低渗透砂岩气层岩心润湿性改善实验

EXPERIMENTAL STUDY ON IMPROVING CORE WETTABILITY OF LOW-PERMEABILITY GAS SANDS

低渗透砂岩气层容易受到水锁伤害,从而降低该类储层的开发效果.砂岩储层一般带有负电荷,阴离子表面活性剂溶液能够降低吸附伤害,为了研究该类液体对低渗透砂岩储层岩心润湿性改善情况,设计了一套实验流程及实验方法.首先注入地层水,分析气层岩心水锁伤害程度,然后选择不同浓度阴离子表面活性剂溶液,进行岩心润湿性实验研究,通过测量注入前后岩心含水饱和度及渗透率,分析气层岩心水锁改善情况.实验结果显示,随着阴离子表面活性剂溶液浓度增加,实验岩心原始含水饱和度降低,基质渗透率增大,有效地改善了气层岩心润湿性.综合考虑成本影响,选择阴离子表面活性剂溶液质量分数为3%.实验过程也证明,设计实验流程及方法简捷、操作性强.

Low-permeability gas sands are easy to be damaged by water locking so that the development effectivehess of these reservoirs can be decreased. Sandstone reservoirs usually have negative charge, so the anionic surfacrant solution could reduce adsorbtion damage. A set of experimental process and method is designed to study the improvement of the solution to the core wettability of sandstone reservoirs with low permeability. Firstly, the formation water is injected and the damage degree of water locking is analyzed. Then the core wettability experiment is peformed by selecting the anionic surfactant solution with different concentrations. Improvement of water locking can be analyzed by measuring the water saturation and permeability of the tested core before and after injection. The result shows that with increase of anionic surfactant solution concentration, the original water saturation of the tested core decreases and the permeability of matrix increases, and the core wettability is effectively improved. The mass fraction of anionic surfactant solution should be 3% comprehensively considering the cost effect. The experimental process shows that the designed experimental process and method are simple and direct and have a strong operability.