| Drilling Definitions Balling Formation Rock or formations that, when drilled, produce cuttings and sludge, which tend to collect on, and adhere to, the boreholes walls and drill-stem equipment in sticky or gummy masses. Ball Valve A device allowing liquids to flow unimpeded in one direction, consisting of a ball or sphere of steel or other suitable material held against a circular opening of smaller diameter than the ball by gravity or a spring. When liquid flow is from the direction of the ball toward the opening, the ball is forced against the seat and seals the opening. If flow is from the opening toward the sphere, the ball is pushed away from the opening allowing the liquid to pass. Basket Core Lifter A type of core lifter consisting of several finger like springs brazed or riveted to a smooth-surface ring having an inside diameter slightly larger than the core size being cut. Also called Basket. Basket lifter, Finger lifter. Bell Tap A cylindrical fishing tool having an upward-tapered inside surface provided with hardened threads. When slipped over the upper end of lost, cylindrical, down hole drilling equipment and turned, the threaded inside surface of the bell tap cuts into and grips the outside surface of the lost equipment. Also called Bell, Bell screw. Bell socket, Box bell, Die, Die collar, Die nipple. B.H. Abbr. Commonly used for Blast hole and/or boreholes. Bit Any device that may be attached to, or is, an integral part of a drill string and is used as a cutting tool to bore into or penetrate rock or other materials by utilizing power applied to the bit percussively or by rotation. Bit Clearance Technically, the difference between the outside diameter of a set bit and the outside set diameter of the reaming shell. Loosely, the term is used to denote the clearing action of a bit, which is a function of the waterways and the mode in which the diamonds or other cutting media are set in the cutting face of the bit, and also the difference between the outside set diameter of a bit and outside diameter of the bit shank. Incorrectly and loosely used as a synonym for Diamond exposure. See Diamond exposure. Bit Cost Bit-use cost generally expressed in monetary units per foot or per hundred feet of boreholes drilled. For a specific diamond bit the bit cost per foot drilled usually is calculated in the manner shown as follows: (R-S)Z-(CO+BL+ST-SC) =X Y Where R=Diamonds in original bit, in carats S=Reset table diamond salvaged, in carats z=Diamond cost per carat, in dollars CO=Cut-out charge, in dollars BL=Cost of bit blank in dollars ST=Setting charge in dollars SC=Credit value of scrap diamonds in dollars Y=Number of feet drilled X=Bit costs in dollars, per foot drilled Bit Face That part of the bit crown that comes in contact with the bottom of a bore hole. It does not include that part of the bit crown that contacts the walls of the bore hole. Bit Gage The inside and/or outside diameter of a set bit; also, a tool or device used to measure such diameters. Compare Gage ring. Bit Life The average number of feet a bore hole type bit may be expected to drill in a specific type of rock under normal operating or specified conditions. Bit load The weight or pressure applied to a bit in drilling operations expressed as the number of pounds or tons of weight applied. Also called Bit pressure, Bit weight, Drilling pressure, Drilling weight, Drill pressure. Bit Performance The achievement of a bit is gauged by the overall cost of using a specific bit per a unit measure of bore hole drilling, or by the total number of feet of bore hole is drilled per bit. Bit Shank The treaded part of a bit. Sometime incorrectly used as a synonym for Bit blank. Bit Speed The number of revolutions a bit is rotated per minute. A term sometimes incorrectly used to express the number of bit revolutions required to advance the bit 1 inch with a screw-feed diamond-drill machine. Bit Thrust The hydraulic pressure applied to a drill bit when drilling, as shown in pounds per square inch by the pressure gages on the hydraulic-feed cylinders of a diamond drill or the total pressure in pounds as calculated by multiplying the recorded hydraulic pressure by the square-inch area of the piston in the hydraulic-feed cylinder. Also called Drilling thrust. Bit Wall The portion of a bit between the crown and the shank of the bit. Bit weight Total weight, in carats, of the diamonds set in a diamond bit. Weight or load applied to a diamond bit during drilling operation. See Bit load. Blank Reaming Shell A reaming shell in which no reaming diamonds or the cutting media are inset on the outside surface. Block The wedging of core or core fragments or the impaction of cuttings inside a bit or core barrel, which prevents further entry of core into the core barrel, thereby producing a condition wherein drilling must be discontinued and the core barrel pulled and emptied to forestall loss of core through grinding or the serious damage of the bit or core barrel. Also called Core block. Sell also Grind 1. An obstruction in a bore hole. A grooved pulley or sheave encased in a frame shell, which is provided with a hook, eye, clevis, or strap by which it may be attached to an object. It is used to change the direction of a pull applied by a rope or cable, or, when used in pairs, to exert increased force. Blocks are classed as single, double, triple, etc., according to the number of pulleys contained in a single shell. A sheave. Bore hole survey The