Abstract: Several techniques for reducing the amount of time between initiation of a terminal request through a dial-up telephone line and the actual initiation of transactions between the terminal and a host computer. By using a ring down or hotline circuit configuration dialing and call setup time can be saved. With the ring down use no login procedure is necessary to ensure secure access to the host computer. The ring generation period is shortened to just an interval sufficient to allow the host modem to recognize the ring, with the ring indication period also begin shortened. The modems can be set to fixed baud rates, but in a more preferred embodiment the terminal modem transmits the originate carrier prior to the host modem picking up the line. The host modem then senses the originate carrier quickly and provides the answer carrier. The silent interval prior to operation of the host modem is removed.

Abstract: A firing system for marine seismic sources 14 grouped and fired in subarrays 18. Each source 14 is provided with a firing circuit 30 including an energy storage device, such as a storage capacitor 32, adapted to pass firing current through the source actuator 24 in response to receiving a low power trigger signal from a source control system 28 located on the ship 16 from which the seismic survey is conducted. The firing circuit 30 corresponding to each source 14 is situated proximate the source 14. An umbilical 20 extends between the control system 28 and each subarray 18. The umbilical 20 includes a trigger signal conductor corresponding to each source, a charging conductor to which the storage capacitors of each firing circuit 30 are connected in parallel and a ground conductor.

Abstract: A method and apparatus utilizing inelastic neutron scattering for measuring the volume fractions of the various constituents of a multiconstituent substance. A source of fast neutrons is positioned proximate the substance. A detection system is provided to monitor the gamma emissions resulting from inelastic scattering of the fast neutrons from the various nuclides within the substance. The resulting measurement of the relative abundance of gamma emissions characteristic of the various nuclides within the substance is used to determine the relative concentrations of the major constituents of the substance. In a preferred embodiment, the present invention is used to provide a real-time measurement of the volume fractions of oil, gas and water in the production flowstream from an oil well.

Abstract: A releasable latch-type connector for a tension leg platform tether. A tether portion of the latch is provided with an annularly arranged set of shear lugs. The tether portion of the latch is adapted to be received within a generally cylindrical second portion of the latch. The second portion of the latch is also provided with an annularly arranged set of shear lugs. The two sets of shear lugs are arranged so that the tether portion of the latch may be inserted into the second portion of the latch and then rotated and lifted to cause the two sets of shear lugs to come into abutment, preventing further withdrawal of the tether portion of the latch. This connector is particularly well suited for securing the lower end of a tension leg platform tether to a foundation on the ocean bottom.

Abstract: Described herein are a system for securing and tensioning the tethers 12 of a tension leg platform 10 and a TLP installation method incorporating such a system. The tethers 12 preferably extend upward from the ocean bottom 16 to a position slightly below the bottom of the unballasted TLP hull 20. At least one tether tensioning tool 26 is situated within the hull 20 for lowering a tether extender 22 to each tether 12 and then biasing each tether-tether extender unit upward to tension the tether 12. The use of a removeable tensioning tool 26 avoids the need for a dedicated tensioning system for each tether 12. The tensioning system 28 of the present invention permits use of a simplified method for installing a TLP 10. Because the tethers 12 extend to an elevation which, at least initially, is below the draft of the TLP hull 20, the tethers 12 may be installed offshore prior to hull installation.

Abstract: A compliant offshore structure in which the primary restoring force to lateral displacement is provided by elongate flex elements. A gravity base is rigidly secured to the ocean bottom. A tower extends vertically upward from the base to a position above the ocean surface. A work deck is supported atop the tower. The tower is secured to the base by elongate flex elements which are arranged in an array surrounding the central axis of the structure. Each flex element has one end secured to the base and a second end secured to the tower. The flex elements permit the tower to pivot about its lower end, thus providing the tower and deck with a compliant response to environmental forces. The flex elements also support the tower above and free from contact with the base. This eliminates the need for a vertical load bearing joint between the tower and base.

Abstract: A system for supporting one end of a riser or other elongate element from a marine structure. In the preferred embodiment, a plurality of gas springs are symmetrically disposed about the upper end of a riser. The axis of compression of each gas spring is parallel to the axis of the riser. One end of each gas spring is secured to the riser and the other end of each gas spring is secured to the marine structure. Relative motion between the riser and marine structure along the riser axis is accommodated by contraction or extension of the gas springs. A gas reservoir can be provided to reduce pressure changes as the gas springs extend and contract. This reduces changes in the loading applied to the riser as the marine structure moves relative to the ocean bottom.

