Amoco Corporation

Other

The Standard Oil Company

Carl H Sondergeld

Chandra S Rai

Martin L Smith

Leon A Thomsen

Houston B Mount, Ii

Keith K Millheim

Kenneth E Hanson

Paul R Gutowski

Albert L Frisillo

Richard M Alford

Christopher Crowe

Janice O Norris

Richard J O'Connell

The present invention relates generally to a method and system for geophysical exploration and more particularly to a method and system for obtaining selected physical properties of the subterranean formations surrounding a wellbore so as to aid the geophysicist in evaluating the oil and gas bearing potential of such formations. In one embodiment of the invention, core samples are obtained along the length of a wellbore and labeled with a machine readable bar code. A plurality of separately arranged measurement stations, each having a unique machine readable bar code, are provided for measuring properties of each sample. By use of a bar code a reader interconnected to a CPU, measurement of physical properties of the samples can be initiated at each measurement station. A log of each physical property as a function of depth can then be prepared with which explorationists can evaluate geophysical survey data for oil and gas potential.

Bar code system used in geophysical exploration

A method of exploring for hydrocarbons is disclosed wherein core is obtained over substantially the entire length of a well and substantially all lithologies represented within the core are analyzed at a core analysis facility located adjacent the well. A measurement of a plurality of physical properties of the core are made promptly after the core is removed from the well. Thereafter, from the measurement of these physical properties, a depth correlated record is generated, and is used (a) to adjust the drilling plan for that well while it is being drilled, (b) used as inputs into other exploration processes, such as seismic surveys, magnetic surveys and gravity surveys, or (c) used for correlation with other depth correlated records obtained from other wells.

Method of exploration for hydrocarbons

A system and method of geophysical exploration is described whereby composition logs of the minerals comprising the formations surrounding a wellbore can be obtained. Samples of the formations surrounding a wellbore are obtained at selected intervals along the length of the wellbore. Each of the core samples is irradiated with electromagnetic radiation and a spectral response signal, representative of the electromagnetic response of each sample to the electromagnetic radiation is recorded. Peaks in the spectral response signals are located and correlated with minerals exhibiting similar electromagnetic characteristic response peaks. Since the samples were obtained from known depths within the wellbore, a composition log of the minerals comprising the formations surrounding the wellbore can be prepared displaying the minerals identified as a function of depth in the wellbore.

Method an system of geophysical exploration

The present invention provides a novel method for obtaining quality indices for objectively characterizing seismic velocity estimates in geophysical data bases.

Method for characterizing velocity estimates

The present invention relates generally to a method for determining seismic velocities and more particularly to a method and system for objectively determining seismic velocities from samples of the earth's subterranean formation. Additionally, the present invention provides a method for obtaining a measure of the variation of seismic velocities of propagation with pressure.

Method for determining seismic velocities

A novel method for detecting and measuring elastic anisotropy in a sample of the earth's formations is provided. A dyad of time series signal representative of the sample's response to imparted shear waves is recorded. The dyad of time series signals can then be processed to detect and measure elastic anisotropy in the sample. More particularly, the dyad of time series signals are collected by imparting shear waves having first and second polarizations into the samples with a shear wave transducer and recording the sample's response to each of the imparted shear waves by shear wave transducers having first and second polarizations. In one embodiment of the invention, the dyad of time series signals can be diagonalized to detect and measure elastic anisotropy in the sample. In another embodiment, the dyad of time series signals can be processed for a plurality of rotation angles and the resulting rotated dyad of time series signals can be displayed to detect and measure elastic anisotropy in the sample.

Method and apparatus for detecting and measuring elastic anisotropy

A sonic well logging system and apparatus for determination of seismic wave velocities from a seismic wave propagating in a subterranean formation about a wellbore. The system includes the process of imparting a seismic wave into the subterranean formation about the wellbore, and receiving the seismic wave after it has interacted with the subterranean formation at a plurality of semismic receivers positioned in the wellbore. The seismic waves are transformed at each of the seismic receivers into a seismic signal and these signals nonlinearly staked for a selected position in the wellbore to generate a velocity spectrum of seismic wave velocities. Coherency peaks are then selected from the velocity spectrum with each coherency peak having associated therewith a unique seismic wave velocity, such as P-wave, S-wave, tube wave and the like.

