苏里格西区苏X区块致密砂岩气藏地层水分布规律

Study on formation water distribution law in tight sandstone gas reservoir of Su X Block in west area of Sulige,Ordos Basin,China

致密砂岩气藏孔隙结构复杂,气井产量低,开发易受地层水的影响。以鄂尔多斯盆地苏里格气田为例,应用地质、测井、测试及生产动态等资料,通过生烃强度、成岩作用、构造及非均质特征的研究,分析了气田地层水的主要控制因素,并将地层水按成因特征划分为低部位滞留水(Ⅰ型)、致密透镜状滞留水(Ⅱ型)、孤立透镜体水(Ⅲ型)3种类型;通过对井网较密的苏X区块东部的精细解剖,分析并总结了不同类型地层水的分布规律及生产特征。低部位滞留水在储层中气水分异明显,测井解释通常为水层或含气水层,水体的厚度大,地层水活跃;致密透镜状滞留水通常分布于气层之中,呈透镜状分布,测井曲线含水特征不明显,识别难度较大,测井解释多为含气层、气水层,部分井测井解释为气层,但试气或投产有水产出;而孤立透镜体水则主要分布于主含气层系以上的层位,在测井曲线上易于识别,测井解释以水层为主。

The pore structure of a tight sandstone gas reservoir is complicated,the production of the gas wells is low and the development is easily affected by the formation water.Taking the Sulige gas field of Ordos Basin as example,by using the data of geology,well logging,testing and production dynamics and combined with the researches of hydrocarbon-generating intensity,diagenesis,structure and heterogeneity,this paper analyzes the main controlling factors of the gas field formation water and divides the formation water into three types： lower water of retention（Type Ⅰ）,tight lentoid water of retention（Type Ⅱ） and isolated lens water of retention（Type Ⅲ）,according to the genesis.Through the fine analysis of the east part of Su X Block where the well network is dense,this paper summarizes the distribution rule of different types of formation water and the production characteristics.The differentiation of the gas and water in the lower water of retention is obvious in the reservoir.The interpretation of logging indicates that the lower water of retention is usually the water reservoir or gas-bearing water reservoir,the thickness of the water body is thick,and the formation water is active.The tight lentoid water of retention is lens-shaped and spreads over the gas-bearing reservoir.The characteristic of the logging curves indicating that the reservoir contains water is not obvious and is difficult to identify.Although the interpretation of logging partly demonstrates that the tight lentoid water of retention is the gas-bearing reservoir or gas-and water-bearing reservoir,the trial pits show that there occurs water in this reservoir.The isolated lens water mainly spreads over the horizons above the gas-bearing reservoir and is easily identified.The interpretation of logging indicates that it is primarily the water-bearing reservoir.