含水层越流补给对煤层气井产能影响的数值模拟:以柿庄南区块为例

doi:10.19657/j.geoscience.1000-8527.2024.130

摘要/Abstract

摘要：

含水层越流补给是我国煤层气开发过程中存在的常见问题,严重制约了煤层气的高效开发。以山西省沁水盆地柿庄南区块煤层气直井为例,通过数值模拟敏感性分析,综合评价含水层越流补给参数对煤层气井产能的影响。结果表明,依据含水层自身水源供给能力,将含水层类型划分为有限补给和无限补给,这是造成越流补给作用效果差异的根本原因。导水裂缝发育位置、发育形态及其与压裂缝的空间展布关系对产能特征的敏感性较强,在无限补给和有限补给含水层中分别体现为对产气量大小和产气曲线形态的影响。含水层越流补给参数对煤层气产能的敏感性由强到弱依次为含水层类型、越流通道性质、含水层物性和地层水性质。基于此绘制生产判别流程图,将含水层越流补给影响下煤层气井的产能特征划分为六类,并进一步划分了不同产能特征煤层气井在研究区的分布。该判别流程为含水层越流补给影响下煤层气产能特征分析和产能潜力评价提供科学指导。

关键词: 煤层气, 含水层, 越流补给, 数值模拟, 产能特征敏感性分析

Abstract:

Aquifer leakage recharge is a common issue in coalbed methane (CBM) development in China, significantly hindering efficient production. Taking a vertical CBM well in the Shizhuang South Block of the Qinshui Basin as a case study, this research comprehensively evaluates the impact of aquifer leakage recharge parameters on CBM well productivity through numerical simulation and sensitivity analysis.The results indicate that classifying aquifers into finite and infinite recharge types based on their water supply capacity is the fundamental reason for the varying effects of leakage recharge. The location, morphology, and spatial distribution of water-conducting fractures relative to hydraulic fractures exhibit high sensitivity to productivity characteristics: in infinite recharge aquifers, they primarily affect gas production volume, while in finite recharge aquifers, they influence the shape of gas production curves.The sensitivity of aquifer leakage recharge parameters to coalbed methane productivity, from strongest to weakest, is aquifer type, properties of leakage channels, aquifer physical properties, and formation water properties.Based on these findings, a production discrimination flowchart is developed, categorizing CBM well productivity characteristics under the influence of aquifer leakage recharge into six types, and further delineating the distribution of wells with different productivity characteristics in the study area. This flowchart provides scientific guidance for analyzing CBM productivity characteristics and evaluating productivity potential under the influence of aquifer leakage recharge.

Key words: coalbed methane, aquifer, leakage recharge, numerical simulation, sensitivity analysis of productivity characteristics

中图分类号:

P618.13

闫欣璐, 唐书恒, 傅小康, 董宪姝, 李忠城, 邓志宇, 孟艳军. 含水层越流补给对煤层气井产能影响的数值模拟:以柿庄南区块为例[J]. 现代地质, 2025, 39(04): 1143-1155.

YAN Xinlu, TANG Shuheng, FU Xiaokang, DONG Xianshu, LI Zhongcheng, DENG Zhiyu, MENG Yanjun. Numerical Simulation of the Influence of Aquifer Leakage Recharge on CBM Productivity:A Case Study from Shizhuan South Block[J]. Geoscience, 2025, 39(04): 1143-1155.

图/表 13

图1 柿庄南区块3#煤层海拔标高(a)及地层柱状图(b)

Fig.1 Elevation of 3# coal seam (a) and stratigraphic histogram (b) in Shizhuang South Block

图2 柿庄南区块含水层越流补给模式图(剖面位置见图1)

Fig.2 Chart showing aquifer leakage recharge mode in Shizhuang South Block (See Fig.1 for profile’s location)

图3 数值模拟建模方法(a)及导水裂隙分布设置(b)

Fig.3 Numerical simulation modeling method (a) and setting of fracture distribution (b)

表1 煤储层数值模拟参数

Table 1 Numerical simulation parameters of coal reservoir

模拟数值参数	数值	模拟数值参数	数值
埋深(m)	714.7	兰氏体积(m³∙t^-1)	24
煤厚(m)	5.8	兰氏压力(MPa)	2.8
储层压力(MPa)	3.9	含气量(m³∙t^-1)	10
临界解吸压力(MPa)	2.0	人工压裂缝范围(m²)	110 $×$ 20
渗透率(mD)	0.8	压裂缝渗透率(mD)	20
裂缝孔隙度(%)	4.0	煤岩密度(g∙cm^-3)	1.3

