The expressions of three types of stress sensitivity coefficients (S, α, β) are obtained on the basis of analysis of the empirical models and theoretical models on the relationships between permeability and effective stress, and the stress sensitivity evaluation standard is proposed considering experiment data and rock micro-structural features. Then the empirical models and theoretical models were used to fit experiment data of low-permeability and tight sandstones and different types of granites, which promotes the understanding of the empirical models and the physical meanings of the stress sensitivity coefficients. According to the study of the three types of stress sensitivity coefficients and the relationship of effective stress and permeability, it is found that the stress sensitive coefficient S was suitable for evaluating the stress sensitivity (strong stress sensitivity: S>0.40; low stress sensitivity: S<0.25; medium stress sensitivity: 0.25≤S≤0.4). Meanwhile, it is also found that strong-stress-sensitivity cores are more suitable to be characterized by the logarithmic model, while the exponential model (or binomial model) occurred more frequently in low-stress-sensitivity cores, and medium-stress-sensitivity cores are more likely to be described with the power model. Finally, the evaluation standard is discussed based on the micro-structure in the low-permeability and tight sandstones. The results show that the crack-like pores in the strong-stress-sensitivity cores are obvious, but low-stress-sensitivity cores have the characteristics of porous rocks; moreover, the types of cemented clay minerals, the size of rock grain and lithology have impact on stress sensitivity.
[1] 贾承造, 邹才能, 李建忠, 等. 中国致密油评价标准、主要类型、基本特征及资源前景[J]. 石油学报, 2012, 33(3): 343-350.
JIA Chengzao, ZOU Caineng, LI Jianzhong, et al. Assessment criteria, main types, basic features and resource prospects of the tight oil in China[J]. Acta Petrolei Sinica, 2012, 33(3): 343-350.
[2] 邹才能, 翟光明, 张光亚, 等. 全球常规-非常规油气形成分布、资源潜力及趋势预测[J]. 石油勘探与开发, 2015, 42(1): 13-25.
ZOU Caineng, ZHAI Guangming, ZHANG Guangya, et al. Formation, distribution, potential and prediction of global conventional and unconventional hydrocarbon resources[J]. Petroleum Exploration and Development, 2015, 42(1): 13-25.
[3] 杨智, 侯连华, 陶士振, 等. 致密油与页岩油形成条件与“甜点区”评价[J]. 石油勘探与开发, 2015, 42(5): 555-566.
YANG Zhi, HOU Lianhua, TAO Shizhen, et al. Formation condition and “sweet spot” evaluation of tight oil and shale oil[J]. Petroleum Exploration and Development, 2015, 42(5): 555-566.
[4] JONES F O, OWENS W W. A laboratory study of low-permeability gas sands[J]. Journal of Petroleum Technology, 1980, 32(9): 1631-1640.
[5] DAVID C, WONG T F, ZHU W L, et al. Laboratory measurement of compaction-induced permeability change in porous rocks: Implications for the generation and maintenance of pore pressure excess in the crust[J]. Pure and Applied Geophysics, 1994, 143: 425-456.
[6] SIGAL R F. The pressure dependence of permeability[J]. Petrophysics, 2002, 43(2): 92-102.
[7] 李传亮. 储层岩石的应力敏感性评价方法[J]. 大庆石油地质与开发, 2006, 25(1): 40-42.
LI Chuanliang. Evaluation method for stress sensitivity of reservoir rock[J]. Petroleum Geology & Oilfield Development in Daqing, 2006, 25(1): 40-42.
[8] DONG J J, HSU J Y, WU W J, et al. Stress-dependence of the permeability and porosity of sandstone and shale from TCDP hole-A[J]. International Journal of Rock Mechanics & Mining Sciences, 2010, 47(7): 1141-1157.
[9] 肖文联, 李闽, 赵金洲, 等. 低渗致密砂岩渗透率应力敏感性试验研究[J]. 岩土力学, 2010, 31(3): 775-779.
