Abstract: In accordance with an illustrative embodiment of the present invention, a valve placed in a subsea blowout preventer stack during a production test of a well producing gas comprises a valve body containing two valve elements in series and a releasable control unit. A fluid to inhibit the formation of natural-gas hydrates can be injected into the valve body by means of a pump on the surface and through a high-pressure hose. A lateral connector fixed to the control unit is fitted in a sealed manner into a receptacle on the valve body to allow reconnection of the inhibiting fluid injection system.

Abstract: In accordance with an illustrative embodiment of the present invention, a new and improved valve system for retaining production fluids in the subsea production pipe upon disconnection of the riser from the subsea wellhead during a production test of an offshore well includes a normally closed valve releasably connected to a normally open valve. The normally open valve can be hydraulically closed from a remote control station upon disconnection of the riser in order to retain fluids in the production pipe thereabove, and when closed will hold pressure in either longitudinal direction.

Abstract: In accordance with an illustrative embodiment of the present invention, a shock limiting apparatus for mounting an instrumentality in a drill collar comprises piston and cylinder means subject to hydrostatic well fluid pressure for preventing longitudinal movement of the instrumentality within the drill collar unless a predetermined level of deceleration is exceeded, and a combination of hydraulic damping and Coulomb friction means for dissipating kinetic energy of the instrumentality in a substantially uniform manner when applied deceleration exceeds said predetermined level.

Abstract: A lubricator valve apparatus adapted for use when running wireline tools into an offshore well during a production test of the well. The valve includes a valve body having a central flow passage and a ball valve element for opening and closing the passage, hydraulically operable means responsive to surface-controlled pressure for opening and closing the ball valve, latch means for releasably holding the ball valve in both the open and the closed positions, and bypass valve means for equalizing pressures across the ball valve prior to opening thereof and arranged in the event hydraulic control of the ball valve is lost to be opened in response to pressure applied at the surface to the production pipe to provide a flow path for well control fluids.

Abstract: In accordance with an illustrative embodiment of the present invention, the respective volume flow rates of a gas and a liquid flowing in a conduit are determined by measuring the total volume flowrate, the pressure and the temperature of the two-phase mixture at first and second spaced points in the conduit, creating a pressure drop in the conduit between the first and second points, and determining the respective volume flowrates of the gas and liquid utilizing the measured values of total volume flowrates, pressures and temperatures. The invention has particular utility in well testing.

Abstract: A measuring-while-drilling system having a downhole, motor-driven acoustic signal generator includes a motor speed control circuit featuring feedback compensation which accounts for varying loading conditions on the motor. The acoustic signal generator is motor driven at speeds for imparting to well fluid an acoustic signal having phase states representative of data derived from measured downhole conditions. The motor control circuit includes circuitry which forms a phase locked loop for driving the motor at a reference phase and at a substantially constant carrier frequency producing speed in the absence of data of one logic state and also includes circuitry for temporarily changing the speed of the motor, according to a pre-programmed function, to effect a predetermined amount of phase change in the carrier signal upon data of the predetermined logic state.

Abstract: In accordance with an illustrative embodiment of the present invention as disclosed herein, a combination slip joint-safety valve tool includes telescoping mandrel and housing members, a full-opening valve on the housing member operable when closed to prevent upward flow of fluid through said members, and hydraulically operable valve actuator means responsive to contraction of said telescoping members for closing said valve and to extension of said members for opening said valve.

Abstract: In accordance with an illustrative embodiment of the present invention, apparatus for use in measuring weight-on-bit downhole during a drilling operation includes tubular telescoping members having resilient means reacting therebetween whereby relative longitudinal movement of the members is functionally relative to axial loading of a drill bit, sensor means mounted on one member and connected by linkage means to the other member for sensing the amount of relative movement, and means providing an elastic discontinuity in said linkage means for substantially isolating said sensor means from vibratory movement of said other member due to the cutting action of the bit.

Abstract: A casing pressured operated, variable orifice valve is employed as the operating valve in a single point injection well assembly with tubing pressure (fluid) operated unloading valves acting above the operating valve to provide a continuous flow system. The operating valve includes a throttling range which extends between optimum injection gas pressure levels based on the amount of injection gas pressure available at the well head to thereby increase the overall efficiency of the system. The variable orifice valve includes a pressure charged bellows and a coil spring in series to produce a linear resultant load rate which in turn cooperates with contoured closure surfaces in the valve to produce a linear relationship between orifice size and injection gas pressure. Gas is thus injected into the production column or tubing at a rate which is linearly related primarily to the casing pressure with the throttling range of the operating valve producing a broad response in the gas injection rate.

Abstract: In accordance with an illustrative embodiment of the present invention, a hollow mandrel mounted in a production string has an eccentrically disposed, lateral recess adapted to receive a measuring instrument. A plug-in contact assembly is located at the lower end of the recess and is connected to an electric cable which is fixed to the outside of the production string. The measuring instrument includes a receptacle assembly on its lower end which is fitted onto the contact assembly during emplacement of the instrument in the recess, thereby to provide in combination with the cable an insulated electric connection between the measuring instrument and the surface. The measuring instrument can be placed into, or removed from, the recess as desired, for example by means of conventional running and pulling tools that are lowered into the production string at the end of a wireline.

