酒东油田深层K1g3砂岩成岩演化与优质储层分布

针对酒泉盆地酒东油田深层K₁g₃砂岩优质储层分布规律不明确的问题,通过铸体薄片、扫描电镜、物性等资料,开展成岩特征、成岩演化、成岩相与优质储层分布等研究。结果表明:酒东油田深层K₁g₃砂岩具有3类成岩特征,且Ⅱ、Ⅲ类成岩特征的砂岩是由Ⅰ类含铁白云石胶结致密砂岩在酸性溶蚀流体差异化作用下形成。酸性溶蚀流体有3期,前2期为大气淡水,第3期为有机酸流体,对砂岩溶蚀作用贡献最大的酸性流体是第2期大气淡水。K₁g₃砂岩可以划分为4类成岩相和2个成岩相带,B类成岩相为高孔高渗优质储层,D类成岩相为中孔低渗差储层,A、C类成岩相为含铁白云石胶结致密非储层;长2断层以西的主产油区为B类成岩相带,以东的扩边区为D类成岩相带,A、C类成岩相总体不发育。该成果可为酒东油田开发方案调整和扩边勘探部署提供依据。

Diagenetic Evolution of Deep K1g3 Sandstone and Distribution of High-quality Reservoirs in Jiudong Oilfield

In view of the unclear distribution pattern of in deep high-quality K₁g₃ sandstone reservoirs in Jiudong Oilfield, Jiuquan Basin, the diagenetic characteristics, diagenetic evolution, diagenetic facies and high-quality reservoir distribution of sandstone were studied according to casting slice, scanning electron microscope, physical properties and other data. The results showed that the deep K₁g₃ sandstone in Jiudong Oilfield had three types of diagenetic characteristics, and the sandstone with Type Ⅱ and Ⅲ diagenetic characteristics was developed from Type Ⅰ iron-bearing dolomite cemented tight sandstone under the differential action of acidic dissolution fluid. There were three stages of acid dissolution fluid. The fluid was atmospheric freshwater in the first two stages, and was organic acid fluid in the third stage. The atmospheric freshwater then became a acidic fluid that contributed the most to sandstone dissolution. K₁g₃ sandstone could be divided into 4 types of diagenetic facies and 2 diagenetic facies belts. Type B diagenetic facies were high-quality reservoirs with high porosity and permeability, Type D diagenetic facies were reservoirs with medium porosity and low permeability, and Types A and C diagenetic facies were ankerite-bearing cemented tight and heterogeneous reservoirs. The main oil-producing area to the west of Chang2 Fault was a Type B diagenetic facies band, the expanded-margin area to the east was a Type D diagenetic facies band, and Types A and C diagenetic facies were not developed in general. The study results are of providing important reasons for the development plan adjustment and expanded-margin exploration and deployment of Jiudong Oilfield.