超临界二氧化碳压裂过程中注入压力对致密砂岩力学特征的影响
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摘要
针对致密砂岩气藏采用超临界二氧化碳压裂技术开发中,未考虑二氧化碳流体对储层岩石力学影响,从而导致设计压裂施工参数与现场实际不吻合问题,取苏里格气田2 800 m左右石盒子组地层岩心,在围压38 MPa、温度85℃下,模拟地层条件开展超临界二氧化碳压裂致密砂岩岩石力学特征实验,测试二氧化碳注入压力从3 MPa增加到35 MPa,然后加轴向压力至岩石破坏,获得致密砂岩岩石应力—应变曲线。研究表明,随超临界二氧化碳注入压力增大,致密砂岩抗压强度、弹性模量均减小,泊松比则增加,脆性指数先略微增大而后呈减小趋势。拟合出脆性指数与二氧化碳注入压力的关系式,相关系数为0.903 6,注入压力为4.55 MPa时脆性指数极值为0.483 5。超临界二氧化碳压裂时应考虑注入压力对岩石力学参数的影响,弹性模量、泊松比、脆性指数等岩石力学参数影响致密砂岩裂缝起裂及扩展规律。
Aiming at the development of supercritical carbon dioxide fracture on tight sandstone gas reservoirs, the carbon dioxide fluid effect on rock mechanics is not considered, and the fracturing parameters are not consistent with the oilfield. The test of rock mechanics on tight sandstone by supercritical carbon dioxide fracturing in simulating lab test Confining pressure 38 MPa and temperature 85 ℃, injection pressure of supercritical carbon dioxide is from 0 to 35 MPa. Axial pressure on the tight sandstone result in damage, the stress-strain curve of tight sandstone rock was obtained. With the increase of supercritical carbon dioxide injection pressure, the compressive strength and elastic modulus of tight sandstone decreases, Poisson's ratio increases, and the brittleness index increases first and then decreases. The fitting brittleness index and carbon dioxide injection pressure are several binomial relations.The maximum of brittleness index is 0.483 5 when injection pressure is equal to 4.55 MPa. The results show that the influence of injection pressure on rock mechanics parameters should be taken into account in supercritical carbon dioxide fracturing. Rock mechanics parameters such as elastic modulus, Poisson's ratio and brittleness index should influence the initiation and propagation law of cracks in tight sandstone in the late stage.
Aiming at the development of supercritical carbon dioxide fracture on tight sandstone gas reservoirs, the carbon dioxide fluid effect on rock mechanics is not considered, and the fracturing parameters are not consistent with the oilfield. The test of rock mechanics on tight sandstone by supercritical carbon dioxide fracturing in simulating lab test Confining pressure 38 MPa and temperature 85 ℃, injection pressure of supercritical carbon dioxide is from 0 to 35 MPa. Axial pressure on the tight sandstone result in damage, the stress-strain curve of tight sandstone rock was obtained. With the increase of supercritical carbon dioxide injection pressure, the compressive strength and elastic modulus of tight sandstone decreases, Poisson's ratio increases, and the brittleness index increases first and then decreases. The fitting brittleness index and carbon dioxide injection pressure are several binomial relations.The maximum of brittleness index is 0.483 5 when injection pressure is equal to 4.55 MPa. The results show that the influence of injection pressure on rock mechanics parameters should be taken into account in supercritical carbon dioxide fracturing. Rock mechanics parameters such as elastic modulus, Poisson's ratio and brittleness index should influence the initiation and propagation law of cracks in tight sandstone in the late stage.
引文
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[2]DENNIS.Drainage efficiency in naturally fractured tight sandstone gas reservoirs[J].Journal of Petroleum Technology,1998,50:37-39.
[3]ZHANG Ruxin,HOU Bing,SHAN Qinglin,et al.Hydraulic fracturing initiation and near-wellbore nonplanar propagation from horizontal perforated boreholes in tight formation[J].Journal of Natural Gas Science&Engineering,2018,55:337-349.
[4]蒋官澄,张弘,吴晓波,等.致密砂岩气藏润湿性对液相圈闭损害的影响[J].石油钻采工艺,2014,36(6):50-54.JIANG Guanchen,ZHANG Hong,WU xiaobo,et al.Effects of wettability of tight sandstone gas reservoir on liquid trap damage[J].Oil Drilling&Production Technology,2014,36(6):50-54.
