特低渗透油藏注水诱导动态裂缝实验及数值模拟

Experiment and numerical simulation of water injection induced dynamic fractures in ultra-low permeability reservoirs

梁卫卫 党海龙 刘滨 张天龙 王小锋 侯玢池 崔鹏兴 王谦 张凤远

LIANG Weiwei DANG Hailong LIU Bin ZHANG Tianlong WANG Xiaofeng HOU Binchi CUI Pengxing WANG Qian ZHANG Fengyuan

陕西延长石油(集团)有限责任公司研究院, 西安 710065 陕西省特低渗透油气田勘探与开发工程技术研究中心, 西安 710065 中国石油大学(北京) 石油工程学院, 北京 102249

Research Institute of Shaanxi Yanchang Petroleum (Group) Co., Ltd., Xi'an, Shaanxi, 710065, China Ultra-low Permeability Oil and Gas Exploration and Development Engineering Research Center of Shaanxi Province, Xi'an, Shaanxi, 710065, China School of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102249, China

为了进一步明确特低渗透油藏注水诱导动态裂缝形成机理及其对特低渗透油藏注水开发的影响，基于注水诱导动态裂缝室内实验，阐述了注水诱导动态裂缝成因机理及延伸过程，建立了注水诱导动态裂缝数值表征方法并进行了相对应的油藏数值模拟研究。注水诱导动态裂缝按照成因主要分为天然闭合型、人工压裂诱导型和超储层破裂压力型3类。注水诱导动态裂缝生长机理主要为注入压力与岩石破裂压力或裂缝延伸压力的反复作用促使岩石发育裂缝或使已存在的裂缝不断延伸。改进的注水诱导动态裂缝实验表明，注入压力呈现反复的“升—降”特征，且注入压力是岩石产生注水诱导动态裂缝的主控参数。注水诱导动态裂缝数值模拟结果也验证了注入井井底压力呈现周期性“憋压上升—起裂下降”趋势。诱导动态裂缝产生后，裂缝体系内的压力和饱和度场是随着动态裂缝的开启和延伸而动态变化的，且沿裂缝体系变化明显，裂缝系统两侧波及范围小。

In order to further clarify the mechanism of water injection induced dynamic fractures in ultra-low permeability reservoirs and its influence on water injection development in ultra-low permeability reservoirs, the genetic mechanism and propagation process of dynamic fractures induced by water injection were expounded based on the laboratory experiments of water injection induced dynamic fractures. A numerical characterization method of water injection induced dynamic fractures was established, and the corresponding reservoir numerical simulation was researched. The results indicate that the water injection induced dynamic fractures include natural closure type, artificial fracturing induced type and super reservoir breakdown pressure type. The main growth mechanism of water injection induced dynamic fractures was that the continuous extension of the fractures developed in rocks or the existing fractures through repeated action of injection pressure and rock breakdown pressure or fracture propagation pressure. The improved water injection induced dynamic fracture experiment shows that the injection pressure presents the characteristics of repeated "up and down", and the injection pressure is the main controlling parameter for the rock to generate water injection induced dynamic fractures. The numerical simulation results verify that the bottom hole pressure of the injection well shows a periodic trend of "pressure-build rise and crack initiation drop". After the dynamic fracture was induced, the pressure and saturation fields in the fracture system change dynamically with the opening and extension of the dynamic fracture and the changes are mainly obvious along the fracture system, and the influence range on both sides of the fracture system is small.

陕西省科技统筹创新工程计划项目“延长难采储量有效动用开发技术研究” 2016KTCL01-12

https://doi.org/10.11781/sysydz202303566