D)  [3]
 E21B 4/00
Drives used in the borehole  [3]
 E21B 4/02
·  Fluid rotary type drives (hydraulic turbines for drilling wells F03B 13/02)  [3]
 E21B 4/04
·  Electric drives (E21B 4/12 takes precedence)  [3]
 E21B 4/06
·  Down-hole impacting means, e.g. hammers (percussion drill bits E21B 10/36; boring rams E21B 11/02; releasing-jars E21B 31/107)  [3]
 E21B 4/08
·  ·  impact being obtained by gravity only, e.g. with lost-motion connection  [3]
 E21B 4/10
·  ·  continuous unidirectional rotary motion of shaft or drilling pipe effecting consecutive impacts  [3]
 E21B 4/12
·  ·  Electrically operated hammers  [3]
 E21B 4/14
·  ·  Fluid operated hammers  [3]
 E21B 4/16
·  Plural down-hole drives, e.g. for combined percussion and rotary drilling (E21B 4/10 takes precedence); Drives for multi-bit drilling units  [3]
 E21B 4/18
·  Anchoring in the borehole  [3]
 E21B 4/20
·  combined with surface drive (E21B 4/10 takes precedence)  [3]
 E21B 6/00
Drives for combined percussion and rotary drilling (drives used in the borehole E21B 4/00)  [3]
 E21B 7/00
Special methods or apparatus for drilling
 E21B 7/02
·  Portable drilling rigs, truck- or skid-mounted, with their own drive (portable drilling rigs for use on underwater floors E21B 7/124)
 E21B 7/04
·  Directional drilling (derricks or masts specially adapted therefor E21B 15/04)
 E21B 7/06
·  ·  Deflecting the direction of boreholes
 E21B 7/08
·  ·  ·  Special apparatus for deflecting the boring, e.g. special drill bits, knuckle joints, whipstocks (directional window cutting E21B 29/06; deflecting the direction of fishing tools E21B 31/14)
 E21B 7/10
·  ·  Correction of deflected boreholes
 E21B 7/12
·  Underwater drilling (derricks or masts specially adapted therefor E21B 15/02; telescoping joints E21B 17/07; using heave compensators E21B 19/09)
 E21B 7/124
·  ·  with underwater tool drive prime mover, e.g. portable drilling rigs for use on underwater floors  [3]
 E21B 7/128
·  ·  from floating support with independent underwater anchored guide base  [3]
 E21B 7/132
·  ·  from underwater buoyant support  [3]
 E21B 7/136
·  ·  from non-buoyant support (E21B 7/124 takes precedence)  [3]
 E21B 7/14
·  Drilling by use of heat, e.g. flame drilling
 E21B 7/15
·  ·  of electrically generated heat  [3]
 E21B 7/16
·  Applying separate balls or pellets by the pressure of the drill, so-called shot-drilling
 E21B 7/18
·  Drilling by liquid or gas jets, with or without entrained pellets (E21B 7/14 takes precedence; hydraulic monitors E21C 45/00)  [5]
 E21B 7/20
·  Driving or forcing casings into boreholes, e.g. sinking; Simultaneously drilling and casing boreholes (placing piles E02D 7/00; sinking shafts while moving the lining downwards E21D 1/08)  [3]
 E21B 7/22
·  ·  Surface means for applying alternating rotation movements to the casing  [3]
 E21B 7/24
·  Drilling using vibrating or oscillating means, e.g. out-of-balance masses (percussion drilling E21B 1/00)  [3]
 E21B 7/26
·  Drilling without earth removal, e.g. with self-propelled burrowing devices (down-hole drives E21B 4/00)  [3]
 E21B 7/28
·  Enlarging drilled holes; Counterboring (drill bits for enlarging the borehole E21B 10/26)  [3]
 E21B 10/00 - 
E21B 12/00
Drilling tools
 E21B 10/00
Drill bits (specially adapted for deflecting the direction of boring E21B 7/08; valve drill bits E21B 27/00)  [3]
 E21B 10/02
·  Core bits (characterised by wear resisting parts E21B 10/46; obtaining undisturbed cores E21B 25/00)  [3]
 E21B 10/04
·  ·  with core destroying means  [3]
 E21B 10/06
·  ·  Roller core bits  [3]
 E21B 10/08
·  Roller bits (roller core bits E21B 10/06; with leading portion E21B 10/26; characterised by wear resisting parts E21B 10/46)  [3]
 E21B 10/10
