The fate of fracturing water: A field and simulation study
The fate of fracturing water: A field and simulation study
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DOI：
10.1016/j.fuel.2015.09.040
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发表时间：
2016-01-01
期刊：
影响因子：
7.4
通讯作者：
Dehghanpour, Hassan
中科院分区：
文献类型：
--
作者：
Ghanbari, Ebrahim;Dehghanpour, Hassan
页岩气开采多分支水平井水力压裂需用水量大。现场数据表明，在清理阶段，只能回收一小部分注入水。特别是当页岩油气井在经过多阶段压裂后经历长达一个月的关闭期时。现场数据还表明，在一些井中，这种关井事件令人惊讶地提高了油气流速。然而，对油藏中未回收水的去向以及长时间关井后早期油气产量增加的原因尚不清楚，本文首先解释了霍恩河盆地18井垫的排液数据。然后，我们利用数值模拟器研究了排液过程中控制水和气生产的参数。在模拟模型中，页岩储层用一个裂隙矩阵模型来表示，裂隙形成了一个相互连通的网络连续体。模拟结果表明，关井过程中压裂水的逆流渗吸会导致裂缝内大量积气，从而提高早期产气量。研究还得出结论，早期产水产气取决于毛管压力、裂缝网络形成的复杂程度等储层性质，以及关井时间等作业参数。毛管压力较高的油藏排液初期产气量较高，但后期产气量下降。水力压裂过程中产生的裂缝网络的复杂性对产能恢复和产气量有很大影响。随着复杂性的增加，由于裂缝与页岩基质之间产生了更高的接触面，天然气产量增加，负荷采收率降低。此外，现场数据和模拟结果表明，延长关井周期增加了早期产气量，但降低了负荷采收率和后期产气量。(C)2015爱思唯尔有限公司。保留所有权利。
Hydraulic fracturing of multi-lateral horizontal wells for shale gas production usually requires a great amount of water. Field data indicate that only a small fraction of the injected water can be recovered during the clean-up phase. Especially, when shale oil and gas wells undergo month-long shut-in periods after multi-stage fracturing processes. Field data also indicate that in some wells, such shut-in episodes surprisingly increase the oil and gas flow rate. However, the fate of non-recovered water in the reservoir and the reasons behind increased early-time oil and gas production after a long shut-in period are poorly understood.In this paper, we first interpret the flowback data of a 18-well pad completed in the Horn River Basin. Then, we use a numerical simulator to investigate the parameters controlling water and gas production during the flowback process. In the simulation model, the shale reservoir is represented by a fracturematrix model, where the fractures form a continuum of interconnected network. The simulation results show that the counter-current imbibition of fracturing water during the shut-in period can result in a significant gas build-up in the fractures and therefore increases early-time gas production rate. It was also concluded that early-time water and gas production depends on reservoir properties such as capillary pressure and complexity of created fracture network and operational parameters such as shut-in time. The gas production rates from reservoirs with higher capillary pressure is higher at the beginning of flowback process but the production rate falls later. The complexity of fracture network created during hydraulic fracturing process has a great effect on load recovery and gas production. As the complexity increases, the gas production rate increases and load recovery decreases due to higher contact surface created between fractures and shale matrices. Further, field data and simulation results show that extended shut-in period increases early-time gas production but it decreases load recovery and late-time gas production. (C) 2015 Elsevier Ltd. All rights reserved.