Modeling analysis of coalbed methane co-production interference: A case study in Eastern Yunnan Basin, China
Modeling analysis of coalbed methane co-production interference: A case study in Eastern Yunnan Basin, China
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DOI：
10.1016/j.jngse.2022.104631
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发表时间：
2022-05
影响因子：
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通讯作者：
Fangkai Quan;Chongtao Wei;Jingsheng Ma;Shuqing Hao;Yu Song
中科院分区：
文献类型：
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作者：
Fangkai Quan;Chongtao Wei;Jingsheng Ma;Shuqing Hao;Yu Song
煤层气合采威尔斯井的层间干扰制约了多煤层区煤层气资源的有效开发，但由于地质构造演化和储层开发技术复杂，至今难以建立定量干扰指标。本文从煤层的瞬态流入动态关系（IPR）曲线出发，推导了煤层的返流速率和产水抑制指数，以表征层间干扰。以滇东盆地某煤层气井为例，利用改进的储层模型计算了不同储层参数和含水层参数下的IPR曲线。通过对层间干扰指标的数据处理发现，煤储层间压差是产生反向流体的最关键因素，压差为15%，干扰量为244.08 m3 d·KPa−1，其次是煤层厚度和渗透率（18.00-25.00 m3 d·KPa−1）。含气量、朗缪尔压力和朗缪尔体积对层间干扰的贡献较小。第二，含水层厚度或渗透性的任何增加都会由于水的涌入而显著增加煤层的产水率。值得注意的是，当含水层位于较高的流体压力系统中时，回流率将增加。相反，在较低压力系统的情况下，反向流率将降低。最后，持续的压力下降导致煤层和含水层的补给能力高于设定的排水系统，导致煤层水不能被有效地排除。煤层产水抑制指数与含水层厚度和渗透率呈正相关，与排水强度呈负相关。本文的研究成果弥补了干扰识别指标与产层可能组合之间的差距，为滇东盆地煤层气开发提供了新的思路。
The interlayer interference in coalbed methane (CBM) co-production wells restricts the effective development of CBM resources in multi-seam areas; however, the establishment of quantitative interference indicators still remains difficult to date resulting from the complex geological formation evolution and reservoir development techniques. In this paper, the reverse flow rate and the water production inhibition index of the coal seam were derived from the transient inflow performance relationship (IPR) curve to characterize the interlayer interference. The IPR curves of different reservoir and aquifer parameters were calculated on the modified reservoir model using a CBM well as a case in East Yunnan Basin. From the data processing for obtaining interlayer interference indicators, the pressure difference between coal reservoirs was found to be the most critical factor in generating reverse fluids, with a 15% difference and the interference amounting to 244.08 m3d·KPa−1, followed by coal seam thickness and permeability (∼18.00–25.00 m3d·KPa−1). Gas content, Langmuir pressure, and Langmuir volume contribute slightly to the interlayer interference. Second, any increase in thickness or permeability of the aquifer will significantly increase the water production rate of the coal seam due to water influx. Significantly, the reverse flow rate will be increased when the aquifer is located in a higher fluid pressure system. Instead, the reverse flow rate will be decreased in the case of a lower pressure system. Finally, continuous pressure drops lead to the coal seam and aquifer recharge capacity higher than the set drainage system, resulting in the coal seam water not being removed effectively. The coal seam's water production inhibition index shows a positive correlation with the thickness and permeability of the aquifer and a negative correlation with the drainage intensity. The results of this paper bridge the gap between the identification interference indicators and the possible combination of production layers, and it also provides new insights for enhancing CBM development in the East Yunnan Basin.