Analytical Cyclic Steam Modeling Revisited and Applied to the Shallow Low Permeability California Diatomite

Abstract

The commercial production of oil from the low permeability and shallow Opal A diatomite in California has been one of the most important resource development accomplishments of recent times. Corresponding oil-in-place estimates range from 24 to 80 billion barrels with oil recovery efficiencies of 50% and more. Most of the production comes from cyclic steam stimulation (CSS). This paper discusses changes made to an existing analytical thermal simulator to modelCSS production from diatomite. Algorithms were added to enable well stimulation and reservoir dilation. Field production data was compiled from public sources and history matched to calibrate the input parameters. The model was then run to show how stimulation and dilationinfluence oil and water production. The conclusions give new insightson production from the diatomite. This is the first published application of CSS analytical modeling for this resource.