Abstract: Measurements of reservoir characteristics of a core sample of a subsurface formation are carried out with the core sample being subjected to pressure cycling. Pore volume changes during such pressure cycling are measured. Pore compressibility is determined from a plot of the measured pore volume change versus pressure. Scanning of the core sample with X-rays each pressure cycle identifies the pressure at which fracturing is initiated.

Abstract: A seismic marine survey is carried out by traversing a line of exploration with an acoustic energy source, an array of spaced-apart receivers, and a recording system. A plurality of receivers along the receiver array are selected and the maximum amplitude wavelets of the seismic reflection signals recorded from such receivers are compared to identify any trend in a select seismic survey parameter.

Abstract: Core samples are obtained from a plurality of differing depths in a subterranean formation. The samples are dried to effect an evaporation of the water content, leaving behind a salt precipitate. The dried samples are weighed. The salt precipitate is then leached out of the samples and the samples are again weighed, the difference in such weighings identifying the amount of salt precipitate. Alternatively, the salt content can be more accurately determined by chemical analysis of the leached solution. A measurement is made of the pore volume of the samples. From the measured weights of salt precipitates and sample pore volumes, the salt content in mass per unit volume is determined for each sample. Such salt content is plotted versus formation depth from which the core samples were taken. Trends in such plotted salt content are used to identify fluid characteristics of the formations at the in-situ reservoir conditions of pressure and temperature and at the in-situ wettability state of the reservoir.

Abstract: Hydrocarbons are produced from a subterranean reservoir by maintaining the effective reservoir pressure below the reservoir crushing pressure during a first production period, causing the effective reservoir pressure to exceed the reservoir crushing pressure after such first production period so as to crush the reservoir and reduce the reservoir permeability, and then producing hydrocarbons from the reservoir during a second production period in which hydrocarbon production is enhanced due to better sweep efficiency as a result of the lowered permeability of the reservoir.

Abstract: A bender acoustic transducer has a flat, piezoelectric element affixed to a flat, elongated inert element. The ends of the inert element are hinged on a supporting rectangular frame which has a rectangular opening. Two sides of the elements are exposed so that when a voltage is applied, a dipole acoustic wave is generated by the transducer.

Abstract: A core sample of a porous media of identified porosity at atmospheric conditions is saturated with a fluid having an identified X-ray attenuation coefficient. The fluid saturated sample is scanned with X-rays. Confining stress is applied to the sample and the sample is again scanned with X-rays. Porosity of the sample at confining stress is then determined from the porosity at zero confining stress, the X-ray attenuation coefficient of the saturating fluid, and X-ray attenuation coefficients determined from the scanning of the sample at both atmospheric conditions and at confining stress. Pore volume compressibility is determined from the changes in porosity and X-ray attenuation coefficients from atmospheric to confining stress conditions.

Abstract: A borehole logging tool is rotated within a borehole and also advanced along the borehole. A log of the formations surrounding the borehole is recorded. An interval of the borehole intersected by a formation fracture is identified on the recorded log. The fracture dip angle and dip direction are determined from the location of the center of the fracture with respect to the borehole and the peak amplitude and phase angle of the recorded borehole signal at the fracture location.

Abstract: In a well logging system that is subjected to high temperatures and pressures, an improved thermos flask pressure housing is used to insulate sensitive electronic circuits to the detrimental effects of high temperature and extreme pressure. An evacuated area between an inner shell and an outer shell acts as insulation between electronic circuits within such inner shell and the borehole environment surrounding such outer shell.

Abstract: A fluid filled marine seismic streamer employs a plurality of hydrophones spaced apart along its length to detect seismic reflection signals from subsurface formations below a water layer. A plurality of fluid blocking members are also spaced apart along the length of the streamer. A plurality of flow through spacers having varying flow through apertures are positioned between each hydrophone adjacent to a fluid blocking member that generates pressure pulses in the fill fluid of significant magnitude to be detected by such hydrophone. The size of the flow through apertures of such spacers progressively increases in a direction leading from the fluid blocking member toward the hydrophone.

Abstract: A hosewall terminating apparatus for a streamer section utilizing a load bearing flexible hosewall includes an inner sleeve having radially extending outward protrusions and an outer sleeve having radially extending inward protrusions. With the inner sleeve positioned within the outer sleeve, the radial distance between ends of these protrusions are spaced-apart to provide a gap for the position of the flexible hosewall of the streamer section. The hosewall of the streamer section is secured between these protrusions and the sleeve surfaces when the outer sleeve is reduced in diameter by swaging.

