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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 64 (1980)

Issue: 5. (May)

First Page: 759

Last Page: 759

Title: Study of Diagenetic Processes in Sandstone from Cerro Prieto Geothermal Field, Baja California, Mexico: ABSTRACT

Author(s): John E. Noble, Stephen Van Der Har

Article Type: Meeting abstract

Abstract:

The economic exploitation of a geothermal resource is dependent on an adequate reservoir porosity and permeability and awareness of the distribution of each during development. Exploitable reservoir porosity and permeability are the results of diagenetic alteration of the reservoir's original porosity.

In this study, we have used petrographic, SEM, and X-ray diffraction analysis of well-bore cutting and core to model the diagenetic processes evident in the Cerro Prieto geothermal field. Porosity distribution was matched with lithologic and hydrothermal alteration distribution and a composite distribution model was constructed. This model was then analyzed for porosity trends.

The ratio of fracture to dissolution porosity and the ratio of detrital dissolution secondary porosity to authigenic dissolution secondary porosity were critical to this study. The role of fracture-dominated porosity and authigenic mineral plugging may have been overstated in geothermal system development.

The role of diagenetic studies in any reservoir evaluation is paramount. Diagenetic processes determine porosity from its origins through to distribution of porosity and permeability. Studies of these processes will contribute to better prediction of reservoir porosity distribution and subsequently better management of the geothermal resource.

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Copyright 1997 American Association of Petroleum Geologists