Abstract: An acoustic borehole logging system employs an acoustic tranmitter excited by a sweep frequency tone burst to produce an acoustic output having a free-field frequency spectrum of at least one resonant frequency of vibration. A closely-spaced acoustic receiver detects a borehole frequency spectrum that is representative of the acoustic transmitter free-field frequency spectrum altered by the effects of the properties of the subsurface formulation materials comprising the borehole wall. Such detected borehole frequency spectrum is recorded in correlation with depth as a log of the material properties of the subsurface formations surrounding the borehole.

Abstract: An acoustic logging tool traverses a fluid-filled cased well with a monopole acoustic energy source. Pressure waves in the well fluid by the source generate symmetric tube waves in the well casing immediately adjacent the source. At least one spaced-apart receiver detects these tube waves after they have traveled directly to the receiver through the well casing. Asymmetry imparted to said tube waves as they travel along the well casing by the maximum and minimum earth stresses behind the well casing are identified and used to predict the azimuthal direction of subsequent hydraulic fractures.

Abstract: An acoustic borehole logging tool traverses a fluid-filled cased well with an acoustic energy transmitter. Pressure waves created in the well fluid by the transmitter generate tube waves in the well casing. A closely spaced receiver detects tube waves that have traveled along the cased wellbore and been reflected by fracture interfaces. These reflected tube waves are recorded and used to identify the top and bottom of any fracture interval in the formation behind the well casing.

Abstract: An acoustic transmitter for use in a borehole logging tool employs multiple Helmholtz resonators stacked such that apertures in opposite sides of each of the resonators are in linear alignment so as to provide increased acoustic energy output over a broad band of low frequency seismic frequencies.

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: An acoustic well logging system employs a sine wave tone burst generator which drives a bender-type transmitter in a borehole logging tool to sequentially produce acoustic compressional and tube waves. A sine wave tone burst is selectively swept or fixed in frequency between 10 kHz and 1.5 kHz to generate a constant frequency compressional wave and below 1.5 kHz to generate a constant frequency tube wave. The constant frequency of the compressional wave along a particular subsurface formation interval is characteristic of the rock material of such subsurface formation interval.

Abstract: A borehole logging tool employs an acoustic transmitter and at least one spaced-apart receiver. The transmitter is excited with a tone burst to cause the transmitter to resonate and generate acoustic tube waves. The rate of decay of the amplitudes of the tube waves recorded at the receiver following termination of the excitation of the transmitter is used to determine the amount of damping of the tube waves in the subsurface formation along the borehole wall.

Abstract: A method for identifying the location of the extent of travel of a combustion front following an in situ oil recovery operation employs a source of seismic energy and at least one seismic receiver for detecting seismic reflection signals from boundaries between subterranean formations on either side or opposite sides of such location. The properties of these seismic reflection signals are changed by the reduction in water saturation in the oil reservoir caused by the drying effect of the combustion front, and any such change is detected as an identification of the location of the extent of travel of the combustion front through the oil reservoir.

Abstract: The present invention relates to a method for recovering oil from a subterranean, viscous oil-containing formation by injecting a gaseous driving fluid such as carbon dioxide into the formation and recovering oil therefrom while simultaneously transmitting vibrations in the seismic frequency range having an amplitude not exceeding 100 Angstrom units through the formation which enhances the flow of the carbon dioxide and thereby increases the efficiency of recovering the oil. The frequency of the vibrations is within the range of 0.1 the 500 Hz and preferably 1 to 100 Hz.

Abstract: A well casing penetrating a plurality of subterranean hydro carbon-bearing formations is perforated adjacent select ones of such hydrocarbon-bearing formations that are expected to exhibit at least a minimum pressure increase during fracturing operations. A fracturing fluid is pumped down the well through the perforations, and into the formations so as to fracture each of the select formations during a single fracturing operation.

Abstract: A simple harmonic oscillator for use in measuring dynamic elastic constants of rock material samples includes a pair of masses vertically suspended from a support position by a pair of wires. At least one mass is driven by a permanent magnet with the driving coil positioned in the air gap to the magnet. The rock sample is horizontally positioned between the pair of masses such that the rock sample acts as a spring element connecting the masses, thereby forming the simple harmonic oscillator.

Abstract: A simple harmonic oscillator for use in measuring dynamic elastic constants of rock material samples includes a pair of masses vertically suspended from a support position by a pair of wires. At least one mass is driven by a permanent magnet with the driving coil positioned in the air gap to the magnet. The rock sample is horizontally positioned between the pair of masses such that the rock sample acts as a spring element connecting the masses, thereby forming the simple harmonic oscillator. Resonance measurements are determined for various pore fluid contents by introducing various ratios of gas/water/oil into the rock sample.

Abstract: Circumferential and longitudinal strain measurements are carried out on a rock material under oscillatory loading conditions at seismic frequencies. The phase angle between each of these strains and the oscillatory driving force is determined by synchronous and quadrature detection.

Abstract: A confining pressure system includes a pressure cell containing a mechanical oscillator and a gas supply for carrying out resonance measurements of rock material under confining pressure at seismic frequencies. An appropriate gas is used to avoid significant damping of oscillations under confining pressures of various ranges.

Abstract: A novel sand control method is disclosed wherein high viscosity, high sand concentration, fracturing fluids are pumped through sets of vertically oriented perforations in borehole casings located in unconsolidated or loosely consolidated pay zones. Various techniques are utilized to insure that sand fills disposed on either side of the borehole casing cover and substantially overlap each borehole casing perforation set. Procedures are then followed to bring the well into production without washing out the sand fills in these areas, whereby the resulting perforation-sand fill configurations effectively control sand production from the treated zone.

Abstract: A harmonic oscillator and motion detection system for use in measuring dynamic elastic constants of rock material samples includes a pair of masses vertically suspended from a support position by a pair of wires. At least one mass is driven by a permanent magnet with the driving coil positioned in the air gap to the magnet. The rock sample is horizontally positioned between the pair of masses such that the rock sample acts as a spring element connecting the masses, thereby forming the simple harmonic oscillator. The motion detection system includes a pair of coil-magnets mounted to each mass for use in determining the amplitude and phase of the motion of the pair of masses.

Abstract: A novel method is disclosed for using the resonance behavior of reservoir sand to distinguish between oil-rich, gas-rich and water-rich zones. A wellbore is logged, as for example with a long spaced acoustic logging tool, to obtain data which are then interpreted to determine the damping of the acoustic signal in one sand versus another, or in that sand versus a reference sand having similar resonance characteristics.

Abstract: This specification discloses a method of creating a horizontally disposed fracture in a subterranean formation that is penetrated by a wellbore. Two packers are set in the wellbore against the formation to be fractured to define with the wellbore and intermediate the packers a fracture treatment zone. Hydraulic pressure is applied to the fracture treatment zone in an amount slightly less than that required to create a vertical fracture in the formation. Acoustical energy is applied in the fracture treatment zone to form a resonant condition therein and to provide rigid coupling of acoustic stress pulses between the packer and the formation and form a horizontal fracture in the formation. The horizontal fracture is propagated into the formation by the continued application of the hydraulic pressure to the fracture treatment zone.