松北致密气藏砂砾岩储层脆性特征实验研究  

Experimental study on brittleness of glutenite formation in tight gas reservoir of Songbei area

作　　者：唐鹏飞[1] TANG Pengfei(Research Institute of Oil Production,Daqing Oilfield Co.,Ltd.,PetroChina,Daqing City,Heilongjiang Province,163454,China)

机构地区：[1]中国石油大庆油田有限责任公司采油工程研究院

出　　处：《油气地质与采收率》2019年第6期46-52,共7页Petroleum Geology and Recovery Efficiency

基　　金：国家科技重大专项“大型油气田及煤层气开发”（2016ZX05046-006）

摘　　要：以松北致密气藏砂砾岩储层为研究对象,通过三轴压缩实验,开展含不同粒径砾石的砂砾岩脆性特征研究。在岩样破坏特征、偏应力-应变曲线特征分析的基础上,利用能量演化理论,研究不同粒径对砂砾岩力学性质和脆性特征的影响,并对岩样破坏过程中的声发射响应特征进行分析,结果表明:在三轴压缩实验中不同粒径砾石对砂砾岩岩样的破坏特征具有不同影响。相比于小粒径(<1 mm)砾石为主的岩样,大粒径(2~6 mm)砾石为主的岩样在更低的围压下被剪切破坏,且破裂面倾角较小。由于大量弱胶结砾石界面的存在,大粒径砾石为主的岩样通常具有更低的抗压强度,形成的破裂面更复杂。破裂面凹凸不平导致岩样破坏过程中一部分能量耗散于破裂面的摩擦,因此,大粒径砾石为主的岩样脆性更低,在剪切事件中占比更高,岩样破坏过程中以剪切破坏占主导。Taking the glutenite formation in tight gas reservoir of Songbei area as an example,the brittleness characteristics of glutenite containing different gravel size are studied by performing tri-axial compression tests. Based on the theory of energy evolution,the influence of gravel size on the mechanical properties and brittleness of glutenite is analyzed according to the investigation of the characteristics of broken rock and deviator stress-strain curve. Additionally,the acoustic emission response during the rock being broken process is analyzed. The experimental results of tri-axial compression test show that gravel size has a significant influence on the characteristics of broken rock samples. Compared with small size(<1 mm)gravel-dominated rock samples,large size(2-6 mm)gravel-dominated glutenite samples are sheared and broken at lower confining pressures with a smaller dip angle of fracture plane. Because of the existence of a large number of weak cemented gravel interfaces,the rock samples with larger size gravel are usually of lower compressive strength,while the broken pattern is more complex. In addition,the unevenness of the fracture surface leads to a part of the energy dissipated by the friction of the fracture surface during the failure process of the rock sample. Consequently,the brittleness of the gravel with larger gravels is lower. Moreover,the interpretation results of acoustic emission show that the proportion of shear events is higher in small size gravel-dominated rock samples,indicating shear failure tended to be dominant.

关 键 词：砂砾岩 三轴压缩实验 偏应力-应变曲线 脆性特征 致密气藏 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]