致密砂岩储层可压裂性测井评价方法  

Logging evaluation method of fracturability of tight sandstone reservoirs

作　　者：徐波[1] 王振华 宋婷 张淑侠 彭娇[1] XU Bo;WANG Zhenhua;SONG Ting;ZHANG Shuxia;PENG Jiao(College of Petroleum Engineering,Xi’an Shiyou University,Xi’an City,Shaanxi Province,710065,China;Research Institute of Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi’an City,Shaanxi Province,710065,China;No.11 Oil Production Plant,Changqing Oilfield Company,PetroChina,Qingyang City,Gansu Province,745000,China)

机构地区：[1]西安石油大学石油工程学院,陕西西安710065 [2]延长石油(集团)有限责任公司研究院,陕西西安710065 [3]中国石油长庆油田分公司第十一采油厂,甘肃庆阳745000

出　　处：《油气地质与采收率》2024年第6期57-64,共8页Petroleum Geology and Recovery Efficiency

摘　　要：储层的可压裂性是射孔选段和预测水力压裂效果的重要因素,但目前致密砂岩储层的可压裂性评价缺乏统一的方法和标准。以鄂尔多斯盆地东南部某油田长6油层组致密砂岩储层为例,基于常规测井资料优选岩石力学参数的表征模型,通过分析储层岩石脆性、断裂韧性和地应力差异系数与日产液量的关系,建立了致密砂岩储层的可压裂性评价模型及评价标准,获得了与测井曲线对应的压裂品质因子曲线,形成了一种精度较高的致密砂岩储层可压裂性测井评价方法。研究结果表明:①脆性指数与可压裂性呈正相关,断裂韧性和地应力差异系数与可压裂性呈负相关。②当压裂品质因子≥25时,为Ⅰ类储层,可压裂性最好,压裂时容易形成复杂的裂缝网络,属于优质的致密砂岩储层;当14≤压裂品质因子<25时,为Ⅱ类储层,可压裂性中等,压裂时需要采用黏度较小的压裂液或控制较高的缝内净压力,才能形成较好的裂缝网络;当压裂品质因子<14时,为Ⅲ类储层,可压裂性差,压裂时通常不会形成理想的裂缝网络,且压裂后裂缝容易闭合。③致密砂岩储层的压裂品质因子越高,其压裂后的人工裂缝展布形态特征越好,压后产能越高,新建模型的评价结果与微地震裂缝监测结果及试油成果的符合率在80%以上。The fracturability of reservoirs is an essential parameter for selecting perforation stages and predicting hydraulic fracturing effects,but fracturability evaluation for tight sandstone reservoirs lacks unified methods and standards.This paper studies Chang 6 tight sandstone reservoir in an oilfield in the southeastern part of Ordos Basin and optimizes the characterization model of rock mechanics parameters based on the conventional logging data.The paper analyzes the relationships among reservoir rock brittleness,fracture toughness,in-situ stress difference coefficient,and daily fluid production,establishes the fracturability evaluation model and evaluation standard for tight sandstone reservoirs,and obtains fracture quality factor curves corresponding to logging curves.As a result,a high-precision logging evaluation method for the fracturability of tight sandstone reservoirs was developed.The results indicate as follows:①The brittleness index is positively correlated with the fracturability,and the fracture toughness and in-situ stress difference coefficient are negatively correlated with the fracturability.②The fracturing quality factor is greater than 25 for Class I reservoirs,indicating the best fracturability;it is easy to form a complex fracture network during fracturing and belongs to high-quality tight sandstone reservoirs.The fracturing quality factor ranges from 14 to 25 for Class II reservoirs,indicating medium fracturability;it is necessary to use fracturing fluid with low viscosity or keep high net pressure in fractures to form a better fracture network.The fracturing quality factor is less than 14 for class III reservoirs,indicating poor fracturability;an ideal fracture network is usually not formed during fracturing,and fractures are easy to close after fracturing.③Higher fracturing quality factors of tight sandstone reservoirs indicate better characteristics of artificial fracture morphologies and higher production capacity after fracturing.The evaluation results by the established model ar

关 键 词：致密砂岩 可压裂性 脆性指数 断裂韧性 地应力差异系数 鄂尔多斯盆地 

分 类 号：TE319[石油与天然气工程—油气田开发工程]