Abstract: An outer tube (26) provided with rolling bearings (28) is rotatably mounted on an inner tube (10) which can be connected to a drilling tool or a pipe string. Radially mobile guiding rails are arranged in longitudinal channel-like recesses on the outer surface of the outer tube (26). Belleville springs lodged in spring housings (36) arranged in recesses in the guide rails (35) press against the outer tube (26) and force the guide rails (35) radially outward. The guide rails (35) help prevent rotation of the outer tube, enable it to slide longitudinally in the bore, and guide the inner tube (10) mounted in the outer tube (26) and the drilling tool or pipe string attached to the inner tube (10).

Abstract: A pressure-medium driven ram boring machine for boring in the earth, having an impact tip acted on by a percussion piston reciprocating in the machine housing, wherein the impact tip is arranged to be radially adjustable in the housing whereby controlled directional changes of the machine can be effected.

Abstract: A downhole centralizer is provided for positioning along a drill pipe string passing through a deviated well bore. A centralizer body is connected to an upper sub by a plurality of lobe-shaped connectors which permit angular deviation of the central axis of the upper sub with respect to the central axis of the centralizer body. The centralizer body is preferably connected to a lower sub by similar lobe-shaped connectors. The opposite ends of each of the upper and lower subs are threaded for fixed engagement with respective upper and lower pipe joints in the tubular string. A flexible flow conduit is positioned within a passageway through the centralizer body, and a pair of upper and lower sealing member are provided to maintain sealed engagement between the respective upper and lower subs and the flow conduit for transmission of fluid through the centralizer.

Abstract: A drill string deflection tool is arranged to function as a segment of drill string. An upper and a lower portion telescope together to form a mid-section with limited telescoping movement and limited angular deflection of the axes of the opposite ends. Axial load compresses the tool and a cam and fulcrum arrangement deflects the tool when it is axially compressed. The tool extends axially when pulled in tension and the axis becomes straight. Drilling fluid pressure acts on rams in the tool to lock it in whatever state exists when pressure is applied. The locking mechanism acts upon the drilling fluid channel to cause a pressure drop, detectable at the surface, that indicates the state of the tool downhole.

Abstract: Soil displacement hammer for driving holes in the ground, comprising a substantially cylindrical body (5), a soil displacement head (1) at a forward end of the body, a longitudinally reciprocable striking member (12) housed within the body, and an anvil member (13) within the body adjacent its forward end and adapted to receive hammer blows from the striking member to cause the body to be driven forward. A retractable baffle member (4) is mounted adjacent the forward end of the body and is moveable between a retracted position in which it does not project from the body so that the soil displacement hammer describes a straight path in the ground, and an extended position in which it projects transversely from one side of the body to cause the soil displacement hammer to describe a curved path in the ground. The invention also provides a method of tracking such a soil displacement hammer in the ground.

Abstract: The invention relates to a process and a device for the production of drilling holes from an angled position with respect to the drilling axis, wherein the system has a free-moving drilling support with a drilling machine axially movable thereon. According to this process the drilling rod is provided with a flexible configuration that is diverted by passing through a bend guide affixed to a drilling support, from the rotation axis of the drilling machine to the axis of the drill hole. According to this device, the flexible drilling rod system consists of a tubular core and of wires or rods twisted around this core.

Abstract: A process and device making possible the guidance of the drilling tool through geological formations including an analytical device for directional geological analysis that carries out measurements as the drilling advances for guiding the drilling tool through the geological formation. The drilling column at its lower end includes the drilling tool (1) driven by a turbine (2) mounted on an elbow (4), a directional analytical device (3) that carries out measurements according to well set directions, a logging sensor (5), a drilling sensor (6) and a topographic probe (7). When drilling through specific geological formations, the information provided by the directional analytical device (3) is used for guiding the drilling tool in real time.

Abstract: Oil well drilling apparatus for drilling deep boreholes. The apparatus includes a high frequency, high voltage, AC generator at the surface of the ground which is connected to an electromagnetic hammer drill bit located at the bottom of the borehole. Electric current is conducted along a special drill string to the electromagnetic hammer drill located at the bottom of the hole. The drill string is a co-axial electrically conductive drill pipe which forms spaced annular current flow paths to the downhole electromagnetic hammer drill, while at the same time, drilling fluid flows along an axial flow path to the vibrating bit located at the bottom of the borehole. A special directional drill collar is positioned immediately above the electromagnetic hammer drill for controlling hole deviation.

