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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractOil is produced from the Manderson Field, in Big Horn County, Wyoming, from a fracture system with possible significant lateral connectivity. So characterizing the fractures in this field is of great importance. Amplitude Versus Offset (AVO) and Azimuth (AVAZ) analysis of 3D seismic data is used to determine fracture strike and density at well locations in the Manderson 3D. The result of the analysis described in Gray et al (1999) is compared to fracture strike analysis from oriented cores for three wells within the Manderson 3D, to outcrop analogues and to outcrop at the Zeissmann Dome, 10 miles to the SE of Manderson Field.

Parameters of interest in hydraulic fracturing are the principal stresses, hoop stress and rock strength parameters such as Young's modulus and Poisson's ratio. Modern seismic inversion algorithms allow us to extract rock strength parameters. We show that they can be estimated between wells from seismic data. The azimuthal response of conventional and/or multicomponent seismic data is related to the stress field of the earth. By combining these methods, the magnitude of the principal stresses and the directions of the horizontal stresses may be estimated and then, hoop stress and fracture breakdown pressure can be approximated. These estimates may be used to guide field development away from existing wells.

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