process of determining the course of, and the target point reached by a bore hole, using one of the several different azimuth and dip-recording apparatuses small enough to be lowered into a bore hole; also the record of the information thereby obtained. Also called drill-hole survey. The process of determining the mineralogical, structural, or physical characteristics of the formation penetrated by a bore hole using electrical logging apparatus small enough to be lowered in to a bore hole; Bottom Discharge Bit Face discharge bit, q.v. Box The internal-threaded portion of a coupling or connector. The accepted standard synonym for Female thread. Core tray. To place core samples in a lidded, tray like, partitioned container for safekeeping after they have been removed from the core barrel; also, the container in which core samples are placed after they have been removed from a core barrel. Also called Core box, To drill boreholes at the four corners of a square area at equal distances from a centrally located and already completed bore hole. Box Thread The thread on the inside surface of a coupling or tubular connector. Accepted as the standard term to be used in lieu of Female thread. Box-Thread Bit A bit having threads on the inside of the upper end or shank of the bit by means of which the bit may be couple to reaming shell, core barrel, or drill rod. Box to Box The two internal-threaded ends of a sub, coupling, or tubular connector piece. See Box 1. Box To Pin The internal-and external-threaded ends of a sub, coupling, or tubular connector piece. Break To unscrew, as rods, casing, drill pipe, etc. To separate core where it is attached to rock at the bottom of a bore hole by a tensional pull applied to the drill string. A fault, rupture, fracture, or discontinuity in rock formations. Break Out To pull drill rods or casing from a bore hole and unscrew them at points where they are joined by threaded coupling to form lengths that can be stacked in the drill tripod or derrick. Breakout Tongs A heavy wrench, usually mechanically actuated, used to couple or uncouple drill rod, drill pipe, casing, or drive pipe. Also called Makeup tongs. Compare Chain tongs. Broken Ground A shattered rock formation, or a formation crisscrossed with numerous, closely spaced, non-cemented joints and cracks. Rock or mineral formation fragmented by blasting with explosives, such as the broken material in a shrinkage stope. Burn To permit a bit to become overheated in use. Burn In To run a bit with too little coolant until the heat generated by the bit fuses the cuttings, core, bit, and the bottom of the bore hole. To deliberately run a bit with reduced amount of coolant until core is jammed inside the bit. See Bry block. Burn Bit A bit that has been overheated and sometimes partially fused. See Burn in. Bypass To pass to the side of an obstruction in a bore hole by deflecting the hole. Also called Drill by. A pipe passing around a valve to prevent complete stoppage of the flow of a gas or liquid when the valve is closed. Cable Clamp A U-shaped steel rod with threaded ends and a bar with nuts, provided to clamp over two or more cylindrical pieces to bind them together, as the overlapped ends of two wire ropes. Also called Cable clip, Clamp, Clip. Cable Speed Rate, measured in feet per minute (f.p.m.), at which a cable, under a load, may be wound on a hoist drum. Also called Hoist speed, Line speed, Rope speed. Capacity As applied to diamond and rotary drills, the load that the hoisting and braking mechanisms of a drill are capable of handling on a single line, expressed in lineal footage of a specific-diameter drill rod. As applied to pumps, the volume of a liquid the pump will deliver, expressed in gallons per minute (g.p.m). Carbide Either the carbide compound of tungsten or the bit-crown matrices and shaped pieces formed by the pressure-molding and centering of a mixture of powdered tungsten carbide and there binder metals, such as cobalt, copper, iron and nickel. Carbide Insert Shaped pieces of a hard metal compound, sometimes inset with diamonds, formed by the pressure molding and centering of a mixture powdered tungsten carbide and other binder metals, such as iron, copper, cobalt, or nickel. Inset into holes, slots or grooves in bits, reaming shells, or core barrels, the hard metal pieces become cutting points or wear-resistant surfaces. Also called Carbide slugs. Compare Carbide. Case To line a bore hole with steel tubing such as casing or pipe. Casing Special steel tubing welded or screwed together and lowered into a bore hole to prevent entry of loose rock, gas, or liquid into the bore hole or to prevent loss of circulation liquid into porous, cavernous, or crevassed ground. Process of inserting casing in a bore hole. Casing Clamp A mechanical device designed to facilitate the hoisting or suspension of casing in a bore hole. Made by forming a half circle in a heavy steel bar. When bolted together, in pairs, the bars fit around the outside and tightly grip the casing. Size of clamp is determined by outside diameter of the casing to be handled. Casing Cutter A tool used to cut off a length of casing in a bore hole at any desired point below the collar of the bore hole. Casing Off Process of inserting a line of casing in a bore hole. See Case. Casing Puller A screw or hydraulic jack used to pull casing or drill rods stuck in a bore hole. Casing Shoe A steel sleeve threaded to fit and be coupled to the bottom end of