Abstract: The orientation of a downhole steering assembly used in drilling a horizontal well is located with respect to the earth using a sub placed above the downhole assembly. The sub comprises a housing having a central bore defining an inlet flow passageway said housing further defining a toroidal chamber in communication with said passageway. The toroidal chamber has a pocket, a valve seat, and a spherical valve that is rotatable in said toroidal chamber from a normally seated position in the pocket. Upon rotation of the drill string the spherical valve plugs the valve seat and causes an increase in the resistance to flow in the drilling mud through the drill string that can be detected at the surface.

Abstract: A directional drill bit utilizing pressurized fluid as a means for eroding earth in a forward path of the bit and being used to drill at least a portion of an arcuate path, comprises an elongate hollow body having two sections joined one to the other by a flexible joint, a box end connection, a jet nozzle, an articulation device comprising a spring and a stop, the articulation device being responsive to changes in fluid pressure by permitting a forward portion of the bit bearing the nozzle structure to change angular position with respect to an aft portion of the bit, by the forward portion moving from a first position relative to the aft portion to a second position relative to the aft portion.

Abstract: A device for transmitting a thrust from one of a pair of adjacent pipes so as to propel the other comprises a pair of annular members adapted to be slidable relatively to each other along their spherical surfaces.

Abstract: An improved directional drilling tool permits changing the downhole drilling assembly between straight and directional drilling configuration by manipulation of conventional drilling fluid flow controls at the surface. A housing, with stabilizer features, shrouds a shaft which functions as an extension of the drill string and attaches to a drill head. A drilling fluid flow rate responsive selector valve is situated in the shaft and responds to drilling fluid flow rate manipulations to change assembly configuration. In the straight configuration the shaft remains straight and is rotationally locked to the housing. In the directional configuration the housing is rotationally unlocked from the shaft, normally after directional orientation, so that the shaft can rotate through it. The same action transversely displaces the shaft midsection relative to the housing and the shaft and drill head below is angularly deflected by way of a hinge arrangement near the drill head end of the housing.

Abstract: Well bore deviation from vertical is reduced or corrected by inducing a lateral deflection of the drill string at a predetermined location above the drill bit to force the drill bit to return to vertical. The lateral deflection occurs periodically and creates a nutating effect in the drill string which causes the drill bit to angle toward vertical. An eccentrically mounted roller becomes effective when it contacts the low side of a deviated well bore and preferably induces the lateral deflection as it rotates while in contact with the low side of the well bore.

Abstract: A non-rotating drill string is formed from a plurality of independent, cylindrical sections pivotally connected together by a latch mechanism. The adjacent ends are partially beveled such that the sections can bend in a single direction. Means are disclosed for varying the effect of the beveled surfaces, thus controlling the angle of bend for a given one of the sections. A downhole mud motor (PDM) drives the drill bit through the use of a flexible drive shaft running through the center of a metal-lined, neoprene drilling fluid hose which runs through the interior of the independent cylindrical sections. The total curvature of the borehole drilled by the system equals the sum of the angles of bend between the individual sections.

Abstract: An assembly for driving a drilling tool in rotation about an axis related to the drilling tool from a drive column, rotating at its lower end about a second axis, with the axes being substantially convergent at the same point and forming therebetween an angle alpha. The assembly comprises in combination a remote controlled deflector adapted for creating a deviation of an angle alpha, a controller for controlling the value of the angle alpha, a guide for rotating a drilling tool and the drive column at its lower end about the axes relatively to the deflector and a controller for controlling the polar position of the deflector relatively to second axis.

Abstract: A directional guidance device, for deflecting a drill bit away from the longitudinal axis of a substantially horizontal section of a wellbore, takes advantage of gravitational force to move a deflector member therein between first and second positions. In the first position, the deflector member prevents the drill bit from advancing past the directional guidance device. In the second position, the deflector member allows the bit to pass out of the guidance device, and deflects the bit away from the longitudinal axis of the horizontal section of the wellbore.

