Abstract: Tight sandstone gas is a key filed of natural gas exploration and development. However, there is yet no perfect technical system for comprehensive well logging evaluation as well as logging evaluations of both geological and engineering sweet spots, thus limiting the exploration and exploitation process of natural gas. This study clarifies the characteristics of storage spaces and micro-pore structures in tight sandstone gas reservoirs. It also reveals the primary controlling factors for reservoir quality from the perspectives of tectonics (fractures and in-situ stress), sedimentation and diagenesis. Conventional well logs can be used for lithology identification, reservoir parameter calculation, and fluid property discrimination; moreover, image logs, nuclear magnetic resonance logs, and array acoustic logs can be applied to fracture detection, pore structure classification, and engineering quality evaluation. Additionally, machine learning methods can be employed to quantitatively calculate reservoir parameters. The well logging classification evaluation of reservoir quality can be achieved through the combination of sedimentary microfacies, diagenetic characteristics, fractures and pore structures. Moreover, in terms of the well logging evaluation for tight sandstone gas, a focus is put on the well logging identification and evaluation of matrix pore structures and fractures. Finally, the well logging classification evaluation of geological and engineering sweet spots in tight sandstone is achieved through the coupling of reservoir parameters, pore structures, fractures, in-situ stress, and brittleness. The comprehensive evaluation and prediction of tight sandstone gas reservoirs has been realized using geophysical well log data, which can provide theoretical guidance and technical support for gas reservoir exploration and development.

Key words: tight sandstone gas, reservoir quality, geological and engineering sweet spots, comprehensive well logging evaluation, fracture, pore structure

摘要： 致密砂岩气是天然气勘探开发重点领域之一,但目前尚未建立完善的测井综合评价、地质与工程双"甜点"测井评价技术体系,制约了致密砂岩气勘探开发进程。通过阐述致密砂岩气储层储集空间、微观孔隙结构等特征,从构造(裂缝和地应力)、沉积和成岩角度揭示了储层品质主控因素。常规测井可以用于岩性识别、储层参数计算和流体性质判别,成像测井、核磁共振测井和阵列声波测井则可用于裂缝探测、孔隙结构分类及工程品质评价,同时可采用机器学习方法实现储层参数定量计算。根据储层沉积微相、成岩特征、裂缝和孔隙结构的叠加可实现储层品质测井分类评价,致密砂岩气测井评价重点在于基质孔隙结构和裂缝测井识别与评价。最后通过储层参数、孔隙结构、裂缝、地应力和脆性等耦合实现致密砂岩地质与工程"甜点"测井分类评价。利用地球物理测井资料实现致密砂岩气储层综合评价与预测,可为气藏勘探开发提供理论指导与技术支撑。

关键词: 致密砂岩气, 储层品质, 地质与工程甜点, 测井综合评价, 裂缝, 孔隙结构