11 6 formation pressure and matrix stress

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Unformatted text preview: ation Pressure and Matrix Stress Calculations: 3. Matrix stress gradient, S =P+σ SPσ or =+ DDD σSP i.e., =− = (1.000 − 0.478 ) DDD psi psi/ft psi / ft σ / D = 0.522 Fracture Gradients psi/ft 1.11- 7 Formation Pressure and Matrix Stress Calculations: 4. Matrix stress at 14,000 ft = 0.522 psi/ft * 14,000 ft σ = 7,308 psi Fracture Gradients 1.11- 8 Fracture Gradient Determination In order to avoid lost circulation while drilling it is important to know the variation of fracture gradient with depth. Leak-off tests represent an experimental approach to fracture gradient determination. Below are listed and discussed three approaches to calculating the fracture gradient. Frac...
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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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