碳酸盐岩超压岩石物理模拟实验及超压预测理论模型
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摘要
碳酸盐岩地层超压预测目前仍然是超压研究的难点问题,常用的碎屑岩地层超压预测方法是建立在Terzaghi有效应力理论基础上的、经验性的、且需要有明确响应超压的测井和地震参数(主要是纵波速度)。这些经验性的方法不适用于岩性致密且物性极不均一的碳酸盐岩地层的超压预测。通过碳酸盐岩样品超压岩石物理模拟实验剖析岩石弹性性质与孔隙流体压力和有效应力的关系,基于含流体岩石多孔介质弹性理论和广义胡克定律,从分析碳酸盐岩地层应力-应变-孔隙压力本构关系着手,建立表征孔隙压力与岩石弹性参数定量关系的超压预测理论模型(超压预测量化模型)。利用实测碳酸盐岩样品矿物组分含量并结合Voigt-Reuss-Hill模型计算岩石基质弹性模量,利用Wood模型和Patchy模型计算孔隙流体弹性模量,然后再利用碳酸盐岩样品岩石物理模拟实验得到的实际有效应力与岩石骨架弹性模量相关关系,根据Biot有效应力定律,计算得到岩石样品的等效骨架弹性模量。利用上述获得的碳酸盐岩样品各弹性参数,通过超压预测量化模型计算碳酸盐岩超压,并与碳酸盐岩样品岩石物理模拟实验加载的孔隙流体压力进行对比,验证了超压预测量化模型的合理性,提出了基于实测资料的模型校正方法。该超压预测理论模型所需的岩石弹性参数也可通过研究测井和地震资料计算获得,并可利用地震资料实现碳酸盐岩地层的超压钻前预测。
Prediction of overpressure in carbonate formations is still a difficult problem in overpressure researches.The most common methods on overpressure prediction in clastic formations are empirical based on Terzaghi effective stress theory as well as logging and seismic parameters(mostly P-wave velocity) which have a clear response to overpressure.These empirical methods are not applicable to predict overpressure in carbonate formations with dense matrix and extremely heterogeneous physical properties.We selected carbonate rock samples to carry out the rock physics modeling experiment with overpressure,and analyzed the relationship of rock elastic property with pore fluid pressure and effective stress.Based on the poroelasticity theory and generalized Hooke's law in fluid-bearing rocks,a theoretical model for overpressure prediction(a quantitative model of overpressure prediction) was established to reflect the quantitative relationship between pore pressure and rock elastic parameters by analyzing the constitutive relation between stress,strain and pore pressure in carbonate formations.The elastic modulus of rock matrix was calculated by Voigt-Reuss-Hill model and mineral composition content in carbonate rocks is obtained through lab measurements.The Wood and Patchy models were used to calculate the elastic modulus of pore fluids,and then the equivalent elastic modulus of rock framework is calcula-ted indirectly by the Biot effective stress theory and the correlation between effective stress and elastic modulus of rock framework was acquired through the rock physics modeling experiment.The above obtained elastic parameters were in turn used to calculate overpressure in carbonate rocks by the quantitative overpressure prediction model.In comparison with the pore fluid pressure artificially loaded in the carbonate rock physics modeling experiment,we verified the applicability of the quantitative model of overpressure prediction in carbonate rocks,and proposed the idea for correction of the theoretical model of overpressure prediction.The rock elastic parameters required for the theoretical model of overpressure prediction can also be calculated by studying logging and seismic data,and the pre-drilling overpressure prediction with seismic data could also be achieved in carbonate formations.
