Abstract Hydraulic fracturing with proppants is the key technology in developing coalbed methane (CBM) reservoirs. However, coal fine retention in the fracturing proppant will directly affect its permeability and drop the CBM production. In this paper, coal fine retention experiments in fracturing proppants not containing coal fines, along with permeability tests of fracturing proppants containing coal fines, were successively conducted. The results showed that as the suspension concentrations of the coal fine increased, the coal fine retention amounts (Wr) of fracturing proppants increased monotonously, while the permeability decreased monotonously. Furthermore, as the suspension concentrations of the coal fines increased, the coal fine retention rate (Rr = Wr/Wt, where Wt represents the coal fine injected mass) first sharply increased monotonously to a peak level, and then slowly decreased monotonously. In addition, with the increases in the coal fine residue rates (Rcp = Wr/Wp, where Wp represents the mass of the proppants), the fracturing proppants permeability loss rates (η) were observed to first sharply increase and then slowly increase, indicating that the influences of the Wr on the permeability mainly occurred during the initial stage of the coal fines intrusions into the fracturing proppants. Furthermore, the relationship between the Rcp and η was also derived in this study as η = 0.71578 R cp 0.4575 .

中文翻译：

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煤层气储层细密滞留对压裂支撑剂渗透率影响的试验研究

摘要 支撑剂水力压裂是煤层气储层开发的关键技术。然而，压裂支撑剂中煤粉的滞留将直接影响其渗透率，降低煤层气产量。本文先后开展了不含煤粉压裂支撑剂的煤粉截留试验和含煤粉压裂支撑剂的渗透性试验。结果表明，随着煤粉悬浮浓度的增加，压裂支撑剂的煤粉滞留量（Wr）单调增加，而渗透率单调降低。此外，随着煤粉悬浮浓度的增加，煤粉保留率（Rr = Wr/Wt，其中 Wt 代表煤粉注入质量）首先单调急剧增加到峰值水平，然后缓慢单调下降。此外，随着煤粉残渣率（Rcp=Wr/Wp，其中Wp代表支撑剂质量）的增加，压裂支撑剂渗透率损失率（η）先急剧增加，然后缓慢增加，表明Wr 对渗透率的影响主要发生在煤粉侵入压裂支撑剂的初期。此外，本研究还得出 Rcp 和 η 之间的关系为 η = 0.71578 R cp 0.4575 。观察到压裂支撑剂渗透率损失率（η）先急剧增加然后缓慢增加，表明Wr对渗透率的影响主要发生在煤粉侵入压裂支撑剂的初始阶段。此外，本研究还得出 Rcp 和 η 之间的关系为 η = 0.71578 R cp 0.4575 。观察到压裂支撑剂渗透率损失率（η）先急剧增加然后缓慢增加，表明Wr对渗透率的影响主要发生在煤粉侵入压裂支撑剂的初始阶段。此外，本研究还得出 Rcp 和 η 之间的关系为 η = 0.71578 R cp 0.4575 。