diamond-drill casing as a cutting head and protector when the casing is driven through overburden. The inside diameter of a specific letter named range casing shoe (whether plain or inset with diamonds or other cutting media) is always large enough to permit other down hole drill fittings having the same letter named range designation to be run inside and through the casing shoe. When a casing shoe is set with diamonds or other cutting media it is called a Set casing shoe, which should not be confused with Casing bit. Also called Casing drive shoe. Compare Casing bit. Set casing shoe. Cat head A small, deep-flanged, spool like winch or capstan mounted on the counter shaft of the draw works or hoisting drum near the front and generally to one side of the swivel head of a diamond drill. It is used to wind a line when breaking or making up rod, casing, or pipe joints, or to operate a drive hammer. Also called Slip Rope Drum. Colloquial synonym for drum of the drill hoist. A small capstan Cave Fragmented rock materials, derived from the side-walls of a bore hole, that obstruct the hole or hinder drilling progress. The partial or complete failure of bore hole sidewalls or mine workings A naturally formed underground cavity. Chain Tongs A steel bar fitted with serrated end provided with a sprocket chain to embrace the pipe used by drillers to couple and uncouple drive pipe or casing. Also called Chain wrench, Pipe tongs. Chatter Rapid vibrations caused by overfeeding the bit and/or by drill rods rubbing against sidewalls of bore hole. Chatter Mark Spiral or flute like, round-topped ridge, sometimes seen on outside surface of core. Some drillers claim that such spiral ridges are formed when bit and drill stem chatter or vibrate or when the bit has been overfed. One of a series of short, curved gauge marks on a glaciated rock surface. Check Valve Generally a ball-type valve device placed in core barrels, soil samplers, or drill rods to control the directional flow of liquids. When used on a core barrel, the check blocks the downward flow of the circulation liquid through the inner tube. When used on a rod string, it blocks the upward flow of the circulation liquid through the rods. Any device that permits a liquid or gas to pass in one direction but automatically closes when the flow is stopped or reversed. Chuck The part of a diamond or rotary drill that grips and holds the drill rods or kelly and by means of which longitudinal and/or rotational movements are transmitted to the drill rods or kelly. The part of a rock-drill machine that grips or holds the drill rod or steel. Chuck Screw A set screw in the periphery of a diamond-drill chuck body by means of which a serrated jaw within the body of the chuck may be made to grip and hold the drill rod. Also called chuck bolt, Chuck nut. Circulating Fluid A fluid pumped into a bore hole through the drill stem, the flow of which cools the bit, washes away the cuttings from the bit, and transports the cuttings out of the bore hole. Circulation Velocity The speed, generally expressed in lineal feet per second, at which a fluid or gas travels upward in a bore hole after passing the face of the bit. Circulation Volume The amount of liquid or gas circulated through the drill-string equipment in drilling a bore hole. The amount of liquid circulated is expressed in gallons per minute (g.p.m.), and the amount of a gas, as air, is expressed in cubic feet per minute (c.f.m.). Clamp A device to grip and hold in position a piece or part or hold together two or more parts, usually with jaws or checks, at least one of which is movable. Also incorrectly called clip. Compare Cable clamp. Clevis A U-or stirrup-shaped steel piece with the holes in the end of each arm through which a bolt connects, thus forming a link. Used as a connecting link between chains or lines or to hang a sheave in a drill tripod or derrick. Collar The mouth or opening of a bore hole or the process of starting to drill a bore hole. A pipe coupling or sleeve. The mouth of a mine shaft. Collaring The process of beginning the drilling of a bore hole. The process of beginning the excavation of a mine shaft or the drilling of rock-drill holes. Condition The Hole To circulate a higher than normal volume of drill fluid while slowly rotating and lowering the drill string from a point a few feet above the bottom to the bottom of the bore hole to wash away obstructing materials before resuming coring operations. Coolant Any medium, such as air, water, gas, oil, mud etc., used as a circulation medium in drilling operations. A cooling agent, such as a liquid applied to the edge of a cutting tool to absorb and carry off frictional heat. Core A cylindrical sample of rock and/or the process of cutting such a sample by use of an annular (hollow) drill bit. Sometimes incorrectly called Bit core. The central portion of a bit mold, that forms the inside diameter of the bit. A cone or inverted V-shaped stub of rock left in bottom of a drill hole by a cone nonscoring bit. Compare Stand off. The central part of a rope or cable that forms a cushion for the strands. Core Barrel A length of tubing, usually 10 feet long, designed to form the coupling unit between the core bit and reaming shell and the drill-rod string. It carries or contains the core produced until the core can be raised to the surface. The barrels can be single, double or triple tube and of swivel or rigid type. Core-Barrel Head The coupling unit between the