Abstract: A drill bit comprises a shank member (31), a bit body (32) provided with cutters (33) and flexible material (35) between the shank (31) and the bit body (32) allowing relative tilting movement therebetween to reduce adverse effects caused by vibration of the bit. In other embodiments, flexible material is provided between the bit body and the cutters. In further embodiments, the flexible material may be provided in a tiltable sub-assembly for incorporation in a drilling above the drill bit. An apparatus for simulating drilling conditions is also provided.

Abstract: A core sampler, particularly for oil prospecting, including a coring bit (2), an outer barrel (3) for rotating the coring bit (2), and an inner barrel (5) for receiving the core sample (7) in its internal space (8) during coring, the inner (5) and outer (3) barrels being substantially coaxial, and further comprising an intermediate barrel (15) coaxially arranged between the inner (5) and outer (3) barrels and defining a first longitudinal coring fluid channel (16) with the outer barrel (3), and a second longitudinal coring fluid channel (17) with the inner barrel (5), as well as said longitudinal channels (16, 17) and valving for at least temporarily selectively causing and/or cutting off coring fluid communication between the rear end (17B) of the second longitudinal channel (17) and/or the rear end (16B) of the first longitudinal channel (16) and/or the rear end (8B) of the internal space (8).

Abstract: Drilling fluids are designed for drilling and cementing through shallow water flows and unconsolidated formations. Such drilling fluids utilize hollow microspheres to increase the volume of the drilling fluid without adding too much weight to the drilling fluid. The drilling fluid is also designed to employ an admixture of silicate, high surface area fibrous material, deformable graphite particles, and an activatable cementitious material to stabilize unconsolidated formations and form a tough filter cake that will bond with the cement casing.

Abstract: The invention relates particularly to sensing devices and techniques which may be used to provide measurement data to aid an inertial navigation system, or attitude and heading reference system, and so bound the growth of errors which increase with time in such systems when operating autonomously. In one aspect, the invention relates to a method of determining the path length along a borehole from a known reference point to a probe or tool which progresses through a drillpipe or tubular string, to provide data to aid an inertial navigation system. A sensing device 15 is used to detect joints 11 between sections of drillpipe or tubular string within the borehole and the path length is determined from the number of joints detected and a known length of each section of drillpipe or tubular string. In another aspect, a flow measuring device, such as an impeller, is used to measure the velocity of the probe or tool through the drillpipe or tubular string.

Abstract: A core sampler, particularly for use in oil prospecting, including a flexible movable ring (5), provided in particular at the front end (2) of the core sampler, which end is connected to a coring bit (3), for grasping a core sample (C) to be brought to the surface. The ring has a cylindrical internal surface (6) to be clamped around the core sample (C), and a frustoconical external surface (7) tapering towards the front end (2). In the end or starting position, the ring (5) is exposed to zero or minimal strain from the bearing surface (12) and has an internal diameter no smaller than the outer diameter of the core sample (C) to be grasped. The core sampler (1) comprises control mechanism for longitudinally moving the movable ring (5) from the end starting position to an end clamping position. A flexible sleeve (15) is advantageously substantially coaxial with the movable ring (5) and engages the side thereof opposite the front end (2) of the core sampler (1).

Abstract: A borehole survey is conducted at a drilling site S by a so-called Interpolated In-Field Referencing (IIFR) method in which: (a) absolute local geomagnetic field data is obtained by spot measurement of the earth's magnetic field at a local measurement site R which is sufficiently close to the drilling site S that the measurement data is indicative of the earth's magnetic field at the drilling site S but which is sufficiently remote from the drilling site S that the measurement data is unaffected by magnetic interference from the drilling site and other man-made installations; (b) time-varying geomagnetic field data is obtained by combining the absolute local geomagnetic field data with data indicative of variation of the geomagnetic field with respect to time obtained by monitoring variation of the earth's magnetic field with respect to time at a remote monitoring site P1, P2; (c) downhole magnetic field data is obtained by monitoring by means of a surveying instrument the magnetic field in the vicinity of th

Abstract: The present invention is directed to an oil-free, water-soluble, liquid, polymer dispersion for use in thickening aqueous mediums, particularly completion and workover fluids used in the oil and gas drilling business. The dispersions of the present invention are comprised of hydroxyethyl cellulose and propylene glycol derivatives, preferably both propylene glycol polyether polyols and an aliphatic propylene glycol ether. Optionally these dispersions include water. Because of their low toxicity, these dispersions are particularly useful for drilling in offshore environments. These compositions rapidly disperse in and viscosity a variety of brines, including sea water and other light brines, with minimum shear and without fisheye formation.

