致密砂岩储层压裂液渗吸滞留及解除水锁微观作用机制研究

"Fracture network fracturing + imbibition displacement + unlocking flow back" is a new attempt for effective development of tight sandstone reservoirs. Fracturing fluid is not only a carrier to carry sand and make cracks, but also a tool for imbibition and displacement of oil recovery. At present, the microscopic mechanism of imbibition and retention of fracturing fluid and the mechanism of releasing water lock in tight sandstone reservoir are still unclear, there are few literatures on the study of the boundary and quantitative characterization of the main throat in the imbibition and retention of different types of tight sandstone reservoirs, relieving water blocking technology optimization methods and limit indicators need to be further improved. This project takes the domestic tight sandstone reservoir as the main research object, and takes the rock core model experiment as the main research method. Based on the classification of tight sandstone reservoirs and the quantitative characterization of the pore throat structure, It builds the microscopic visual physical model of the imbibition and retention of fracturing fluid and the release of water blocking, analyzes the dynamic and static characteristics of imbibition and retention of fracturing fluids in different types of tight sandstone reservoirs, presents the main throat boundary of imbibition and retention of fracturing fluid in different types of tight sandstone reservoirs, and the water blocking technology method and the boundary indicator corresponding to different configuration relationships were explored. The study has important implications for the evaluation and screening of tight sandstone reservoirs, the optimization design of fracturing flow back system, and the improvement of the productivity of tight reservoirs.

“缝网压裂+渗吸置换+解锁返排”是致密砂岩储层有效开发的一种新尝试，压裂液不仅是携砂造缝的载体，更是渗吸置换的工具。目前，致密砂岩储层压裂液渗吸滞留微观机理及解除水锁微观作用机制尚不明确，鲜有文献对不同类型致密砂岩储层渗吸滞留主流喉道界限及量化表征进行研究，解除水锁技术优化方法及界限指标亟待进一步完善。本项目以国内致密砂岩储层为主要研究对象，物模实验为主要研究手段，在致密砂岩储层分类及孔喉结构量化表征基础上，构建压裂液渗吸滞留及解除水锁微观可视化物理模型，系统研究不同类型致密砂岩储层压裂液渗吸滞留微观渗流机理及解除水锁微观作用机制，分析不同类型致密砂岩储层压裂液渗吸滞留效应动静态特征，给出不同类型致密砂岩储层压裂液渗吸滞留主流喉道界限，探索不同配置关系对应的解水锁技术方法及界限指标。研究对致密砂岩储层评价及筛选、压裂返排制度优化设计、提高致密储层产能都具有重要意义。

“缝网压裂+渗吸置换+解锁返排”是致密砂岩储层有效开发的一种新尝试，压裂液不仅是携砂造缝的载体，更是渗吸置换的工具。目前，致密砂岩储层压裂液渗吸滞留微观机理及解除水锁微观作用机制尚不明确，鲜有文献对不同类型致密砂岩储层渗吸滞留主流喉道界限进行研究，解除水锁技术优化方法及界限指标亟待进一步完善。本项目以国内致密砂岩储层为主要研究对象，物模实验为主要研究手段，结合铸体薄片、扫描电镜、X-ray衍射、润湿性测试、相渗测试、高压压汞等基础实验，分析了致密砂岩储层矿物组成、成岩演化、流体性质以及孔喉结构等特征，给出了致密砂岩储层分类及分类标准，基于8个参数的聚类分析，将致密砂岩储层细分为三类。构建了微观可视化压裂液渗吸滞留物理模型，研究了压裂液渗吸滞留微观渗流机理；分析了不同类型致密砂岩储层压裂液渗吸滞留效应动静态特征，定量表征渗吸滞留对不同类型致密砂岩储层的伤害。分析了影响压裂液渗吸滞留的主控因素，界面张力越小、气测渗透率越大、流体粘度越低、矿化度越小，则渗吸滞留占比越大，因素影响从大到小排序为界面张力>渗透率>矿化度>粘度；给出了不同类型致密砂岩储层压裂液渗吸滞留主流喉道界限，渗吸滞留主流喉道界限范围为0.002μm-0.04μm，排液主流喉道界限范围为0.04μm-0.81μm；构建了微观可视化解除水锁微流控物理模型，研究了致密砂岩储层解除水锁微观作用机制，初步探索了不同配置关系对应的解水锁技术方法及界限指标。研究对致密砂岩储层评价及筛选、压裂返排制度优化设计、提高致密储层产能都具有重要意义。