| 高孔高渗型特稠油藏油水界面不统一特征及成因: 以辽东湾坳陷旅大5油藏为例 |
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| 引用本文： | 刘艺萌,杜晓峰,黄晓波,张藜,徐伟.高孔高渗型特稠油藏油水界面不统一特征及成因: 以辽东湾坳陷旅大5油藏为例[J].地球科学,2022,47(5):1669-1683. |
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| 作者姓名： | 刘艺萌 杜晓峰 黄晓波 张藜 徐伟 |
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| 作者单位： | 中海石油(中国)有限公司天津分公司, 天津 300459 |
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| 基金项目： | “十三五”国家科技重大专项课题“渤海海域勘探新领域及关键技术研究”（No.2016ZX05024-003）； |
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| 摘 要： | 辽东湾坳陷新近系旅大5特稠油油藏存在储层高孔高渗，油水关系不统一，界面呈波状等特殊现象.通过油源对比、原油稠化分析、岩性相划分、孔喉类型分类等研究表明:旅大5油藏为次生油藏，原油为来自辽西南洼沙三段的低熟稠油，原油先期在东营组地层聚集成藏，受新构造运动破坏后再次运移至浅层，再次运移使低熟稠油进一步次生稠化，导致原油在浅层聚集前已稠化为次生稠油，为异常油水关系提供先决条件；研究区新近系发育辫状河相沉积，可识别出4种沉积微相、10种岩性相，沉积作用控制不同岩性相微观孔喉类型影响储层渗透性，进而决定稠油充注效能；油层间的砂砾岩储层主要为块状层理砾岩相和大型交错层理砂砾岩相沉积，喉道类型为中高排驱压力细喉道型，储层渗透率低形成物性封堵，限制次生稠油充注形成水层；次生稠油密度高、粘度大、流动性差，进入储层后难以及时和孔隙水置换形成水平油水界面，而是呈倾斜式由外部充注压力驱动“平推挤入”储层，充注过程中优先充注渗透率高的储层，充注停止后原油不再流动，此时低渗透储层未被充注，从而形成油水关系不统一、界面呈“波形”等现象.
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| 关 键 词： | 辽东湾坳陷 高孔高渗 特稠油油藏 油水界面不统一 波状油水界面 岩性相 孔喉类型 油气地质 |
| 收稿时间： | 2021-11-10 |
Characteristics and Genesis Analysis of Oil-Water Interface Inconsistency of Extra-Heavy Oil Reservoir with High Porosity and High Permeability:Taking LD5 Reservoir in Liaodongwan Depression as an Example |
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| Liu Yimeng,Du Xiaofeng,Huang Xiaobo,Zhang Li,Xu Wei.Characteristics and Genesis Analysis of Oil-Water Interface Inconsistency of Extra-Heavy Oil Reservoir with High Porosity and High Permeability:Taking LD5 Reservoir in Liaodongwan Depression as an Example[J].Earth Science-Journal of China University of Geosciences,2022,47(5):1669-1683. |
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| Authors: | Liu Yimeng Du Xiaofeng Huang Xiaobo Zhang Li Xu Wei |
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| Abstract: | The Neogene LD5 extra-heavy oil reservoir in Liaodongwan depression shows special phenomena of high porosity and permeability, inconsistent oil-water relationship and wavy interface. In this paper it presents a study on the oil source correlation, crude oil thickening, lithologic facies of reservoir and classification of pore throat types. The analysis shows that LD5 reservoir is a secondary reservoir, and the crude oil is low-maturity heavy oil from E2s3 in the southwest of Liaoxi sag. In the early stage, the crude oil gathered and reservoirs formed in the Dongying Formation, which were destroyed by neotectonic movement and migrated to shallow formation in the later stage. Secondary thickening occurred in the secondary migration, and as a result, the crude oil had been thickened into secondary heavy oil before accumulation in the shallow layer, which provided a prerequisite for abnormal oil-water relationship. Braided fluvial deposits developed in the Neogene in the study area, 4 kinds of sedimentary microfacies and 10 lithologic facies were identified in braided fluvial facies. Sedimentation affects reservoir permeability by controlling the microscopic pore-throat types of different lithologic facies, and then determines the filling efficiency of heavy oil. The interbedded sand conglomerate reservoir is mainly composed of massive bedding conglomerate facies and large cross bedding sand conglomerate facies, with narrow throat leading to low reservoir permeability, resulting in physical plugging, restricting secondary heavy oil charging and forming water layer. After the secondary heavy oil entered reservoir, the free flow of crude oil was limited due to its high density and viscosity, so it could not replace with pore water in time to form a horizontal oil-water interface. Instead, it was pushed into the reservoir by external pressure in an inclined manner. During the filling process, the reservoir with high permeability was preferentially charged, and the crude oil no longer flowed after the filling stopped, and the low-permeability reservoir was not filled at this time, thus forming the phenomena of inconsistent oil-water relationship and wavy interface. |
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