·  ·  with roller axle supported at both ends (with disc cutters E21B 10/12)  [3]
 E21B 10/12
·  ·  with disc cutters  [3]
 E21B 10/14
·  ·  combined with non-rolling cutters other than of leading-portion type  [3]
 E21B 10/16
·  ·  characterised by tooth form or arrangement  [3]
 E21B 10/18
·  ·  characterised by conduits or nozzles for drilling fluids  [3]
 E21B 10/20
·  ·  characterised by detachable or adjustable parts, e.g. legs or axles (cross axle roller bits E21B 10/10)  [3]
 E21B 10/22
·  ·  characterised by bearing or lubricating details (bearings in general F16C; lubricating in general F16N)  [3]
 E21B 10/24
·  ·  ·  by lubricating details  [3]
 E21B 10/26
·  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 E21B 10/40; augers with leading portion E21B 10/44)  [3]
 E21B 10/28
·  ·  with non-expansible roller cutters  [3]
 E21B 10/30
·  ·  ·  Longitudinal axis roller reamers, e.g. reamer stabilisers  [3]
 E21B 10/32
·  ·  with expansible cutting tools  [3]
 E21B 10/34
·  ·  ·  of roller-cutter type  [3]
 E21B 10/36
·  Percussion drill bits (characterised by wear resisting parts E21B 10/46)  [3]
 E21B 10/38
·  ·  characterised by conduits or nozzles for drilling fluids  [3]
 E21B 10/40
·  ·  with leading portion  [3]
 E21B 10/42
·  Fork-type rotary drill bits, e.g. fish tail bits with detachable blades (augers with teeth E21B 10/44; characterised by wear resisting parts E21B 10/54)  [3]
 E21B 10/44
·  Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts (fork-type rotary drill bits E21B 10/42; drilling rods with helical structure E21B 17/22)  [3]
 E21B 10/46
·  characterised by wear resisting parts, e.g. diamond inserts  [3]
 E21B 10/48
·  ·  the bit being of core type  [3]
 E21B 10/50
·  ·  the bit being of roller type  [3]
 E21B 10/52
·  ·  ·  with chisel- or button-type inserts  [3]
 E21B 10/54
·  ·  the bit being of fork type  [3]
 E21B 10/56
·  ·  Button-type inserts (E21B 10/52 takes precedence)  [3]
 E21B 10/58
·  ·  Chisel-type inserts (E21B 10/52, E21B 10/54 take precedence)  [3]
 E21B 10/60
·  characterised by conduits or nozzles for drilling fluids (for roller bits E21B 10/18; for percussion drill bits E21B 10/38)  [3]
 E21B 10/62
·  characterised by parts or cutting elements which are detachable or adjustable (E21B 10/64 takes precedence; for roller bits E21B 10/20; for fork-type rotary drill bits E21B 10/42; for augers E21B 10/44)  [3]
 E21B 10/64
·  characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe (retrievable core receivers E21B 25/02)  [3]
 E21B 10/66
·  ·  the cutting element being movable through the drilling pipe and laterally shiftable  [3]
 E21B 11/00
Other drilling tools
 E21B 11/02
·  Boring rams (percussion drives used in the borehole E21B 4/06; percussion drill bits E21B 10/36)
 E21B 11/04
·  Boring grabs
 E21B 11/06
·  with driven cutting chains or similarly-driven tools
 E21B 12/00
Accessories for drilling tools  [3]
 E21B 12/02
·  Wear indicators  [3]
 E21B 12/04
·  Drill bit protectors  [3]
 E21B 12/06
·  Mechanical cleaning devices  [3]
 E21B 15/00 - 
E21B 41/00
Other equipment or details for drilling; Well equipment or well maintenance
 E21B 15/00
Derricks; Masts
 E21B 15/02
·  specially adapted for underwater drilling (E21B 15/04 takes precedence; floating drilling platforms B63B 35/44; drilling platforms on legs E02B 17/00)  [3]
 E21B 15/04
·  specially adapted for directional drilling, e.g. slant hole rigs  [3]
 E21B 17/00
Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Casings; Tubings (rod couplings in general F16D; tubes or tube couplings in general F16L)
 E21B 17/01
·  Risers (riser connectors E21B 33/038)  [3]
 E21B 17/02
·  Couplings; Joints
 E21B 17/04
·  ·  between rod and bit, or between rod and rod
 E21B 17/042
·  ·  ·  threaded
 E21B 17/043