Abstract: An apparatus is provided whereby a standard percussive-type downhole drill may be utilized in directional drilling. This eliminates the need for less efficient tri-cone type downhole motors in this application. A motor is provided directly on top of the hammer at the end of the drill string, which both rotates the hammer and allows the passage of compressed air to the hammer for its piston operation. A preferred embodiment of the motor is an air-driven turbine with a replaceable connecting subassembly to link the motor shaft to the hammer apparatus.

Abstract: The drilling device comprises at least two stabilizers (7a, 7b, 7c) spaced apart in the longitudinal direction of the set of rods. The pistons (17a, 17b, 17c) of these stabilizers are interconnected and include common members (35, 37) for creating a pressure drop in the drilling fluid. Actuating surfaces (19a, 19b, 19c) including ramps (40) and complementary parts interconnecting the ramps cooperate with finger members (20) for effecting the extension of the bearing plates (21). The ramps (40) and the complementary parts of the actuating surfaces of the stabilizers (7a, 7b, 7c) are aligned in the longitudinal direction and are such that for each stable successive position of the pistons (17a, 17b, 17c), the bearing plates (21) are in positions of extension constituting a combination different from the preceding one.

Abstract: A method of directionally drilling a borehole makes use of a drilling assembly including an apparatus having an upper section with a longitudinal axis I, and a lower section having a central axis II and including at least part of a rotary drill bit, said sections being interconnected by a universal pivot mechanism. The method comprises rotating the assembly in such a manner that the upper section rotates about said longitudinal axis I and the lower section rotates about said central axis II. During at least part of the drilling operations said central axis II is tilted and rotated in an orbital mode relative to said longitudinal axis I such that a plane containing said two axes is maintained in a predetermined orientation relative to a reference direction.

Abstract: An earth boring apparatus has a pneumatically operated earth boring tool, a flexible conduit or drill pipe connected to the tool and to a source of pneumatic fluid. The tool has an earth boring member and a reciprocally movable hammer positioned in the tool to apply a percussive force. A valve assembly in the flexible conduit or drill pipe substantially adjacent to the tool between the tool and the source of pneumatic fluid controls the flow of pneumatic fluid to the tool. The valve assembly has a pneumatic pressure-operated valve which is operable in response to the pressure of pneumatic fluid in the flexible conduit or drill pipe to be opened to permit flow of pneumatic fluid to the tool at a predetermined operating pressure to transmit an initial pulse of pneumatic fluid to initiate operation of the hammer. The valve is kept open at a lower pressure than that required to open it.

Abstract: The opening method to drill openings with required largeness on thick reinforced concrete walls such as a reinforced concrete dam body is presented.This method comprises (1) the process of drilling cable penetrations in the depth direction on each corner around the opening domain on a reinforced concrete wall, (2) the process of penetrating cutting cable through cable penetrations and to carry out wire sawing with water injection, (3) the process to break and remove the separated core.According to this method, the required opening for thick reinforced concrete walls such as a reinforced concrete dam body which has been regarded as difficult if not impossible, can be safely and exactly drilled with the smallest number of processes, having no bad influence on the surrounded wall.

Abstract: A body and driveshaft extension for down hole drilling motors to allow the down hole assembly to operate as part of a drill string responsive to selected manipulations of the drilling fluid flow rate, carried out at the earth surface, to assume either a straight hole drilling configuration or a directional drilling configuration by choice of the driller.In the directional drilling configuration, the drill head driving output shaft rotates about a centerline deflected from the motor general centerline. The point of deflection is between the drilling motor and the drill head.

Abstract: A device for drilling lateral boreholes from a cased parent well comprises selecting and coupling means adapted to cooperate with a deflection unit placed within the parent well. The selecting and coupling means are mounted at the lower end of an extension unit formed by interassembled tubular elements. The upper end of the extension unit is rigidly fixed to a suspension swivel within the wellhead and at least one slip joint is interposed between two tubular elements. The internal diameter of each tubular element is such that a drilling packer can be housed within the tubular elements.

