塔里木克深致密砂岩气藏基质钻井液伤害评价

塔里木克深致密砂岩气藏储层基质致密，发育微纳米孔喉，毛管力作用明显，在钻井过程中受到钻井液侵入从而受到伤害，导致油气藏产能降低。常规稳态方法评价低渗致密储层钻井液伤害驱替压差大、稳定时间长，评价效率低。因此，在瞬态压力传导法的基础上建立渗透率数学模型，并使用拉氏变换对模型进行求解。基于模型的解，使用压力传导渗透率仪定量分析了钻井液对克深致密砂岩基质的伤害规律。实验结果表明，油基钻井液平均伤害率为31.24%，水基钻井液平均伤害率为23.67%。该研究成果为评价入井流体伤害提供新的思路。 

Evaluation of Drilling Fluid Damage to Matrices of Tight Sandstone of Keshen Gas Reservoir in Tarim Basin

Micrometer-and nanometer-sized pores are very developed in the matrices of the tight sandstone of Keshen gas reservoir in Tarim Basin, and capillary force plays an important role in formation damage by drilling fluid invasion during drilling, leading to reduced reservoir productivity. Using conventional steady state method to evaluate damage to low permeability tight sandstone by drilling fluid requires high displacing pressure and long stabilization time and is therefore unacceptable. Hence, a mathematic model for permeability calculation was established on the basis of transient pressure transmission method, and the model was solved using Laplace transformation. Based on the solutions to the model, the patterns of damage of the tight sandstone matrices in Keshen gas field by drilling fluids was quantitatively analyzed using pressure transmission permeability tester. Experimental results showed that average percent formation damage by oil base drilling fluids was 31.24%, with water base drilling fluids, on the other hand, this value was 23.67%. The research outcome provides a new clue for evaluating the damaging potential of fluids to be injected into the hole.