Prediction of overpressure in carbonate formations is still a difficult problem in overpressure researches.The most common methods on overpressure prediction in clastic formations are empirical based on Terzaghi effective stress theory as well as logging and seismic parameters(mostly P-wave velocity) which have a clear response to overpressure.These empirical methods are not applicable to predict overpressure in carbonate formations with dense matrix and extremely heterogeneous physical properties.We selected carbonate rock samples to carry out the rock physics modeling experiment with overpressure,and analyzed the relationship of rock elastic property with pore fluid pressure and effective stress.Based on the poroelasticity theory and generalized Hooke's law in fluid-bearing rocks,a theoretical model for overpressure prediction(a quantitative model of overpressure prediction) was established to reflect the quantitative relationship between pore pressure and rock elastic parameters by analyzing the constitutive relation between stress,strain and pore pressure in carbonate formations.The elastic modulus of rock matrix was calculated by Voigt-Reuss-Hill model and mineral composition content in carbonate rocks is obtained through lab measurements.The Wood and Patchy models were used to calculate the elastic modulus of pore fluids,and then the equivalent elastic modulus of rock framework is calcula-ted indirectly by the Biot effective stress theory and the correlation between effective stress and elastic modulus of rock framework was acquired through the rock physics modeling experiment.The above obtained elastic parameters were in turn used to calculate overpressure in carbonate rocks by the quantitative overpressure prediction model.In comparison with the pore fluid pressure artificially loaded in the carbonate rock physics modeling experiment,we verified the applicability of the quantitative model of overpressure prediction in carbonate rocks,and proposed the idea for correction of the theoretical model of overpressure prediction.The rock elastic parameters required for the theoretical model of overpressure prediction can also be calculated by studying logging and seismic data,and the pre-drilling overpressure prediction with seismic data could also be achieved in carbonate formations.
引文
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[12] Knight R,Nolen-Hoeksema R.A laboratory study of the dependence of elastic wave velocities on pore scale fluid distribution[J].Geophysical Research Letters,1990,17(10):1529-1532.
[13] Biot M A,General theory of three-dimensional consolidation[J].Journal of Applied Physics,1941,12(2):155-164.
[14] 刘鸿文.材料力学[M].北京:高等教育出版社,2011.Liu Hongwen.Mechanics ofmaterials[M].Beijing:Higher Education Press,2011.
[15] Skempton A.W.Thepore-pressure coefficients A and B[J].Géotechnique,1954,4(4):143-147.
[16] Biot M A,Willis D G.The elastic coefficients of the theory of consolidation[J].Journal of Applied Mechanics,1957,15(2):594-601.
[17] Hashin Z,Shtrikman S.A variational approach to the theory of the elastic behaviour of multiphase materials[J].Journal of the Mechanics & Physics of Solids,1963,11(2):127-140.
[18] Reuss A.Berechnung der flie?grenze von mischkristallen auf grund der plastizit?tsbedingung für einkristalle.[J].Zeitschrift für Angewandte Mathematik und Mechanik,1929(1):49-58.
[19] Voigt W.Ueber die beziehung zwischen den beiden elasticit?tscon- stanten isotroper k?rper.[J].Annalen der Physik,1989(12):573-587.
[20] Hill R.Theelastic behaviour of a crystalline aggregate[J].Proceedings of the Physical Society,1952,65(5):349-354.
[21] Mavko G,Mukerji T,Dvorkin J.The rock physics handbook:tools for seismic analysis of porous media[M].New York:Cambridge University Press,2009.
[22] 张金强,马中高,曲寿利,等.碳酸盐岩储层流体替换中混相流体体积模量的计算[J].石油物探,2012,51(2):133-137.Zhang Jinqiang,Ma Zhonggao,Qu Shouli,et al.Calculation of bulk modulus for mixed-phase fluid in fluid substitution for carbonate reservoir[J].Geophysical Prospecting for Petroleum,2012,51(2):133-137.
[23] 巴晶.岩石物理学进展与评述[M].北京:清华大学出版社,2013.Ba Jing.Progress and review of rock physics[M].Beijing:Tsinghua University Press,2013.
[2] Eaton B A.Graphical method predictsgeopressure worldwide[J].Word Oil,1972:51-56.
[3] 杨姣,何生,王冰洁.东营凹陷牛庄洼陷超压特征及预测模型[J].地质科技情报,2009,28(4):34-40.Yang Jiao,He Sheng,Wang Bingjie.Characteristics and prediction model of the overpressures in the Niuzhuang sag of Dongying depression[J].Geological Science and Technology Information,2009,28(4):34-40.
[4] Fillippone W R.On the prediction of abnormally pressured sedimentary rocks from seismic data[C]//Offshore Technology Conference,Houston,Texas.1979:2667-2676.
