Abstract: Abstract: 3D and 4D Seismic Imaging in the Coalinga Field, Fresno County, CA
KEMPNER, WILLIAM, Chevron USA Production Co, Bakersfield, CA; ED VONDOHLEN, Chevron North America Exploration and Production, Bakersfield, CA; LOUIS KLONSKY, Chevron North America Exploration and Production, Bakersfield, CA; CHRISTINE ECKER, Chevron Overseas Production Inc., San Ramon, CA
Coalinga Field is a harvest asset for the Chevron San Joaquin Basin Business Unit and is undergoing enhanced steam recovery programs throughout the properties. Production is primarily from the Temblor formation at depths of 400 to 1800 feet. In 1996, a baseline one square mile pilot 3D seismic program was acquired as a feasibility test in section 36D. With the successful acquisition of the initial survey, a second survey covering nine square miles was acquired in 1997. This survey overlapped the original pilot area creating a time lapse image (4D) of section 36D as well as providing for nearly complete coverage of the field. In 1998, the acquisition of a small survey to the north completed coverage of the field.
Multiple approaches to seismic imaging of the data have been used to develop a new, detailed reservoir model that is now being used to guide development drilling. Standard 3D seismic horizon mapping shows a complex series of tidal channel and tidal bar sands that appear to exert primary control not only on porosity but, more importantly, steam distribution. Lab results from the temperature and steam effects on the Vp and Vs velocities, coupled with 2D models verify a strong, direct relationship on the seismic amplitude with both temperature and steam. Using Voxelgeo as an imaging tool additional detail of the Temblor depositional model has been established.
The 4D results in the one sq. mile area to the south are very encouraging. The observed seismic anomalies centered on steam injector locations indicate strong stratigraphic control on the steam distribution that can be used to explained the production response of a recently implemented steam pilot. Horizontal drilling should test the 4D interpretation.
Finally, our recent efforts are centered on reservoir characterization techniques to bridge our understanding of the well information and the seismic data. These images provide another method to view this complex Temblor reservoir.
KEMPNER, WILLIAM, ED VONDOHLEN, LOUIS KLONSKY, and CHRISTINE ECKER
AAPG Search and Discovery Article #90911©2000 AAPG Pacific Section and Western Region Society of Petroleum Engineers, Long Beach, California