Novel Method for Calculating the Effective Stress Coefficient in a Tight Sandstone Reservoir

다국어 초록 (Multilingual Abstract)

Determining the influence of effective stress on rock deformation is essential for geotechnical stability analysis in oil and gas production. There is no universal effective stress coefficient for all rock properties, and different values of effective stress coefficient apply for different physical quantities (Gurevich, 2004). Although the effective stress law and its application is not new, frequently overlooked or misapplied. Hence, a novel method was proposed for measuring and calculating the effective stress coefficient in this work. Firstly, pore compressibility under different confine pressure values was measured using reservoir fluid or experimental fluid.
Secondly, effective stress was calculated by comparing pore compressibility under different confine pressure and then, the range of effective stress coefficients was determined eventually. Finally, the reliability of the proposed method was validated via the stresssensitive curves of tight sandstone core samples and by comparing the results with those of two other calculation methods for the effective stress coefficient. This work suggests that the stress-sensitive curves of the two core samples from the same location and with similar physical properties have given similar effective stress coefficient (η = 0.201) calculated using the proposed method, which indicates that the calculation is reasonable. The comparison of the proposed method with other methods also indicate that the proposed technique is reliable.

참고문헌 (Reference)

1 Terzaghi, K, "The shearing resistance of saturated soils and the angle between the planes of shear" 1 : 54-56, 1936

2 Ojala, I. O., "The effective stress coefficient in porous sandstone" American Rock Mechanics Association 2007

3 Y. Bernabe, "The effective pressure law for permeability in Chelmsford granite and Barre granite" Elsevier BV 23 (23): 267-275, 1986

4 Yves Bernabe, "The effective pressure law for permeability during pore pressure and confining pressure cycling of several crystalline rocks" Wiley-Blackwell 92 (92): 649-, 1987

5 The Oil and Gas Professional Standards Compilation Group of China, "SY/T 5358-2002 the Evaluation Methods of Reservoir Sensitivity and Liquidity" Pet. Ind. Press 2002

6 Warpinski, N. R., "Laboratory measurements of the effective-stress law for carbonate rocks under deformation" 30 (30): 1169-1172, 1993

7 Maurice A. Biot, "General Theory of Three‐Dimensional Consolidation" AIP Publishing 12 (12): 155-164, 1941

8 Chen, M., "Experiments and analysis on hydraulic fracturing by a large-size triaxial simulator" 19 (19): 868-872, 2000

9 Li, M., "Experimental study on permeabilityeffective- stress law in low-permeability sandstone reservoir" 27 (27): 3535-3540, 2008

10 Bear, J., "Dynamics of fluids in Porous Media" American Elsevier Publishing Company 59-113, 1972

11 Terzaghi, K., "Die theorie der hydrodynamischen spannungserscheinungen und ihr erdbautechnisches anwendungsgebiet" 288-294, 1924

12 N.R. Warpinski, "Determination of the Effective-Stress Law for Permeability and Deformation in Low-Permeability Rocks" Society of Petroleum Engineers (SPE) 7 (7): 123-131, 2013

13 Zheng, L. L., "Determination of effective stress coefficient of permeability using maximum-likelihood function approach" 29 (29): 747-749, 2008

14 L.P. Qiao, "Determination of Biot's Effective-Stress Coefficient for Permeability of Nikanassin Sandstone" Society of Petroleum Engineers (SPE) 51 (51): 2014

15 Bodaghabadi, S., "A simple practical method to determine the biot coefficient for hydromechanical analyses" 227-229, 2008

16 Boris Gurevich, "A simple derivation of the effective stress coefficient for seismic velocities in porous rocks" Society of Exploration Geophysicists 69 (69): 393-397, 2004

17 Dassanayake, A. B. N., "A new approach to evaluate effective stress coefficient for strength in Kimachi sandstone" 131 (131): 70-79, 2015