tubular body of a core barrel and the drill-rod string. For the swivel-type double-tube core barrel, the core-barrel head also contains the bearing mechanism to which the inner of the two body tubes is attached. Core Bit An annular-shaped bit designed to cut a core sample of rock in boreholes. The cutting points may be serration's, diamonds, or other hard substances inset in the face of the bit. Core Block An obstructions inside a bit, reaming shell, or core barrel consisting of impacted core fragments or drill cuttings, which prevents entry of core into the core barrel. Core Box A lidded wood, metal, or cardboard container designed to hold core in parallel grooves. Core Drill A mechanism designed to rotate and cause an annular-shaped rock-cutting bit to penetrate rock formation, produce cylindrical cores of the formations penetrated, and lift such cores to the surface, where they may be collected and examined. See Diamond drill. The act or process of producing a cylindrical core of rock, using a core-drilling machine and equipment. Core Drilling Process of obtaining cylindrical rock samples by means of annular-shaped rock-cutting bits rotated by a bore hole-drilling machine. Core Exposure Length of core that is subjected to washing action of circulation medium when exposed between the bit face and lower end of the inner tube of a core barrel or core-barrel extension. Core Lifter A name for a split, fluted ring of spring steel used in a core-barrel assembly to hold and retain core while the core is being hoisted from a bore hole. Other types sometimes used are: Basket, finger, and Sliding wedge. Also called Core catcher, Core grabber, Core gripper, Core spring, Ring lifter, Spring lifter, Split ring lifter. Core-Lifter Case Lifter case, q.v. Core Picker A core-fishing device consisting of a tube fitted internally at its lower end with flat, flexible spring fingers that permit core to enter the tube but close when the device is hoisted from the bore hole, preventing its escape. Also called Basket, Core basket, Core extractor, Core fisher, Core grabber. Core lifter, q.v. Core Pusher A piston type device for extracting the core from the core barrel tube. Core Recovery Core withdrawn from a bore hole. The amount withdrawn generally is expressed as a percentage of the theoretical total obtainable or in general terms, as excellent, good, fair, or poor. Core Splitter Tool employing a chisel to split core longitudinally in half, rarely in quarter, sections. One half usually is assayed, and the other half is retained and stored. Term also may be applied to a diamond saw used for the same purpose. Core Spring Core lifter, q.v. Core-Spring Adapter Core-lifter adapter, q.v. Core-Spring Carrier Lifter case, q.v. Crown As used by the drilling and bit-setting industries, the portion of the bit inset or impregnated with diamonds formed by casting or pressure-molding and centering processes; hence the steel bit blank to which the crown is attached is not considered part of the crown. Used in some countries as a synonym for Bit. Crown Block A pulley, set of pulleys, or sheaves at the top of a drill derrick on and over which the hoist and/or other lines run. Also called Crown pulley. Crown wheel. Crystal The regular solid geometric form assumed by a crystallized chemical element of compound, such as the dodecahedral, octahedral, cuboid, or other shapes assumed by a diamond. A clear, flawless diamond. Cutting Face That part of a bit containing the cutting points, excluding the points inset as reamers. Cuttings The particles of rock produced in a bore hole by the abrasive or percussive action of a drill bit; excess material caused by the rubbing of core against core or core against steel; erosive effect of the circulating liquid; or cavings from the bore hole. Also called Borings, Drill cuttings, Drilling, Sludge. DCDMA Abbr. Diamond Core Drill Manufacturers Association. A group of drilling-equipment manufacturers associated for the purpose of standardizing drill equipment and fittings in the United States. Dead End The end of a drilling line or cable made fast to some stationary part of the drill rig or to a dead man. The closed end of a pipe or pipe system. An unventilated underground mine passage extending some distance beyond other mine workings into solid rock. Dead man A buried log, timber, concrete block, or the like serving as an anchor for a guide line or a deadline, or as an anchor to which a pulling line can be attached. Deep Hole According to diamond drillers, a term currently understood to apply to boreholes 3,000 feet or more in dept. In petroleum drilling, a bore hole over 8,000 feet deep. Deflect To intentionally change the course of a bore hole at a point some distance below the collar. Also called Wedge, Wedge off. Deflecting Wedge A class of devices intentionally placed in a bore hole to change its course. All such devices are basically long, tapered, concave metal plugs which can be set at a predetermined point and bearing in a boar hole to deflect or change its course. Also called Correcting wedge, Deflecting plug, Deflection wedge, Hall-Rowe wedge, Spade-end wedge, Thompson wedge. Deflection A change in the intended course of a boar hole produced intentionally or unintentionally by various condition encountered in the drill hole or by the operational characteristics of the drilling equipment used. Also call Deviation. Development Drilling Delineation of the size, mineral, content, and disposition