Abstract: Methods and apparatus are described for forming a window of optimum dimensions in casing wall. A window of maximum width is cut when the center line of the mill tool is located inside of the inner diameter of the casing where a maximum amount of casing is drilled away by the mill tool. A whipstock is described which deviates the mill tool outwardly so that the center line of the mill tool is in approximately this position. The whipstock then maintains the mill tool at this approximate location until a window of desired length is cut having a substantially maximum width.

Abstract: The well reference apparatus and method of the present invention includes a reference member preferably permanently installed within the borehole at a preferred depth and orientation in one trip into the well. The reference member provides a permanent reference for the location of all operations, particularly in a multi-lateral well. The assembly of the present invention includes disposing the reference member on the end of a pipe string. An orienting tool such as an MWD collar is disposed in the pipe string above the reference member. This assembly is lowered into the borehole on the pipe string. Once the preferred depth is attained, the MWD is activated to determine the orientation of the reference member. If the reference member is not oriented in the preferred direction, the pipe string is rotated to align the reference member in the preferred direction. This process is repeated for further corrective action and to verify the proper orientation of the reference member.

Abstract: A method and apparatus to affix a tool downhole in a cased wellbore, one embodiment comprising a tubular body with a slot along its length. A portion of the slot is V-shaped to accommodate a wedge with a corresponding V-shape. The outside of the tubular body has integral teeth. To set the apparatus, the wedge is driven into the V-shaped slot. This movement widens the slot and expands the diameter of the tubular body until it intersects with the casing. The teeth on the outside of the body bite into the casing wall to affix the tool to the casing.

Abstract: An orientation and locator system including a receiver sub disposed in and installed with a casing string in the borehole. The receiver sub has azimuth and depth profiles for positively locating a predetermined position within the borehole. The profiles are within the inside diameter of the casing string and do not restrict the flowbore of the casing. The orientation and locator system further includes a locator sub attached to a well tool and adapted to engage the casing receiver sub to orient and locate the well tool within the borehole for conducting a well operation. The locator sub has an alignment key and a plurality of dogs for engaging the azimuth and depth profiles, respectively. Further, the locator sub may pass completely through the receiver sub en route to another receiver sub located in the casing string further downhole. The locator sub and receiver sub are configured such that they may be engaged whether the locator sub is passing upstream or downstream through the casing string.

Abstract: The well reference apparatus and method of the present invention includes a reference member preferably permanently installed within the borehole at a preferred depth and orientation in one trip into the well. The reference member provides a permanent reference for the location of all operations, particularly in a multi-lateral well. The assembly of the present invention includes disposing the reference member on the end of a pipe string. An orienting tool such as an MWD collar is disposed in the pipe string above the reference member. This assembly is lowered into the borehole on the pipe string. Once the preferred depth is attained, the MWD is activated to determine the orientation of the reference member. If the reference member is not oriented in the preferred direction, the pipe string is rotated to align the reference member in the preferred direction. This process is repeated for further corrective action and to verify the proper orientation of the reference member.

Abstract: A junction for the intersection of a main borehole and a lateral borehole includes a main tubular having a main window with a ramp aligned with the main window and a lateral tubular adapted to be telescopingly received within the main tubular and having a lateral window. The main tubular and lateral tubular each have an orientation surface. The lateral tubular has a first position with one end partially disposed within the main tubular. The lateral tubular is telescoped into the main tubular with the end of the lateral tubular engaging the ramp which guides the end of the lateral tubular through the main window and into the lateral bore. The orientation surfaces engage to orient the lateral window with the main window and form a common opening between the tubulars.

Abstract: The reference member provides a permanent reference for the depth and orientation of all well operations and includes a body with an engaging surface for an attaching engagement to the interior surface of an existing casing in a borehole and an orienting surface for orienting well tools within the cased borehole. No sealing engagement is required with the casing. The engaging surface on the body has a first non-engaged position where the engaging surface does not engage the casing and an engaged position where the engaging surface does engage the casing which causes adequate engagement between the body and the casing to permanently dispose the well reference member within the casing. The well reference member further includes an actuation member for actuating the engaging surface from the non-engaged position to the engaged position.