[5]谢润成,韩振林,周文,等.深层致密砂岩气藏高异常破裂压力影响因素分析[J].石油钻采工艺,2009,31(5):60-64.XIE Runcheng,HAN Zhenlin,ZHOU Wen,et al.Analysis of factors influencing high abnormal fracture pressure in deep tight sandstone gas reservoir[J].Oil Drilling&Production Technology,2009,31(5):60-64.
[6]ALIREZA B,KHALIL S,MOSLEM F,et al.Investigating the applicability and effects of hydraulic fracturing technology on well productivity in one of the Iranian gas condensate reservoirs[J].Carbonates and Evaporites,2017,7:1-14.
[7]辛俊和,吴广义,张华北,等.加拿大致密气藏长水平段工厂化钻完井技术[J].石油钻采工艺,2014,36(2):7-11.XIN Junhe,WU Guangyi,ZHANG Huabei,et al.Factory-like drilling and completion techniques for long horizontal wells in tight gas reservoirs of Canada[J].Oil Drilling&Production Technology,2014,36(2):7-11.
[8]TORSTEN L,MARTIN S,MICHAEL H,et al.Hydraulic fracturing in unconventional gas reservoirs:risks in the geological system part 1[J].Environmental Earth Sciences,2013,70:3839-3853.
[9]DANNY D,SORAYA H,CHAU C,et al.Handbook of environmental technology in the oil industry of environmental impacts of hydraulic fracturing[M].USA,Lubbock,FL:CRC Press,2016.
[10]叶亮,邹雨时,赵倩云,等.致密砂岩储层CO2压裂裂缝扩展实验研究[J].石油钻采工艺,2018,40(3):361-368.YE Liang,ZOU Yushi,ZHAO Qianyun,et al.Experiment research on the CO2 fracturing fracture propagation laws of tight sandstone[J].Oil Drilling&Production Technology,2018,40(3):361-368.
[11]王海柱,沈忠厚,李根生,等.CO2气体物性参数精确计算方法研究[J].石油钻采工艺,2011,33(5):65-67.WANG Haizhu,SHEN Zhonghou,LI Gensheng,et al.Research on the precise calculation method of physical parameters for CO2[J].Oil Drilling&Production Technology,2011,33(5):65-67.
[12]侯冰,宋振云,贾建鹏,等.超临界二氧化碳对致密砂岩力学特性影响的实验研究[J].中国海上油气,2018,30(5):109-115.HOU bing,SONG Zhenyun,JIA Jianpeng,et al.Experimental study on the effect of supercritical carbon dioxide on mechanical properties of tight sandstone[J].China Offshore Oil and Gas,2018,30(5):109-115.
[13]XU Y G,ZHAO Z F,WANG Y J,et al.Hydra-jetting staged horizontal completion via multiple sliding sleeve in Changqing Sandstone tight gas reservoir[C]//Paper presented at the IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition,China,Tianjin,July,9-11,2012.
[14]WANG Y,LI X,TANG C A.Effect of injection rate on hydraulic fracturing in naturally fractured shale formations:a numerical study[J].Environ Earth Sci,2016,75:935.
[15]KENNETH,IMO-IMO ESHIET,YONG S.Carbon dioxide injection and associated hydraulic fracturing of reservoir formations[J].Environmental Earth Sciences,2014,72:1011-1024.
[16]王钒潦,李相方,汪洋,等.考虑压力拱效应的苏里格气田上覆压力计算[J].大庆石油地质与开发,2013,32(5):61-66.WANG Fanliao,LI Xiangfang,WANG Yang.Calculation of overburden pressure in Sulige gas field considering pressure arch effect[J].Daqing Petroleum Geology&Development,2013,32(5):61-66.
[17]陈勉,金衍,张广清,著.石油工程岩石力学[M].北京:科学出版社,2008:8-9.CHEN Mian,JIN Yan,ZHANG Guangqing,et al.Petroleum engineering rock mechanics[M].Beijing:Science Press,2008:8-9.
[18]李庆辉,陈勉,金衍,等.页岩脆性的室内评价方法及改进[J].岩石力学与工程学报,2012,31(8):1681-1686.LI Qinghui,CHEN Mian,JIN Yan,et al.Indoor evaluation method for shale brittleness and improvement[J].Chinese Journal Rock Mechanics and Engineering,2012,31(8):1681-1686.