Abstract: An improved technique to more accurately calculate pore pressure of sedimentary rock due to subsurface fluid expansion. The technique is built upon a combination of known force balanced in situ loading limb mineralogical stress/strain relationships with locally variable unloading stress/strain relationships. In stress/strain space, the material properties governed loading limb is an upper limit for the many possible unloading limbs. A method for relating these different natural stress/strain paths and applying the correct path to calculate pore fluid pressure from in situ force balance is disclosed. This method preferably calibrated with in situ stress/strain data which allows for a lithologic sealing caprock to be identified and the locally prevailing in situ unloading limb stress/strain relationship to be estimated. The forced balance loading and unloading calibrations are applied to more accurately determine well casing depths using either wireline or real-time measured while drilling petrophysical data.

Abstract: A dry mix additive, which is used to form a clay-free, i.e., non-argillaceous, inorganic salt-free, i.e., non-brine, biodegradable and chemically degradable aqueous-based wellbore fluid, which is capable of imparting non-Newtonian, pseudoplasticity and fluid loss controlling properties to aqueous systems for use in horizontal directional drilling, finding utility in horizontal environmental well installation for soil and groundwater remediation. The dry mixture comprises (1) from about 80-90 by weight of pre-gelatinized corn starch heteropolysaccharide, and (2) from about 10-20 by weight of a synthetic biopolymer such as Xanthan gum treated with a dispersing agent (glyoxal) for ease of dispersion. Sodium hypochlorite can be added, if desired, to the wellbore fluid to provide resistance to bacterial attack. The dry mixture is added to either fresh water or acidic water in amounts of 12-15 pounds of the dry mixture to a barrel (42 U.S.

Abstract: A downhole sensor sub is provided in the lower end of a drillstring, such sub having three orthogonally positioned accelerometers for measuring vibration of a drilling component such as the drill bit and/or the bottom hole assembly (BHA) along the X, Y and Z axes. The lateral acceleration is measured along either the X or Y axis and then analyzed in the frequency domain as to peak frequency and magnitude at such peak frequency. Backward whirling of the drilling component is indicated when the magnitude at the peak frequency exceeds a predetermined value. A low whirling frequency accompanied by a high acceleration magnitude based on empirically established values is associated with destructive vibration of the drilling component. One or more drilling parameters (weight on bit, rotary speed, etc.) is then altered to reduce or eliminate such destructive vibration.

Abstract: An improved technique to more accurately calculate pore pressure of sedimentary rock due to subsurface fluid expansion where the technique is built upon a combination of known force balanced in situ loading limb mineralogical stress/strain relationships with locally variable unloading stress/strain relationships, including that in stress/strain space, the material properties governed loading limb is an upper limit for the many possible unloading limbs; also, a method for relating these different natural stress/strain paths and applying the correct path to calculate pore fluid pressure from in situ force balance is disclosed such that the method is preferably calibrated with in situ stress/strain data which allows for a lithologic sealing caprock to be identified and the locally prevailing in situ unloading limb stress/strain relationship to be estimated, where the forced balanced loading and unloading calibrations are applied to more accurately determine well casing depths using either wireline or real-time "

Abstract: A method is disclosed for correcting for the distorting effect of cross-axial magnetic interference on the readings of a well survey tool using a reduced number of measurements and measuring locations. A well survey tool connected to a drill string assembly measures the gravitational and distorted terrestrial magnetic fields at two or more axially displaced locations in an axially extending well bore. The measurements are made from two or more different orientations (tool faces) of the tool about the well axis. Initial values for the tool inclination, azimuth and tool face angle are first determined without correction for the cross-axial magnetic interference introduced by the drill string assembly and the survey tool. Measurements made at each location and tool face are referred to the toots coordinate system and variations introduced by the different tool face angles are used to estimate the cross-axial interference. The estimated interference is used to improve the estimate of the azimuth.