of an ore body by drilling boreholes. Deviation =Deflection, q.v. The distance, measured in a horizontal plane, between two surveyed points in a bore hole or between the collar and any point below the collar in a bore hole. Also called Dislocation, Throw. Diamond Bit Any bit having diamonds inset in its crown, which serve as the cutting points or media. Commonly also called Boart bit, Boart-set bit, Bort bit, Bort-set bit, Bortz bit, Bortz-set bit. Diamond Core Drill A rotary-type drill machine using equipment and tools designed to recover rock samples in the form of cylindrical cores from rocks penetrated by boreholes. See Core drill. Diamond drill. Diamond Impregnated Having diamonds distributed throughout a matrix. Compare Surface set. Dip The angle of a slope, vein, rock stratum, or bore hole as measured from the horizontal plane downward. Discharge Outflow from a pump, drill hole, piping system, or other mechanism. Displacement The volume of liquid delivered by a single stroke of a pump piston. Sometimes used as a synonym for Offset Deflection, Deviation, Dislocation, throw the capacity of an air compressor, usually expressed in cubic feet of air per minute (c.f.m.). Double-Tube Core Barrel Core barrels consisting of two nesting tubes attached to a common headpiece threaded to connect to a drill rod. The inside tube holds the core, and the bottom end of the outside tube is threaded to connect with a reaming shell to which a coring bit is fitted. A narrow annular space is left between the tubes; through this the cuttings-removal fluid is conducted from the drill rod to the face of the bit and thence to the outside of the outer tube. The core enters the inner tube and the face of the bit. Numerous kinds of rigid-and swivel-type double-tube core barrels are manufactured. Double-Tube Core Barrel, Rigid Type A double-tube core barrel having the upper end of the inner tube coupled to the core-barrel head by means of an anti-friction device such as a roller or ball bearing; hence the inner tube tends to remain stationary when the outer tube, which is rigidly coupled to the core-barrel head, is rotated. Down Time Drilling time lost in repair, fishing, cementing operations, or moving rig from one hole to another. Drag Bit Various kinds of rigid steel bits provided with fixed (as contrasted to the movable or rolling cutting point of a roller bit) and sometimes replaceable cutting points, which are rotated to drill boreholes in soft to medium-hard rock formations. See Fishtail bit. Drill ability The relative speed at which a material may be penetrated by a drill bit. High drill ability denotes easy penetration at a fast rate. Drill Collar: Drilling Collar A length of extra heavy wall drill rod or pipe connected to a drill string directly above the core barrel or bit, the weight of which is used to impose the major part of the load required to make the bit cut properly. A drill collar is usually of nearly the same outside diameter as the bit or core barrel on which it is used. Not to be confused with Guide rod. Drilling Fluid Usually water or mud-laden water (sometimes applied to compressed air, natural gas, or oil) circulated through a drill string to keep the bit cool and to wash cuttings produced away from the bit face. Also called Circulation fluid, Fluid circulation. Drill Mud: Drilling Mud Water mixed with clay (usually Benoite) and sometimes other material such as ground Bartie, oil, etc., used as a rotary and/or diamond-drill circulation medium. Compare Circulation fluid, Drill fluid. Drill Out: Drilling Out To penetrate or remove an obstruction in a bore hole by a drilling operation. To complete a bore hole or group of boreholes. To determine location and areal extent of an ore body or petroleum reservoir by a number of boreholes. Drill Pipe A petroleum driller's term for dill rods. The term "pipe" usually is applied to 2 2/3 inch OD and larger size drill rods, all of which may or may not be externally flush coupled. Compare Drill rod. Drilling Rate The number of feet of bore hole drilled in a specific interval of time. Example: Drilling rate was 80 feet per day. Price, expressed in dollars, per foot of bore hole completed in accordance with terms specified in a drill contract. A synonym for Feeding rate, Feed rate. Drill Rod Hollow, externally flush-coupled rods connecting the bit and core barrel in a bore hole to the swivel head of a rotary-drill rig on the surface. Unit lengths of rod are usually 10 feet long and composed of two threaded parts, (a short pin-threaded coupling and a box-threaded length of heavy-wall steel tubing) connected together. The term "drill pipe" is applied to rods used in a similar manner on rotary rigs in petroleum-drilling operations. Also called Diamond-drill pipe, Diamond-drill rod, Drill pipe. Drill Stem See Drill string. As used by churn drillers, the heavy steel shaft connecting the blunt chisel-face bit to the churn-drill cable. Drill String The assemblage of drill rods, core barrel and bit or drill rods; drill collars, and bit in a bore hole, which is connected to and rotated by the drill machine on the surface at the collar of the bore hole. Also called Drill stem. As used by cable tool or churn drillers, the assemblage of bit, stem, rope, or cable in a bore hole connected to the walking beam of the churn drill on the surface. Drive Casing Heavy, thick-walled casing, which is stronger than standard casing, and hence may be driven through overburden or material