Identification, Classification and Prediction of Reservoir Nonuniformities Affecting Production Operations
- C.A. Hutchinson Jr. (The Atlantic Refining Co.) | C.F. Dodge (Arlington State College) | T.L. Polasek (The Atlantic Refining Co.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- March 1961
- Document Type
- Journal Paper
- 223 - 230
- 1961. Original copyright American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Copyright has expired.
- 1.14 Casing and Cementing, 1.6.9 Coring, Fishing, 1.2.3 Rock properties, 5.1.1 Exploration, Development, Structural Geology, 5.5.2 Core Analysis, 5.8.5 Oil Sand, Oil Shale, Bitumen, 5.1.4 Petrology, 2.4.3 Sand/Solids Control, 5.3.4 Integration of geomechanics in models, 5.3.2 Multiphase Flow
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A study of sandstone outcrops typical of producing horizons has been undertaken to develop a method for predicting the size, shape and permeability contrast of reservoir nonuniformities. This paper is a progress report and presents the tentative conclusions reached from the study of several Cretaceous age outcrops in the Four Corners area and of the Woodbine outcrop around Dallas.
The results to date suggest that nonuniformities in sandstone reservoirs may be classified according to (1) depositional environment and (2) rock texture and cement content. Within a sandstone unit, there will be no drastic variations in permeability providing the cement content is not sufficient to control the permeability. For this noncement-controlled or texture-controlled permeability situation, up to a 5:1 ratio of maximum-to-minimum permeability is expected for measurements on 1 x 7/8-in. core plugs. When the permeability of the sand is cement-controlled, the maximum-to-minimum ratio of permeability values within a sand unit may exceed 100:1.
Clean shale sections tend to be continuous over great distances, whereas sandy shale sections will be fairly continuous only in ripple-marked and horizontally bedded layers of the formation. In cross-bedded sandstones, the sandy shale sections will tend to be discontinuous.
The conclusions reached in this study so far suggest that, if the bedding, textural qualities and cement content are known in blanket sandstones, the sizes, shapes and permeability contrast of nonuniformities within the sandstone are predictable. The bedding, textural properties and cement content can be determined from well cores.
This is a progress report on a major research study that is far from completion. The report is presented with the hope that the limited accomplishments to date may impart worthwhile insight to some and that others of the industry will become sufficiently interested in this frontier of technology to lend their efforts to developing an understanding of reservoir nonuniformities and the engineering procedures for including their effects in reservoir performance.
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