低渗砂岩气藏应力敏感性特征及产量影响预测——以S6区为例

Stress sensitivity characteristics of low-permeability sandstone gas reservoirs and forecasting its influence on the output——taking S6 area as an example

低渗砂岩气藏开发过程中有效应力增加所带来的渗透率应力敏感损害是导致气井产量快速递减的一个重要原因,故对应力敏感性损害机理研究能够为气层保护工作提供合理依据。在考虑不同岩性、裂缝、含水饱和度和伤害恢复等因素的同时,对S6区气田低渗砂岩应力敏感性进行了评价,指出水的存在对低渗砂岩气藏应力敏感性具有强化作用;裂缝岩样的渗透率应力敏感程度远大于基块;理论计算表明,在实际生产中井底存在渗透率漏斗,压敏效应对气井影响显著。

During the development process of sandstone gas reservoirs,the decrease of permeability stress sensitivity caused by the increase of effective stress is a key factor responsible for the rapid descent of gas reservoirs production.As a result,the study of stress sensitivity damage mechanism can provide a reasonable reference for the protection of gas reservoir.Taking S6 gas field as an example,the factors of different lithology,fracture,water saturation and damage recovery were considered in this paper for the evaluation of low-permeability sandstone stress sensitivity.The results showed that water could strengthen the stress sensitivity of low-permeability sandstone and the permeability stress sensitivity of cracked sample was stronger than that of the matrix.Through theoretic calculation,it was also found that permeability funnel existed downhole,and the pressure-sensitive effect had a significant impact on gas wells.