Abstract: Improved techniques are provided for drilling a deviated borehole through earth formations utilizing a rotary bit powered by a drill motor, and for obtaining information regarding the borehole or earth formations. A sensor permanently positioned in the drilling string between the drill bit and the drill motor detects a downhole parameter. An MWD tool may be provided within a non-magnetic portion of the drill string for receiving and transmitting a sensor representative signal to the surface. The sensor signal allows the drilling operation to be altered, and highly reliable and near-bit information thus improves the drilling operation.

Abstract: Control structure for extending and retracting at least two stabilizing arms (2) in a drill or core device, in particular stabilizing arms (2) in a drill or core bit (3), each arm (2) having an extremity pivoted around an axis (6) parallel to the axis (4) of the drill bit, comprising, per arm (2), a piston (8) provided for pivoting the arm (2) around said axis (6) so that it takes the arm to two extreme positions, a first position wherein it is housed in the bit (3) and a second position wherein it projects with respect to this bit. The control structure (10) and synchronization means (11) are provided respectively for displacing the pistons (8) under the influence of the drill fluid and for making the pistons (8) act substantially simultaneously in the same direction and to the same amplitude.

Abstract: A keyless latch assembly automatically aligns and fixes the axial and circumferential position of a whipstock within a surrounding casing joint. Alignment and fixing of the whipstock ensures proper engagement and orientation of a drill bit relative to an access window formed in the casing wall. Spring loaded latches in the assembly register with and extend into corresponding receiving recesses formed on the inner surface of the casing joint. The recesses, which are spaced circumferentially around the interior of the casing joint, contain differing profiles that uniquely mate with corresponding profiles on the latches. The position of the latches relative to the recesses determines the amount of radial latch movement which controls the anchoring and orientation of the assembly within the casing. Confirmation of correct axial location and proper circumferential orientation may be made by surface monitoring of the setting string weight and turning torque.

Abstract: A drag bit having a plurality of blades or ribs on its end face has one or more pockets milled into the top surfaces of said blades. A tungsten carbide button or insert is positioned at the gauge diameter to reduce impact on the gauge diameter cutter in each of the fibs. The tungsten carbide button extends to the borehole gauge diameter to stabilize the bit within the borehole to limit bit whirling. The tungsten carbide button extends just forward of at least the final cutter assembly with respect to the direction of bit rotation to take the impact instead of the cutters. An additional tungsten carbide button or a shaped cutter is used along the blades in line with PDC cutting assemblies for limiting the penetration of the PDC cutting assemblies to thereby limit bit whirling or tilting instabilities.

Abstract: A method and combination of materials for freeing stuck pipe involves first the spotting of a clear brine, preferably calcium chloride, calcium bromide or zinc bromide, or mixtures thereof, for a given period of time, preferably at least about 8 hours, in the stuck region of the pipe, followed by the spotting of a spotting agent selected from wetting agents, surfactants, lubricants, or mixtures thereof, in the region of the stuck pipe.

Abstract: Apparatus for steering a drill bit at the end of a drill string within the borehole to selectively effect drilling along either a curved path or a substantially straight path comprises a first downhole motor assembly coupled to the drill bit and operable to rotate the drill bit to effect drilling, the assembly being arranged to angularly tilt the rotational axis of the drill bit relative to the axis of the section of the borehole being drilled, and a second downhole motor coupled to the first motor assembly to the drill string and operable to rotate the first motor assembly.

Abstract: A sacrificial anode sub and method are disclosed which provide a lower voltage at the proximately located bit than at the sacrificial anode disposed on sub to thereby deter bit balling. An electromotive force (emf) dynamo is built into the sacrificial anode sub to provide a direct current voltage source for this purpose. Annular insulator electrically insulates sacrificial anode from tubular body. An electrical connection to drill bit is made through threaded lower connector with bit. Impeller rotates in response to drilling fluid flow to rotate the rotor assembly of dynamo.

Abstract: Methods and apparatus for detecting the approach of a boundary stratum while drilling in a substantially horizontal subsurface zone using sensor tools having sensors with different depths of investigation. The two depths of investigation signals are used to reduce spurious signals. In some cases, dips or angles of the boundary strat with the borehole may be determined. In alternative embodiments, one or more electromagnetic energy transmitters are used with a single receiver pair to generate a characteristic signature of approaching boundary stratum.

Abstract: The present invention discloses a core bit comprised of a body having blades thereon, with several cutters on each blade, and nozzles that emerge on the face of the body. The nozzles deflect liquids substantially obliquely with respect to an axis of rotation of the body, preferably according to an angle greater than 45.degree.. The nozzle defines an elbow portion formed from a molded portion of the body and from an insert opposite said molded portion on the side of the largest curvature of radius of the elbow. An inner hollow core retaining element includes an axial annular lip to engage an annular groove in the body. The annular lip and groove define a passage gap to regulate coring liquid flow therethrough. An inner portion between the blades has a cross-section with a curve having a most forward point adjacent the core, the curve having a first convex portion from the forward point to adjacent the insert and a second convex portion extending laterally outwardly.

Abstract: A trench is excavated from the top surface of an earthen dike, all the way down into the foundation below the base of the dike. Dry powder, partially hydrolyzed polyacrylamide (PHPA) is mixed with fresh water and soda ash in proportions of 20 lbs PHPA, to 4 lbs of soda ash, to 68 barrels of fresh water (2856 gallons) to form a slurry having a funnel viscosity of at least 45 sec/quart. As the trench is being excavated, the slurry is pumped into the trench immediately. A section of geo-membrane having a thickness of 0.080" is placed in the trench all the way to the bottom of the trench, overlapping at the top of the membrane onto the top surface of the dike. Dry sand is then pumped into the trench to displace the slurry in the trench.