Sonic logging system

A borehole logging method and system are provided for obtaining a measure of formation anisotropy in formations adjacent the borehole. The system comprises an elongated housing for suspension within the borehole. First and second asymmetric pressure wave sources for generating shear waves directly within formations adjacent the borehole are mounted with the housing. Additionally, first and second sets of receivers are mounted with the housing for recording first and second signals representative of the earth's response to the first and second shear waves propagating in the formations adjacent the borehole, respectively. The first set of receivers have an orientation matching the first source, and the second set of receivers have an orientation matching the second source. The system further includes a processor for determining a measure of formation anisotropy from the first and second recorded signals. With a first set of source/receiver pairs having matched polarizations and azimuthal orientations, first signals, representative of the imparted acoustic shear wave energy after propagation through a portion of the formations adjacent the borehole, are recorded. With a second set of source/receiver pairs having matched polarizations and azimuthal orientations different from the first set of source/receiver pairs, second signals, representative of the imparted acoustic shear wave energy after propagation through a portion of the formations adjacent the borehole, are recorded. The first and second recorded signals can be processed for events representative of first and second shear wavefront arrivals of the imparted acoustic shear wave energy. Formation anisotropy can be characterized with measures of the events representative of the first and second shear wave arrivals in the first and second recorded signals.

Acoustic well logging method and system for obtaining a measure of

A method and system for acoustic well logging for obtaining an indirect measure of shear wave velocities for earth formations surrounding a well borehole. The method and system relate to an indirect technique for inverting Stoneley wave velocity data to obtain an estimate of shear wave velocities of formations surrounding the borehole substantially concurrent with the logging operation. A subassembly adapted to be connected to an acoustic well logging sonde and form a part thereof provides measures of fluid density and velocity, and borehole radius as well as formation density and impedance. By combining the output of the well logging sonde and subassembly with the aid of a processor, one is able to obtain a measure of formation shear wave velocities, by constraining the inversion of measured Stoneley wave velocity data, substantially in real-time. This method is especially useful in slow formations where direct shear wave velocities cannot be obtained or where shear wave velocities are difficult to obtain.

Acoustic well logging method and system

The present invention provides a method of logging a subterranean formation through a wellbore containing a fluid, wherein no shear wave signal is obtainable utilizing conventional sonic well logging tools suspended in the wellbore. The shear wave signal is not obtainable usually because the acoustic velocity of the wellbore fluid is greater than the shear wave velocity of the formation to be logged. In the present method, the acoustic velocity of the wellbore fluid is adjusted until a shear velocity signal is obtainable by lowering the acoustic velocity of the wellbore fluid until it is less than the shear wave velocity of the formation. Thereafter, the formation is logged through the wellbore to obtain a shear wave signal.

Means for obtaining shear wave velocities

A sonic well logging system and apparatus for determination of seismic wave velocities from a seismic wave propagating in a subterranean formation about a wellbore. The system includes the process of imparting a seismic wave into the subterranean formation about the wellbore, and receiving the seismic wave after it has interacted with the subterranean formation at a plurality of seismic receivers positioned in the wellbore. The seismic waves are transformed at each of the seismic receivers into a seismic signal and these signals nonlinearly stacked for a selected position in the wellbore to generate a velocity spectrum of seismic wave velocities. Coherency peaks are then selected from the velocity spectrum with each coherency peak having associated therewith a unique seismic wave velocity, such as P-wave, S-wave, tube wave and the like.

The present invention relates to a method for identifying and separating the effects of elastic and anelastic formation properties in a seismic signal representative of the earth's response to seismic energy imparted therein. The seismic signal is decomposed into a measure of the absorptive contrast and impedance contrast across reflecting boundaries in the earth's subterranean formations. The resulting measures of impedance contrast can be used to obtain a measure of the earth's elastic properties. The resulting measures of the absorptive contrast can be used to obtain measures of the earth's anelastic properties.

Method for identifying and separating the effects of elastic and

Methods and related apparatus are described for determining lithological characteristics, such as formation material type and porosity, of an underground formation by utilizing compressional velocity (V.sub.p) and shear velocity (V.sub.s) data. One described method utilizes the plotting of V.sub.p and/or V.sub.s versus a Seismic Parameter, such ad K/.rho. or the Bulk Velocity, and boundaries of velocity values of certain formation material types to define a field of data points. By comparing the position of the data points to the boundaries of the formation material types, the formation material type and, later, porosity can be determined. A method is described for determining the presence of a hydrocarbon gas at a particular location in an underground formation utilizing the above methods. Also, a method is described for determining V.sub.s from V.sub.p data and obtained ratios of V.sub.p and V.sub.s for at least one formation material type.

Growing community of inventors

Broken Arrow, OK, United States of America

Carl H Sondergeld