Abstract: Apparatus for releasably attaching a buoyant module to a submerged pipeline and for releasing the module therefrom is disclosed. The apparatus comprises a strap wrapped over the top of the module and around the underside of the pipeline and a link connected between the opposing ends of the strap. The link is breakable upon application thereto of a design tension greater than that exerted thereon by the positive buoyancy force of the module. The apparatus also comprises a sled slideably mounted on the upper surface of the pipeline, means for engaging the sled to a source of propulsion and a wedge attached to the leading end of the sled which has an inclined surface sloping downwardly from the top of the sled to the pipeline and pryably engageable with the module.

Abstract: A riser tensioner safety system for preventing damage to a floating drilling vessel in a broken cable event or an emergency disconnect of the riser is disclosed. The system uses standard pneumatic/hydraulic tensioning devices together with a safety valve which is installed in the hydraulic fluid supply line to the tensioning device. The valve is held open by tension in the riser tensioner lines. If tension drops below a predetermined level due to a broken cable event or an emergency disconnect of the riser, the valve closes rapidly preventing acceleration of the tensioner piston.

Abstract: Apparatus is disclosed for separating a multiphase liquid mixture of lighter and heavier liquids which includes a caisson into which the liquid mixture is introduced. A surge plate extends horizontally across the interior of the caisson dividing it into upper and lower sections. The lower section forms a reservoir for receiving the liquid mixture. A wier plate extends vertically from the surge plate forming a reservoir and a spillover bucket chamber in the upper section for the lighter liquid. An opening in the surge plate communicates the lower and upper section reservoirs. Means are provided for supplying liquids to the lower section reservoir and for removing the lighter liquid from the bucket chamber.

Abstract: Two adjacent riser pipes having substantially a common axis are connected by the riser connector of this invention in the manner described below.A connector box, adapted to be attached to the end of one of the pipes, has an abutment surface and adjacent to it a channel transverse to the common axis of the pipes. A locking dog fits slidably in the channel, and has a tapered surface facing the abutment surface of the box and at an angle less than 45.degree. to the direction of the channel. A connector pin, adapted to be attached to the end of the other pipe, has a flange. When the flange is in contact with the abutment surface of the box and when the locking dog is pushed towards the flange by a force applying means, the flange of the pin is held between the tapered surface of the dog and the abutment surface of the box, and the connections between the box, pin, and dog are preloaded by forces greater in magnitude than the force applied by the force applying means.

Abstract: An adjustable two-piece rope guiding device [21, 26], particularly adaptable for use on offshore guyed tower drilling and production structures [11]. On such structures it is necessary to deflect a taut guy rope [14] into a direction that may not be precisely known, or that may vary with time. Such deflection must not damage the rope by excessive static or cyclic straining or by wearing. To minimize problems of clearance within the structure the guiding is performed in two parts: (1) a permanent deflection into a direction that satisfies the foregoing clearance requirements and (2) a variable deflection occurring beyond clearance problems that completes the required total deflection.

Abstract: A hydraulically operated actuator employs multiple metal-to-metal static seals to isolate the hydraulic fluid and to isolate the actuator from surrounding contaminating (ambient) fluids. A housing contains at least two linearly spaced apart chambers. A piston reciprocates from a retracted position to an extended position (power stroke) and from the extended position to the retracted position (return stroke) in one of the chambers (hydraulic chamber). The hydraulic chamber is separated by the piston into two sections, one of which contains high pressure hydraulic fluid and the other of which contains low pressure hydraulic fluid. A first static metal seal ring unit is designed to seal first at the completion of the power stroke of the piston to isolate the low pressure hydraulic fluid section from external contaminating fluids which may be at a higher pressure.

Abstract: A method for recovering oil from a subterranean formation by alternately injecting water and fluid miscible with the oil into the formation to displace the oil is disclosed. In this method, the wells are spaced sufficiently close together, and the water and miscible fluid are injected at a rate, such that a value between 0.3 and 1.5 is obtained for a dimensionless parameter. This parameter is a ratio of viscous flow forces to gravity forces. It is equal to the total injection rate of the water and miscible fluid divided by the product of the density difference between the miscible fluid and the water, the average vertical permeability of the reservoir, the area of the reservoir to be flooded by an injection well, and the sum of the mobilities of the miscible fluid and the water at steady state around the injection well.

Abstract: A porous layer is placed on the outside of various well implements. The layer allows movement of liquid toward sites of localized low pressure and therefore prevents differential pressure stickage of the well implements on the borehole wall.

Abstract: An apparatus and method are disclosed for aligning equipment lowered from the ocean surface with a fixed subsea structure without the use of guidelines. The apparatus comprises a guide frame including primary and secondary members, a mating guide base including primary and secondary members, vertical channeling means and rotational engagement means. In the practice of the method, the frame is generally positioned above the base using known means of limited precision. Using remote means, the frame is first lowered to vertically channel the primary members into alignment, then rotated until the secondary members are engaged and finally lowered further to fully land the frame on the base.