with less danger of being damaged than standard casing. Drive head a heavy iron cap or annular coupling fitted to top of pipe or casing to receive and protect the casing from the blow delivered by a drive block when casing or pipe is driven through overburden or other material. Also called Drive cap, Driving cap. The swivel head of a diamond-or rotary-drill machine. Dry Block: Dry Blocking The intentional act or process of running a core bit without circulating a drill fluid until the cuttings at and inside the bit wedge the core solidly inside the bit. Duplex Pump A positive displacement pump with two water or liquid cylinders side by side and geared so that the piston strokes in the cylinders alternate. Such a pump may be either single or double action, depending on the number and placement of intake and discharge valves on the cylinder and may be designed so as to deliver a low volume of liquid at high pressure. Compare Triplex pump. Elevator A hinged circle or latch block provided with long links to hand on the hoist-line hook and used to hoist collared pipe, drill pipe and/or casing, and drill rods provided with elevator plugs. Some large elevators are fitted with slips for use on non-collared or flush-outside tubular equipment. A term sometimes and incorrectly used as a synonym for Lifting bail. Elevator Plug A short steel plug provided with a pin thread by means of which it may be coupled to the upper end of a stand of drill rods. Its diameter is greater than that of the drill rod to which it is attached, and hence it provides a shoulder that can be grasped by an elevator. When each stand of rod is provided with an elevator plug and an elevator is used in lieu of a rod-hoisting plug, the handling of rods is facilitated and a round trip can be made in less time. Also called rod plug. Expanding Waterway A channel or groove incised into and across the face of a bit the depth and/or width of which gradually increases from the inside to the outside walls of the bit. Expansion Cutter A bore hole drill bit having cutters that may be expanded to cut a larger size hole than the size of the bit in its unexpanded state; also, a device equipped with cutters that may be expanded inside casing or pipe to sever, or cut slits or holes in the casing or pipe. Extension Core Barrel A core barrel the length of which may be increased by coupling similar sections. Face That part of a bit in contact with the bottom of a bore hole when drilling is in progress and which cuts the material being drilled. Also called Cutting face, Working face. To cover or build up a surface, such as the face or cutting points of a bit, with a layer of metal usually applied by a welding method. See Hard face. One of the flat, more or less smooth, surfaces of a mineral crystal. The bottom of a drill or bore hole. In any adit, tunnel, stope, or other underground workplace, the end at which work is progressing or was done last. Also called Working face. Face-Discharge Bit A bit designed for drilling in soft formations and for use on a double-tube core barrel, the inner tube of which fits snugly into a recess cut into the inside wall of the bit directly above the inside reaming stones. The bit is provided with a number of holes drilled longitudinally through the wall of the bit through which the circulation liquid flows and is ejected at the cutting face of the bit. Also called Bottom-discharge bit, Face-ejection bit. Fast Gear As used by drillers in referring to the feed gears in a gear-feed swivel head, the pair of gears installed in the head that produces the greatest amount of bit advance per revolution of the drill stem. Also called Fast feed, High feed. As used by drillers in referring to the speed at which the drill motor rotates the drill stem or hoist drum, the transmission gear position giving the fastest rotation per engine r.p.m. FC Abbr. Flush-coupled Feed The longitudinal movements imparted to a drill stem to cause the bit to cut and penetrate the formation being drilled. The distance a drill stem on a diamond drill may be advanced into the rock before the rods must be rechucked. Example: A driller may say "A drill is equipped with an 18-inch feed," meaning that the bit may be made to drill a maximum distance of 18 inches each time the drill stem is chucked-up in the drive rod of the swivel head. Feed Control System of valves or other mechanical device controlling the rate at which longitudinal movements are imparted to the diamond- or rock-drill stem and/or the cutting teeth on a coal-cutting machine. Feed-Control Valve A small valve, usually a needle valve, on the outlet of the hydraulic-feed cylinder on the swivel head of a diamond drill used to control minutely the speed of the hydraulic piston travel and, hence the rate at which the bit is made to penetrate the rock being drilled. Also called Drip valve, Needle valve. Feed Cylinder A hydraulic cylinder and piston mechanism, such as that on a diamond-drill swivel head to transmit longitudinal movements to the drive rod and chuck to which the drilling stem is attached. Also called Hydraulic cylinder. Feed Pressure Total weight or pressure, expressed in pounds or tons, applied to drilling stem to make the drill bit cut and penetrate the formations being drilling. Pressure, expressed in pounds per square inch, required to force grout into a rock formation. Pressure, expressed in pounds per square inch (p.s.i.), required to force-feed water into a steam boiler. Feed Rate