XIAO Wenlian, LI Min, ZHAO Jinzhou, et al. Laboratory study of stress sensitivity to permeability in tight sandstone[J]. Rock and Soil Mechanics, 2010, 31(3): 775-779.
[10] TERZAGHI K. Principles of soil mechanics[J]. Engineering News Record, 1925, 95(3): 874-878.
[11] BERNABLE Y. The effective pressure law for permeability in Chelmsford granite and Barre granite[J]. International Journal of Rock Mechanics & Mining Science & Geomechanics Abstracts, 1986, 23(3): 267-275.
[12] ZHAO Jinzhou, XIAO Wenlian, LI Min, et al. The effective pressure law for permeability of clay-rich sandstones[J]. Petroleum Science, 2011, 8(2): 194-199.
[13] JONES F O. A laboratory study of effects of confining pressure on fracture flow and storage capacity in carbonate rocks[J]. Journal of Petroleum Technology, 1975, 27(1): 21-27.
[14] 尹尚先, 王尚旭. 不同尺度下岩层渗透性与地应力的关系及机理[J]. 中国科学: D辑: 地球科学, 2006, 36(5): 472-480.
YIN Shangxian, WANG Shangxu. The relationship and mechanism between permeability and formation stress under different scale[J]. SCIENCE CHINA Earth Sciences, 2006, 49(7): 714-723.
[15] WALSH J B. Effect of pore pressure and confining pressure on fracture permeability[J]. International Journal of Rock Mechanics and Mining Sciences, 1981, 18(5): 429-435.
[16] 国家能源局. SY/T 5358-2010 储层敏感性流动实验评价方法[S]. 北京: 石油工业出版社, 2010.
National Energy Administration. SY/T 5358-2010 Formation damage evaluation by flow test[S]. Beijing: Petroleum Industry Press, 2010.
[17] JAEGER J C, COOK N G W, ZIMMERMAN R W. Fundamentals of rock mechanics[M]. Malden, USA: Blackwell Publishing, 2007.
[18] SEEBYRGER D A, NURA A. A pore space model for rock permeability and bulk modulus[J]. Journal of Geophysical Research, 1984, 89(B1): 527-536.
[19] YALE D P. Network modeling of flow, storage, and deformation in porous rocks [D]. Stanford, California: Stanford University, 1984.
[20] 肖文联, 李闽, 赵金洲, 等. 非线性有效压力计算[J]. 地球物理学报, 2013, 56(8): 2808-2817.
XIAO Wenlian, LI Min, ZHAO Jinzhou, et al. Calculation of non-linear effective pressure[J]. Chinese Journal Geophysics, 2013, 56(8): 2808-2817.
[21] KRANZ R L, FRANKEL A D, ENGELDER T, et al. The permeability of whole and jointed Barre granite[J]. International Journal of Rock Mechanics and Mining Sciences, 1979, 16(4): 225-234.
[22] LI M, BERNABE Y, XIAO W L, et al. Effective pressure law for permeability of E-bei sandstones[J]. Journal of Geophysical Research, 2009, 114(B7): B07205.
[23] LI M, BERNABE Y, XIAO W L, et al. Nonlinear effective pressure law for permeability[J]. Journal of Geophysical Research, 2014, 119(1): 302-318.
[24] FREDRICH J T, MENENDEZ B, WONG T F. Imaging the pore structure of geomaterials[J]. Science, 1995, 268(5208): 276-279.
[25] 邹才能, 朱如凯, 吴松涛, 等. 常规与非常规油气聚集类型、特征、机理及展望: 以中国致密油和致密气为例[J]. 石油学报, 2012, 33(2): 173-187.
ZOU Caineng, ZHU Rukai, WU Songtao, et al. Types, characteristics, genesis and prospects of conventional and unconventional hydrocarbon accumulations: Taking tight oil and tight gas in China as an instance[J]. Acta Petrolei Sinica, 2012, 33(2): 173-187.
