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塔里木盆地奥陶系多个层段发育碳酸盐岩台地边缘高能沉积相带,但其台缘礁滩体储层性能差异显著。统计表明,进积-加积型镶边台缘在薄片面孔率、岩样孔隙度及录井异常方面总体超过退积-缓坡型台缘带。前缘斜坡角度与台缘带储地比之间存在良好的正相关性。斜坡角度大、建隆高的进积-加积型台缘带礁滩体在准同生期遭受较强的暴露和大气淡水淋滤,且早期存在的孔隙也有利于后期叠加埋藏溶蚀作用,因而储层厚度较大,储集条件较好;而斜坡角度小的缓坡台缘带需要裂缝、热液和白云石化作用等额外因素才能形成有效储集体。
The Ordovician Member of the Tarim Basin develops high-energy sedimentary facies along the carbonate platform margin at various intervals, but the reservoir performance of the margin reef bank is significantly different. The statistic results show that the geocenter-accretion edge generally exceeds that of the alluvial-gentle ramp margin in terms of sheet porosity, rock sample porosity and logging abnormalities. There is a good positive correlation between the front slope angle and the margin ratio of the margin zone. The geo-accretionary type margin-reefed beach body with large slope angle and built-up height suffered strong exposure and atmospheric freshwater leaching during quasi-contemporaneous period, and the earlier existing pores also contributed to the later superimposed burial dissolution. As a result, reservoirs are thick and have good reservoir conditions. However, the gentle slope margin with small slope angle requires additional factors such as fractures, hydrothermal fluids and dolomitization to form effective reservoirs.