苏里格气田西区S47区块石盒子组八段沉积微相

Detailed Sedimentary Facies of the 8th Member of Shihezi Formation in the Block S47 in Western Sulige Gas Field

摘要:

鄂尔多斯盆地苏里格气田是我国陆上产能最大的气田，其主力产气层——二叠纪石盒子群八段岩性致密，储层的分布主要受沉积微相控制。但S47区块作为苏里格气田西区一个重要的新区，有关沉积微相的认识仍存在分歧。在岩心观察、钻井资料及样品分析的基础上，重点研究了S47区块盒8段沉积微相，认为该区盒8段属辫状河三角洲前缘沉积，并识别出水下分流河道、河口坝、席状砂、水下天然堤、分流间湾等5种微相；最有利的储集砂体主要为水下分流河道叠置砂体，其次为河口坝砂体。沉积微相及其展布特征的新认识为该区储层预测、水平井整体开发提供了地质理论依据。

Abstract:

Sulige gas field in Ordos basin is the largest terrestrial gas production field in China. As a typical tight sandstone gas pool, distribution of reservoirs of the main gas-producing strata in Sulige gas field—— the 8th member of Shihezi formation in Permian system (P2h8 for short), is mainly controlled by detailed sedimentary facies. But disagreements about detailed sedimentary facies still exist in the Block S47——an important new region in the western part of Sulige gas field. Detailed sedimentary facies of P2h8 in the Block S47 were studied on the basis of drilling core observation, analysis of well logs and samples. It is considered that the strata of P2h8 in the Block S47 was deposited in braided delta front, which can be further sub-divided into subaqueous distributary channel, estuary bar, sand sheet, subaqueous levee and interdistributary bay etc. 5 detailed sedimentary facies. The most favorable reservoir is subaqueous distributary channel overlaid sand bodies and estuary bar sand bodies secondarily. New understandings on detailed sedimentary facies and distribution features provide theoretical foundations for reservoir prediction and integrated exploitation by horizontal wells in the Block S47.