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Title: Hydraulic fracturing of jointed formations

Abstract

Measured by volume, North America's largest hydraulic fracturing operations have been conducted at Fenton Hill, New Mexico to create geothermal energy reservoirs. In the largest operation 21,000 m/sup 3/ of water were injected into jointed granitic rock at a depth of 3.5 km. Microearthquakes induced by this injection were measured with geophones placed in five wells drilled into, or very close, to the reservoir, as well as 11 surface seismometers. The large volume of rock over which the microearthquakes were distributed indicates a mechanism of hydraulic stimulation which is at odds with conventional fracturing theory, which predicts failure along a plane which is perpendicular to the least compressive earth stress. A coupled rock mechanics/fluid flow model provides much of the explanation. Shear slippage along pre-existing joints in the rock is more easily induced than conventional tensile failure, particularly when the difference between minimum and maximum earth stresses is large and the joints are oriented at angles between 30 and 60 degrees to the principal earth stresses, and a low viscosity fluid like water is injected. Shear slippage results in local redistribution of stresses, which allows a branching, or dendritic, stimulation pattern to evolve, in agreement with the patterns of microearthquakemore » locations. These results are qualitatively similar to the controversial process known as ''Kiel'' fracturing, in which sequential injections and shut-ins are repeated to create dendritic fractures for enhanced oil and gas recovery. However, we believe that the explanation is shear slippage of pre-existing joints and stress redistribution, not proppant bridging and fluid blocking as suggested by Kiel. 15 refs., 10 figs.« less

Authors:
;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (USA)
OSTI Identifier:
6002163
Report Number(s):
LA-UR-85-3701; CONF-860325-1
ON: DE86002406
DOE Contract Number:  
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Petroleum equipment and technology meeting and exhibition, Beijing, China, 14 Mar 1986; Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; GRANITES; HYDRAULIC FRACTURING; SHEAR PROPERTIES; GEOLOGIC FRACTURES; HOT-DRY-ROCK SYSTEMS; MATHEMATICAL MODELS; NEW MEXICO; STIMULATION; COMMINUTION; ENERGY SYSTEMS; FEDERAL REGION VI; FRACTURING; GEOLOGIC STRUCTURES; GEOTHERMAL SYSTEMS; IGNEOUS ROCKS; MECHANICAL PROPERTIES; NORTH AMERICA; PLUTONIC ROCKS; ROCKS; USA; Geothermal Legacy

Citation Formats

Murphy, H D, and Fehler, M C. Hydraulic fracturing of jointed formations. United States: N. p., 1986. Web.
Murphy, H D, & Fehler, M C. Hydraulic fracturing of jointed formations. United States.
Murphy, H D, and Fehler, M C. 1986. "Hydraulic fracturing of jointed formations". United States. https://www.osti.gov/servlets/purl/6002163.
@article{osti_6002163,
title = {Hydraulic fracturing of jointed formations},
author = {Murphy, H D and Fehler, M C},
abstractNote = {Measured by volume, North America's largest hydraulic fracturing operations have been conducted at Fenton Hill, New Mexico to create geothermal energy reservoirs. In the largest operation 21,000 m/sup 3/ of water were injected into jointed granitic rock at a depth of 3.5 km. Microearthquakes induced by this injection were measured with geophones placed in five wells drilled into, or very close, to the reservoir, as well as 11 surface seismometers. The large volume of rock over which the microearthquakes were distributed indicates a mechanism of hydraulic stimulation which is at odds with conventional fracturing theory, which predicts failure along a plane which is perpendicular to the least compressive earth stress. A coupled rock mechanics/fluid flow model provides much of the explanation. Shear slippage along pre-existing joints in the rock is more easily induced than conventional tensile failure, particularly when the difference between minimum and maximum earth stresses is large and the joints are oriented at angles between 30 and 60 degrees to the principal earth stresses, and a low viscosity fluid like water is injected. Shear slippage results in local redistribution of stresses, which allows a branching, or dendritic, stimulation pattern to evolve, in agreement with the patterns of microearthquake locations. These results are qualitatively similar to the controversial process known as ''Kiel'' fracturing, in which sequential injections and shut-ins are repeated to create dendritic fractures for enhanced oil and gas recovery. However, we believe that the explanation is shear slippage of pre-existing joints and stress redistribution, not proppant bridging and fluid blocking as suggested by Kiel. 15 refs., 10 figs.},
doi = {},
url = {https://www.osti.gov/biblio/6002163}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 01 00:00:00 EST 1986},
month = {Wed Jan 01 00:00:00 EST 1986}
}

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