Abstract: An earth drilling bit incorporating a tensioned linkage type bit wear indicator. A tensioned linkage extends through the bit between a wear sensor and a device for altering the resistance of the bit to receiving drilling fluid from the drill string. On detecting a predetermined degree of wear, the wear sensor releases the tension in the tensioned linkage. This activates the flow resistance altering device, causing the flow rate and/or pumping pressure of the drilling fluid to change. The tensioned linkage passes through two intersecting passageways in the bit. A guide element is inserted at the intersection of the two intersecting passageways. The guide element routes the tensioned linkage between the two passageways.

Abstract: An earth drilling bit incorporating a bit wear indicator. The bit wear indicator includes: a sensor to detect wear at a selected point on the bit; a device for altering the resistance of the bit to receiving drilling fluid from the drill string; and, a tensioned linkage extending between the wear sensor and the flow resistance altering means. On detecting a predetermined degree of wear, the wear sensor releases the tension in the tensioned linkage. This activates the flow resistance altering device, causing the flow rate and/or pumping pressure of the drilling fluid to change. This serves as a signal that the predetermined wear condition has been achieved. The bit wear indicator can be adapted to monitor many different types of bit wear, including bearing wear in roller-cone type bits and gauge wear in all types of bits.

Abstract: An arctic offshore platform adapted for use in hydrocarbon exploration and production operations conducted in relatively shallow waters with low to moderate ice environments. The arctic offshore platform of the present invention includes one or more support legs. Each support leg includes a base resting on the ocean floor, a central support column extending upward through the base to a position above the ocean surface and a sloped-sided member seated atop the base and extending upward around the central support column to a position above the ocean surface. In installation, the base and central support column are installed and secured to the ocean floor as a unit. Following this, the sloped-sided member is secured atop the base. The sloped-sided member causes ice sheets which may impact the support leg to fail in flexure, thus reducing the overall ice loadings on the support leg relative to the loading which would exist were the sloped-sided member absent.

Abstract: A method for logging a cased well to determine the quantity and location of any barite weighted drilling fluid in the annulus between the casing and the wall of the wellbore. A tool assembly having a neutron generator and a gamma scintillation detector is used to log the zone of interest. The neutrons introduced into the well by the neutron generator convert a portion of the barium-138 in the drilling fluid to barium-137m. The magnitude of the gamma photon peak charactristic of the decayof barium-137 is used to identify the quantity of drilling fluid present in the annulus as a function of depth. This method is especially useful identifying the existence of channels in a cemented wellbore annulus.

Abstract: A tether and tether tensioning system for a tension leg platform. A plurality of elongate tethers 12 are used to secure a tension leg platform hull 20 to a foundation 14 at the ocean floor. Each tether 12 has a lower end secured to the ocean floor foundation 14. The tethers 12 extend upward to a position slightly below the bottom of the hull 20. A tether securing and tensioning system 30 is positioned within the hull 20 for each tether 12. This system includes a tether extender 22 positioned within a shroud 28 in the hull bottom. The tether extender 22 includes a tether latch 24 at its lower end. The tensioning system is adapted to lower the tether extender 22 downward below the hull 20 to permit the tether extender 22 to latch to the tether 12. The securing and tensioning system 30 then raises the tether extender 22 to tension the tether 12. The tether tensioning system of the present invention permits use of a simplified method for installing TLPs.

Abstract: A compliant offshore structure in which stabilization against excessive sway is provided by a resilient pile assemblies. A series of drive piles extend into the ocean floor beneath the base of the structure. Drive piles extend upward to a position proximate a pile attachment location on the structure a spaced distance above the ocean floor. The upper end of each drive pile is secured to the structure at the pile attachment location by a resilient coupling. The resilient coupling permits the structure to move upward and downward a slight distance relative to the substantially rigid drive pile. This accommodates sway of the structure. The resilient coupling biases the structure back to a vertical orientation in response to sway of the structure. In a preferred embodiment the pile attachment location is situated proximate the base of the offshore structure.