·  ·  ·  ·  with locking means
 E21B 17/046
·  ·  ·  with ribs, pins, or jaws, and complementary grooves or the like, e.g. bayonet catches
 E21B 17/05
·  ·  ·  Swivel joints
 E21B 17/06
·  ·  ·  Releasing-joints, e.g. safety joints
 E21B 17/07
·  ·  ·  Telescoping joints for varying drill string lengths; Shock absorbers (heave compensators in the derrick E21B 19/09; releasing-jars E21B 31/107)  [3]
 E21B 17/08
·  ·  Casing joints
 E21B 17/10
·  Wear protectors; Centralising devices (drives used in the borehole with anchoring means E21B 4/18)
 E21B 17/12
·  ·  Devices for placing or drawing out wear protectors
 E21B 17/14
·  Casing shoes
 E21B 17/16
·  Drill collars  [3]
 E21B 17/18
·  Pipes provided with plural fluid passages (circulation of drilling fluid by means of such pipes E21B 21/12)  [3]
 E21B 17/20
·  Flexible or articulated drilling pipes  [3]
 E21B 17/22
·  Rods or pipes with helical structure (drill bits with helical conveying portion E21B 10/44)  [3]
 E21B 19/00
Handling rods, casings, tubes or the like outside of the borehole, e.g. in the derrick (surface drives E21B 1/02, E21B 3/02)
 E21B 19/02
·  Rod or cable suspensions (load-engaging elements for hoisting or lowering purposes in general B66C 1/00; crown blocks or pulley blocks B66D; cable guides B66D 1/36)
 E21B 19/04
·  ·  Hooks
 E21B 19/06
·  ·  Elevators, i.e. rod- or tube-gripping devices
 E21B 19/07
·  ·  ·  Slip-type elevators (slips in rotary tables E21B 19/10)
 E21B 19/08
·  Apparatus for feeding the rods or cables (E21B 19/22 takes precedence; hoisting drums B66D); Apparatus for increasing or decreasing the pressure on the drilling tool; Apparatus for counterbalancing the weight of the rods  [3]
 E21B 19/09
·  ·  specially adapted for drilling underwater formations from a floating support using heave compensators supporting the drill string (drilling-pipe telescoping joints E21B 17/07)  [3]
 E21B 19/10
·  Slips; Spiders
 E21B 19/12
·  Rope clamps (rope clamps in general F16G 11/00)
 E21B 19/14
·  Racks, ramps, troughs or bins, for holding the lengths of rod singly or connected; Handling between storage place and borehole (E21B 19/20, E21B 19/22 take precedence)  [3]
 E21B 19/15
·  ·  Racking of rods in horizontal position; Handling between horizontal and vertical position  [3]
 E21B 19/16
·  Connecting or disconnecting pipe couplings or joints (E21B 19/20 takes precedence; pipe wrenches or the like B25B)  [3]
 E21B 19/18
·  Connecting or disconnecting drill bit and drilling pipe  [3]
 E21B 19/20
·  Combined feeding from rack and connecting, e.g. automatically  [3]
 E21B 19/22
·  Handling reeled pipe or rod units, e.g. flexible drilling pipes  [3]
 E21B 21/00
Methods or apparatus for flushing boreholes (freeing objects stuck in boreholes by flushing E21B 31/03; well drilling compositions C09K 7/00; dust eliminating or removing in mining or quarrying E21C 7/00)  [2]
 E21B 21/02
·  Swivel joints in hose lines
 E21B 21/06
·  Arrangements for treating drilling fluids above ground (treating steps per se, see the relevant subclasses)  [3]
 E21B 21/08
·  Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure (valve arrangements therefor E21B 21/10)  [3]
 E21B 21/10
·  Valves arrangements in drilling-fluid circulation systems (valves in general F16K)  [3]
 E21B 21/12
·  using drilling pipes with plural fluid passages, e.g. closed circulation systems (pipes with plural fluid passages E21B 17/18)  [3]
 E21B 21/14
·  using liquid and gaseous fluids, e.g. foams  [3]
 E21B 23/00
Apparatus for displacing, setting, locking, releasing or removing tools, packers or the like in boreholes or wells (setting of casings, screens, or liners E21B 43/10)
 E21B 23/02