表1 煤储层数值模拟参数

Table 1 Numerical simulation parameters of coal reservoir

模拟数值参数	数值	模拟数值参数	数值
埋深(m)	714.7	兰氏体积(m³∙t^-1)	24
煤厚(m)	5.8	兰氏压力(MPa)	2.8
储层压力(MPa)	3.9	含气量(m³∙t^-1)	10
临界解吸压力(MPa)	2.0	人工压裂缝范围(m²)	110 $×$ 20
渗透率(mD)	0.8	压裂缝渗透率(mD)	20
裂缝孔隙度(%)	4.0	煤岩密度(g∙cm^-3)	1.3

表2 含水层数值模拟参数

Table 2 Numerical simulation parameters of aquifer

越流补给性质	影响参数	参数取值
含水层物性	渗透率(mD)	无限补给含水层 50/100/200	有限补给含水层 10/20/40
	孔隙度(%)	10/20/30
	厚度(m)	5/10/15
	大小(m $×$ m)	200 $×$ 100/200 $×$ 200/200 $×$ 300
	综合压缩系数 ( $10 - 4$ MPa^-1)	1/2/3
地层水性质	黏度(mPas)	0.5/1/1.5
越流通道性质	越流距离(m)	0/100/200
越流通道性质	越流方向 (m $×$ m)	法向5 $×$ 80/法向80 $×$ 5/方形 20 $×$ 20/径向5 $×$ 80/径向80 $×$ 5

表2 含水层数值模拟参数

Table 2 Numerical simulation parameters of aquifer

越流补给性质	影响参数	参数取值
含水层物性	渗透率(mD)	无限补给含水层 50/100/200	有限补给含水层 10/20/40
	孔隙度(%)	10/20/30
	厚度(m)	5/10/15
	大小(m $×$ m)	200 $×$ 100/200 $×$ 200/200 $×$ 300
	综合压缩系数 ( $10 - 4$ MPa^-1)	1/2/3
地层水性质	黏度(mPas)	0.5/1/1.5
越流通道性质	越流距离(m)	0/100/200
越流通道性质	越流方向 (m $×$ m)	法向5 $×$ 80/法向80 $×$ 5/方形 20 $×$ 20/径向5 $×$ 80/径向80 $×$ 5

图4 无限补给含水层对煤层气生产敏感性分析

Fig.4 Sensitivity analysis of infinite recharge aquifers on CBM production

图5 裂缝方向敏感性影响煤储层压力传播云图

Fig.5 Pressure propagation contour map in coal reservoir affected by fracture direction sensitivity

图6 有限补给含水层对煤层气生产敏感性分析

Fig.6 Sensitivity analysis of finite recharge aquifers on CBM production

表3 含水层越流补给的产气敏感性 (%)

Table 3 Gas production sensitivity of aquifer leakage recharge (%)

产能敏感性	时间(d)	大小	厚度	孔隙度	综合压缩系数	渗透率	黏度	越流距离	越流方向
无限补给含水层	1000	7.6	7.6	0	0	10.2	8.9	190.5	70.0
	3000	15.3	15.3	0	0	18.2	13.1	185.4	109.1
	5000	11.7	11.7	0	0	14.0	9.3	227.7	130.0
有限补给含水层	1000	25.7	36.4	31.2	31.2	14.4	9.6	83.1	31.3
	3000	39.2	41.0	46.5	46.5	0.9	1.4	72.6	9.8
	5000	34.4	30.9	33.3	33.3	6.0	5.4	48.4	32.6

图7 含水层越流补给影响煤层气生产判别流程图

Fig.7 Flow chart of the influence of aquifer leakage recharge on CBM production

图8 TS-10井组产能特征

Fig.8 Productivity characteristics of TS-10 well group

图9 TS-02井组产能特征

Fig.9 Productivity characteristics of TS-02 well group

图10 柿庄南区块含水层越流补给类型分布

Fig.10 Distribution of aquifer leakage recharge types in Shizhuang South Block

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