摘要
根据伊拉克中部A油田主力开发层上白垩统Khasib组碳酸盐岩油藏当前注水开发现状及需要对其进行流动单元的研究,针对该储层岩石及孔隙类型多样,孔喉结构及孔渗关系复杂特征,运用岩心、薄片、扫描电镜、物性分析和压汞资料,在岩相、沉积相、物性及孔喉结构研究基础上,运用微观孔隙结构法对流动单元进行了划分。对多级喉道半径与渗透率关系的分析表明,对本区储层渗透率表征最为敏感的为拐点喉道半径而非传统R35参数。采用该参数并结合岩相、物性、孔隙结构划分出Ⅰ~Ⅲ类流动单元:Ⅰ类流动单元岩相主要为砂屑颗粒灰岩,粒间孔、溶孔配合孔隙缩小型喉道对储层渗流起主要作用,拐点喉道半径大于0.8μm,渗流能力好,孔隙度为22%,渗透率为180×10^(-3)μm^2,发育在高能砂屑滩中;钻遇该类流动单元井初期产量高,但注水开发中易形成早期注水突破,应采取温和注水开采。Ⅱ类流动单元岩相主要为砂屑泥粒灰岩和绿藻泥粒灰岩,砂屑泥粒灰岩以粒间孔配合缩颈喉道,绿藻泥粒灰岩以绿藻铸模孔、溶孔配合网络状、孔隙缩小型喉道对储层渗流起主要作用,但主渗流孔喉组合所占比例较Ⅰ类流动单元小,拐点喉道半径介于0.35~0.8μm之间,渗流能力较好,非均质性强,孔隙度为25%,渗透率为10×10^(-3)μm^2,发育在中-高能的砂屑滩和中-低能的藻屑滩中;该类流动单元井初期产量较高,非均质性强导致剩余油分布差异大,是进一步开采和挖潜的主要区域。Ⅲ类流动单元岩相为抱球虫粒泥灰岩,体腔孔、微孔配合管束状喉道对渗流起主要作用,拐点喉道半径小于0.35μm,渗流能力差,孔隙度平均值仍高达24%,但渗透率平均值仅为1.5×10^(-3)μm^2,发育在较低能的缓斜坡中,含油饱和度低,储量低,较难开采。
Situated in central Iraq,the main development zone of the A Oilfield is the Upper Cretaceous Khasib Formation,and the oil is exploited by the water flooding nowadays.Therefore,the flow unit identification and distribution in reservoir is very important for oilfield development.Due to the multi type character of the lithofacies and pore type of the Khasib carbonate reservoir and the complexity of porethroat texture and porosity-permeability relationship,the micro-pore structure method is used to identify the flow unit based on the solid analysis of the lithofacies,petro-physical property and pore-throat structure on the data sets including coring,casting,SEM and MICP.By the study on the relationship of the throat radius of different levels and reservoir permeability and comparison with the traditional R35,we assume that the inflexion pore-throat radius is the better parameter to characterize the reservoir permeability（flow capability）,and consequently,identify three types of flow unit.TypeⅠ：The lithofacies is the intraclastic grainstone and the flow capability is mainly impacted by the intraclastic intergranular pore coordinate the necking throat.The average porosity is the 22% and permeability is the 180×10^（-3）μm^2,and inflexion pore-throat radius is larger than 0.8μm.The initial production is very high,however,if the injection water into this flow unit may cause the early water breakthrough,so the moderate injection is suitable for the development of this flow unit.TypeⅡ：The lithofacies is the intraclastic packstone and the algal packstone,the intraclastic intergranular pore coordinate the necking throat in intraclastic packstone,and the algal moldic pore and vug coordinate the net throat and scaled-down pore throat in algal packstone mainly impacts the flow capability.Owing to the amount of the isolated bioclast moldic pore and visceral foramen in these two,the main pore-throat which impacts the flow capability is weaker than typeⅠ.The average porosity is 25% and permeability is the 10×10^（-3）μm^2,and inflexion pore-throat radius is 0.35-0.8μm.The initial production is high,but the strong heterogeneity leads the large residual oil to remain in the reservoir.TypeⅢ：The lithofacies is the Gobigerina wackstone,and the visceral foramen and matrix micro-pore coordinate,the control shape throat mainly impacts the flow capability.The average porosity is 24% and permeability is only 1.5×10^（-3）μm^2,and inflexion pore-throat radius is less than 0.35μm,with low oil saturation and reserve.
作者
汪娟
杜洋
熊舒
陈明江
黄婷婷
程亮
辛军
Wang Juan Du Yang Xiong Shu Chen Mingjiang Huang Tingting Cheng Liang Xin Jun(Geology and Exploration Research Institute of CCDC, CNPC, Chengdu 610051,China School of Geosciences and Technology, Southwest Petroleum University, Chengdu 610000 College of Geosciences, China University of Petroleum, Beijing 102249, China)
出处
《地质科技情报》
CAS
CSCD
北大核心
2016年第5期154-162,共9页
Geological Science and Technology Information
基金
中国石油天然气股份有限公司重大科技专项"中国石油海外油气上产2亿吨开发关键技术研究"(2011E-2501)