Abstract: Hydraulic drilling apparatus and method suitable for use in a variety of applications including the drilling of deep holes for oil and gas wells and the drilling of vertical, horizontal or slanted holes, drilling through both consolidated and unconsolidated formations, and cutting and removing core samples. The drill head produces a whirling mass of pressurized cutting fluid, and this whirling fluid is applied to a discharge nozzle to produce a high velocity cutting jet. The cutting action is enhanced by abrasive material in the drilling fluid. The direction of the borehole is controlled by controlling the discharge of the drilling fluid either in side jets directed radially from the distal end portion of the drill string which carries the drill head or in a plurality of forwardly directed cutting jets.

Abstract: An orienting and circulating sub is disclosed for connection in an apparatus for angular drilling in the earth. The drilling apparatus comprises a drill string extending into a substantially vertical well bore in the earth supporting a fluid operated motor and drill bit at its lower end. The drill bit is supported for angular drilling by either using a bent sub for supporting the drilling motor or be using a drilling motor with a bent housing. A surveying tool is connected above the motor for determining and controlling the direction of drilling. A mule shoe keying sub is connected to the surveying tool for orienting the position of the motor in relation to said surveying tool. The orienting sub comprises a tubular housing formed in two sections threaded together with one end connected to the surveying tool by the mule shoe keying sub and the other end connected to the bent sub or to the bent motor housing.

Abstract: A length of drill string, or a sub, functions as a body to which an encircling sleeve is rotationally and axially secured. The sleeve is arranged to permit some radial movement on the body and is spring biased in one radial directiion. A radial projection of some axial length extends from the sleeve in the biased direction to engage the well bore wall. During drill string rotation, the projection engages a near side wall more forcefully than other parts of the well bore periphery. The forceful engagement between projection and wall deranges the tendency for a curved drill string centerline to lie in a stationary plane when the drill bit has a tendency to depart from an original course while drilling. The bias allows the sleeve to be pushed toward a more centralized position on the body but the fluid damping inherent by changing clearances between sleeve and body, while the tool is immersed in drilling fluid, retards the centralizing movement.

Abstract: Bearing rings containing PCD faced bearing inserts are mounted adjacent tungsten carbide radial bearing surfaces at the ends of respective bearing sleeves attached to the drive shaft of a down hole well drilling motor, thereby preventing excessive wear at the extremities of the radial bearing surface in controlled and steerable drilling applications.

Abstract: The apparatus for making a substantially vertical slot in the ground, especially in a single operation in making a sealing or supporting wall, comprises a machine frame with a rectangular cross section guided in the slot in the ground with a plurality of guide surfaces and at least one driven cutting wheel positioned at the lower end of the machine frame. The machine frame and the cutting wheels have a width which correspond to the width of the slot in the ground within tolerances defined by the guide free play and the cutting free play. The machine frame is guided in the vertical slot with a plurality of guiding surfaces and comprises an upper guide frame and a lower guide frame. The cutting wheels are mounted on the lower guide frame. The controlling piston cylinder unit for control of the lower guiding frame is mounted between the upper and lower guiding frames.

Abstract: A method and associated apparatus for lateral drilling in an oil and/or gas well involving either stopping the drilling or temporarily cementing in a plug in the existing well bore at the desired location for deviation. A tight radius of curvature is then rotary drilled by use of a flexible drilling collar made up of a series of short drill string sections interconnected by universal joints that terminate within an eccentric collar on the final drill string section. The eccentric collar is equipped with a sidewall engaging means to hold the eccentric collar from rotating during rotary drilling. A flexible collar (e.g., ball and socket) extending outwardly and downwardly from the far end of the final drill string section passing through the eccentric collar connects to a drill bit collar and rotary drill bit.

Abstract: A directional drilling tool permits the control of the angle of drilling of a drill bit through the repeated placement or removal of a ball within the mudstream. The ball activates a clutch mechanism within the directional drilling tool. The clutch mechanism, upon activiation, locks the exterior of the directional drilling sub to a fixed angular orientation. Simultaneously, there is activated a deflection mechanism to deflect a drive shaft which is normally fixed in an aligned straight position within the tube body, so as to shift the normally straight aligned shaft to a deflected position, causing the bit and the sub to angle for drilling at a controlled angle of offset from the vertical. The unit is aligned and located using wireline measuring equipment of known design.

