Abstract: A method for measuring and using anisotropy in a coal bed sequence. The method includes the steps of: stripping layers where polarization changes are indicated by applying a static shift to components aligned with the slow shear wave polarization direction and applying one half of the static shift to components neither aligned with the slow shear wave polarization direction nor aligned with the fast shear wave polarization direction; obtaining for a coal bed a measure of the amplitude of the envelope of the fast polarization trace; rotating, by about 45 degrees away from a principal direction, the data set for that coal bed; obtaining a measure of the amplitude of the envelope of at least one of the mixed/mismatched polarization traces of that coal bed; and obtaining the ratio of the amplitude of the envelope of the fast polarization trace to the amplitude of the envelope of one mixed/mismatched polarization trace in that coal bed.

Abstract: 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.

Abstract: 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.

Abstract: Methods of geophysical exploration are provided for estimating the burial conditions of sedimentary material in a selected basin. The burial conditions can include measures of porosity, lithology, pore fluid pressure, effective pressure, and density. In particular, a reference velocity profile is developed for a model of the sedimentary material comprising the basin and is compared to a velocity profile obtained from seismic data to obtain estimates of the burial conditions of the sedimentary material.

Abstract: A novel method of seismic exploration has been developed to resolve confusing and distorted shear wave reflection seismic data which can be obtained in areas having anisotropic formations. In particular, the present method of shear wave seismic exploration comprises imparting first shear wave seismic energy into the earth at selected points with a first source having a first polarization with respect to the line of survey, and recording first signals representative of the earth's response with first geophones having a first polarization with respect to the line of survey. Also, second shear wave energy is imparted into the earth at selected points along the line of survey, with a second shear wave source having a second polarization with respect to the line of survey, and recording second signals representative of the earth's response with second geophones having a second polarization with respect to the line of survey.

Abstract: A novel method of seismic exploration has been developed to resolve confusing and distorted shear wave reflection seismic data which can be obtained in areas having anisotropic formations. In particular, the present method of shear wave seismic exploration comprises imparting first shear wave seismic energy into the earth at selected points with a first source having a first polarization with respect to the line of survey, and recording first signals representative of the earth's response with first geophones having a first polarization with respect to the line of survey. Also, second shear wave energy is imparted into the earth at selected points along the line of survey, with a second shear wave source having a second polarization with respect to the line of survey, and recording second signals representative of the earth's response with second geophones having a second polarization with respect to the line of survey.

Abstract: Polarized shear wave surveys are performed to determine azimuthal variations in the earth's subsurface caused by fracture orientation and density. The surveys may be done by using the same polarization (either horizontal or vertical) shear waves along two different seismic lines of profile, or by using different polarization shear waves along one common line of profile. The survey data are then processed and compared; any differences constitute a measure of fracture orientation and density. Subsurface zones of high fracture density, once identified, have been found to afford a higher likelihood of successful well completion.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method for quantitatively distinguishing seismic events on a seismic record for inferring changes in the geological character of the subterranean formations. Reflection coefficients are obtained for such seismic events and a first set of attributes indicative of amplitude variations in the offset seismic signals corresponding to the seismic event as a function of incident angle are obtained therefrom. The first set of attributes provide a seismologist with a diagnostic tool for quantitatively evaluating subtle changes in the seismic event. A second set of attributes which are functions of the first set of attributes provide the seismologist with additional diagnostic tools for evaluating subtle changes in the seismic events.