·  for locking the tools or the like in landing nipples or in recesses between adjacent sections of tubing (E21B 23/03-E21B 23/06 take precedence)  [3]
 E21B 23/03
·  for setting the tools into, or removing the tools from, laterally offset landing nipples or pockets  [3]
 E21B 23/04
·  operated by fluid means, e.g. actuated by explosion (E21B 23/06, E21B 23/08 take precedence)  [3]
 E21B 23/06
·  for setting packers
 E21B 23/08
·  Introducing or running tools by fluid pressure, e.g. through-the-flow-line tool systems (special provisions on heads therefor E21B 33/068; cementing plugs E21B 33/16; scrapers operated by fluid pressure E21B 37/04)  [3]
 E21B 23/10
·  ·  Tools specially adapted therefor  [3]
 E21B 23/12
·  ·  Tool diverters  [3]
 E21B 25/00
Apparatus for obtaining or removing undisturbed cores, e.g. core barrels, core extractors (core bits E21B 10/02; using explosives or projectiles in boreholes E21B 49/04; side-wall sampling or coring E21B 49/06)
 E21B 25/02
·  the core receiver being insertable into, or removable from, the borehole without withdrawing the drilling pipe (retrievable drill bits E21B 10/64)  [3]
 E21B 25/04
·  ·  the core receiver having a core forming cutting edge or element, e.g. punch type core barrels  [3]
 E21B 25/06
·  the core receiver having a flexible liner or inflatable retaining means  [3]
 E21B 25/08
·  Coating, freezing, consolidating cores (E21B 25/06 takes precedence); Recovering uncontaminated cores or cores at formation pressure  [3]
 E21B 25/10
·  Formed core retaining or severing means (E21B 25/06, E21B 25/08 take precedence)  [3]
 E21B 25/12
·  ·  of the sliding wedge type  [3]
 E21B 25/14
·  ·  mounted on pivot transverse to core axis  [3]
 E21B 25/16
·  for obtaining oriented cores  [3]
 E21B 25/18
·  the core receiver being specially adapted for operation under water  [3]
 E21B 27/00
Bailers (cement bailers E21B 33/132); Valve drill bits
 E21B 29/00
Cutting or destroying pipes, packers, plugs, or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows (perforators E21B 43/11); Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground
 E21B 29/02
·  by explosives or by thermal or chemical means (destroying objects in boreholes or wells by explosives E21B 31/16)
 E21B 29/04
·  Cutting of wire lines or the like (E21B 29/02 takes precedence)  [3]
 E21B 29/06
·  Cutting windows, e.g. directional window cutters for whipstock operations (E21B 29/08 takes precedence; whipstocks E21B 7/08)  [3]
 E21B 29/08
·  Cutting or deforming pipes to control fluid flow (blow-out preventers E21B 33/06)  [3]
 E21B 29/10
·  Reconditioning of well casings, e.g. straightening  [3]
 E21B 29/12
·  specially adapted for underwater installations (E21B 29/08 takes precedence)  [3]
 E21B 31/00
Fishing for or freeing objects in boreholes or wells (provisions on well heads for introducing or removing objects E21B 33/068; locating or determining the position of objects in boreholes or wells E21B 47/09)
 E21B 31/03
·  Freeing by flushing  [3]
 E21B 31/06
·  using magnetic means  [3]
 E21B 31/08
·  using junk baskets or the like  [3]
 E21B 31/107
·  using impact means for releasing stuck parts, e.g. jars (telescoping joints E21B 17/07)  [3]
 E21B 31/113
·  ·  hydraulically operated  [3]
 E21B 31/12
·  Grappling tools, e.g. tongs or grabs
 E21B 31/14
·  ·  with means deflecting the direction of the tool, e.g. by use of knuckle joints (apparatus for deflecting the boring E21B 7/08)  [3]
 E21B 31/16
·  ·  combined with cutting or destroying means (cutting or destroying means per se E21B 29/00)  [3]
 E21B 31/18
·  ·  gripping externally, e.g. overshot  [3]
 E21B 31/20
·  ·  gripping internally, e.g. fishing spears  [3]
 E21B 33/00
Sealing or packing boreholes or wells
 E21B 33/02
·  Surface sealing or packing
 E21B 33/03
