Fine description and geologic modeling for volcanic gas reservoirs

Abstract

To understand the geology of volcanic gas reservoir development, research was carried out on volcanic rock, body lithology, lithofacies, fractures, gas and water zones, reservoir classification, and geologic modeling for volcanic gas reservoirs. The volcanic rock body identification and anatomy reveals the spacial distribution and geometric parameters of volcanic rock body. The lithology and lithofacies research shows that, favorable lithology of volcanic rock includes volcanic breccia, vesicular basalt, vesicular ryolite and breccia lava, and favorable lithofacies includes air fall and spatter subfacies of explosive facies, and upper and lower subfacies of effusive facies. Based on FMI imaging, nuclear magnetic logging and traditional logging methods, fracture parameters were interpreted. By use of coherence, curvity and dip angle methods, comprehensive fracture prediction were performed, which reveals the distribution of fractures in volcanic rock. Nuclear magnetic, dublet transverse wave and traditional logging data were applied to identify gas and water zones, with the conformity ratio up to 90%. The prediction research on reservoir classification based on “volume control” indicates the spacial distribution of volcanic reservoirs. By means of volume control structure modeling and seismic control attribute modeling, models of structure, framework, matrix and fracture parameters for volcanic dual-media reservoir were built. 摘 要: 为了解决中国火山岩气藏开发的地质认识问题，对火山岩气藏的火山岩体、岩性、岩相、裂缝、气水层、储集层分类及地质建模进行了研究。通过岩体识别与解剖，揭示了火山岩气藏内部火山岩体的空间展布及几何参数。岩性、岩相研究表明，火山岩有利岩性为火山角砾岩、气孔玄武岩、气孔流纹岩及角砾熔岩，有利岩相为爆发相空落、溅落亚相及溢流相上部、下部亚相。通过FMI成像、核磁及常规测井开展了裂缝参数解释，利用相干、曲率、倾角等方法进行了裂缝综合预测，揭示了火山岩裂缝的分布。综合利用核磁、偶极子横波及常规测井等资料开展了气水层识别研究，符合率达到90%。通过基于“体控”的储集层分类预测研究，揭示了火山岩储集层的空间展布。运用体控构造建模和震控属性建模方法，建立了火山岩双重介质储集层的构造、骨架、基质与裂缝物性参数模型。图14参13 Key words: volcanic gas reservoir, internal structure, reservoir prediction, geologic modeling, volcanic rock body