伊拉克哈法亚油田白垩系Mishrif组碳酸盐岩孔隙结构及控制因素

伊拉克哈法亚油田Mishrif组碳酸盐岩储层孔隙结构类型的差异性及对其控制因素的认识是制约该类储层分类评价的一个关键问题。综合利用岩芯、铸体薄片、扫描电镜、常规物性、压汞分析等手段及统计分析方法对储层的主要孔隙类型、喉道类型、喉道分布特征进行了研究，确定了孔隙结构划分依据和方案，并划分出了中低孔超低渗细喉型、中低孔低渗细喉型、中高孔中低渗中细喉型、高孔中低渗细喉型、中高孔中低渗细喉型、中高孔中低渗中喉型六种孔隙结构类型，并通过毛管压力曲线的形态划分出了Ⅰ-Ⅴ五类线型；研究区主要发育开阔台地相，并划分出8种储集岩类型，分别是泥晶灰岩、生屑粒泥灰岩、生屑泥粒灰岩、砂屑生屑泥粒灰岩、生屑颗粒灰岩、砂屑生屑颗粒灰岩、介壳类漂浮岩和岩溶建造岩，其中岩溶建造岩储层具有较特殊的网络状孔隙结构。因此，可以认为哈法亚Mishrif组储层主要受早成岩期岩溶作用影响，其早成岩期溶蚀具有明显的相控特征，是孔隙结构差异性的主要控制因素，极大的改善了该套储层的物性。

Pore Structure Characteristics and Control Factors of Carbonate Reservoirs: The Cretaceous Mishrif Formation,Halfaya oilfield,Iraq

The classification of reservoir pore configurations and differential genesis for the Cretaceous Mishrif formation in the Halfaya oilfield, Iraq, restrains as one of the key question for reservoir evaluation. The pores and throats are studied by cores, cast thin sections, scanning electron microscopy, routine physical properties and mercury analysis, to define the types and criteria of pore configuration. The pore configuration are divided into six types: (a) thin throat with low-middle porosity and ultra-low permeability; (b) thin throat with low-middle porosity and low permeability; (C) middle-thin throat with high-middle porosity and low-middle permeability;(d) thin throat with high porosity and low-middle permeability; (e) thin throat with high-middle porosity and low-middle permeability; (f) medium throat with high-middle porosity and low-middle permeability. Five shapes (from I to V) of capillary pressure curves are also divided. The research area is located in an open platform facies with eight types of rocks deposited, including micrite limestone, bioclastic wackestone, bioclastic packstone, intraclast bioclastic packstone, bioclastic grainstone, intraclast bioclastic grainstone, shell floatstone and karstic rock, respectively. Besides, the karstic rock is a special network structure. It is comprehensively suggested that the Mishrif reservoir in Halfaya was mainly affected by eogenetic karstification obviously controlled by facies. So the eogenetic karstification is the key factor controlling the diversity of pore configuration and further improving the reservoir quality greatly.