大牛地马家沟组储层酸压残酸规律

Damage Mechanism of Spent Acid in Acid Fracturing of Majiagou Formation in Daniudi Gas Field

酸压施工中经过酸岩反应后残留在地层的酸液,破胶后仍能吸附、滞留和堵塞岩石孔隙,对储层造成伤害,影响储层渗流能力,导致单井产能和经济效益降低。为明确大牛地马家沟组碳酸盐岩储层残酸伤害的影响,通过配制施工酸液体系,开展了对基质、微裂缝和酸蚀裂缝三种形态的残酸伤害实验,且从微观和宏观角度分析其伤害规律。研究结果表明:残酸对基质伤害较高,残酸进入基质,以堵塞孔隙形式污染岩心,残酸伤害率30%左右;微裂缝次之,残酸滞留微裂缝表面,且渗透率越大,伤害越小,残酸伤害率为10%~20%;酸蚀裂缝几乎没有受到残酸伤害影响。因此,残酸伤害主要以堵塞伤害为主,吸附伤害较低,影响较小。

The acid solution remaining in the formation after acid rock reaction in acid compression construction can still adsorb,retain and block rock pores after glue breaking,causing damage to the reservoir,affecting the seepage capacity of the reservoir,leading to the reduction of single well productivity and economic benefits.In order to clarify the influence of residual acid damage on carbonate reservoir of Majiagou Formation in Daniudi gasfield,the residual acid damage experiments on matrix,micro fracture and acid erosion fracture were carried out through the configuration and construction of acid system,and the damage laws were analyzed from micro and macro perspectives.The experimental results show that spent acid has a high damage rate to matrix.The spent acid enters matrix and pollutes core in the form of clogging pores,and the damage rate of spent acid is about 30%.The spent acid remains on the surface of micro-cracks,and the greater the permeability,the less damage.The damage rate of residual acid is 10%~20%.Acid etched cracks are hardly affected by residual acid damage.Therefore,the damage of spent acid is mainly caused by blockage,and the adsorption damage is relatively low.