煤层气复杂渗流机制下水平井压裂参数优化研究

doi:10.3969/j.issn.1672-7703.2019.06.015

摘要/Abstract

摘要： 为了优化不同煤层条件下的水平井压裂参数，考虑气体解吸和气水两相流动特征建立了渗流模型，采用PEBI 网格和有限体积法进行求解。根据煤层的渗透率和厚度特征，划分了4 种煤储层类型，建立了相应的机理模型，进而模拟计算了不同水平井压裂参数下的累计产气量和压力场。研究发现：煤层性质极大影响了多段压裂水平井的产能，通过分析不同煤层性质条件下水平井压裂参数与累计产气量的关系曲线，得到了模拟条件下水平段长度、裂缝半长和裂缝间距的最优值。对于厚度大的煤层建议水平段长度控制在1300m，裂缝间距为75～100m，裂缝半长为 60m；对于厚度小、渗透率高的煤层建议水平段长度控制在1500m 以上，裂缝间距为75m，裂缝半长则是越大越好；对于性质很差的煤层不建议采用多段压裂水平井开发。

关键词: 煤层气, 多段压裂水平井, 渗流模型, 水平段长, 压裂裂缝间距, 压裂裂缝半长

Abstract: Flow models are established based on gas desorption and gas-water two-phase flow characteristics to optimize fracturing parameters for horizontal wells under different coal seam conditions. The PEBI grid and finite volume method are used to solve the problems. According to the permeability and thickness of coal seams, coal reservoirs are divided into four types and corresponding mechanism models are established. Then, cumulative gas production and pressure fields are simulated with different fracturing parameters. The study shows that coal seam properties greatly affect the productivity of horizontal wells with multiple stages fracturing. By analyzing the relationship between fracturing parameters and cumulative gas production with different coal seam properties, optimal horizontal section lengths, fracture half-lengths, and fracture spacing can be obtained under simulated conditions. For thick coal seams, it is recommended that the length of the horizontal section could be 1300 m, the fracture spacing of 75100 m, and the fracture half-length of 60 m. For thin and permeable coal seams, it is recommended that the length of the horizontal section could be above 1500 m, the fracture spacing of 75 m, and the fracture half-length could be as long as possible. For coal seams with poor properties, multi-stage fracturing stimulation will not be recommended.

中图分类号:

朱卫平, 甄怀宾, 刘曰武, 张天翔, 高大鹏, 孙伟, 何东琴. 煤层气复杂渗流机制下水平井压裂参数优化研究[J]. 中国石油勘探, 2019, 24(6): 822-830.

Zhu Weiping, Zhen Huaibin, Liu Yuewu, Zhang Tianxiang, Gao Dapeng, Sun Wei, He Dongqin. Study on optimization of fracturing parameters for coalbed methane horizontal wells under complex flow mechanism[J]. China Petroleum Exploration, 2019, 24(6): 822-830.

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