煤储层测井分析和精细地质建模技术——以澳大利亚Surat盆地煤层气区为例

CBM reservoir log and fine geo-model analysis techniques:Taking CBM in Surat basin as an example

煤层气储层测井地质分析的深入和建立合理的煤层气精细地质模型对于提高煤层气开发效果影响巨大。澳大利亚东部Surat盆地煤层气区开发的目的层系是低煤阶的煤系地层,钻井井数多、测井时间跨度长,准确的单煤层精细识别和岩相定量解释技术需要测井标准化研究,同时,已钻井井距差别大,产量高低变化大,储层认识仅仅限于煤组和煤组模型,不利于细化开发和进一步提高单井产量。因此根据现场实际,建立一套煤储层测井地质分析和精细地质模型分析技术,首先以层序旋回识别为基础,进行多级层序高分辨率的煤小层层序划分和对比,解决单煤层空间分布和单井泄流面积的认识,同时,建立一套适用于全区的煤储层测井曲线标准化流程,解决煤储层厚度解释不准确的问题,在此基础上,建立单煤层PLY-BASE为基础的煤层气田精细地质模型,获得煤储层分布和地质储量基础。该研究建立的煤层序多级高分辨率层序格架,刻画了单煤层储层的尖灭合并分布特征和单井泄流面积范围。以测井标准化为基础的煤层精细解释和多岩性定量分析确保了煤层解释的准确性,并确定了包括5种微相类型的河流相概念模式。建立了气田范围内ply-based煤层气精细地质模型,为确定未来在全区进行河流相控煤沼随机模拟的研究重点和开发方案优化以及优选开发有利区提供依据。

Deep geological knowledge of CBM reservoir log and geo-model are very important aspects that will influence the development effect of CBM gas field.Targeted at the low rank coal-bedding strata,the CBM project in Surat basin Australia had hundreds of wells that were measured in large time span.Also,these wells are in different well-spacing but in big variance in production rate.The reservoir study in old days was only to focus on the coal member,which is too coarse to meet the need of finer development and higher production rate.According to actual production need,the authors propose a set of techniques of deeply understanding reservoir.The first one is to build a multi-level framework of high resolution coal sequence strata in order to reveal the rules of coal ply space distribution and drainage area.The second is to create a workflow to do the log normalization so as to accurately interpret the coal thickness in wells.And then based on all analysis above,a coal-ply based model is built to explicate the complex of coal and the gas in place of gas field.This study has built a coal-based multi-stage high resolution sequence framework in order to depict pinch-out,merge features and drainage area of coal ply.Fine-coal log interpretation and quantitative complex lithology based on log normalization ensure the accuracy of coal ply and other lithology.Five micro-facies concept model was built.Gas field ply-based geo-model will be used to test the future regional stochastic swamp-based geo-model so as to reasonably optimize whole regional development plan and improve production rate based on the learning from ply model.