Joint geophysical and geomechanical analysis of in-situ stress, Wattenberg Field, Colorado, USA.

摘要

The Wattenberg Field, Denver Basin, is a prolific oil and gas field currently ranked as the seventh largest domestic gas field within the United States. The Reservoir Characterization Project, in cooperation with Anadarko Petroleum Corporation, undertook an integrated dynamic reservoir characterization of a portion of Wattenberg Field integrating the disciplines of geophysics, geology, geomechanics, petrophysics, and petroleum engineering. My study focuses primarily on the integration of geophysics and geomechanics via relationships between stress, production, and completions. Eleven horizontal wells are present in the study area --- seven Niobrara Chalk wells and four Codell Sandstone wells. Several vertical wells exist within the study area as well. Various seismic surveys were acquired over the study area with the intent of carrying out time-lapse (4D) multicomponent reservoir characterization.;The objective of my research is to integrate and correlate geophysical and geomechanical data in an effort to provide a better reservoir characterization in Wattenberg Field. With varying well spacing, completion methods, and target intervals, there are a plethora of variables to be evaluated here. Relationships have been found between various completion parameters, production, stress, and geology that could have an impact on the way in which we drill and complete wells in Wattenberg Field. Through this study I have found that little correlation exists between completions parameters (fluid and proppant injection) and production, or between ISIP and fracture network complexity. The largest control on production variability in the study area appears to be geology, both at the seismic- and sub-seismic scale. I have shown that stress differences within the study area exist due to complex geologic structure and fault systems and could be the reason behind differences in production, seismic attributes, and microseismic trends. Additionally, stress compartments subdivide the study area even further and account for localized stress rotations within complex geologic structures largely controlled by faults. These features control pressure and stress distribution throughout the reservoir and are considered to be the main driving factors for production variability across the study area.