Applying Modern Petrophysical Techniques to Vintage E-log's, Kettleman Hills North Dome Field, CA

Jason B.Robbins¹ and Jonathan P. Lange^2
1California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA 93311
²Chevron USA, 9525 Camino Media, Bakersfield, CA 93311

Kettleman Hills North Dome (KND) is a major asset that contained over 2 BBOE of light oil and gas initially and covers 20,000 acres in the San Joaquin Valley. Between the 1930's-60's over 500 wells were drilled and logged with electrical tools (resistivity & spontaneous potential) in the field. Prospecting with such data until recently has yielded only qualitative identification of major sand bodies and net pay. Deep resistivty measurements in thin and thick beds often mis-represent true formation resistivity (Rt) due to the lack of vertical resolution (shadow or dead zones). Typically in thin beds this results in bypassed pay or underestimation of hydrocarbons. Additionally, the lack of neutron-porosity data at Kettleman has also hindered the ability to accurately calculate fluid saturations. Today, commercially available software can correct environmental effects on resistivity and spontaneous potential (SP) logs to account for borehole conductivity, invasion, shoulder-bed effects, washouts, low contrast pay, and dipping beds. Normalization and modeling of SP and resistivity improves the measurements of Rt, flushed zone resistivity (Rxo), and estimation of V-shale from SP. Addition of neural networks allows for the training of core data to Rt, Rxo, and V-shale to generate quantitative pseudo porosity and permeability curves. Application of such software and techniques allowed for the utilization of vintage data where otherwise it would be cost prohibitive to collect sufficient modern data to fully characterize the reservoirs. Modeling resistivity and SP logs in combination with porosity and permeability transforms improved the recognition of hydrocarbons and helped identify bypassed and untested zones at Kettleman Hills North Dome.

AAPG Search and Discovery Article #90076©2008 AAPG Pacific Section, Bakersfield, California