·  ·  Well heads; Setting-up thereof (valve arrangements therefor E21B 34/02)
 E21B 33/035
·  ·  ·  specially adapted for underwater installations (E21B 33/043, E21B 33/064, E21B 33/076 take precedence)  [3]
 E21B 33/037
·  ·  ·  ·  Protective housings therefor  [3]
 E21B 33/038
·  ·  ·  ·  Connectors used on well heads, e.g. for connecting blow-out preventer and riser (connecting a production flow line to an underwater well head E21B 43/013)  [3]
 E21B 33/04
·  ·  ·  Casing heads; Suspending casings or tubings in well heads (setting of casings in wells E21B 43/10)
 E21B 33/043
·  ·  ·  ·  specially adapted for underwater well heads (E21B 33/047 takes precedence)  [3]
 E21B 33/047
·  ·  ·  ·  for plural tubing strings  [3]
 E21B 33/05
·  ·  ·  ·  Cementing-heads, e.g. having provision for introducing cementing plugs
 E21B 33/06
·  ·  ·  Blow-out preventers  [3]
 E21B 33/064
·  ·  ·  ·  specially adapted for underwater well heads (connectors therefor E21B 33/038)  [3]
 E21B 33/068
·  ·  ·  having provision for introducing objects or fluids into, or removing objects from, wells (cementing-heads E21B 33/05)  [3]
 E21B 33/072
·  ·  ·  ·  for cable-operated tools (E21B 33/076 takes precedence)  [3]
 E21B 33/076
·  ·  ·  ·  specially adapted for underwater installations  [3]
 E21B 33/08
·  ·  Wipers; Oil savers
 E21B 33/10
·  in the borehole
 E21B 33/12
·  ·  Packers; Plugs (used for cementing E21B 33/134, E21B 33/16)
 E21B 33/122
·  ·  ·  Multiple-string packers
 E21B 33/124
·  ·  ·  Units with longitudinally-spaced plugs for isolating the intermediate space
 E21B 33/126
·  ·  ·  with fluid-pressure-operated elastic cup or skirt (E21B 33/122, E21B 33/124 take precedence)
 E21B 33/127
·  ·  ·  with inflatable sleeve (E21B 33/122, E21B 33/124 take precedence)
 E21B 33/128
·  ·  ·  with a member expanded radially by axial pressure (E21B 33/122, E21B 33/124 take precedence)
 E21B 33/129
·  ·  ·  with mechanical slips for hooking into the casing (E21B 33/122, E21B 33/124 take precedence)
 E21B 33/13
·  ·  Methods or devices for cementing, for plugging holes, crevices, or the like
 E21B 33/132
·  ·  ·  Cement bailers
 E21B 33/134
·  ·  ·  Bridging plugs
 E21B 33/136
·  ·  ·  Baskets, e.g. of umbrella type
 E21B 33/138
·  ·  ·  Plastering the borehole wall; Injecting into the formation
 E21B 33/14
·  ·  ·  for cementing casings into boreholes
 E21B 33/16
·  ·  ·  ·  using plugs for isolating cement charge; Plugs therefor
 E21B 34/00
Valve arrangements for boreholes or wells (in drilling fluid circulation systems E21B 21/10; blow-out preventers E21B 33/06; oil flow regulating apparatus E21B 43/12; valves in general F16K)  [3]
 E21B 34/02
·  in well heads  [3]
 E21B 34/04
·  ·  in underwater well heads  [3]
 E21B 34/06
·  in wells  [3]
 E21B 34/08
·  ·  responsive to flow or pressure of the fluid obtained (E21B 34/10 takes precedence)  [3]
 E21B 34/10
·  ·  operated by control fluid supplied from above ground (above ground control means E21B 34/16)  [3]
 E21B 34/12
·  ·  operated by movement of casings or tubings  [3]
 E21B 34/14
·  ·  operated by movement of tools, e.g. sleeve valves operated by pistons or wire line tools  [3]
 E21B 34/16
·  Above-ground control means therefor  [3]
 E21B 35/00
Methods or apparatus for preventing or extinguishing fires (cutting or deforming pipes to control fluid flow E21B 29/08; controlling flow of fluid to or in wells E21B 43/12; fire fighting in general A62C, A62D)
 E21B 36/00
Heating, cooling, or insulating arrangements for boreholes or wells, e.g. for use in permafrost zones (drilling by use of heat E21B 7/14; secondary recovery methods using heat E21B 43/24)  [3]
 E21B 36/02
·  using burners  [3]
 E21B 36/04
·  using electrical heaters  [3]
 E21B 37/00
