塔里木盆地阿克库勒凸起卡拉沙依组储层特征研究

The clastic reservoir rocks from the Kalashayi Formation on the Akkol uplift of the Tarim Basin,Xinjiang

关键词:  塔里木盆地  阿克库勒凸起  石炭系  储层  新疆

Key words:  Tarim Basin  Akkol uplift  Carboniferous  reservoir rock  Xinjiang

摘要:

阿克库勒凸起石炭系卡拉沙依组碎屑岩储层中,长石的含量大于岩屑的含量,储集层成分成熟度和结构成熟度均较低,颗粒之间多呈点-线接触。胶结类型为孔隙式,主要为碳酸盐岩胶结。虽然早期碳酸盐岩胶结降低了砂岩的原始孔隙度和渗透率,但也为次生孔隙的形成提供了物质基础。该组储集层中次生孔隙的含量远大于原生孔隙。从压汞资料上可以看出,孔喉分布不均,但呈粗歪度,储层孔渗性均较低,属中低孔,低渗的储层。该组成岩作用已达到晚成岩A期,早期方解石交代石英颗粒并发生大量溶蚀,生成大量次生孔隙;晚期方解石没有发生溶蚀,但交代早期方解石和各种自生粘土矿物。

Abstract:

The clastic reservoir rocks from the Carboniferous Kalashayi Formation on the Akkol uplift of the Tarim Basin,Xinjiang consist mostly of lithic arkosite,and the feldspar contents are found to be higher than those of lithoclastics.The clastic reservoir rocks exhibit low compositional maturity and textural maturity,point to linear contact between grains and pore-space cementation by carbonate rocks.Although the early carbonate cementation may cause the decrease of the primary porosity and permeability of sandstones,it has contributed to the formation of secondary porosity.The amounts of secondary porosity are much more than those of the primary porosity.It can be seen from the data obtained from mercury-injection method that the pore throats display an inhomogeneous distribution,and both the porosity and permeability are relatively low,indicating the moderate or low porosity and low permeability of the reservoir rocks.The diagenesis in the Kalashayi Formation may be assigned to Stage A of late diagenesis.Abundant secondary pore spaces created by the dissolution of early calcite are considered as the important oil-bearing structures in the study area.