Abstract: A single trip tool and method for cutting a subsurface window through a well casing and installing an anchoring and orienting sleeve in the casing adjacent the window for subsequent downhole well procedures and equipment installation. A mill held in position within the casing by a hydraulic and weight-set tubular anchor sleeve is used to cut multiple vertical slots in the casing wall to form a single, large window. An indexing mechanism controls circumferential placement of the mill to ensure contact between adjacent slots. The mill is supported for rotation and longitudinal movement by a carriage mount that advances along dual sloping rails causing the mill to form an increasingly deeper cut during its initial cutting movement. Following formation of the window, the mill is retrieved leaving the anchoring sleeve in place for subsequent well procedures. A second embodiment anchors and orients the cutting assembly with an internally contoured coupling that is part of the casing string.

Abstract: A diverting tool having a deflecting surface is equipped with an anchor that secures the tool at a desired subsurface location within the casing of a primary well bore to divert drilling equipment used to drill a lateral bore. An annular cup-type seal on the tool seals with the casing. A passage through the tool permits fluid bypass across the seal as the tool is lowered through the casing. The passage is closed from the well surface when the tool is anchored. After the lateral bore is drilled, the tool is used to divert a liner into the lateral bore. The upper end of the liner extends into the casing where it is centralized. The liner is cemented in the lateral bore and in the casing with the cement placed to effect sealing of the intersection of the liner and casing. A tubular mill removes the cement and liner from the casing above the diverter tool leaving a flush opening from the casing into the liner.

Abstract: Bit instrumentation and method for controlling drilling are disclosed that include multiple resistivity sensors 5B and accelerometer sensors 4 disposed within an insert portion 1B of the drill bit 1. The resistivity sensors have a beveled portion to provide an interference fit with a cavity formed within the insert portion 1B of the drill bit. Resistivity sensors 5B may be used to determine the motion of the bit 1 within the wellbore 106 including unstable bit operation such as bit whirling and bit tilting. As well, accelerometer sensors 4 may also be provided in conjunction with the resistivity sensors 5B to provide information concerning motion, accelerations and stresses applied to or within the drill bit 1.

Abstract: Method and device for detecting and/or measuring at least one geophysical parameter from a core sample (1), in particular in the oil sector, comprising, during an operation of core drilling with a sampler (2); arranging, substantially fixed relative to the sampler (2), a sensor (3) for detecting and/or measuring said parameter, directly downstream of the exit orifice (5) of the sampler (2) relative to the direction of withdrawal of the core sample (1), in the vicinity of the withdrawal path of the core sample (1), detecting and/or measuring values of the parameter at at least one location on the core sample (1) while the latter is being withdrawn from and/or moved back in the sampler (2), and processing of the detected and/or measured values of the parameter, in order to store them in memory and/or use them immediately.

Abstract: A centralizing tool for use in drilling an earth borehole. Drilling fluid pressure extends contact members radially from the tool into engagement with the borehole walls. A timing wheel engages each of the contact members to coordinate their radial movement. A fluid driven tubular central piston extending through the timing wheel causes the wheel to rotate as the piston is moved axially through the tool. High fluid pressure drives the contact members radially outwardly and moves the piston axially to compress a central coil spring surrounding the piston. Reduction of the drilling fluid pressure allows the spring force to return the piston to its initial axial position which rotates the timing wheel to retract the contact elements.

Abstract: A joint of tubular casing with a pre-formed window in its sidewall has a tubular sleeve fixedly attached to the interior of the tubular casing by a plurality of shearable set screws. The exterior surface of the sleeve is sealed to the interior surface of the tubular casing on opposing sides of the window. The window is filled with a fluid, and then the window is covered with one or more layers of a composite material such as fiberglass. In use, the joint of tubular casing is run down to the depth of interest in an earth borehole, and then the window is oriented with respect to the formation of interest at the depth. The joint of tubular casing is then cemented in place, after which the tubular sleeve is retrieved by the use of a fishing tool, causing the set screws to shear upon the upward movement of the fishing tool. After the interior sleeve is retrieved, a whipstock is lowered into the cased borehole, until it is oriented and anchored therein.

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: 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 while drilling. An inclinometer is positioned below the drill motor and within a sealed cavity of a housing fixed to a drill motor sub, and a transmitter within the sealed cavity forwards acoustic or radial wave signals to a receiver provided in a measurement-while-drilling tool. The MWD tool may be provided within a non-magnetic portion of the drill string, and further houses an accelerometer for sensing borehole direction. Both borehole inclination and directional signals are transmitted to the surface by the MWD tool, and the drilling trajectory is altered in response to the signals.