Amoco Corporation

Other

Chandra S Rai

Carl H Sondergeld

Houston B Mount, Ii

Keith K Millheim

Kenneth E Hanson

Leon A Thomsen

Richard M Alford

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 novel method of geophysical exploration is described for obtaining estimates the formation lithology from measures of formation anisotropy. First and second measures of formation anisotropy can be transformed into estimates of formation lithology by crossplotting them onto a lithology diagram. In one embodiment of the present invention, the lithology diagram comprises two separate axes representing measures of formation azimuthal anisotropy and transverse isotropy for a selected formation property which defines regions of separate lithologies. The lithology diagram can provide a novel means for discriminating formation lithology from the measures of formation anisotropy.

Method for estimating formation lithology

A method for determining in-situ formation properties is provided. Through regression analyses, empirical systematic relations are obtained using measures of formation properties obtained form formation samples of at lest one reference well over a range of effective pressures and pore fluids. The formation properties are selected from the group comprising shear velocity, compressional velocity, as well as porosity and mineralogy content. Direct measurements of at least two in-situ formation properties selected from the group of shear velocity, compressional velocity, porosity and mineralogy content are obtained for an exploratory well. The empirical systematic relations of formation properties are inverted to determine estimates of the balance of the insitu formation properties selected from the group including shear wave velocity, compressional wave velocity, porosity and mineralogy content not directly measured.

Method for determining in-situ formation properties

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.

Growing community of inventors

Tulsa, OK, United States of America

Chandra S Rai