延长气田气井山2层产水成因及其影响因素分析

Causes of Produced Water in Shan2 Reservoir of Yanchang Gas Field and Its Influencing Factors

在延长气田气藏开发过程中,山2层产水普遍,平均产水2.85m3/d且存在多种类型,气水分布在纵向和横向上都相对复杂。根据试气、测井和生产动态资料,将气井产水划分为纯水层、致密水层、气层产水和煤层水4种类型,每种类型都受成藏环境、构造条件、储层岩性与物性等方面控制。除正常边底水类型的纯水层外,在延长气田部分井区中,由于储层条件变差,气体驱替能量不足,造成孔隙中水未受到天然气的大规模排驱而残留了大量地层水,形成致密水层、气层产微量地层水和压裂改造与煤层沟通后的煤层水,影响因素主要为成藏环境,古今构造以及储层岩性和物性等。

During gas reservoir development process of Yanchang gas field,there is generally produced water in Shan2 reservoir,average produced water is 2.85 m3/d and types are multiple.Based on wire-line logging and trial production in formation,the origination of produced water is classified as aquifer,tight sand aquifer,remnant water in pay zone and coal seam water,and the discrimination between them is also clarified.It is concluded that the distribution of sand channel,the micro-tectonics of the zone,the migration process of hydrocarbon and the heterogeneity of sand are the controlling factors of aquifer distribution in lithologic gas reservoir.Besides the normal aquifer,due to the deficiency of gas energy,the local tight zones in some parts of sand body permit the preservation of abundant formation water,the typical tight aquifer and remnant water in pay zone are formed.The classification of aquifer can play a key role in the deployment of production well.Major influencing factors are reservoir formation environment,past and present structure,lithology and physical properties.