Abstract: The side tracking system includes a window mill having a full diameter cutting surface and a reduced diameter tapered cutting surface and a whipstock having a ramp engaging the reduced diameter cutting surface. The materials of the whipstock have a first cutablity and the materials of the casing have a second cutability. The reduced diameter cutting surface contacts the whipstock ramp at a first contact area and the full diameter cutting surface contacts the wall of the casing at a second contact area. As weight is applied to the mill, there is a first contact stress at the first contact area and a second contact stress at the second contact area. A cutability ratio is the first cutability divided by the second cutability and a contact stress ratio is the first contact stress divided by the second contact stress. The mill cuts the casing rather than the whipstock by maintaining the product of the cutability ratio and the contact stress ratio less than one.

Abstract: An underreamer opens a borehole below a restriction that is larger than the restriction itself. The underreamer includes cutters which engage the formation by traversing outward and upward. The force pushing the cutters to the extended position is supplied by a piston built into each cutter support. Pressure acting on these pistons comes from the pressure differential between the annulus and drill string during circulation of drilling fluid. The cutters are supported on both sides of the cutting structure by arms that are supported by and in sliding contact with the body. A spring opposes the upward and outward motion of the cutter mechanism and returns the cutters to their collapsed position in the absence of differential pressure. The body of the tool incorporates by-pass ports for transmitting fluid through the tool to the remainder of the bottom hole assembly.

Abstract: A tie-back insert is installed in a primary wellbore and includes a housing which includes one or more axial bores therethrough and a lateral bore which extends laterally out the side of the housing. The lateral bore allows a liner to pass through the top of the insert, through the lateral bore and into the lateral borehole to a new producing formation. The annulus formed between the housing and the casing is sealed at the upper end of the housing by an upper packer and the lower end of the housing is sealed by stabbing into a lower packer. The upper and lower packers seal around the window cut in the casing. The axial bores allow production fluid from the primary wellbore to be transmitted through the insert to the surface of the well. The insert is placed within the primary wellbore so that the lateral bore is located and oriented adjacent the lateral borehole allowing production fluid from the lateral borehole to transmitted to the surface of the well.

Abstract: Methods and apparatus are described for forming a window of optimum dimensions in casing wall. A window of maximum width is cut when the center line of the mill tool is located inside of the inner diameter of the casing where a maximum amount of casing is drilled away by the mill tool. A whipstock is described which deviates the mill tool outwardly so that the center line of the mill tool is in approximately this position. The whipstock then maintains the mill tool at this approximate location until a window of desired length is cut having a substantially maximum width.

Abstract: A dual function drag bit is used in a method for both milling well casing or liner and subsequently drilling rock formation without the sequential removal of a milling assembly and replacement with a drilling assembly. The method employs a cutting tool that is capable of both milling steel pipe casing in a well bore and subsequently drilling rock formation outside the well bore after passing through the casing. In one embodiment an insert embedded into the surface of the cutting tool comprises at least an outer layer, such as cemented tungsten carbide, capable of milling steel casing, and at least a second layer, such as polycrystalline diamond, capable of drilling formation, the two layers being bonded together and to a carbide substrate. In another embodiment, inserts with a polycrystalline diamond cutting face for drilling rock formation are in parallel with cemented tungsten carbide cutters for milling steel casing.

Abstract: Flow control devices and associated control methods are described for use with hydraulic tools, such as those in a drill string. The described flow control device is typically incorporated into a drill string and is selectively operable in either a flow-through mode or a valve control mode. In the valve control mode, fluid pressure is increased or decreased within the drill string to selectively actuate a valve which is associated with the flow control device. In the flow-through mode, fluid pressure may be increased or decreased without operating the valve. Techniques are described for selectively moving the flow control device between the flow-through mode and the valve control mode. Wellbore fluid pressure readings provide signals to a rig operator for selectively moving the device in this manner.

