阿联酋东鲁卜哈利盆地白垩系Mishrif组碳酸盐岩储层孔隙特征

Pore characteristics of carbonate reservoir of the Cretaceous Mishrif Formation in East Rub Al Khali Basin,UAE

上白垩统Mishirif组是阿联酋东鲁卜哈利盆地主要的产油层,目前对Mishrif-1段和Mishrif-3段储层孔隙特征差异的研究较为薄弱。在岩心描述、薄片鉴定、气测、压汞及核磁共振测试的基础上,对Mishrif组储层储集空间、孔隙结构进行了系统研究,明确了储层的相控特征以及Mishrif-1段和Mishrif-3段的差异。结果表明:①Mishrif组岩石类型主要包括泥晶生屑灰岩、生屑泥晶灰岩、亮晶厚壳蛤灰岩,储集空间类型以粒内溶孔、粒间孔、铸模孔、生物体腔孔和晶间溶孔为主,属孔隙型储层。②Mishrif组储层具有明显的相控特征,优质储层集中在Mishrif-1段生物礁和生屑滩微相,Mishrif-3段厚壳蛤礁滩和生屑滩微相,平均孔隙度高于20%,平均渗透率大于100×10^(-3)μm^(2),为高孔高渗储层。③Mishrif-1段生物礁微相压汞曲线为斜线型,核磁共振曲线为锯齿型,孔隙为大孔径生物体腔孔,束缚水饱和度低;Mishrif-3段厚壳蛤礁滩微相压汞曲线为斜线型,核磁共振曲线为双峰锯齿复合型,铸模孔、生物体腔孔发育,同时发育一定的粒间溶孔,束缚水饱和度低;Mishrif-1段生屑滩微相压汞曲线为斜线型,核磁共振曲线为双峰锯齿复合型,铸模孔、粒间溶孔同时发育,束缚水饱和度低;Mishrif-3段生屑滩微相压汞曲线为斜线型,核磁共振曲线为锯齿型,孔径分布不集中,孔隙类型多样,以粒间溶孔为主。

The Upper Cretaceous Mishirif Formation is the main oil producing reservoir in Eastern Rub Al Khali Basin.At present,the research on the difference of reservoir pore properties between the Mishrif Member 1(Mishrif-1)and Member 3(Mishrif-3)is relatively weak.On the basis of the analysis of core,thin section,gas injection,mercury injection and nuclear magnetic resonance(NMR),the reservoir space types and pore structure types of Mishrif Formation are systemically studied.The results show that:(1)The rock types of Mishrif Formation include micritic bioclastic limestone,bioclastic micritic limestone,and rudist limestone.There are mainly intragranular solution pore,intergranular pore,mold pore,biological cavity pore,and intergranular solution pore in the reservoir,indicating that it is a porous reservoir.(2)The reservoir of Mishrif Formation has obvious facies-controlled characteristics.The high quality reservoirs are concentrated in microfacies including reed and bioclastic shoal of Mishrif-1,bioclastic shoal and rudist reef-shoal of Mishrif-3,with an average porosity of more than 20%and an average permeability of more than 100×10^(-3)μm^(2),which is a high porosity and high permeability reservoir.(3)The mercury injection curve of the reef in Mishrif-1 is oblique,the NMR curve is serrated,the pores are large biological cavities with pore size of 50-100μm,and the irreducible water saturation is low.The mercury injection curve of Rudist reef-shoal in Mishrif-3 is oblique,and the NMR curve is bimodal-serrated composite,mold pores and biological cavities are developed with pore size of 1-100μm,and certain intergranular dissolved pores are developed with pore size of 0.4-1μm at the same time,and the irreducible water saturation is low.The mercury injection curve of bioclastic shoal in Mishrif-1 is oblique,the NMR curve is bimodal-serrated composite,mold pores and intergranular dissolved pores are developed with pore size of 0.1-10μm,and the irreducible water saturation is low.The mercury injection curve of bioclastic shoal in Mishrif-3 is oblique,the NMR curve is serrated,the pore size distribution is not concentrated,and the pore types are diverse,mainly intergranular dissolved pores.