四川盆地须二段综合成岩相特征研究

RESEARCH OF INTEGRATED DIAGENETIC FACIES CHARACTERISTICS OF T_3x_2 RESERVOIR IN SICHUAN BASIN

四川盆地上三叠统须家河组二段是重要的含气层位,但由于其砂体具有非均质性强、且低孔低渗的特点,直接影响了油气勘探开发的效果。本文有针对性地提出了综合成岩相的概念,目的是寻找一套有效的方法预测储层有利发育区。综合成岩相,即是多种成岩环境下叠加与改造的多种成岩作用中占主体地位的成岩作用的综合体。相比于单因素成岩相,综合成岩相更能反映储层的成岩特征,它既有主要成岩作用的分析,也有主要成岩作用强弱顺序的分析。在大量薄片分析、岩芯观察及单因素成岩相研究的基础上,用半定量的方法将须二段综合成岩相划分为7类,并对四川盆地须二段的综合成岩相进行了研究,发现须二段储层发育相对集中,其中在川中地区发育较好,在盆地的边缘和东部地区发育较差。因此,川中及川西的部分地区是须二段勘探开发的有利区域。

It is an important gas-bearing strata in T3x2 reservoir in the Xujiahe Formation of Upper Triassic,Sichuan Basin.But the inhomogeneity of the sand bodies is serious,and low porosity and permeability of the reservoir directly influence the exploration and development effect of the oil and gas well.This paper is aimed at proposing the conception of synthetical diagenetic facies,the purpose of which is to find out an effective method of forecasting the range of profitability of the reservoir.Synthetical diagenetic facies is just a complex which takes the dominant part in the multi-diagenesis folded and reformed under different diagenetic environment.Compared with uni-factor diagenetic facies,synthetical diagenetic facies can reflect the diagenetic characteristic of the reservoir better,which has the analysis of the main diagenesis,also has the analysis of the strong and weak order of the main diagenesis.According to the optical thin section study,core observation and the research of uni-factor diagenetic facies,the paper divides the diagenetic facies in T3x2 Segment reservoir into 7 types,and researches the synthetical diagenetic facies in the T3x2 Section reservoir in Sichuan Basin.The research result indicates that the developmental condition of the T3x2 reservoir is centralized relatively,and the reservoir develops well in the middle of the basin,and develops badly in the edge and the east area of Sichuan Basin.Therefore,the part of the middle and the west area of Sichuan Basin is the range of profitability in the exploration and development in T3x2 Section reservoir.