裂缝应力敏感性对煤层气井单相流段产水影响及排采对策

Influence of Fractures Stress Sensitivity on Water Production Law for the Single-phase Flow of CBM Wells and Drainage Countermeasures

为了研究应力敏感性对煤层气井单相流段产水规律的影响,文章通过理论推导建立基于煤层应力敏感性的单相流段产水量模型,并在拟合研究区生产井排采数据的基础上,预测应力敏感性对产水规律的影响。研究结果表明,煤岩渗透率与有效应力呈负指数幂关系,应力敏感性系数越大,煤岩应力敏感性越强;且随着应力敏感性系数的增大,产水量曲线由持续上升型转变为先升后降型,且上升段持续缩短,因此不同的应力敏感性储层应该采用不同的生产压差和降压速度,保障最佳排水效率。

This article aims to study the effect of stress sensitivity on reservoir water rate. Through the theoretical derivation, It establishes the model of water production rate with single-phase flow based on stress sensitivity of coal seam, and predicts the influence of stress sensitivity on water production law on the basis of the data fitting of the exponent relations between the ov production wells in the researched areas. The results show a negative erall permeability of coal and rock fracture and the effective stress. The stress sensitivity coefficient will increase with stress of the coal and rock. As the sensitive coefficient increase, the curve of water production rate keeps rising fist and then shift to rise first and fall later, and the greater the stress sensitivity coefficient is, the shorter the rise period will be. Therefore, reservoirs with different stress sensitivity should adopt separated production pressure difference and pressure decrease rate, so as to guarantee the best water production efficiency.