基于灰色关联分析法的深层页岩气储层“甜点”优选——以川中Z3井区五峰组–龙一1亚段页岩储层为例

Optimization of Deep Shale Gas “Sweet Spots” Based on Grey Relational Analysis—A Case Study of the Wufeng Formation-The First Sub-Member of Longmaxi Formation in the Z3 Well Block, Central Sichuan Basin

摘要: 页岩储层普遍表现出强烈的非均质性，且受多因素控制，仅靠单一参数的定性评价或多参数的简单叠合难以准确评价页岩储层品质。为定量确定页岩气储层评价参数的权重，本文以四川盆地中部Z3井区五峰组–龙一₁亚段为例，基于测井和实验数据，选取孔隙度、总有机碳含量、含气量及脆性指数四个关键参数，以产能指数作为母序列，采用灰色关联分析方法，量化评估各参数对产能影响。结果表明：(1) 四个参数与产能指数的关联度大小顺序为：含气量 > TOC > 孔隙度 > 脆性指数，其权系数比值为0.2739：0.2626：0.2334：0.2301，明确含气量为研究区产能主要控制因素。(2) I类地质甜点主要位于五峰组上部–龙一1亚段1小层，横向发育连续性较好，研究区西南部为下一步建议勘探区域。本研究为川中Z3井区地区页岩气勘探开发中的靶层优选提供了依据，并表明灰色关联分析法适用于页岩储层多参数综合评价。

Abstract: Shale reservoirs commonly exhibit strong heterogeneity and are controlled by multiple factors. Qualitative evaluation based on a single parameter or simple superposition of multiple parameters is insufficient for accurately assessing shale reservoir quality. To quantitatively determine the weighting of evaluation parameters for shale gas reservoirs, this study takes the Wufeng Formation-Long 1₁ Sub-member in the Z3 Well Block of the central Sichuan Basin as an example. Based on logging and experimental data, four key parameters were selected: porosity, total organic carbon content (TOC), gas content, and brittleness index. Using the productivity index (PI) as the reference sequence, grey relational analysis (GRA) was employed to quantitatively evaluate the influence of each parameter on productivity. The results show that: (1) The order of relational degree between the four parameters and the productivity index is: gas content > TOC > porosity > brittleness index, with weight coefficients ratios of 0.2626: 0.2334: 0.2739: 0.2301, indicating that gas content is the main controlling factor for productivity in the study area. (2) Class I geological sweet spots are mainly located in the upper part of the Wufeng Formation-Long 1₁ Sub-member, exhibiting good lateral continuity. The southwestern part of the study area is recommended as the next target for exploration. This study provides a basis for target layer optimization in shale gas exploration and development in the Z3 Well Block of the central Sichuan Basin and demonstrates that grey relational analysis is suitable for multi-parameter comprehensive evaluation of shale reservoirs.