Abstract: Oil well drilling apparatus for drilling deep boreholes. The apparatus includes a high frequency, high voltage, AC generator at the surface of the ground which is connected to an electromagnetic hammer drill bit located at the bottom of the borehole. Electric current is conducted along a special drill string to the electromagnetic hammer drill located at the bottom of the hole. The drill string is a co-axial electrically conductive drill pipe which forms spaced annular current flow paths to the downhole electromagnetic hammer drill, while at the same time, drilling fluid flows along an axial flow path to the vibrating bit located at the bottom of the borehole. A special directional drill collar is positioned immediately above the electromagnetic hammer drill for controlling hole deviation.

Abstract: Directional drilling is carried out with a rotary drilling tool having a drill string, a drill bit, a drill motor for rotating the drill bit independently of the drill string, an extension sub having both axially contracted and axially extended positions for providing weight to the drill bit when moving from a contracted to an extended position so as to effect a drilling stroke by the drill bit into the wellbore bottom when drilling with the drill bit independently of rotation of the drill string and a relaxation device for removing any excess weight on the drill bit that would otherwise be detrimental to the direction drilling of a deviated wellbore.

Abstract: A body, functioning as a length of drill string, has an eccentric roller mounted for rotation around the body. The roller and body have cooperating cam surfaces that cause the roller to reciprocate axially when the body rotates relative to the roller. In use, the extended radius of the eccentric roller engages the near side of the well bore walland tends to become stationary relative to earth. The forced axial motion of the retarded roller induces some peripheral motion at each turn of the drill string. The eccentric roller turns freely with the drill string when the extended radius is adjacent the far side of the well bore wall. The extended radius of the roller tends to spend most of the drilling time between the drill string and the near side, or low side, of the well bore to aid in well bore deviation control.

Abstract: A method and associated apparatus for lateral drilling in an oil and/or gas well involving either stopping the drilling or temporarily cementing in a plug in the existing well bore at the desired location for deviation. A tight radius of curvature is then rotary drilled by use of a flexible drilling collar made up of a series of short drill string sections interconnected by universal joints that terminate within an eccentric collar on the final drill string section. The eccentric collar is equipped with a sidewall engaging means to hold the eccentric collar from rotating during rotary drilling. A flexible collar (e.g., ball and socket) extending outwardly and downwardly from the far end of the final drill string section passing through the eccentric collar connects to a drill bit collar and rotary drill bit.

Abstract: Structure is passed into an earth well including a whipstock attached to piping and a retractible anchor. The whipstock includes a number of connected guide assemblies. Erection means is connected at one end to a forward guide assembly and at the other end to an extension projecting to the earth surface. To erect the whipstock, an extension of the erection means is pulled from the surface to cause the guide assemblies to swing into a curved pathway. Thereafter, a drilling tube is passed through the whipstock into the adjacent formation. The whipstock may be deerected by releasing the extension means. Then, the anchor is released and the structure is pulled out of the well.

Abstract: An apparatus and method for drilling a pilot bore hole (B) along an underground arcuate path (P) between two surface locations (O, E). The pilot bore hole (B) is drilled in one direction with a drill string (10) having a leading pipe section (10A) of a reduced diameter to provide increased flexibility. Upon completion of the pilot bore hole (B), a reamer (48) connected to a product conduit (46) is connected to the drill string (10). Drill string (10) pulls the reamer (48) and product conduit (46) along the pilot bore hole (B) in an opposite direction for enlarging the bore hole (B) to receive the product conduit (46). A spud bit (34) has a flat or blunt leading end portion (34A) with a discharge opening (34D) therein to discharge high velocity drilling fluid into the formation at a location offset from the longitudinal axis of the drill string (10) to assist in guiding the drill string (10). An in-hole hydraulic motor (70) is provided in an embodiment (FIG.

Abstract: A system and method for controlled directional drilling utilizes a system approach to design the hardware for drilling according to the well plan. The bend angle of a bent housing, connected between the bit and a down-hole motor, the diameter of a plurality of stabilizers and placement of the stabilizers with respect to the drill bit are selected and predetermined on the basis of the desired well plan. With the use of an MWD, the direction of the progressing borehole is tracked from the surface. Direction changes as required are controlled from the surface simply by controlling rotation of the drillstring. For curved path drilling, only the downhole motor is rotated, causing the borehole to travel along the curve determined by the bend angle in the bent housing and the diameter and location of the concentric stabilizers. When straight hole drilling is required, both the down-hole motor and the entire drill string are rotated, effectively nullifying the effect of the bend angle in the bent housing.

