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| 煤层气井近井压裂裂缝充填特征与堵塞机制 |
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陈立超, 王生维, 何俊铧, 李瑞, 刘建华, 吕帅锋1,2,3
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1. 内蒙古工业大学矿业学院, 内蒙古呼和浩特 010051;2. 晋煤集团煤与煤层气共采国家重点实验室, 山西晋城 048204;3. 中国地质大学(武汉)资源学院, 湖北武汉 430074
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| 摘要: |
| 近井部位压裂裂缝内微粒运移与堵塞是煤层气井减产的重要因素之。客观查明近井压裂裂缝内充填特征规律与堵塞机制对气井解堵理论深化、解堵工艺改进非常关键。基于煤矿掘进工作面开挖观测现象，对沁水盆地南部煤层气直井近井压裂裂缝内充填特征与裂缝堵塞机制进行系统分析。结果表明：煤层气井近井压裂裂缝内充填物由煤粉、支撑剂及完井滤饼组成；完井滤饼对压裂裂缝启裂、延展及支撑剂分布具有关键控制作用，近井裂缝壁面完井滤饼能够减缓压裂液的滤失速率，但在滤饼尖灭位置压裂液滤失速率突然增大时极易脱砂形成脱砂楔体，楔体在流体冲击下压实致密，排采期气液两相流携带煤粉流经脱砂楔体时卡在砂粒间形成裂缝堵塞；基于颗粒堆积模型与黄金过滤原则，针对研究区粒度中值0.045 mm的煤粉，脱砂楔体处注入支撑剂粒径大于0.900 mm可降低裂缝内煤粉堵塞程度。 |
| 关键词: 煤层气井 压裂裂缝 完井滤饼 煤粉运移 堵塞 |
| DOI：10.3969/j.issn.1673-5005.2017.06.014 |
| 分类号: |
| 基金项目:山西省煤层气联合基金项目（2016012007）；内蒙古自然科学基金项目（2016MS0402）；内蒙古自治区高等学校科学研究项目（NJZY16090）；甘肃省油气资源研究重点实验室开放基金项目（SZDKFJJ20160606）；内蒙古工业大学科学研究项目（X201534） |
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| Filling characteristics and plugging mechanisms of hydraulic fractures near CBM vertical wells |
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CHEN Lichao, WANG Shengwei, HE Junhua, LI Rui, LIU Jianhua, LÜ Shuaifeng1,2,3
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1. School of Mining and Technology in Inner Mongolia University of Technology, Hohhot 010051, China;2. State Key Laboratory of Coal and CBM Co-mining in Jincheng Anthracite Mining Group, Jincheng 048204, China;3. Faculty of Earth Resources in China University of Geosciences, Wuhan 430074, China
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| Abstract: |
| Particle migration and blocking in fracturing fractures near wellbore area can be one of the important factors to production reduction of coalbed methane (CBM) wells. It is essential to reveal the filling characteristics and plugging mechanism of fracturing fractures in order to remove the plug and increase production. In this study, based on the in-site observations of the fractures appeared in tunnels of underground coal mines, the filling characteristics and blocking mechanisms in the fractures of vertical CBM wells in southern Qinshui Basin were investigated. The observation shows that the fillings contain coal fines, proppant and well completion filter cake in the fractures near wellbore. Completion filter cake can control the initiation and propagation of fractures, and proppant distribution, and it can reduce the filtration rate of fracturing fluid. But when the fluid flows through the location where the filter cake is pinched out, significant fluid-loss can occur, which can take off sands and form sand wedge, and further the wedges become compacted and filled with coal fines carried by gas-liquid phase flow, then blocking or plugs of the fractures can be formed, reducing the flow capacity of the fracture seriously. It proposes that, based on a particle gathering model and the golden filtration principle, the size of proppants used in fracturing should be greater than 0.900 mm in order to reduce the plugging coal fines with median size of 0.045 mm that found in the study CBM area. |
| Key words: coalbed methane wells hydraulic fracture completion filter cake coal fines migration plugging |