Abstract: A coupling 10 for connecting an elongate first member 12 to a second member 14. The first member 12 is provided with external radial fins 16. The second member 14 defines a recess provided with a number of internal radial fins 20. The first and second members 12,14 and their fins 16,20 are sized such that the first member 12 can be positioned within the recess of the second member 14 with each fin of each member extending between two corresponding fins of the other member. At least one wedge 24 is positioned in the space intermediate each set of opposing fins 16,20. The fins 16,20 and wedge 24 are configured such that biasing the first member 12 in a first axial direction relative to the second member 14 causes the wedge 24 to lock the fins 16,20 together, preventing movement of the first member 12 in the first axial direction. The present coupling 10 can be used to support the members 12,14 under either a tensile or compressive axial loading.

Abstract: The present invention is an improvement to conventional baseplates for imparting seismic energy to an earth formation. A baseplate typically has a plurality of downwardly disposed triangular prism-shaped cleats for engagement with the earth surface above an earth formation under seismological investigation. At least one leaf spring is supported about midway along its length from the lower surface of the baseplate and between the cleats. An elongate horizontal ejector member is slidably interconnected to the respective ends of the spring. In operation, as the baseplate is lowered into engagement with the earth surface the ejector member is moved upward and the leaf spring is compressed. When the baseplate is lifted upward the restoring force of the leaf spring results in a generally downward force against the ejector member.

Abstract: An articulated, compliant offshore structure having a base portion establishing a gravity-type foundation on the ocean bottom, a tower extending upward from the base portion and a deck seated on the tower a spaced distance above the ocean surface. The tower is secured to the base portion by an articulated joint which permits the tower and deck to undergo limited pivoting about the base. This provides compliancy in response to forces imposed on the structure by wind, waves and ocean currents. A set of tensioned members, preferably cables, are secured between anchorages on the base and at an elevated position on the tower to provide controlled resistance to pivoting of the tower. In the preferred embodiment the tower and base are concrete shell structures.

Abstract: A pile assembly adapted for use in a compliant piled tower. A plurality of drive piles are driven into the ocean floor in a symetric array about a central, substantially vertical axis. A flex pile is secured to the upper end of each drive pile and extends upward to a preselected elevation above the ocean floor. The longitudinal axes of each drive pile flex pile pair are laterally offset from one another with the flex piles also being arranged in symetric array about the central axis. A tie member is provided to restrain the flex piles from lateral motion relative to one another. The tie member serves to balance the moments established by virtue of the eccentric axes of the flex pile drive pile pairs. The use of eccentric axes in the pile assemblies simplifies driving the drive piles, permits the drive piles to be placed relatively far from one another to minimize pile group effects and permits the flex pile to be designed without being constrained by driving considerations.

Abstract: A complaint offshore platform in which the primary restoring force to lateral displacement is established by flex piles driven into the seafloor and fixedly secured to the platform legs a preselected distance above the seafloor. The platform includes a substantially rigid space-frame structure extending from the ocean bottom to a position above the ocean surface. A drilling and production deck is secured atop the space-frame structure. Shear piles extend through the base of the space-frame structure to prevent lateral displacement of the base while permitting the space-frame structure to pivot about its base. As the platform sways about its base in response to environmental forces, the flex piles establish a vertical couple at the location at which they are attached to the space frame structure. This couple resists movement of the platform away from a vertical orientation. In the preferred embodiment, the flex piles are secured to the platform at or near one-half the total height of the space-frame structure.

Abstract: A method useful in seismic data processing for correcting data for the effects of the low velocity layer. At least three sets of traces having common offsets are displayed as a function of centerpoint. From this, the first refraction arrival for each trace may be hand picked, this first refraction arrival representing a compressional wave refracted along the lower boundary of the low velocity layer. An equation is set up for each source-receiver pair in which the transit time of the first refraction arrival is a function of three independent factors: the source to receiver distance; a low velocity layer component for the source; and a low velocity layer component for the receiver. These equations are solved in a simultaneous, least squares fashion to yield surface consistent solutions to the low velocity layer component at each source and receiver location.

Abstract: An improved process is described for the separation and recovery of substantially all the propane and heavier hydrocarbon components in a hydrocarbon gaseous feedstream. In this process, the vapor stream from a deethanizer is cooled to liquefaction and contacted with a vapor phase from the hydrocarbon gaseous feedstream. The contact takes place within a direct heat exchanger, and the resulting vapor fraction, which is essentially ethane and methane, is the gaseous product of the process.