1.11 Fracture Gradients

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Unformatted text preview: Kelly F = D D In this case P and D are known, σ may be calculated, and K i is determined graphically. (i) First, determine the pore pressure gradient. P = 0.735 psi / ft (given ) D Fracture Gradients 1.11- 17 Example - Matthews and Kelly (ii) Next, calculate the matrix stress. S=P+σ σ =S-P = 1.00 * D - 0.735 * D = 0.265 * D = 0.265 * 11,000 σ = 2,915 psi Fracture Gradients S = overburden, psi σ = matrix stress, psi P = pore pressure, psi D = depth , ft 1.11- 18 Example - Matthews and Kelly (iii) Now determine the depth, D i , where, under normally pressured conditions, the rock matrix stress, σ would be 2,915 psi. Sn = Pn + σ n n = “normal” 1.00 * Di =...
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This note was uploaded on 09/18/2012 for the course ENGINEERIN 102 taught by Professor Clyde during the Spring '12 term at A.T. Still University.

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