川西气藏老井挖潜压井液地层伤害实验研究

Experiment Research on Damage of Killing Fluid to the Formation During Tapping the Potential of Old Wells in Western Sichuan Gas Reservoir

川西气藏开发已经进入中后期,区域内中浅层老井一般都需经过挖潜、压裂改造后重新投产。挖潜使用的压井液多数为清水基,清水由原产层向储层滤失渗透的可能性很大,进而引起储层的孔渗性变化,使油气在流通通道中受阻损害气藏。为查明压井液滤失对地层的实际伤害,首先分析了研究区储层矿物流体敏感性,然后进行了大量敏感性实验并依据实验结果对致密砂岩气藏损害做出评价。实验结果有助于定量研究低伤害压井液体系配比,以及定性评价老井挖潜对储层损害程度。

Western Sichuan gas reservoir development has entered the later period; regional shallow old wells are always required to reproduce by potential tapping and fracturing. Most of killing fluid used in potential tapping is water-based fluid, water often leaks from the origin layer to the reservoir, which will change the porosity and damage the reservoir. In order to find out the actual damage of the kill fluid to the formation, the reservoir fluid sensitivity in the study area was analyzed. Then large amount of sensitivity experiments were carried out to estimate the sandstone gas reservoir damage. The results are helpful to the quantitative study of low damage killing fluid system, and the quantitative evaluation of the damage of old well potential tapping to the reservoir.