Abstract: A wedging assembly for steering or branching a borehole comprises a wedge defining the steering or branching angle, a locking device for locking the wedge in a desired position, and an actuator for actuating the locking device, the locking device including cooperable male and female locking members which are relatively moveable to cause an annular locking surface on the female member to lock firmly about the wall of the borehole.

Abstract: A rotary well drilling system employs a drill pipe with a drill bit affixed at its lower end for the drilling of a wellbore. Drilling fluid is circulated through the drill pipe to remove drill cuttings. When raising and lowering the drill pipe in the wellbore, the drill pipe is continuously rotated along with continued drilling fluid circulation to prevent sticking of the drill pipe. The drill bit is rotated by a mud motor in the opposite direction from that of the drill pipe and at the same speed so that the drill bit remains rotationally stationary with respect to the wellbore and does not side-track as it is dragged along the lower side of the wellbore wall when being raised or lowered in an inclined wellbore.

Abstract: A rotary well drilling system employs a drill pipe with a drill bit affixed at its lower end for the drilling of a deviated wellbore. Drilling fluid is circulated through the drill pipe to remove drill cuttings. The drill bit is rotated in the opposite direction from that of the drill pipe to reduce the torque required to rotate the drill pipe as it is rotationally dragged along the lower side of the wellbore walls during the drilling of the deviated wellbore.

Abstract: A tool for boring cavity holes in concrete walls and the like comprises a cutting blade pivotally mounted about a transverse pin at the end of an elongate body and having a camming profiled portion. A ball is placed at the bottom of the hole which has first been bored with a conventional drill and the tool cutting blade is brought into contact with the ball while causing rapid rotation of the tool body and exerting an axial pressure. The ball cooperates with the blade camming profiled portion so as progressively to orient the blade in a transverse direction.

Abstract: A direction and angle maintenance tool and a method for using same are provided for drilling directionally oriented boreholes. The tool generally comprises a mandrel and a sleeve, which is rotatably attachable around the mandrel. The mandrel has a longitudinal bore and is attachable at its upper end to a rotary drill string and at its lower end to a rotary drill bit sub which is attached to a rotary drill bit. The sleeve has an eccentric longitudinal bore, forming a heavy, or weighted, side of the sleeve. A gauge insert is provided which is longitudinally attachable to the weighted side of the sleeve. By varying the size of the insert, the angle of deviation of a directionally drilled borehole may be maintained or adjusted. A self-adjusting blade may be added in order to aid in maintaining a desired angle of deviation or to induce a desired change of direction.

Abstract: A steering system is disclosed for percussion boring tools for boring in the earth at an angle or in a generally horizontal direction. The steering mechanism comprises a slanted-face nose member attached to the anvil of the tool to produce a turning force on the tool and movable tail fins incorporated into the trailing end of the tool which are adapted to be selectively positioned relative to the body of the tool to negate the turning force. The fins are constructed to assume a neutral position relative to the housing of the tool when the tool is allowed to turn and to assume a spin inducing position relative to the housing of the tool to cause it to rotate when the tool is to move in a straight direction. Turning force may also be imparted to the tool by an eccentric hammer which delivers an off-axis impact to the tool anvil. For straight boring, the tail fins are fixed to induce spin of the tool about its longitudinal axis to compensate for the turning effect of the slanted nose member or eccentric hammer.

Abstract: The invention relates to a drilling equipment whose annular bit (4) for cutting the rock located in the deepest point of the drill hole is provided with high-pressure water-jet nozzles and is connected via a flexible high-pressure hose pipe (13) with a high-pressure pump. In order to be able to drill with the aid of such a drilling equipment small-diameter drill holes of high directional stability, the invention proposes that the high-pressure hose pipe (13) be constructed to be rigid under torsion, non-rotatably connected to the annular bit (4) and the turning drive (24, 25) of the drilling machine (8) and to be journaled in a non-rotatable jacket tube (15) elastically deflectable from the extension position, said jacket tube being rigid in radial direction and guided in the area of the drill hole mouth in a deflecting device (7) and displaceable together with the high-pressure hose pipe (13) in its longitudinal direction.

