Rock Physics SIG: Integrating laboratory and field data to infer horizntl elastic strain in the Middle Bakken* - Dec 6th

Dec 2nd - Rock Physics SIG: Effective pressure revisited, or what is the effect of capillary pressur
Sponsored by CGG and Ikon Science
Event Location:
CGG
10300 Town Park Dr.
Houston, TX  77072

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5:15pm Refreshments
5:30pm Presentation Begins
6:30pm Adjourn

Speaker: Keith Katahara, Hess Corporation
Co-Authors: Michele Simon and Elizabeth Ritz, Hess Corporation; Greg Boitnott, New England Research

In-situ horizontal stresses are key variables for planning hydraulic fractures in the Bakken Play of North Dakota and other unconventional assets. The oil and gas industry typically uses a poroelastic model to estimate horizontal stresses. This model requires knowledge of poroelastic properties, the vertical or overburden stress, pore pressure and the two horizontal elastic principal strains (assuming one principal strain is vertical). Usually some of these parameters are poorly known; most workers make simplifying assumptions about the poroelastic properties and about the horizontal elastic strains. Typical simplifying assumptions are (a) one or both of the horizontal strains are assumed to be zero and (b) the two independent Biot-Willis effective stress coefficients are assumed to be 1 or, if less than 1, they are assumed to be equal. To test these assumptions, we used extensive laboratory and field measurements to constrain the poroelastic model for the Middle Bakken reservoir in North Dakota. We measured the relevant poroelastic properties on core plugs and found that the Biot-Willis effective stress coefficients were less than 0.8, with significantly different horizontal and vertical components. In conjunction with previously measured in-situ stresses, these properties imply that the horizontal elastic strains are on the order of 10-4 or greater. These strains imply a difference of 103 psi (7 MPa) or more between the actual and the computed minimum horizontal stress that assumes zero horizontal strain. This difference is quite significant in the context of hydraulic fracturing and demonstrates that the common assumptions about strain and effective stress coefficients are incorrect for the Middle Bakken. This study is an initial step toward understanding the variations in lateral strain across the area of interest.
 
Speaker Biography: Keith Katahara, Hess Corporation
Keith Katahara is a Sr. Geophysical Advisor at Hess Corporation.  He has a PhD. in Geophysics from the University of Hawaii. After several years of academic laboratory research on sonic and ultrasonic properties of materials, he joined ARCO Oil and Gas Company in Plano, Texas.  During 34 years in industry he has worked on well-logging tool design and operations, petrophysical analysis, rock physics, geomechanics, pore-pressure analysis and quantitative seismic analysis.  

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When
12/6/2017 5:15 PM - 6:30 PM

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