Baylor University.
The relationship of Permian San Andres facies to the distribution of porosity and permeability in the ODC field, Gaines County, Texas.
Abstract
dc:description.abstractThe ODC field, operated by Fina Oil and Chemical Company of Texas, is located in Gaines County, Texas on the northwestern shelf of the Midland basin. Consisting of 53 wells, the ODC field produces from 800 net acres involved in a water-flood injection program initiated in 1969. The primary reservoirs are dolomitic carbonates in the Permian San Andres Formation. Since the flooding was initiated, 836,043 barrels of crude oil have been produced from an average reservoir depth of approximately 5500 feet. In order to maximize production under utilization of a proposed carbon dioxide injection program, a detailed analysis of porosity and permeability trends in the San Andres reservoirs was made. An assessment of porosity and permeability trends detailing lateral and vertical continuity, lateral and vertical discontinuity, and an investigation of the depositional and diagenetic processes controlling porosity and permeability was made using data including five well cores and corresponding core lab reports. Preliminary analysis of the five San Andres cores involved detailed logging to determine depositional facies and their lateral and vertical relationships. This data was then related to corresponding core lab data which revealed porosity and permeability variations as a result of diagenetic modifications of these lithofacies. The end result of this analysis was the recognition of 13 depositional facies, which fell into groups divided as supratidal facies, intertidal facies, and subtidal facies. The overall trend seen in the distribution of these facies was of higher energy inter tidal and subtidal facies (i.e. algal packstone, skeletal packstone) present most frequently at the western edge of the study area in core No. 46. The remaining lower energy intertidal and subtidal facies were present with increasing frequency to the east. This follows water energy levels related to the bathymetry of the eastward deepening margin of the Midland basin western shelf. In terms of diagenetic modifications of the described facies, the general pattern is one of a porosity inversion as described by Bebout and Leary (1985) in their study of the Dune Field of West Texas. Within the San Andres section of the entire ODC field, the rocks have been completely altered to dolomite. Anhydrite is abundant in the supratidal facies, and there are minor occurrences of authigenic clays, quartz, and chert in some of the more porous subtidal facies. Porosity in the ODC field occurs as three types: (1) predominantly intercrystalline porosity; (2) micro vugular pinpoint porosity; and (3) fracture porosity. Intercrystalline porosity occurs most frequently in the mud dominated lithofacies, while the leached micro vugular porosity is seen most often in the more heavily dolomite occluded and anhydritic lithofacies. Fracture porosity and significantly high permeability occurs preferentially along the northern margin of the ODC field along a flexure line related to a supratidal lithofacies collapse zone.
Degree
thesis:*- Name thesis:degree_name
- M.S.
- Level thesis:degree_level
- Masters
- Grantor
- Baylor University.
- Year dc:date.issued
- 1986
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- McKee, Bryce J.
- Advisor dc:contributor.advisor
-
- Beaver, Harold H.
Subjects
dc:subject × 6Rights
dc:rights- Statement dc:rights
-
- Baylor University works are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact libraryquestions@baylor.edu for inquiries about permission.
- Language dc:language.iso
- en
Identifiers
dc:identifier.*- Handle dc:identifier.uri
- https://hdl.handle.net/2104/13241
- OAI identifier oai:identifier
- oai:baylor-ir.tdl.org:2104/13241