Abstract: A percussion boring tool is disclosed for boring in the earth at an angle or in a generally horizontal direction. The tool has a steering mechanism substantially as shown in a copending patent application and a cylindrical body with overgage sleeves located over a portion of the outer body affixed so that they can rotate but cannot slide axially. The overgage areas at the front and back of the tool, or alternately, an undergage section in the center of the tool body permits a 2-point contact (front and rear) of the outer housing with the soil wall as opposed to the line contact which occurs without the undercut. The 2-point contact allows the tool to deviate in an arc without distorting the round cross-sectional profile of the pierced hole. Thus, for a given steering force at the front and/or back of the tool, a higher rate of turning is possible since a smaller volume of soil needs to be displaced.

Abstract: The invention relates to an arrangement for drilling in soil and rock while simultaneously lining the drill hole with a lining tube. The arrangement includes an asymetric guide which is non-rotatably connected to a drill stem or like element, and an eccentric drill bit or crown which is journalled for limited rotation in the guide. The guide is arranged to lie solely against a part of one side of the inner surface of the lining tube during a drilling operation. Advantageously, the guide is supplemented with a guiding portion on the shank part of the drill bit located opposite the first guide. The drill arrangement enables wide adjustments to be made to the eccentric setting of the drill bit, and makes possible an advantageous forming of the cutting geometry of the drill bit.

Abstract: An improved directional drilling tool permits the control of the angle of drilling of a drill bit through the repeated placement or removal of a ball within the mudstream. The ball activates, clutch mechanism within the directional drilling tool. The clutch mechanism, controlled by the activated valve, locks the exterior of the directional drilling sub to a fixed angular orientation and activates a deflection cam to deflect a drive shaft so as to angle the bit, causing the bit and sub to drill at a controlled angle offset from the vertical. The unit is aligned and located using wire line measuring equipment of known design. Since the sub may be controllably set in a straight line drilling or an angle drilling position, it may be left permanently in position in a drill string significantly reducing the requirement to trip out the well bore during directional drilling and significantly increasing the flexibility available to the driller to deflect the direction of drilling while drilling is in progress.

Abstract: A boring head for forming a horizontal hole for a pipe installation in the subsoil beneath a roadway and the like is provided with an electrical operable guide extending forwardly from its leading end that can be selectively elevated or lowered to change the plane of forward movement of the head through the subsoil so that the location of the hole at the end of the bore can be accurately predicted. The respective movements of the guide, upwardly and downwardly, are automatically effected in response to a battery operated electronic control system designed to sense and maintain a horizontal position and to convert any sensed deviations therefrom into appropriate signals for activating and deactivating movement of the guide. The boring head is provided with a motion detecting component operably connected to the guide so that in the absence of motion in the head, the guide is rendered immobile.

Abstract: Directional drilling is carried out with a rotary drilling tool having a drill string, a drill bit, a drill motor for rotating the drill bit independently of the drill string, and a bent sub affixed between the lower end of the drill string and the drill motor for angularly displacing the axis of rotation of the drill bit from the axis of rotation of the drill string. Both the drill string and drill bit are rotated to provide a straight path for the wellbore, while only the drill bit is rotated during the deviation of the wellbore from a straight path.

Abstract: A directional drill attached to a drill string having periodic concentric collars is advanced in an inverted arcuate path to form a pilot hole underneath an obstacle followed by a larger concentric washover pipe. When the washover pipe reaches the surface on the other side of the obstacle a first reamer is attached to the end of the washover pipe exiting the drilling path, a second reamer of smaller diameter than the first reamer is attached to the other end of the first reamer by means providing for some separation between the two reamers, and a production casing of smaller diameter than the second reamer is attached to the other end of the second reamer with a swivel. The remaining length of the first portion of casing is supported some distance above the ground on rollers located above and beyond the exit point of the pilot hole. The reamers are operated by rotating the washover pipe and simultaneously drawing the washover pipe through the pilot hole.