摘要
Three productive layers have been proved in the Tertiary sequence of Tarim basin. At depths of more than 5 000 m, the Tertiary reservoir sandstones or Northern Tarim is found to have porosities greater than 15% and permeabilities up to 1 000×10-3μm2.These pores are intergrauular and appear to be primary that bave survived rrom compaction and cementation. Based on the lithology data, physical properties and pere conriguration as well as characteristics of oil and gas production, tbe reservoir quality of 8andstones was evaluated and divided into three ranks. The reservoir quaIity of Tertiary sandstone bodies is also depeudent upon diagenetic processes. The author proposes a porosity evolutiou model to explain the origin of primary porosity preservation. Several factors may have contributed to POrosity preservation: rapid burial, low paleogeothermal gradient, early iron oxidation and chlorite coatiug, partlal Pore filling by early calcite and gyp-sum.
Three productive layers have been proved in the Tertiary sequence of Tarim basin. At depths of more than 5 000 m, the Tertiary reservoir sandstones or Northern Tarim is found to have porosities greater than 15% and permeabilities up to 1 000×10-3μm2.These pores are intergrauular and appear to be primary that bave survived rrom compaction and cementation. Based on the lithology data, physical properties and pere conriguration as well as characteristics of oil and gas production, tbe reservoir quality of 8andstones was evaluated and divided into three ranks. The reservoir quaIity of Tertiary sandstone bodies is also depeudent upon diagenetic processes. The author proposes a porosity evolutiou model to explain the origin of primary porosity preservation. Several factors may have contributed to POrosity preservation: rapid burial, low paleogeothermal gradient, early iron oxidation and chlorite coatiug, partlal Pore filling by early calcite and gyp-sum.
