珠江口盆地白云凹陷北部深水低渗气层测井识别与分类

Log Identification and Classification of Deep-Water Low Permeability Gas Layer in the Northern Part of Baiyun Sag of Pearl River Estuary Basin

摘要: 珠江口盆地白云凹陷北部区域珠江组~恩平组水深与埋藏深度较大，气层具有低渗特征，导致气层测井识别与分类困难，给气层勘探开发带来很大困扰。本文在储层孔隙结构与测井响应特征分析的基础上，采用声波时差–电阻率交会图法、补偿中子–电阻率交会图法、补偿密度–电阻率交会图法、泊松比与体积压缩系数–电阻率交会图法和纵横波速度比法共五种方法开展气层识别研究；以渗透率为主要界限，结合铸体薄片、核磁共振、高压压汞等实验结果，开展了低渗气层分类研究。结果表明，泊松比与体积压缩系数–电阻率交会图法和声波时差–电阻率交会图法效果最好；低渗气层可分为三类，I类气层孔隙度 ≥ 10.0%、渗透率 ≥ 10.0 mD；II类气层孔隙度为7.0%~13.0%、渗透率为1.0 mD~10.0 mD；III类气层孔隙度为6.6%~10.0%、渗透率为0.45~1.0 mD。研究提出的气层识别方法和分类方法均在珠江口盆地白云凹陷应用效果较好，可为其他深水低渗气层测井评价提供参考。

Abstract: The water depth and the burial depth of Pearl River Formation and Enping Formation in the northern area of Baiyun sag of Pearl River Estuary Basin are large, and the gas layer has low permeability characteristics, which leads to the difficulty of identification and classification of gas logging, which brings great trouble to the exploration and development of gas layer. Based on the analysis of reservoir pore structure and logging response characteristics, we used five methods, the acoustic transit-resistivity cross-section method, the compensation neutron-resistivity cross-section method, the compensation density-resistivity cross-section method, the Poisson’s ratio and volume compressibility coefficient-resistivity cross-section method and the vertical and horizontal wave velocity ratio method, to conduct the research of layers’ identification. With permeability as the main limit, combined with the experimental results of body sheet, nuclear magnetic resonance and mercury pressure, we conducted the research of layers’ classification. The results showed that the Poisson’s ratio and volume compressibility coefficient-resistivity cross-section method and the acoustic transit-resistivity cross-section method had the best effect; the low permeability gas layer can be divided into three categories, class I gas layer porosity greater than or equal to 10.0% and permeability greater than or equal to 10.00mD, class II gas layer porosity is 7.0%~13.0% and permeability 1.00~10.0 mD, class III gas layer porosity is 6.6%~10.0% and permeability is 0.45~1.0 mD. The gas layer identification method and classification method are well applied in Baiyun Sag of Pearl River Estuary Basin, which can provide reference for logging evaluation of other deep-water low permeability gas layers.