Rate at which a drilling bit is advanced into or penetrates the rock formation being drilled expressed in inches per minute, inch per bit revolution, number of bit revolutions per inch of advance, or feet per hour. Also called Cutting rate, Cutting speed, Forward speed, Penetration feed, Penetration rate. Feed Ratio The number of revolutions a drill stem and bit must turn to advance the drill bit 1 inch when the stem is attached to and rotated by a screw or gear feed type drill swivel head with a particular pair of the set of gears engaged. Example: When a screw-feed swivel head of a diamond drill equipped with three pairs of gears, having a feed ratio of 100, 200 and 400, is operated with the 100-pair engaged the drill stem must revolve 100 times to advance the bit 1 inch. If the 200-pair is engaged, the drill stem rotates 200 times per inch advanced, and if the 400 pair is engaged the stem must rate 400 times to advance the bit 1 inch. Female Thread Bod thread, q.v. Fishing Tools Apparatus of various types used on the end of a drill string to fish or remove from the hole lost pieces of drilling equipment or tramp iron. Fishtail Bit A steel, chisel-shaped bit with the cutting edge split in the center. Each half or wing of the chisel edge is slightly bent so as to come in contact with rock formation at a slight, positive rake when the bit is rotated. The shank is equipped with box threads matching those on drill rods to rotary drill in formations where core is not desired. Also called Drag bit. Flat-Face Bit A diamond core bit the face of which, in cross section, is square. Also called Flat-bottom crown, Flat-nose bit, Square-nose bit. Float Valve A synonym for a ball and seat type apparatus inserted in a pipe, casing, or drill-rod string being lowered into a bore hole. A valve operated by a float. Fluid Pressure The force with which a stream of drilling fluid is ejected from a pump, usually expressed in pounds per square inch. The force, expressed in pounds per square inch, exerted by the weight of the column of drilling fluid measured at any given depth in a bore hole. Fluid Volume The amount of drilling fluid circulated through the drill string, generally expressed in gallons per minutes. Flush To clean out by letting in a sudden rush of liquid or gas, as in flushing material from a bore hole with a strong, rapidly flowing stream of water. Flush-Coupled Provided with couplings the outside diameter of which is the same as that of the unit pieces on which the coupling is fitted. See Flush-coupled casing. Flush-Coupled Casing A length (usually 10 feet) of steel tubing one end of which is provided with a short coupling having pin threads on both ends. The outside diameter of the coupling and the casing tube are equal, and the inside diameter of the coupling is usually about three six tenths of an inch smaller than the inside diameter of the casing tube. Flush Joint; Flush-Jointed Two similar members joined in such a manner that either or both the outside and inside surfaces of the two members are flush. Flush-Joint Casing Lengths (usually 10 feet) of steel tubing provided with a box thread at one end and a matching pin thread on the opposite end. Couple, the lengths form a continuous tube having a uniform inside and outside diameter throughout its entire length. Flute A groove parallel or nearly parallel to the axis of a cylindrical piece, such as the grooves of a split-ring core lifter or the grooves in a core-barrel stabilizer ring. Also applied to grooves or webs following a corkscrew like course around the outside surface of a cylindrical object, like the spiraled webs on an auger stem or rod. Foot Clamp Safety clamp, q.v. Foot Valve A clack or ball and seal type valve placed at the bottom end of an upstanding liquid-piping system to allow liquid to enter but not escape from the system. Formation A rock the character and mineral constituents of which are more or less uniform throughout and/or the rocks encountered in a specific area or comprising rocks having a certain geologic or mineralogical relationship to one another. A large and persistent stratum of a specific kind of rock. Fractured Ground Rock formation shattered and criss-crossed with fissures and fractures. Compare Broken ground. Frame and Skid Mounted Drill machine mounted on a wood or steel framework base the bottom member of which is a sled runner like shaped piece. Full Gage A cylindrical or tubular object such as a bit or reaming shell, the outside and/or inside diameters of which are the size specified. Also called full size. A bore hole's inside diameter of which is uniform enough to allow a new-condition bit to follow portions of the hole drilled by other bits cutting the same X-borehole size without reaming. Also called Full size. As applied to deflection drilling, the branch bore hole is the same diameter as the parent hole. Also called full size. Gage Diameter The diameter of an object as determined by measurement and/or size as compared to a standard. Gage Loss The diametrical reduction in the size of a bit or reaming shell caused by wear through use. Gage Ring; Gaging Ring A circular metal ring the inside diameter of which is a specific standard size. Commonly produced in sizes corresponding to the standard outside set diameters of bits and reaming shells. Gage Stone Any one of several diamonds set in the crown of a diamond bit in a plane parallel with and projecting slightly beyond the inside and/or outside walls of