Methods or apparatus for cleaning boreholes or wells (E21B 21/00 takes precedence; cleaning pipes in general B08B 9/02)
 E21B 37/02
·  Scrapers specially adapted therefor
 E21B 37/04
·  ·  operated by fluid pressure, e.g. free-piston scrapers (operating other tools by fluid pressure E21B 23/08)  [3]
 E21B 37/06
·  using chemical means for preventing or limiting the deposition of paraffins or like substances  [3]
 E21B 37/08
·  cleaning in situ of down-hole filters, screens, or gravel packs (E21B 37/06 takes precedence)  [3]
 E21B 37/10
·  Well swabs  [3]
 E21B 40/00
Tubing catchers, automatically arresting the fall of oil-well tubing
 E21B 41/00
Equipment or details not covered by groups E21B 15/00-E21B 40/00
 E21B 41/02
·  in situ inhibition of corrosion in boreholes or wells (inhibiting corrosion in general C23F)  [3]
 E21B 41/04
·  Manipulators for underwater operations, e.g. temporarily connected to well heads (manipulators in general B25J)  [3]
 E21B 41/06
·  Work chambers for underwater operations, e.g. temporarily connected to well heads (in general B63C 11/00)  [3]
 E21B 43/00
Obtaining fluids from wells  [3]
 E21B 43/00
Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells (applicable only to water E03B; obtaining oil-bearing deposits or soluble or meltable materials by mining techniques E21C 41/00; pumps F04)
 E21B 43/01
·  specially adapted for obtaining from underwater installations (underwater well heads E21B 33/035)
 E21B 43/013
·  ·  Connecting a production flow line to an underwater well head  [3]
 E21B 43/017
·  ·  Production satellite stations, i.e. underwater installations comprising a plurality of satellite well heads connected to a central station (underwater separating arrangements E21B 43/36)  [3]
 E21B 43/02
·  Subsoil filtering (E21B 43/11 takes precedence)
 E21B 43/04
·  ·  Gravelling of wells
 E21B 43/08
·  ·  Screens or liners
 E21B 43/10
·  ·  Setting of casings, screens or liners in wells (driving or forcing casings into boreholes, simultaneously drilling and casing boreholes E21B 7/20; setting of tools, packers or the like E21B 23/00; suspending casings in well heads E21B 33/04)
 E21B 43/11
·  Perforators; Permeators
 E21B 43/112
·  ·  Perforators with extendable perforating members, e.g. actuated by fluid means
 E21B 43/114
·  ·  Perforators using direct fluid action, e.g. abrasive jets
 E21B 43/116
·  ·  Gun or shaped-charge perforators
 E21B 43/117
·  ·  ·  Shaped-charge perforators (E21B 43/118 takes precedence)
 E21B 43/118
·  ·  ·  characterised by lowering in vertical position and subsequent tilting to operating position
 E21B 43/1185
·  ·  ·  Ignition systems  [3]
 E21B 43/119
·  ·  Details, e.g. for locating perforating place or direction
 E21B 43/12
·  Methods or apparatus for controlling the flow of the obtained fluid to or in wells (E21B 43/25 takes precedence; valve arrangements E21B 34/00)
 E21B 43/14
·  Obtaining from a multiple-zone well
 E21B 43/16
·  Enhanced recovery methods for obtaining hydrocarbons (fracturing per se E21B 43/26; obtaining slurry E21B 43/29)
 E21B 43/17
·  ·  Interconnecting two or more wells by fracturing or otherwise attacking the formation (E21B 43/247 takes precedence)  [3]
 E21B 43/18
·  ·  Repressuring or vacuum methods
 E21B 43/20
·  ·  Displacing by water
 E21B 43/22
·  ·  Use of chemicals or bacterial activity (E21B 43/27 takes precedence; chemical features in extracting oils from oil sands or shales C10G)
 E21B 43/24
·  ·  using heat, e.g. steam injection (heating, cooling or insulating wells E21B 36/00)
 E21B 43/241
·  ·  ·  combined with solution mining of non-hydrocarbon minerals, e.g. solvent pyrolysis of oil shale  [5]
 E21B 43/243
·  ·  ·  Combustion in situ  [3]
 E21B 43/247
·  ·  ·  ·  in association with fracturing processes  [3]
