迪那3区块致密砂岩气藏损害机理及储层保护技术

迪那3区块致密砂岩气藏属于典型的低孔、特低渗碎屑岩储层,初始含水饱和度低,非均质性严重,裂缝发育,黏土矿物含量较高,该区块原用钾聚磺体系对迪那区块气藏造成一定的伤害,储层保护效果亟待提高。在分析迪那2及迪那3区块致密砂岩气藏特征及损害机理的基础上,确定钾聚磺体系损害气藏机理为水敏、应力敏感、漏失、毛管力效应及相圈闭损害。通过研制可酸化防漏堵漏材料及防水锁剂,对现用的钾聚磺体系进行改进,形成了一套保护致密砂岩气藏储层的钻井完井液体系,该体系流变性良好,滤失量明显降低,渗透率恢复值大幅提高,储层保护效果明显。

Permeability Impairment and Reservoir Protection for Tight Sand Gas Reservoir in Block Dina-3

The tight sands gas reservoir in Block Dina-3 is characteristic of low porosity, ultra-low permeability, clastic rock, low initial water saturation, severe inhomogeneity, developed fractures, and high clay content. The previously used potassium polymer sulfonate drilling fluid posed damage to the reservoir. By analyzing the mechanism of reservoir damage for the Block Dina-2 and the Block Dina-3, it was believed that the potassium polymer sulfonate drilling fluid caused water sensitivity, stress sensitivity, mud losses, capillary effect and phase trap damage to the reservoir. The potassium polymer sulfonate drilling fluid was modified with lost circulation material water block preventer that can be removed by acid treatment. The new drilling fluid had good rheology, low filter loss and excellent reservoir protection capacity.