Amoco Corporation

The Standard Oil Company

Kenneth E Hanson

Leon A Thomsen

Carl H Sondergeld

Chandra S Rai

Christopher Crowe

Thompson J Taylor

Albert L Frisillo

Mark V Brumbaugh

A method is disclosed for obtaining an estimate of the shear velocity in a formation material. Utilizing compressional velocity (V.sub.p) and density (.rho.) of the formation material, formation aggregate mineral parameters and formation pore fluid parameters together with a relationship that the frame bulk modulus/frame shear modulus is approximately equal to the bulk modulus of the aggregate mineral grains/shear modulus of the aggregate mineral grains, to obtain an estimate of the shear wave velocity (V.sub.s) of the formation material. The present invention is primarily designed for use in the areas where shear wave velocity (V.sub.s) measurements are unobtainable due to unconsolidated formations, and specifically, wherein the acoustic velocity of formation fluids and/or wellbore fluids is greater than the desired shear wave velocity.

Method of shear wave velocity estimation

A method of geophysical exploration for acquiring and processing multicomponent seismic data obtained with seismic sources generating shear waves having time-varying polarizations and seismic receivers recording at least two modes of propagation of the imparted shear waves is provided. More particularly, a method is described for acquiring multicomponent seismic data with torsional seismic sources and multicomponent seismic receivers, as well as a method for processing such multicomponent seismic data so as to ameliorate the effects of shear wave splitting in displayed seismic data. Additionally, principal time-series signals can be obtained which are representative of formation properties along principal axes of an anisotropic formation essentially free of the effects of shear wave splitting.

Method of geophysical exploration

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 of seismic exploration including processing and displaying shear wave seismic data for identifying gaseous hydrocarbon-containing formations and for inferring changes in the geological character of subterranean formations. A measure of the shear wave reflection coefficient is obtained for selected seismic events in the shear wave seismic data. Measures of formation property contrasts represented by the selected seismic event are obtained from the shear wave reflection coefficients.

Method of seismic exploration including processing and displaying shear

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

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.

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Tulsa, OK, United States of America

Kenneth E Hanson