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巨厚灰岩油藏中隔夹层与高渗层成因与发育规律—以伊拉克H油田Mishrif组为例

作    者:乔占峰1,2,孙圆辉3,曹 鹏1,2,朱光亚3, 邵冠铭1,2,王拥军3,张 杰1,2,孙晓伟1,2
单    位:1 中国石油杭州地质研究院;2 中国石油集团碳酸盐岩储层重点实验室;3 中国石油勘探开发研究院
基金项目:本文受中国石油天然气集团有限公司“十四五”项目“海外深层油气成藏机制与勘探评价技术研究”资助
摘    要:
隔夹层和高渗层是影响油田开发效果的重要因素。以伊拉克 H油田 Mishrif组为例,基于岩心和测井资料,在渗透率控制因素分析的基础上,研究了隔夹层和高渗层的成因类型与发育规律,并探讨了对油田开发的指导意义。Mishrif组生物碎屑灰岩渗透率与岩石结构、孔隙类型和成岩改造密切相关,受沉积和成岩作用的共同控制。隔夹层包括隔层、夹层和侧向隔挡层:隔层可进一步划分为深水沉积型隔层和浅水沉积型隔层,受层序地层控制;夹层进一步可划分为沉积型夹层和成岩型夹层,分别受沉积结构和高频层序控制;侧向隔挡层主要为潮道灰泥充填物或下切谷,主要发育于层序界面附近。高渗层具有沉积型和成岩型2种类型:沉积型高渗层以潮道高能生物碎屑灰岩为主,相较周围潟湖相低能细粒沉积构成异常高渗带;成岩型高渗层形成于暴露溶蚀改造,表现为潟湖低能细粒沉积和滩相生物碎屑灰岩溶蚀改造的产物,主要发育于四级或三级层序高水位体系域上部,平面上受微相和地形地貌控制。在油气开发过程中,射孔段应尽量避开主要发育于层序旋回底部和顶部的隔夹层和高渗层,避免破坏开发单元或过早见水,也便于后期措施调整;宜优先采用储层单元内部同层注水,根据夹层发育状况设计注采关系。隔夹层和高渗层认识对于中东、中亚以及南美地区中新生代同类型厚层油气藏开发具有重要指导意义。
关键词:巨厚灰岩油藏;隔夹层;高渗层;成因;Mishrif组;伊拉克

Genesis and development law of barrier and baffles and high permeable streak in the massive bioclastic reservoir: a case study of the Upper Cretaceous Mishrif Formation in H Oilfield, Iraq

Author's Name: QIAO Zhanfeng, SUN Yuanhui, CAO Peng, ZHU Guangya, SHAO Guanming, WANG Yongjun, ZHANG Jie, SUN Xiaowei
Institution: 
Abstract:
Barrier and baffle (BB) and high permeable streak (HPS) are important factors influencing the development effectiveness of the reservoir. Mishrif reservoir in Iraq H Oilfield used to be treated as massive reservoir. However, with the development of the reservoir, some of serious problems, including water breakthrough, unclear water injection response, etc., raise up, which influence the production effectiveness significantly. Based on the cores, thin-sections, petrophysical properties, and logging data, by means of analyzing the controls of rock fabric, pore types, and diagenetic modification on the permeability, the origin and development of BB and HPS of Mishrif Formation in Iraq H Oilfield have been studied. It is known that the permeability of bioclastic limestone of Mishrif Formation is closely related to the rock fabric, pore types, and diagenetic modification, which determine the origin and development of BB and HPS. BB includes barrier, baffle, and lateral barrier, and barrier can be subdivided into deep deposition type and shallow deposition type, consisting of mainly mudstone, wackstone, and coaly mudstone, developed in the lower part and top part of the sequence respectively, especially the barrier occurred in the transgrassive system tract of 3rd-order sequence would be able to comprise the regional barrier separating the reservoirs. Baffle, influencing the fluid flow within the reservoir, can be subdivided into sedimentary type and diagenesis type, controlled by sedimentary architecture and high frequency sequence respectively. Lateral barrier consists of lime mudstone filling in tidal channel and / or incision valley which usually occurred around sequence boundary. HPS also includes sedimentary type and diagenesis type, the former consists of mainly high energy bioclastic grainstone filled in tidal channel or bioclastic shoals with obviously high permeability compared with surrounding lagoonal fine grained sediments; the latter formed by the lagoonal fine grained sediments and/or shoal bioclastic grainstone dissolved by meteoric water during exposure, is mainly developed under the 4th or 3rdorder sequence boundary and controlled by lithofacies and topography. Multiple origins of BB and HPS significantly complicated the reservoir architecture, which influences the production largely. The implication of this study to the development of oilfield are twofold: on one hand, the developing section or perforation could avoid the BB and HPS mostly occurred in the bottom and top part of the sequence, so as not to penetrate the development units; on the other hand, it’s better to adopt the internal injection within the development units and to design the injection and production relation based on the development of baffles. The knowledge of BBs and HPSs are meaningful to the development of massive reservoirs of meso Cenozoic counterparts in Mideast, Mid-Asia, and South American.
Keywords: massive reservoir; barrier and baffle; high permeable streak; genesis; Mishrif Formation; Iraq
投稿时间:2021-09-27  
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