摘要
页岩储层岩石具有基质致密,微裂隙、层理面发育,岩石性脆等非常规地质特征,其力学性质与一般的致密砂岩、碳酸盐岩相比具有一定的特殊性。为探寻这一特殊的岩石力学性质,利用MTS多功能岩石力学实验系统对取自四川盆地某区的M组页岩开展了三轴、单轴、巴西力学实验。结果表明:页岩岩石三轴平均抗压强度为265.75MPa,平均杨氏模量为4.59×104 MPa,平均泊松比为0.25,属于中硬地层;单轴垂向取样抗压强度(151.92MPa)是水平取样抗压强度(为69.18MPa)的2.2倍;页岩抗张强度较低,平均为2.94MPa。综合分析页岩储层脆性指数后认为,M组页岩属于脆性岩石,储层脆性指数均超过50,有利于对页岩储层进行大型水力压裂;压裂应选择以滑溜水为主的体积压裂模式,压裂设计应遵循"大液量、大排量、高前置液比、小粒径支撑剂、低砂浓度"的原则。
Shale reservoirs are featured by tight matrix,well-developed micro-fissures and laminations as well as brittleness and their peculiar mechanical characteristics are different from those of ordinary tight sandstones or carbonates.In view of this,triaxial,uniaxial and Brazilian mechanical experiments are performed on shale samples from the M Formation in one area of the Sichuan Basin by use of an MTS test system.The triaxial average compressive strength is 265.75 MPa,the average Yong's modulus is 45900 MPa,and the average Poisson ratio is 0.25,revealing moderate hardness.The uniaxial vertical compressive strength(151.92 MPa) is 2.2 times of the horizontal compressive strength(69.18 MPa).The tensile strength of shales is relatively low,averaging at 2.94 MPa.The comprehensive analysis of shale reservoir brittleness reveals that the M Formation shales belong to rocks with brittleness index over 50,being favorable for hydraulic fracturing.The volumetric fracturing mode with fracturing fluid dominated by slick water should be selected for fracturing operation.The design of fracturing should follow the principles of 'a large volume of fracturing fluid,large discharge capacity,a high pad fluid ratio,small sizes of proppant grains,and a low sand content'.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2012年第7期12-14,100,共3页
Natural Gas Industry
基金
中国博士后科学基金项目(编号:20090451422)
关键词
四川盆地
页岩
储集层
岩石力学实验
特性
矿物组分
脆性指数
压裂
Sichuan Basin,shale,reservoir rock,rock mechanical experiment,feature,mineral composition,brittleness index,fracturing
