Integrated Formation Evaluation in California's Monterey Formation Siliceous Shales Buena Vista Hills Field California

摘要

A joint project between Chevron and the United States Department of Energy is underway to determine the technical feasibility of implementing a CO2 enhanced oil recovery project in the Antelope Shale (Monterey Formation siliceous shale equivalent) in thernBuena Vista Hills Field, Kern County, California. The project consists of four main components: Reservoir Matrix and FluidrnCharacterization; Fracture Characterization; Reservoir Modeling and Simulation; and CO2 Pilot Flood and Evaluation. This paperrnfocuses on the first phase of the project to apply a variety of advanced reservoir characterization techniques to determine thernproduction characteristics of the Antelope Shale reservoir.rnThe Antelope Shale in the San Joaquin Valley contains an estimated 7 billion barrels of oil in place. The Monterey Shale thatrnunderlies much of California's coastal area and offshore holds nearly 3 billion barrels of oil in place. Thus, the focus of this projectrnis the 10 billion barrel (oil in place) fractured siliceous shale resource.rnExtensive core and log data were acquired in a 1996 project well. 952' of continuous core was cut through the Brown andrnAntelope shale. Routine porosity/permeability/saturation analyses were conducted every one foot at three different confiningrnstresses. Special core analyses on select core plugs included chemical analysis, mineralogic analysis, specific gas, oil, and waterrnpermeability, wettability testing, rock mechanics, nuclear magnetic resonance scanning, and extracted oil geochemicalrnfingerprinting. Logs run included high vertical resolution resistivity, spontaneous potential, high vertical resolutionrnneutron/density, accelerator porosity, total gamma ray, natural gamma ray, full waveform monopole sonic, crossed dipole shearrnsonic (anisotropy), electrical imaging, nuclear magnetic resonance, elemental capture, microlog, formation testing, cementrnevaluation, and carbon/oxygen.rnMineral models from three different combinations of logs were created: 1) triple combo / nuclear magnetic resonance / elementalrncapture, 2) triple combo / nuclear magnetic resonance, and 3) triple combo only. The models consist primarily of five mineralrncomponents: Opal-CT phase biogenic silica, detrital quartz sand, feldspar, carbonate, and clay.rnCorrelations of porosity and drill stem test permeability to shale volume from spontaneous potential were developed to extend thernreservoir characterization fieldwide, where most wells have only old electric logs and spontaneous potential.