Abstract: A method of geophysical prospecting wherein nonhyperbolic distortion is reduced from marine seismic data, or land seismic data over a low seismic velocity layer, is disclosed. The method comprises replacing the seismic velocity of the water or low seismic velocity layer with sediment seismic velocity and using analytic ray tracing to determine a mapping function to correct recorded seismic data for removal of the distortion, which occurs because of the high seismic velocity contrast at the water or low seismic velocity layer.

Abstract: A method for simulating crosswell seismic data between first and second spaced apart wells is disclosed. According to the invention, a surface seismic source is used to generate a seismic signal at a location on the surface of the earth substantially in line with, but not between, the wells and closer to the first well than to the second well. A plurality of downhole seismic receivers are located in the first well and at least one downhole seismic receiver is located in the second well. The actual arrival time of the seismic signal at each of the first well and second well seismic receivers is recorded. For each second well seismic receiver, the actual arrival time is then compared to an estimate of the seismic signal travel time calculated on the basis of an assumed interwell seismic velocity field.

Abstract: An apparatus and a method for installing open-ended tubular members axially into the earth by simultaneously or sequentially driving, drilling, and jetting. A drilling string assembly is located inside the tubular member, but is supported independently from the tubular member. The position of the drill bit on the lower end of the drilling string assembly relative to the lower end of the tubular member may be adjusted so as to control the rate of penetration of the tubular member into the earth.

Abstract: A method for cascading or linking seismic vibrator sweeps to form a cascaded sweep sequence. According to the method, a first cascaded sweep sequence is generated containing N sweep segments linked end-to-end. The N sweep segments are substantially identical, except that the initial phase angle of each sweep segment within the sweep sequence is progressively rotated by a constant phase increment of about 360/N degrees. A second cascaded sweep sequence is generated consisting of (i) N consecutive sweep segments linked end-to-end which correspond to said first cascaded sweep sequence and (ii) an additional sweep segment linked to the N consecutive sweep segments which is positioned and phased so as to substantially suppress harmonic ghosts during correlation. One of these cascaded sweep sequences is used for the vibrator sweep sequence and the other is used for the correlation reference sequence.

Abstract: A method for processing seismic vibrator data. The method utilizes a deterministic signature deconvolution of the vibrator data to compress the impulse response of the data resulting in sharper, clearer seismic images than are possible using cross-correlation techniques. The method may be used in place of or in addition to cross-correlation. Further, the method may be implemented in either the time domain or the frequency domain.

Abstract: A method for suppressing or removing coherent noise from seismic or borehole data is disclosed. The method requires horizontal alignment of the traces, comparison of the amplitude, phase and/or shape of neighboring traces, and subtraction of traces from neighboring traces only where the local correlation is high.

Abstract: A well system, and a method for installing the well system, for use in producing hydrocarbons from a subterranean reservoir located beneath a body of water is disclosed. The well system is intended for use in conjunction with a bottom-founded offshore platform. The inventive well system eliminates the conductors traditionally used in offshore platform well systems. According to the invention, a subsea guide template and an outer casing string extending downwardly from the guide template to a first predetermined depth less than the depth of the reservoir are installed prior to installation of the offshore platform. Thereafter, the platform and the first intermediate casing string are installed, in either order. Drilling for the first intermediate casing string takes place in the open hole defined by the outer casing string with all returns of drilling fluid and drill cuttings occurring at the seafloor.

Abstract: The current invention is an improved method for preventing annular fluid flow following primary cementing of a casing string in a wellbore. The method involves injecting high pressure pulses of a working fluid into a liquid-filled casing string to produce tube waves that will propagate through the casing liquid until they encounter a casing restriction or barrier. This encounter vibrates the casing string. Vibration of the casing string helps to maintain the pressure of the cement slurry at or above the pressure of fluids in the surrounding formations, thereby preventing or reducing annular fluid flow.

Abstract: Controlled phase marine seismic subarray for use in a marine seismic array and methods for constructing such subarray are provided. A controlled phase marine seismic subarrays of the present invention are arranged to operate at a preselected depth and to provide generally downgoing (for angles of emergence from the array that are of interest) far-field pulses having phase spectra that match the phase spectrum of the vertically downgoing far-field pulse up to a ghost-notch frequency. The methods select the depth of operation and type of sources for the subarray, select a maximum number of identical elements and spacing based upon the highest incidence angle and frequency for which phase control is desired, and construct a plurality of parallel, linear, subarrays.

Abstract: Method and apparatus for generating resonant broad band pressure waves in a fluid-filled wellbore for seismic exploration. In the preferred embodiment, a device is provided in a borehole; the device comprises a cylindrical choke body and a means at each end of the choke body for partially or completely blocking off the borehole and creating a fluid-filled borehole cavity. The fluid inside the cavity is oscillated to establish a standing pressure wave of a desired bandwidth in the fluid. The standing wave is radiated through the wellbore into the earth formation and is received by seismic detectors. The fluid is oscillated over a range of frequencies to generate more information about the earth formation.

