页岩储层微观破裂特征实验研究

Experimental study of microscopic fracture characteristics of shale reservoirs

赵志红 郭建春 杨经栋 王杏尊 鲍文辉

ZHAO Zhihong GUO Jianchun YANG Jingdong WANG Xingzun BAO Wenhui

西南石油大学油气藏地质及开发工程国家重点实验室，四川成都　610500 华北油田勘探开发研究院，河北任丘　062552 中海油田服务股份有限公司油田生产事业部，天津塘沽　300450

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China Huabei Oilfield Exploration and Development Research Institute, Renqiu, Hebei 062552, China Oilfield Production Division, China Oilfield Services Co., LTD., Tanggu, Tianjin 300450, China

形成复杂网状裂缝沟通更大的储层体积是页岩储层改造的关键，但在微观上，页岩储层破裂面的特征影响自支撑裂缝的导流能力，破裂时在破裂面上产生的微裂缝影响页岩气的渗透性，这些对页岩储层的改造同样重要。利用四川盆地和济阳凹陷页岩岩样首先进行矿物组成和破裂实验后，利用3D 激光扫描仪对一组岩样的破裂面进行扫描，分析破裂面的平整程度； 利用扫描电子显微镜对两组岩样的破裂面进行不同倍比扫描，分析破裂面的微观形态特征。实验结果发现：方解石含量越高， 破裂面等高线分布规律性越强，且越易在破裂面形成微裂缝；黏土含量越少，方解石和石英含量越高，越易发生剪切断裂。研究成果对认识页岩储层的破裂特征以及指导压裂方案设计具有一定的意义。

For shale reservoir reform it is critical to connect a larger reservoir volume by developing complex fracture network. Microscopically, however, the characteristics of fracture plane in shale reservoir affect the conductivity of self-propping fractures, and the microfractures formed on the fracture plane affect the permeability of shale gas. These aspects are equally important for shale reservoir stimulation. In this paper, the mineral composition and fracture test is conducted firstly for a series of shale samples taken from the Sichuan Basin and Jiyang Depression, and then a 3D laser scanner is used to scan the fracture planes in a group of samples, so as to analyze the flatness of such planes. Next, a scanning electron microscope is used to scan the fracture planes in two groups of samples at different multipliers to analyze the microscopic characteristics of the fracture surfaces. The results show that, higher the calcite content, stronger the fracture planes’ regularity on the contour chart, and more easily the formation of microfractures in the fracture plane; shear fracture is more possible in case of lower clay content and higher content of quartz and calcite. These conclusions are significance for understanding the fracture characteristics of shale reservoir and guiding the fracturing design.

10.13639/j.odpt.2014.03.017