Abstract: A drag bit having a plurality of blades or ribs on its end face has one or more pockets milled into the top surfaces of said blades using a ball-nosed end mill to create a plurality of pockets, each having a spherical or a semi-spherical first end and a second end having a semicircular configuration that intersects with the leading edge face of the rib. A bullet-shaped cutting structure having a spherical first end is brazed into each of the pockets. During the manufacturing process, a pin is brazed into cooperating first and second semicircular receptacles in the spherical end of the cutter and in the semi-spherical end of the pocket, respectively, to prevent the cutter assembly from being pushed up out of the pocket during the drilling operation. In an alternative embodiment, a slot is milled into the top surface of the rib to allow use of a ball-nosed end mill having a reduced diameter shank sized to pass through the slot.

Abstract: A stabilizer-type downhole tool comprises an elongate main body. At least one elongate blade lying generally longitudinally along the exterior of the main body projects radially outwardly therefrom. Attachment means cooperative between the main body and the blade removably retain the blade on the main body so as to permit limited relative longitudinal movement between one end of the blade and the adjacent portion of the main body without necessitating corresponding movement at the other end of the blade. The main body may comprise an instrument-receiving cavity beneath the blade, and an elongate instrument in a sealed housing may be disposed in the cavity, with its ends retained with respect to the adjacent portion of the main body without necessitating corresponding movement at the other end. At least one of the housing ends is so retained as to permit relative longitudinal movement with respect to the main body.

Abstract: A method and combination of materials for freeing stuck pipe involves first the spotting of a clear brine, preferably calcium chloride, calcium bromide or zinc bromide, or mixtures thereof, for a given period of time, preferably at least about 8 hours, in the stuck region of the pipe, followed by the spotting of a spotting agent selected from wetting agents, surfactants, lubricants, or mixtures thereof, in the stuck region of the pipe.

Abstract: Improved techniques are provided for drilling a deviated borehole through earth formations utilizing a rotary bit powered by a drill motor, and for obtaining information regarding the borehole or earth formations. A sensor permanently positioned in the drilling string between the drill bit and the drill motor detects a downhole parameter. An MWD tool may be provided within a non-magnetic portion of the drill string for receiving and transmitting a sensor representative signal to the surface. The sensor signal allows the drilling operation to be altered, and highly reliable and near-bit information thus improves the drilling operation.

Abstract: A grouting composition comprised of (a) 84-95 % by weight of granular water-swellable sodium-based bentonite, (b) 1-8 % by weight of finely divided salt-water hydratable sepiolite, and (c) 4-8% by weight of a clay stabilizer. The grout composition which contains no organic polymeric substances is mixed with fresh water to provide a pumpable, rehydratable, and easily applied grouting slurry. The slurry admixture will form a solid seal with low hydraulic conductivity and high structural stability. The grouting composition is useful for sealing the annular space around a well casing and plugging abandoned wells in practically all types of formations. A preferred grouting compostion comprises 88-90% by weight of granular sodium bentonite, 6-7% by weight of sepiolite, and 4-5% by weight of granular ammonium sulfate.

Abstract: An electromagnetic wave propagation well logging system for measuring dielectric constant and/or formation resistivity (conductivity) includes three transmitters and a pair of receivers. The receiver pair is connected to circuitry that measures the amplitude ratio between the receivers, as well as the phase angle difference between the receivers. Signals representative of the detected amplitude ratio and of the detected phase angle difference are combined in such a manner as to make the depth of investigation controllable. Methods are also disclosed for maintaining a common depth of investigation as the well logging instrument traverses the earth borehole.

Abstract: Coring apparatus and method are disclosed which provide for hydraulic latching of an inner core barrel within an outer core barrel. The apparatus includes a valve face disposed around the inner core barrel and valve seat disposed around the bore of the outer core barrel that close to form a restriction in the drilling fluid flow path. A hydraulic differential force is thereby created which holds the inner barrel in place. Axially oriented bores in a hanger assembly and in stabilizers are disposed along the inner core barrel to provide a flow path for the drilling fluid after the restriction is formed. The bores are calibrated to produce a pre-determined hydraulic force on the inner barrel. A bearing assembly is used to prevent transmission of outer barrel rotation to the inner core barrel. The outer surface of the bearing assembly forms the valve face so as to form the drilling fluid restriction and also provides an axial stop that prevents further axial movement of the inner barrel towards the core head.

Abstract: A drag bit having a plurality of blades or ribs on its end face has one or more pockets milled into the top surfaces of said blades using a ball nosed end mill to create a plurality of pockets, each having a spherical or a semi-spherical first end and a second end having a semi-circular configuration which intersects with the leading edge face of the rib. A bullet-shaped cutting structure having a spherical first end is brazed into each of the pockets. During the manufacturing process, a pin is brazed into cooperating first and second semi-circular receptacles in the spherical end of the cutter and in the semi-spherical end of the pocket, respectively, to prevent the cutter assembly from being pushed up out of the pocket during the drilling operation. In an alternative embodiment, a slot is milled into the top surface of the rib to allow use of a ball nosed end mill having a reduced diameter shank sized to pass through the slot.

Abstract: For steering a drill bit, a trajectory control sub has a lower part adjustable relative to the upper part to produce an axial bend to angularly offset the drill bit so that drilling proceeds along a curved path. Adjustable stabilizer blades are mounted on the sub and are movable between extended positions and retracted positions. An actuator is provided which selectively maintains the drill bit in axial alignment with the section of borehole being drilled, and which is actuable to move the blades into their retracted positions and subsequently, with the blades in their retracted positions, to effect tilting of the lower part relative to the upper part to produce the axial bend leading to tilting of the drill bit.