煤层气井储层气水产出互补性及提产措施探讨

Discussion on Complementary of Gas and Water Production in Coalbed Methane Wells Reservoir and Procurement Measures

为提高煤层气井的产气量,需尽量扩大煤储层的有效压降半径。通过分析煤层气井排采过程中产水产气的互补性变化规律,以贵州多煤层开发井组和山西单一煤层开发区块为例,分析产水对产气的影响,提出煤层气井提产增效的对策。结果表明:煤层气井见套压前后气水产出比发生变化,具有明显的互补性变化规律;单一煤层及多煤层开发的煤层气井均发现压裂液返排率越高,总产气量和平均产气量越高;受地层能量和渗透率的影响,煤层气井压裂液返排率随埋深的变化出现转折,转折深度为该井区煤层气井合适的压裂深度;为尽量扩大煤层气井的有效压降半径,应尽量减小排采过程中的渗透率伤害,避免煤粉颗粒对孔裂隙通道的堵塞。

The effective pressure drop radius of coal reservoir should be enlarged as far as possible to improve the gas production of CBM well.By analyzing the complementary variation law of water production and gas production during the process of CBM well drainage,the multiple coal seam development well group in Guizhou area and the single coal seam development block in Shanxi area are taken as examples to analyze the influence of water production on gas production,and the CBM well extraction measures to increase production efficiency is proposed.The results show that:the CBM wells have changed the gas-water output ratio before and after the casing pressure,and have obvious complementary changes:the CBM wells developed in single coal seam and multiple coal seams all found that the higher the fracturing fluid flow-back rate,the higher the total gas production and average gas production;influenced by the energy and permeability of the formation,the flow-back rate of fracturing fluid in coalbed methane wells has a turning point with the change of burial depth,the transition depth is the appropriate fracture depth for the CBM well in this well area;in order to maximize the effective pressure drop radius of the CBM well,the permeability damage during the drainage process should be minimized,and the blockage of the pores of the pores by the pulverized coal particles should be reduced.