 E21B 43/248
·  ·  ·  ·  ·  using explosives  [5]
 E21B 43/25
·  Methods for stimulating production
 E21B 43/26
·  ·  by forming crevices or fractures
 E21B 43/263
·  ·  ·  using explosives  [3]
 E21B 43/267
·  ·  ·  reinforcing fractures by propping  [3]
 E21B 43/27
·  ·  ·  by use of eroding chemicals, e.g. acids
 E21B 43/28
·  Dissolving minerals other than hydrocarbons, e.g. by an alkaline or acid leaching agent (E21B 43/241 takes precedence)  [5]
 E21B 43/285
·  Melting minerals, e.g. sulfur (E21B 43/24 takes precedence; heating, cooling or insulating arrangements for wells E21B 36/00)  [5]
 E21B 43/29
·  Obtaining a slurry of minerals, e.g. by using nozzles  [5]
 E21B 43/295
·  Gasification of minerals, e.g. for producing mixtures of combustible gases (E21B 43/243 takes precedence)  [5]
 E21B 43/30
·  Specific pattern of wells, e.g. optimizing the spacing of wells (production satellite stations E21B 43/017)  [3]
 E21B 43/32
·  Preventing gas- or water-coning phenomena, i.e. the formation of a conical column of gas or water around wells  [3]
 E21B 43/34
·  Arrangements for separating materials produced by the well (separating apparatus per se, see the relevant subclasses)  [3]
 E21B 43/36
·  ·  Underwater separating arrangements (E21B 43/38 takes precedence)  [3]
 E21B 43/38
·  ·  in the well  [3]
 E21B 43/40
·  ·  Separation associated with re-injection of separated materials  [3]
 E21B 44/00
Automatic control; Surveying or testing  [3]
 E21B 44/00
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 (for non-automatic drilling control, see the operation controlled; automatic feeding from rack and connecting of drilling pipes E21B 19/20; controlling pressure or flow of drilling fluid E21B 21/08; control systems in general G05); Systems specially adapted for monitoring a plurality of drilling variables or conditions (means for transmitting measuring-signals from the well to the surface E21B 47/12)  [3]
 E21B 45/00 - 
E21B 49/00
Surveying or testing
 E21B 45/00
Measuring the drilling time or rate of penetration
 E21B 47/00
Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B 21/08; geophysical logging G01V)
 E21B 47/02
·  Determining slope or direction (clinometers or direction meters G01C)
 E21B 47/022
·  ·  of the borehole
 E21B 47/024
·  ·  of devices in the borehole (E21B 47/022 takes precedence)
 E21B 47/026
·  ·  of penetrated ground layers (apparatus for obtaining oriented cores E21B 25/16; formation testing E21B 49/00)
 E21B 47/04
·  Measuring depth or liquid level (measuring liquid level in general G01F)
 E21B 47/06
·  Measuring temperature or pressure (measuring temperature in general G01K; measuring pressure in general G01L)
 E21B 47/08
·  Measuring diameter (measuring diameter in general G01B)
 E21B 47/09
·  Locating or determining the position of objects in boreholes or wells; Identifying the free or blocked portions of pipes (measuring depth E21B 47/04; measuring diameter E21B 47/08)  [3]
 E21B 47/10
·  Locating fluid leaks, intrusions, or movements
 E21B 47/12
·  Means for transmitting measuring-signals from the well to the surface, e.g. logging while drilling (remote indicating in general G01D, G08)
 E21B 49/00
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 (sampling in general G01N 1/00)
 E21B 49/02
·  by mechanically taking samples of the soil (apparatus for obtaining undisturbed cores E21B 25/00; investigation of foundation soil in situ E02D 1/00)
 E21B 49/04
·  ·  using explosives in boreholes; using projectiles penetrating the wall  [3]
 E21B 49/06
·  ·  using side-wall drilling tools or scrapers
 E21B 49/08
·  Obtaining fluid samples or testing fluids, in boreholes or wells  [3]
 E21B 49/10
·  ·  using side-wall fluid samplers or testers  [3]