摘要
页岩的储层脆性评价是科学展开压裂施工和井壁失稳评价技术的重要依据.为科学快速评价页岩脆性,以苏北盆地海安凹陷曲塘次凹古近系阜宁组二段储层为研究对象,从影响页岩脆性的因素出发,基于层次分析法,多维度地构建了基于矿物组成、孔隙结构、有机质含量、地层温度、热成熟度这5个方面的页岩脆性综合评价模型.在所构建的页岩脆性综合评价模型中,对脆性影响程度从高到低的因素依次为矿物组成、热成熟度、总有机碳含量、地层温度、孔隙度,权重分别为0.4237、0.2707、0.1686、0.0685、0.068 5.将页岩脆性综合评价模型及4种单一影响因素脆性评价模型的评价结果与实际脆性指数进行对比,结果表明该模型与实际脆性指数的误差最低,能够准确地评价页岩储层脆性.该模型能使各个影响因素的权重定量化,且计算方法简便,对指导现场施工具有重要参考意义.
Abstract
The brittleness evaluation of shale reservoirs serves as a crucial basis for scientifically conducting fracturing operations and evaluating wellbore instability technologies.To scientifically and rapidly assess shale brittleness,this study focuses on the Paleogene Funing formation Ⅱ member reservoirs in the Qutang Subsag of the Hai'an Sag,Subei basin.Starting from the factors influencing shale brittleness,a comprehensive evaluation model for shale brittleness is constructed based on the analytic hierarchy process,encompassing five dimensions:mineral composition,pore structure,organic matter content,formation temperature,and thermal maturity.In this comprehensive evaluation model,the factors influencing brittleness,in descending order of importance,are mineral composition,thermal maturity,total organic carbon content,formation temperature,and porosity,with respective weights of 0.423 7,0.270 7,0.168 6,0.068 5 and 0.068 5.By comparing the evaluation results of the comprehensive shale brittleness evaluation model and four single-factor brittleness evaluation models with actual brittleness indices,it is demonstrated that the proposed model exhibits the lowest error compared to actual brittleness indices,enabling accurate assessments of shale reservoir brittleness.This model quantifies the weights of various influencing factors and features a straightforward calculation method,providing significant guidance for field operations.
维普
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