Depositional facies, diagenesis and their impact on the reservoir quality of Silurian sandstones from Tazhong area in central Tarim Basin, western China

作者：Zhang Jinliang^*; Qin Lijuan; Zhang Zhongjie

来源：Journal of Asian Earth Sciences, 2008, 33(1-2): 42-60.

DOI：10.1016/j.jseaes.2007.10.021

• Tazhong area
• depositional facies
• diagenesis
• reservoir quality

The Silurian sandstones of the Tazhong area are an important oil exploration target in the Tarim Basin, western China. This study deals with the Lower Silurian of the Kalpingtag Formation, which was deposited in a braided delta system. Four major depositional microfacies are identified consisting of distributary channel, interdistributary bay, front bar and sand sheet.
In spite of their large lateral extent, exploration of these sandstones is complicated by variation of sediment facies and intense diagenesis, which strongly affected reservoir quality. Depositional environment exerted an essential control on the reservoir quality. Higher energy, well-sorted and relatively coarser grained sandstones have better quality than low-energy fine-grained, clay-rich sandstones.
Diagenesis was mainly composed of mechanical and chemical compaction and cementation by quartz overgrowths, carbonates and various clay minerals. Mechanical compaction was a significant porosity reducing agent in the Silurian sandstones. The presence of carbonate cement exerts a dominant influence on porosity and permeability in Tazhong area. Other cements are less important, but quartz cement is significant. The third significant element is clay minerals. The porosity reduction by compaction and cementation and the relative timing of them indicates that compaction was much more important than cementation in reducing porosity.

• 出版日期2008-6-20
• 单位中国海洋大学