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Analysis of Factors Influencing Fracture Initiation and Orientation in Oil Reservoir Sandstone.

Authors
Komar-CA; Frohne-KH
Source
NTIS: PB 228 738 :22 pages
Link
NIOSHTIC No.
10009080
Abstract
Laboratory-scale hydraulic fracture tests were conducted by the Bureau of Mines on directionally oriented sandstone material, along with measurements of directional rock properties such as tensile strength, permeability, ultrasonic velocity, and dynamic elastic constants. In these tests, fracture orientation was determined as a function of various combinations of stress, rock saturation, rate of borehole pressurization, and direction of minimum tensile strength relative to minimum horizontal compressive stress. The objective of the experiment was to investigate whether horizontal stresses always controlled the orientation of induced vertical hydraulic fractures, or if under conditions of small differences in stress and/or slow borehole pressurization rates, the induced fracture direction was influenced by directional properties of the rock matrix. The study shows that the expected influence of horizontal earth stress on the orientation of an induced hydraulic fracture becomes negligible whenever the magnitude of the difference between the compressive stresses is 200 psi or less. When this occurs, fracture orientation is controlled by the directional properties of the rock--primarily permeability and tensile strength.
Publication Date
19730101
Document Type
IH; Report of Investigation;
Fiscal Year
1973
NTIS Accession No.
PB-228738
NTIS Price
A03
Identifying No.
RI 7813
Source Name
NTIS: PB 228 738
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