大牛地气田下石盒子组盒3段致密储层评价

Evaluation of tight reservoirs in the third member of Lower Shihezi Formation in Daniudi Gas Field

大牛地气田位于鄂尔多斯盆地伊陕斜坡北部,上古生界天然气探明储量2 615.71×108 m3,为大型气田,但气藏具有低压、低孔、低渗、致密的特点,产能普遍较低,储层主要为河流相沉积,非均质性强,气田开发难度很大。该气田主力气层盒3段的储层评价表明,盒3段为辫状河流相沉积,主要储层微相为心滩沉积和河道充填沉积,其中心滩微相是本区高产部位,河道充填微相的产气部位主要分布在下部,也是该气田重要的产气微相类型。通过储层综合评价,把盒3段储层分为4类。

Daniudi Gas Field lies in the north of Yishan slope of Ordos Basin.The proved natural gas reserves in Upper Paleozoic is 261.57 billion cubic meters, so Daniudi Gas Field is a large one. Because the gas reservoirs is characterized by lower pressure, lower porosity, lower permeability and tight sandstone, the general productivity is lower. At the same time, it is difficult to develop because of the reservoir heterogeneity and the fluvial facies sedimentation. Sedimentary facies of the third section of Lower Shihezi Formation is braided river, and the channel filling with deposits and center bar sandbody are main sedimentary microfacies. The highproductivity wells are usually located in the center bar. The channel filling with deposits are usually located in the bottom of braided stream and it is also one of the microfacies that can produce gas. The reservoirs of third section of Lower Shihezi Formation are divided into four types through comprehensive reservoir evaluation.