关键词: 致密砂岩, 微观孔隙特征, 成岩特征, 须五段, 新场地区, 川西坳陷

Abstract:

  It is important for the prediction of effective reservoir distribution and analysis of reservoir characteristics to study the sedimentary environment of basin. Based on the study about petrology, sedimentary structure, palaeobiology, sedimentary sequence and electrofacies, the sedimentary environment of the third member of Shahejie Formation（Es₃） in Gaobei ramp region of Jidong Oilfield was studied. It is revealed that the sedimentary environment of Es₃ is fan delta-shallow lake facies. The evolutionary process is represent that lake was shrinking and fan delta was growing at Es₃³ period, lake was growing and fan delta was shrinking at Es₃² period, and lake was shrink again, fan delta was growing again at Es₃¹ period. There are two relatively independent sedimentary zones in the study area, which are caused by the uplift of central tectonic zone with NE trend in Gaoshangpu Oilfield. Meanwhile, the control role of sedimentary environment on reservoir development was discussed. It is considered that fan delta underwater distributary channel and mouth bar are the main lithosomic bodies for reservoir sand body. The distribution and development scale of reservoir sand body are controlled by the characters of fan delta development. The lithological changes on the horizontal and vertical are caused by the change of sedimentary environment. And it is the important cause of strong reservoir heterogeneity.

Key words: tight sandstone , micro pore features , diagenetic characteristics , the fifth member of Xujiahe Formation , Xinchang area , western Sichuan Depression