Abstract: An exemplary stabilizer and torque reducer which will engage a wellbore casing and locate the drill string substantially toward the concentric center of the wellbore casing. The device is capable of being affixed to a drill string at most any location along the string and features a wear sleeve formed of two mateable semicylindrical halves. Malleable bushings are disposed between the wear sleeve and the drill pipe to prevent damage to the drill pipe. The wear sleeve presents an outer wear surface upon which is disposed a stabilizer housing having a plurality of outwardly radially-extending blades adapted to contact a surface such as surrounding wellbore casing. In use, the stabilizer housing is intended to be non-rotatable with respect to the casing when in contact with the casing, but will rotate with respect to the drill string. The housing is of a durable construction having an elastomer jacket with a reinforcing insert within.

Abstract: The side tracking system includes a window mill having a full diameter cutting surface and a reduced diameter tapered cutting surface and a whipstock having a ramp engaging the reduced diameter cutting surface. The materials of the whipstock have a first cutablity and the materials of the casing have a second cutability. The reduced diameter cutting surface contacts the whipstock ramp at a first contact area and the fill diameter cutting surface contacts the wall of the casing at a second contact area. As weight is applied to the mill, there is a first contact stress at the first contact area and a second contact stress at the second contact area. A cutability ratio is the first cutability divided by the second cutability and a contact stress ratio is the first contact stress divided by the second contact stress. The mill cuts the casing rather than the whipstock by maintaining the product of the cutability ratio and the contact stress ratio less than one.

Abstract: The mill assembly and whipstock assembly include a mill having a tapered end which engages a ramp of the whipstock assembly. The ramp includes a plurality of surfaces having different angles whereby the rate of deflection of the mill by the whipstock varies as the mill is lowered into the borehole. In particular, the ramp of the whipstock includes two surfaces having steep angles, one steep angled surface causing the mill to punch through the wall of the casing and the second steep angle surface moving the center of the mill across the wall of the casing.

Abstract: An automatic closed loop drilling system is disclosed for providing automatic directional drilling capabilities in a bottomhole assembly. The drilling system includes at least one adjustable stabilizer that varies in response to formational and drilling conditions encountered downhole. A microcontroller is preprogrammed with a desired range of formation characteristics or with a desired inclination or target area. The microcontroller compares actual sensed data with the desired data and adjusts the position of the stabilizer blades to vary the direction of drilling.

Abstract: A telemetering system is disclosed for communicating command signals to a downhole adjustable blade stabilizer, and for transmitting encoded time/pressure signals back to the surface. The command signal provides information regarding a desired blade position for an adjustable blade stabilizer. The stabilizer sets a positioning piston in response to the command signal to limit the extent of blade expansion. A position sensor is provided in association with the positioning piston to measure precisely the position of the blades. An encoded signal is generated in response to the measurement and is transmitted to the surface in a combined time/pressure format to uniquely identify the position of the blades.

Abstract: A downhole adjustable blade stabilizer is disclosed for varying the position of stabilizer blades to provide an increased ability to control the direction of drilling. The adjustable blade stabilizer includes a plurality of blades mounted in an angled track to permit axial and radial movement of the blades. The blades are driven by a piston in response to a pressure differential created by a sufficient flow of drilling mud through the stabilizer. The stabilizer blades are retracted by a spring when the pressure differential is eliminated. A positioning piston limits blade extension to a desired position. The positioning piston moves in response to a command signal, and remains in place until a new command signal is received. By maintaining the positioning piston in a locked position, the position of the blades can be reset to the prior position after the loss of pressure differential. A measuring device is provided in association with the positioning piston to enable precise measurement of blade position.

Abstract: A progressive cavity drilling motor is disclosed with a multiplicity of helically formed conduits positioned in a resilient stator. The conduits are placed between an inner wall of a motor casing and a helically formed through hole formed by the stator. The conduits are located in parallel with each of the semi circular lobes thereby reducing the thickness of the elastomer in the lobe area resulting in a reduction of the hysteresis in the elastomer that is caused by cyclic stress reversals of the stator during motor operation. The conduits additionally divert a portion of the drilling fluid through the stator conducting heat therefrom. In addition, one or more of the conduits may be utilized as a communication channel therethrough for measurement while drilling capabilities.