Abstract: A wellbore drill string is formed of a plurality of sections of drill pipe interconnected at tool joints with a drill bit at its lower end. A drilling fluid is circulated down the drill string and up the annulus between the wellbore and the drill string. A plurality of annulus reducers located at spaced-apart positions along the drill string impart a cyclical pumping action to the flowing drilling fluid. During drilling, the drill string is axially reciprocated and an extension capability to the drill string maintains continuous weight on the drill bit.

Abstract: A low-resistivity, hydrocarbon-bearing subsurface sand formation is logged with an electric logging system. Measurements are taken of formation porosity, water resistivity and formation resistivity. Core samples are taken from the formation water and electrical measurements are made on such core samples that reflect both a free-fluid pore network conductance and a rock matrix conductance. From the measurements, a formation water saturation corrected for rock matrix conductance is determined.

Abstract: An acoustic transmitter for borehole logging includes a flexure disc acoustic source affixed to one end of an open-ended pipe. A rubber boot surrounds the pipe and flexure disc source and fluidly isolates them from the surrounding borehole fluid. Oil fills the rubber boot and pipe, such that the borehole fluid pressure is transmitted through the rubber boot to the oil. The flexure disc source is electrically excited to cause the transmitter to generate acoustic energy tube waves at one of the resonances of the flexure disc source within the seismic frequency range.

Abstract: A method for removing bias difference between two or more similarly operated magnetometers is disclosed wherein the inherent bias difference due to the magnetic field of the towing vessel is removed without determining its relative magnitude. Magnetic data is gathered and all time related magnetic events except bias level and slope of the time related magnetic events are removed by mathematical adjustment. Point by point statistical analysis is performed to remove the bias level and the time related slope.

Abstract: A marine seismic streamer employs a plurality of sections connected together sequentially with fluid blocking connectors. Each section contains a plurality of groupings of hydrophones with the hydrophones within each grouping connected together to provide a single seismic signal output for such groupings. The two terminal groupings of each section have variable hydrophone densities along their lengths so as to discriminate against noise generated in the streamer by the action of the fluid blocking connectors in producing pressure waves in the fluid fill within the streamer.

Abstract: A borehole televiewer logging tool employs a transducer assembly having a transmitter of acoustic energy pulses and a receiver of acoustic energy pulses representing reflections of the transmitted acoustic energy pulses from the walls of a borehole traversing a subsurface formation. The transducer assembly is rotated within the borehole and also advanced along the borehole. The received reflection signals are corrected for amplitude modulation resulting from oblique angles of incidence of the transmitted acoustic energy pulses when the logging tool is off-center of the borehole, is in an eliptical borehole, or is tilted from the vertical axis of the borehole. The corrected reflection signals modulate an image display so that the full 360.degree. of the borehole wall can be delineated.

Abstract: A method is disclosed for obtaining shear wave data from common depth point gathered compressional wave traces using variations in the amplitude of the gathered compressional waves with source-receiver offset. The shear wave data can be used to generate pseudo-shear wave seismic sections.

Abstract: A spacer for a marine seismic streamer employs a compliant material that mechanically isolates the spacer from the hosewall and strain members of the streamer and also allows the flow of fill fluid therethrough so as to prevent pressure pulse build-up in such fluid during towing of the streamer along a line of exploration.

Abstract: A core sample invaded by drilling mud is scanned with X-rays and computed tomographic images are produced. The images are calibrated to a density scale based on the barite content of the drilling mud. The mud solid volume in the pores of the core sample are determined from the density contrast created in the computed tomographic images by the presence of barite in the core sample. This mud solid volume is used to provide a corrected porosity measurement on the core sample.

Abstract: Directional drilling is carried out with a rotary drilling tool having a drill string, a drill bit, a drill motor for rotating the drill bit independently of the drill string, an extension sub having both axially contracted and axially extended positions for providing weight to the drill bit when moving from a contracted to an extended position so as to effect a drilling stroke by the drill bit into the wellbore bottom when drilling with the drill bit independently of rotation of the drill string and a relaxation device for removing any excess weight on the drill bit that would otherwise be detrimental to the direction drilling of a deviated wellbore.