the bit. Gear Pump A type of positive-displacement pump consisting of two tightly enmeshing gears within a close-fitted shell. When the gears are rotated at high speed the pump is capable of delivering a liquid under high pressure, as the pressurized oil delivered to the hydraulic-feed cylinders on a hydraulic-feed drill. Glaze The rounded and polished produced on the exposed portion of diamonds inset in a bit when the bit is rotated at a high speed and subjected to a feed pressure much too low to make the bit cut at its optimum penetration rate. The bit is prematurely dulled and make unfit for additional use in that specific rock formation. Also called Polish. Goose Neck A bent pipe or tube having a swivel joint, so that its outer end may be revolved. The bent-tube part of a water swivel to which the water hose is connected. A T-shaped connection for supplying water to the top end of wash rods in penetrating overburden. It is fitted with pipe handles by means of which the wash rods may be turned. Grind; Grinding The act or process of continuing to drill after the bit or core barrel is blocked, there by crushing and destroying any core that might have been produced. To polish or sharpen by friction. Grout A pumpable slurry of neat cement or a mixture of neat cement and fine sand, commonly forced into a bore hole to seal crevices in a rock to prevent ground water from seeping or flowing into an excavation, to seal crevices in a dam foundation, or to consolidate and cement together rock fragments in a breacciated or fragmented formation. Also called Cement grout. The act or process of injecting a grout into a rock formation through a bore hole. Hard Face A layer of hard, abrasion-resistant metal applied to a less abrasion resistant metal part by plating, welding, or other techniques. See Face 2. The crystal face of a diamond lying parallel or nearly so with a hard vector plane of the crystal. Hardness Scale Quantitative units by means of which the relative hardness of minerals and metals can be determined, which for convenience is expressed in Moh's, Knoop, or scleroscope units for minerals and Vickers, Brinnell, or Rockwell units for metals. Hard-Rock Drilling Drilling done in dense and solid ingneous or highly solidified rocks, which can be penetrated economically only by diamond bits, as opposed to that done in softer rocks easily cut by roller or wing-type rotary bits. Head Variously used as a synonym for Core-barrel head, Drill head, Swivel head. Same as Hydraulic head 1 and 2. Head Room Distance between the drill platform and the bottom of the sheave wheel. Height between the floor and the room in a mine opening. Hoisting Plug A pin-thread heavy-bodied coupling provided with a swivel-mounted eye in the end opposite the pin-thread end. When attached to the hook on the drill-hoist line, the pin-thread end can be screwed into the rods to hoist and otherwise handle drill-string equipment when making bore hole round trips. Also called Plug, Screw plug, Swivel plug. Hydraulic Chuck A diamond-drill rod chuck having jaws with clamping and unclamping movements actuated hydraulically instead of by hand-turned setscrews. Also called Automatic chuck. Hydraulic Head A synonym for Hydraulic swivel head. The height of a fluid column, usually considered as water, which maintains a pressure on a surface, the amount of pressure being directly proportional to the depth of the fluid standing above the point at which the pressure is taken. This pressure may be given in pounds per unit area, or simply as the height of the water column in feet or inches. Pure water at 60*F, exerts a pressure of 0.4331 p.s.i. for each foot of depth. In Line To be over the center of a bore hole and parallel with its long axis. A drill motor mounted in such a manner that its drive shaft and the drive rod in the drill swivel head are parallel; also, a drill motor mounted in such a manner that the shaft driving the drill-swivel-head bevel gear and the drill-motor drive shaft are centered in a direct line and parallel with each other. Similar units mounted together in a line. Inner Barrel Inner tube, q.v. Inner Tube The inside tube, which acts as the core container of a double-tube core barrel. Inner-Tube Core Lifter A core lifter designed to fit and work inside a tubular container fitter to the lower end of the inner tube of a double-tube core barrel. Insert; Inserts Formed pieces of sintered cobalt-tungsten carbide mixture (in which diamonds may be inset), brazed into slots or holes in bits or into grooves on the outside surface of a reaming shell to act as cutting points, reaming surfaces, or wear-resistant pads or surfaces of reaming shells or outside surfaces of other pieces of drilling equipment or fittings. Anything placed in a hole, groove, or slot prepared to, it. Insert Bit A bit into which inset cutting points of various preshaped pieces of hard metal (usually a sintered, tungsten carbide-cobalt alloy) are brazed or hand-penned into slots or holes cut or drilled into a blank bit. Hard-metal inserts may or may not contain diamonds. Also called Slug bit. See Insert. Insert Reaming Shell A reaming shell the reaming diamonds of which are inset in shaped, hard metal plates brazed into grooves cut into the outside surface of the shell. Jacking Pressure The amount of pressure exerted by a jack to force a cone penetrometer into a soil being tested. Jar To loosen or free stuck drill-stem equipment or tools by im |
Drilling Definitions