Abstract: A method of preventing overdisplacement of propping agent particles during well treatments to hydraulically induce a fracture in a subterranean formation wherein buoyant or neutrally buoyant ball sealers are incorporated in the trailing end portion of the fracturing fluid. The ball sealers seat on at least some of the well perforations in final stages of particle injection thereby causing the surface pumping pressure to increase, signalling the end of the treating operation. This minimizes proppant overdisplacement and provides for a fully packed fracture in the near wellbore region.

Abstract: A method and apparatus for measuring the thickness of an ice sheet floating on a body of sea water is disclosed. The electrical inductance of a coil embedded in an ice sheet is measured. This inductance is solely dependent on the geometrical factors of the coil and is minimally affected by variations in salinity of the sea water on which the ice sheet is floating. The measured inductance is the actual inductance only of the part of the coil in the ice. The other part of the coil, protruding in the sea water, is shorted out by the sea water. Hence, the thickness of the ice sheet is directly related to the measured inductance.

Abstract: Apparatus for downhole storage of an electrical conductor within a drill string in a borehole. The conductor is stored as a coil in a flexible storage means. The apparatus is desirably used to eliminate the short lengths of cable and the associated connectors which are normally added with each new section of drill pipe added to the drill string. Because the device is flexible, it may be used in deviated drilling.

Abstract: To increase the energy of seismic waves transmitted by a vibrator, one or more compliant members are connected between the driver and the base plate of the vibrator. The compliance of the compliant member is such that it is substantially rigid at the natural frequency of the vibrator, and that the natural frequency of the driven load of the vibrator is in the siesmic spectrum but is higher than the natural frequency of the vibrator.

Abstract: A method for preventing annular fluid flow following primary cementing of oil and gas well casings is disclosed. Pursuant to said method the casing is vibrated so as to maintain the hydrostatic pressure of the cement column surrounding the casing at or above the pressure of the fluids in the various formations penetrated by the well until the cement has acquired its initial set. The vibration may be either continuous or intermittent. Preferably, the vibration has a low frequency. The method may include the additional step of applying pressure to the surface of the cemented annulus while the cement is curing. The vibration may be induced in several ways. For example, the casing may be vibrated by simultaneous or sequential explosions of a slow-burning black powder. Alternatively, hydraulic jars may be used to strike blows on the casing causing the casing to vibrate.

Abstract: A fairing for elongated elements is disclosed for reducing current-induced stresses on the elongated element. The fairing is made as a stream-lined shaped body that has a nose portion in which the elongated element is accommodated and a tail portion. The body has a bearing connected to it to provide bearing engagement with the elongated element. A biasing device interconnected with the the bearing accommodates variations in the outer surface of the elongated element to maintain the fairing's longitudinal axis substantially parallel to the longitudinal axis of the elongated element as the fairing rotates around the elongated element. The fairing is particularly adapted for mounting on a marine drilling riser having flotation modules.

Abstract: A thin shell pressure sensor for sensing in situ pressures in a medium in which the sensor is embedded is provided. The sensor operates on the principle that the membrane stresses near the apex of a thin shell under an external pressure load are proportional to the applied pressure. The constant of proportionality is dependent only on the geometry of the sensor.

Abstract: The instant invention is directed to shear thickening fluids which comprise a water-swellable material (clay), present in a sufficient concentration so as to be capable of forming a stiff paste upon interaction with the water used, and water wherein the clay and water are kept separated by an intervening hydrocarbon-surfactant composition. The intervening oil phase prevents the interaction between the water and the clay phases and results in a stable, nonreacting, pumpable composite until such time as the oil envelope is ruptured by application of a sufficiently high shear force. Upon such rupture, the materials interact rapidly forming a semi-rigid stiff paste. Various well-control problems, such as oil and gas with blowouts, can be controlled by use of the above-described composite. The composite is pumped down the well pipe.

Abstract: An apparatus is disclosed for minimizing the horizontal forces on an offshore arctic structure due to ice movement. The structure includes a base portion, sloped side walls and a smooth, unobstructed top portion. The structure is substantially submerged in a body of water with the top portion at or near the water surface permitting floating ice sheets which strike the side walls to flex slightly upward and advance along and over the structure without substantially destroying the overall integrity of the ice sheet. In this manner, the horizontal forces on the structure resulting from the ice sheet are minimized due to the elimination of a crushing failure mode of the ice sheet commonly associated with conventional offshore arctic structures.

Abstract: A subsea connection unit for securing an offshore structure to a marine bottom is disclosed. The unit comprises a base adapted to be positioned on the marine bottom and an insert member adapted to be connected to the lower end of the offshore structure. The base has a recess thereon adapted to receive the insert member. Releasable vertical latch means comprised of a plurality of tapered shear blocks are carried by the insert member and cooperate with tapered lugs in the recess to lock the insert member against vertical movement within the recess. Releasable horizontal latch means comprised of a plurality of wedge members are positioned on the base around the recess and cooperate with load surfaces on the insert member to center and lock the insert member against horizontal movement within the recess.

Abstract: The invention relates to a marine seismic source which emits an FM signal linearly increasing from 10 Hz to about 100 Hz. The source has a number of transducers which are flexible sleeves containing a pulsing hydraulic fluid.