摘要
为探究准噶尔盆地二叠系乌尔禾组砂砾岩储集层水力压裂裂缝扩展延伸规律,采用真实破裂过程分析软件,研究砾石特征、地应力等因素对裂缝扩展的影响。根据数值模拟,研究不同条件下裂缝的扩展过程,描述岩石裂缝演化及形态,建立砂砾岩储集层可压裂性的评价模型。结果表明:乌尔禾组砾石强度和基质强度差异较大,砾石强度为216.62~2032.64 MPa,是基质强度的2~4倍,砾岩岩石力学特性差异明显;砾石含量较小时,裂缝扩展主要受主应力的影响;砾石粒径较小时,裂缝扩展方式主要为绕砾;随着粒径增大或砾石含量增加,砾石对裂缝的抑制和屏蔽作用明显,裂缝延伸距离减小;砾石强度与基质强度差异越大,裂缝遇砾石受阻越强,扩展方式越易由穿砾变为绕砾,降低了裂缝延伸距离。运用灰色关联法和层次分析法,综合考虑砾石特征、水平地应力差等因素,建立了砂砾岩储集层可压裂性评价系数计算模型,无因次压裂裂缝面积和米采液指数与可压裂性评价系数呈正相关关系。
In order to understand the propagation and extension of hydraulic fractures in the sandy conglomerate reservoirs of Permian Wuerhe formation,Junggar basin,the influences of gravel characteristics,in⁃situ stress,and other factors on the fracture propagation were studied by using the Realistic Failure Process Analysis(RFPA)software.According to the results of numerical simulation,the fracture prop⁃agation process under different conditions was studied,the evolution and shape of the fractures were described,and a model for evaluating the fracabilty of the sandy conglomerate reservoirs was established.The results show that the gravel strength and matrix strength of Wuerhe formation are quite different.The gravel strength ranges from 216.62 MPa to 2032.64 MPa,which is 2-4 times of matrix strength.The rock mechanical properties of conglomerates differ significantly.When gravel content is small,fracture propagation is mainly affected by princi⁃pal stress.When the grain size of gravel is small,fractures mainly extend bypassing the gravel.With the increase of grain size or gravel con⁃tent,the inhibition and shielding effects of gravel on fractures become obvious,which reduces the extension of fractures.The greater the dif⁃ference between gravel strength and matrix strength,the stronger the fractures are blocked by the gravel,and the more easily the fractures extend in the way of bypassing the gravel rather than penetrating the gravel,which reduces the extension of fractures.Based on grey rela⁃tional analysis(GRA)and analytic hierarchy process(AHP),a model for calculating the fracabilty evaluation coefficient of the sandy con⁃glomerate reservoirs was established,which considers the factors such as gravel characteristics and horizontal in⁃situ stress.The fracabilty evaluation coefficient is positively correlated with dimensionless fracture area and fluid production index per meter.
作者
刘向君
王小军
赵保伟
熊健
梁利喜
LIU Xiangjun;WANG Xiaojun;ZHAO Baowei;XIONG Jian;LIANG Lixi(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Daqing Oilfield Company Limited,PetroChina,Daqing,Heilongjiang 163000,China)
出处
《新疆石油地质》
CAS
CSCD
北大核心
2023年第2期169-177,共9页
Xinjiang Petroleum Geology
基金
国家科技重大专项(2016ZX05051-004-008)。
关键词
准噶尔盆地
乌尔禾组
砾石特征
压裂裂缝
扩展规律
可压裂性评价
Junggar basin
Wuerhe formation
gravel characteristic
hydraulic fracture
fracture propagation
fracabilty evaluation