[5] 何生,宋国奇,王永诗,等.东营凹陷现今大规模超压系统整体分布特征及主控因素[J].地球科学—中国地质大学学报,2012,37(5):1029-1042.He Sheng,Song Guoqi,Wang Yongshi,et al.Distribution and major control factors of the present-day large-scale overpressured system in Dongying depression[J].Earth Science(Journal of China University of Geosciences),2012,37(5):1029-1042.
[6] Eberhart-Phillips D M.Investigations of crustal structures and active tectonic processes in the Coast Ranges,Central California[D].Stanford University,1989.
[7] Bowers G L.Pore pressure estimation from velocity data:accountion for overpressure mechanisms besides undercompaction[J].SPE Drillingand44 Completion,1995,10(2):89-95.
[8] 路凤香,桑隆康.岩石学[M].北京:地质出版社,2002.Lu Fengxiang,Sang Longkang.Petrology[M].Beijing:Geological Publishing House,2002.
[9] 邓继新,王尚旭,俞军.不同压力条件下部分饱和砂岩速度实验结果及理论解释[J].石油地球物理勘探,2005,40(5):530-534.Deng Jixin,Wang Shangxu,Yu Jun.Experimental results in partially saturated sand-stone under condition of different pressure and their theoretical interpretation[J].Oil Geophysical Prospecting,2005,40(5):530-534.
[10] 未晛,王尚旭,赵建国,等.致密砂岩纵、横波速度影响因素的实验研究[J].石油物探,2015,54(1):9-16.Wei Xian,Wang Shangxu,Zhao Jianguo,et al.Laboratory investigation of influence factors on vp and vs in tight sandstone[J].Geophysical Prospecting for Petroleum,2015,54(1):9-16.
[11] Endres A L,Knight R.The effects of pore-scale fluid distribution on the physical properties of partially saturated tight sandstones[J].Journal of Applied Physics,1991,69(2):1091-1098.
[12] Knight R,Nolen-Hoeksema R.A laboratory study of the dependence of elastic wave velocities on pore scale fluid distribution[J].Geophysical Research Letters,1990,17(10):1529-1532.
[13] Biot M A,General theory of three-dimensional consolidation[J].Journal of Applied Physics,1941,12(2):155-164.
[14] 刘鸿文.材料力学[M].北京:高等教育出版社,2011.Liu Hongwen.Mechanics ofmaterials[M].Beijing:Higher Education Press,2011.
[15] Skempton A.W.Thepore-pressure coefficients A and B[J].Géotechnique,1954,4(4):143-147.
[16] Biot M A,Willis D G.The elastic coefficients of the theory of consolidation[J].Journal of Applied Mechanics,1957,15(2):594-601.
[17] Hashin Z,Shtrikman S.A variational approach to the theory of the elastic behaviour of multiphase materials[J].Journal of the Mechanics & Physics of Solids,1963,11(2):127-140.
[18] Reuss A.Berechnung der flie?grenze von mischkristallen auf grund der plastizit?tsbedingung für einkristalle.[J].Zeitschrift für Angewandte Mathematik und Mechanik,1929(1):49-58.
[19] Voigt W.Ueber die beziehung zwischen den beiden elasticit?tscon- stanten isotroper k?rper.[J].Annalen der Physik,1989(12):573-587.
[20] Hill R.Theelastic behaviour of a crystalline aggregate[J].Proceedings of the Physical Society,1952,65(5):349-354.
[21] Mavko G,Mukerji T,Dvorkin J.The rock physics handbook:tools for seismic analysis of porous media[M].New York:Cambridge University Press,2009.
[22] 张金强,马中高,曲寿利,等.碳酸盐岩储层流体替换中混相流体体积模量的计算[J].石油物探,2012,51(2):133-137.Zhang Jinqiang,Ma Zhonggao,Qu Shouli,et al.Calculation of bulk modulus for mixed-phase fluid in fluid substitution for carbonate reservoir[J].Geophysical Prospecting for Petroleum,2012,51(2):133-137.
[23] 巴晶.岩石物理学进展与评述[M].北京:清华大学出版社,2013.Ba Jing.Progress and review of rock physics[M].Beijing:Tsinghua University Press,2013.