Abstract: In accordance with an illustrative embodiment of the present invention, a valve apparatus adapted to be incorporated in a string of tubing to permit pressure testing thereof in a well bore includes inner and outer members telescopically disposed and movable between extended and contracted relative positions, main valve means for closing the axial flow passage through said members to downward flow in response to extension of the members, and equalizing passage and valve means for equalizing pressures across the main valve prior to reopening thereof in response to contraction of the members.

Abstract: A measuring-while-drilling system has a digitally implemented motor speed control circuit for controlling a downhole, motor-driven acoustic signal generator. The acoustic generator is motor driven at speeds for imparting to well fluid an acoustic signal having phase states representative of encoded data derived from measured downhole conditions. The digital motor control circuit drives the motor at a substantially constant, carrier frequency producing speed in the absence of data of one logic state and temporarily changes the speed of the motor to effect a predetermined phase change in the carrier signal upon data of the predetermined logic state.

Abstract: In accordance with an illustrative embodiment of the present invention, a valve apparatus adapted for use in drill stem testing to apportion a pressure differential across two vertically spaced packers includes a housing mounted between the packers and having a flow passage leading from the exterior to the interior thereof, a first valve means including a spring-loaded mandrel arranged to close the passage at a preselected difference in pressures inside and outside the housing, and a second valve means that also can close the passage after a measured quantity of fluids has flowed through the passage.

Abstract: In accordance with an illustrative embodiment of the present invention, there is disclosed herein a device for anchoring downhole apparatus such as a safety valve in a tubing landing nipple, and a running tool for lowering the anchoring device at the end of a wire line into the tubing.The anchoring device comprises a body member that carries locking dogs which are shifted outwardly and engaged by the longitudinal movement of an expander mandrel. An expansible ring that is maintained on the mandrel by shear pins functions to lock the mandrel in the engaged position of the dogs. The running tool comprises a control sleeve having pivotally mounted connecting keys which remain engaged with the mandrel until the locking dogs are properly engaged and which then are released automatically from the mandrel. A safety shear pin makes it possible to free the running tool from the anchoring device in the event of incorrect anchoring of the latter and, when sheared, provides a "tell-tale" of incorrect installation.

Abstract: In accordance with an illustrative embodiment of the present invention, a subsurface safety valve assembly includes a dome precharged with a set reference pressure that tends to close the valve, and means responsive to both ambient pressure and to the pressure of a control fluid for holding the valve open under normal conditions, a decrease in either control fluid pressure or tubing pressure, or both, enabling the dome pressure to cause the valve to automatically close and shut-in the well. The valve does not employ a coil spring to cause closure, which permits installation at great depths in a well, and a narrow spread between valve opening and closing pressures.

Abstract: A control valve apparatus adapted to be positioned within a subsea blowout preventer stack for controlling the flow of fluid from an offshore well includes a ball valve element provided with the capability of cutting coil tubing typically employed in well workover and completion operations. The ball element has a cutting edge that coacts with the valve seat to shear the tubing, and a relief slot that receives the tubing during cutting to prevent the tubing from being placed in double shear. Hydraulically operable means is provided to assist in closure of the ball valve element and consequent cutting of tubing extending into the well, in case of emergency.

Abstract: Methods and apparatus for performing a drill stem test of an offshore well utilizing a pressure controlled test valve. The test valve includes a valve element having a transverse pressure area with the high pressure side exposed to the pressure of fluids in the well annulus and the low pressure side subject to the pressure of a compressible fluid medium contained within a chamber in the test valve. The pressure in the chamber is equalized with the hydrostatic head of the well fluids so that at test depth the same pressure is acting on both sides of the transverse pressure area, whereupon this pressure is confined within the chamber. Then a fluid pressure in excess of the hydrostatic head is applied to the well fluids externally of the test valve to develop a pressure difference across the valve element which causes it to shift from closed to open position.

Abstract: In the representative embodiment of the apparatus of the present invention disclosed herein, a first ported or grooved cylindrical member is coaxially disposed within a drill string for directing drilling fluids flowing through the apparatus along one or more selected flow paths .[.through.]. .Iadd.and .Iaddend.a second ported or grooved cylindrical member .[.which.]. is coaxially arranged in the drill string adjacent to the first member for rotation in a transverse plane cutting the flow paths to cyclically obstruct these flow paths. An electric motor is cooperatively coupled by a shaft to the rotatable member for driving this member at a selected speed for developing an acoustic signal of a desired frequency as the flow paths are momentarily obstructed at periodic intervals.

Abstract: In the representative embodiments of the present invention described herein, a drilling mud is circulated through a drill string at a sufficient rate to effectively operate an impeller-driven electrical generator arranged on a tool coupled in the drill string for supplying power to downhole electrical circuits and one or more downhole condition-measuring devices on the tool. By selectively controlling the flow of drilling mud past the impeller in accordance with the conditions being monitored by the condition-measuring devices, data-encoded acoustic signals are produced in the circulating fluid and transmitted to the surface for detecting and decoding as power is simultaneously supplied to the downhole system by the generator.