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Comparison of uniaxial strain and hydrostatic stress pore-volume compressibilities in the Nugget sandstone

Conference · · Soc. Pet. Eng. AIME, Pap.; (United States)
OSTI ID:5361229

This paper presents a comparison of rock compressibilities determined under two different stress states. One stress state was the traditional though unrealistic hydrostatic stress method; the other was the more realistic though more complicated uniaxial strain (triaxial stress) with pore pressure method. Compressibilities were determined by both stress methods on Nugget sandstone core plugs from the Rocky Mountain Overthrust Belt. The resulting relationship between the two types of compressibilities did not match with previously published predictions. The uniaxial strain pore volume compressibilities averaged about one-third of the corresponding hydrostatic stress pore volume compressibilities. This was a greater difference than predicted using standard practices. Also, the uniaxial strain data varied only slightly between samples, while the hydrostatic stress data exhibited a greater range of values. From the uniaxial strain measurements, bulk volume compressibility of the Nugget sandstone is constant over the porosity and pressure range of the reservoir. Pore volume compressibility can therefore be easily determined from the porosity and the bulk volume compressibility.

Research Organization:
Amoco Production Co. (Intl.)
OSTI ID:
5361229
Report Number(s):
CONF-8310121-
Journal Information:
Soc. Pet. Eng. AIME, Pap.; (United States), Journal Name: Soc. Pet. Eng. AIME, Pap.; (United States) Vol. SPE11971; ISSN SEAPA
Country of Publication:
United States
Language:
English