<p>Modern hydraulic fracturing designs assume that drilled formations are both isotropic
and homogeneous, and fractures are linear and symmetrical. However, unconventional
resources are often obtained from formations that are both anisotropic and heterogeneous,
resulting in complex fracture behavior. The objective of this study is to evaluate fracture
behavior based on the influence of anisotropy and water saturation.
Isotropic and homogeneous Austin Chalk, Berea Sister Gray Sandstone, and Silurian
Dolomite, laminated anisotropic and heterogeneous Parker Sandstone, Nugget Sandstone,
and Winterset Limestone Carbonate, and fully anisotropic and heterogeneous Edwards
Brown Carbonate cores were ordered for testing. Brazilian discs were cut according the
ISRM and ASTM standards, and prepared as dry, brine saturated, and fresh water saturated
samples. All samples were fractured by the Brazilian test, and laminated anisotropic samples
were tested at various loading angles (0?, 15?, 30?, 45?, 90?). Tensile strengths were
calculated using the peak load of the primary fracture of each sample, and the fractures were
observed for geometrical trends. Additionally, the strain development of each fracture was
analyzed through the application of Digital Image Correlation (DIC) software.
The results determined that anisotropy and saturation can decrease the tensile strength
of a formation. The fracture geometries were influenced by planes of anisotropic lamination,
and fully anisotropic rocks produced winding, erratic fractures. DIC allowed for closer
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examination of fracture development, and identified that saturation can cause failure along
lamination planes subjected to less than the maximum, load induced stress. This research can
be utilized to improve the hydraulic fracturing design models to optimize formation fractures,
and increase revenue for the oil and gas industry.
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:10287221 |
| Date | 21 December 2017 |
| Creators | Salvati, Peter |
| Publisher | University of Louisiana at Lafayette |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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