基于电阻率变化率的低阻油层测井识别新方法  

Innovative method for identifying low-resistivity oil reservoir based on well-logging resistivity gradient

作　　者：陈明江 李洪玺 赵辉 黄婷婷 CHEN MingJiang;LI HongXi;ZHAO Hui;HUANG TingTing(Geological Exploration and Development Research Institute of Chuanqing Drilling Engineering Co.,Ltd.,CNPC,Chengdu 610051,China)

机构地区：[1]中国石油川庆钻探工程有限公司地质勘探开发研究院,成都610051

出　　处：《地球物理学进展》2022年第5期1933-1940,共8页Progress in Geophysics

基　　金：国家重大科技专项“艾哈代布水平井整体注水稳油控水及综合挖潜技术”(2017ZX05030-001-003)资助。

摘　　要：文章提出了一种基于电阻率变化率的低阻储层含油性和有效性评价新方法.基于油气成藏的基本原理,理论推导了均质油藏电阻率随海拔变化的趋势特征,并针对不同孔隙结构的储层分析了电阻率变化趋势特征的差异,建立了相应的图版.结果表明:不含油的致密层或干层的电阻率基本不随海拔升高而变化,趋势线呈垂直线;有效的油层电阻率随海拔升高呈现四分段的折线变化特征,不同斜率段的交点为流体分界面;储层电阻率随海拔的变化率越大,储层孔隙结构越好,含油性越好;反之,孔隙结构变差,含油性变差.基于该研究成果,对伊拉克A油田未进行开发的潜力层含油性和有效性进行了重新评价.在主力开发油藏Khasib之上的Tanuma层识别出厚约20 m、电阻率下限低至0.8Ω·m的低阻油层,经测试获稳定的日产油35.934 m^(3),证实了该油藏的潜力,减轻了A油田产量递减压力.文章所提出的方法可广泛推广应用于各类孔隙型储层的含油性和有效性评价,具有较高的实用价值.The paper proposes a new method to evaluate the oil content and effectiveness of low-resistivity reservoirs based on well-logging resistivity gradient. Based on the fundamentals of oil and gas formation, the trend characteristics of resistivity change with elevation for homogeneous reservoirs are theoretically deduced, and the differences of resistivity change trend characteristics are analyzed for different pore structure reservoirs, and corresponding plots are established. The results show that: the resistivity of non-oil bearing dense or dry reservoirs basically does not change with elevation, and the trend line is vertical;the resistivity of effective oil reservoirs shows the characteristic of folding line change in quadratic segments with elevation, and the intersection of segments with different slopes is the fluid contact;the greater the change rate of reservoir resistivity with elevation, the better the reservoir pore structure and the better the oil content;on the contrary, the pore structure becomes worse and the oil content becomes worse. Based on the research results, the oil-bearing properties and effectiveness of the unexplored potential reservoirs in the A oil field in Iraq were re-evaluated. An oil reservoir with a thickness of about 20 m and a lower resistivity limit of 0.8 Ω·m was identified in the Tanuma formation above the main development reservoir Khasib, and was tested to produce 35.934 m^(3) of oil per day, which confirmed the potential of the reservoir and reduced the pressure of decreasing production in the A field. The method proposed in this paper can be widely applied to the evaluation of oil content and effectiveness of various types of reservoirs, which has high practical value.

关 键 词：油气成藏 低阻储层 孔隙结构 有效性 电阻率下限 

分 类 号：P631[天文地球—地质矿产勘探]