Abstract: A module model pile tool in situ testing of soils. The tool has an upper instrument section, a lower anchor section, and an axial slip joint located between the instrument section and the anchor section. The anchor section may be configured to model either open-end or closed-end piles. In the open-end configuration, a vent and vent valve are provided to vent trapped fluid during the initial stages of installation by remaining open only to a predetermined depth so as to permit formation of an undisturbed soil plug and to close in order to prevent fluids from being vented into the actual soil to be tested. The instrument section includes instrumentation for measuring axial loads, axial accelerations, pore water pressure, and total lateral pressure. Instrumentation for measuring axial displacement are included in the slip joint. The tool is rugged enough to permit installation by pile driving, and the instrumentation may be monitored both during and after installation.

Abstract: An apparatus and method for detecting seismic waves traveling in an underground formation. The apparatus includes a hydraulic pressure source, preferably a downhole hydraulic pump; a plurality of small, light-weight, flexibly connected clamping detector units having hydraulically actuated clamps; conduit means connecting the hydraulic pressure source to the detector units so that the detector units may be hydraulically clamped to a wellbore with a large force by activation of the clamps; and means for conditioning signals from the detectors. The small, light-weight detector units are securely clamped to the side of the wellbore because of the high clamping force-to-weight ratio thereby allowing high frequency signals to be detected without interference.

Abstract: A method for estimating pore fluid pressure in a subterranean formation is disclosed for use in drilling wells. A pair of velocity-effective stress relations are used to compute pore fluid pressure from velocity data. One relation applies when the current effective stress is the highest ever experienced by the subterranean formation. The second relation accounts for hysteresis effects when the effective stress has been reduced. Pore fluid pressure is found by subtracting the computed effective stress from an estimate of the overburden stress.

Abstract: Improvements in centrifugal pumps are disclosed which minimize flow recirculation effects induced by wear ring leakage flow. The improvements may be used individually or in combination and comprise deflector means attached to the impeller, diverter means attached to the casing or impeller or wear ring inducer means.

Abstract: A method for increasing the end-bearing capacity of an open-ended pile is disclosed. The method comprises first determining the quantity of granular material necessary to insure full mobilization of the available capacity of the soil at the tip of the pile. The granular material is then inserted within the pile on top of the soil column, thereby causing the column of granular material to plug or lock-up within the pile during transient loading and thus mobilize the available capacity.

Abstract: The invention relates to a method for separating two primary components of a multi-component feed stream (e.g., methane and nitrogen) in the presence of a third, freezable component (e.g., carbon dioxide) having a relative volatility less than that of either primary component. The inventive process employs both a distillation section and a controlled freezing zone ("CFZ"). The freezable component is allowed to freeze in the CFZ, and the resulting solids are collected at the bottom of the CFZ. The CFZ also produces a vapor overhead product enriched in one of the primary components and a liquid bottom product enriched in the other primary component. The solids of the freezable component are melted and mixed with the CFZ liquid bottom product to form a liquid feed stream for the distillation section which operates like a conventional distillation section, while tolerating significantly high concentrations (i.e., >0.

Abstract: Method and apparatus for generating seismic energy in offshore areas includes energy propagating means for directing energy downwardly vertically into an earth formation. A carrier contains an elongated rigid coupler means that extends from the carrier at the water level to the seat floor. A base plate may be connected to the lower end of the coupler means. The coupler means may be a section of pipe. Driving means on the carrier drives the coupler means to cause sound energy to emanate from the coupler means or base plate into the sea floor. Such means may be a hammer-type device or a vibrator-type device. Alternatively, the lower end of the coupler means or the base plate may be driven by means of a vibrator-type device to cause sound waves to emanate from the coupler means or the base plate directly into the sea floor.

Abstract: An independent modular structure for providing lateral support for the well conductors of an offshore well platform and a method for designing and using such structure are disclosed. The modular structure can be inserted into a void in the jacket of the well platform. The vertical spacing between adjacent support points on the modular structure is determined by the lateral support requirements of the well conductors. Accordingly, the design of the platform jacket may be optimized without consideration of the lateral support requirements of the well conductors.

Abstract: An improvement to a centralizer that may reduce the torque required to rotate a casing in a borehole during primary cementing is disclosed. In a first embodiment, the improvement is adapted to a bow spring type centralizer having intermediate fixed and slidable sleeves with each sleeve circumscribed by an end band. The end bands are connected to each other by a plurality of bow springs. The improvement includes interposing a sleeve bearing between each end band and its respective intermediate sleeve. The sleeve bearings may be attached to the intermediate sleeves to permit their rotation with the casing relative to the stationary end bands and bow springs. Alternatively, the intermediate sleeves may be eliminated and the sleeve bearings interposed directly between the outer surface of the casing and inner surfaces of their respective end bands.

Abstract: A threaded connection with improved fatigue-life useful for connecting adjacent sections of a pipe string subject to bending, tensile, and compressive stresses such as a drill collar string is disclosed. The connection comprises a pin member which is threadedly engageable with a corresponding box member. In the preferred embodiment, the inventive connection is designed to have bending strength ratio ("BSR") of about 3.20 or greater, and more preferably, in a range between about 3.20 and about 4.00. The preferred thread form of the connection is a V-type thread form having two flank angles of 30 degrees and a 0.038 inch root radius. Other design features may be used in combination with the threaded connection to further improve the connection's fatigue-life.