中国南方海相复杂山地页岩气储层甜点综合评价技术——以昭通国家级页岩气示范区为例

针对中国南方海相页岩气勘探开发所面临的"强改造、过成熟、复杂山地人文"等地质与地理条件,以云南昭通国家级页岩气示范区6年来的页岩气勘探甜点评价及黄金坝产区5×10~8m~3页岩气产能建设实践为支撑,在调研总结国内外页岩气储层评价认识的基础上,明确提出南方海相山地页岩气储层甜点评价中应补充页岩气保存条件、孔隙压力条件这2项关键指标,并应强化地应力与天然微裂缝系统评价研究。以此为基础,融合页岩气多学科资料进行系统分析并开展地质工程一体化综合研究,由此建立了页岩气储层"地球物理、储层地质、裂缝系统、岩石地质力学"三维模型。应用实践结果表明:①地质工程一体化和储层三维建模是中国南方海相复杂山地页岩气储层甜点评价的有效方法;②页岩气储层甜点评价体现了多属性、多项评价参数的三维空间叠合与叠加效应;③木桶短板原理决定了页岩气储层甜点区的分布格局和评选结果。结论认为:该页岩气储层甜点综合评价方法具有创新性,可有效规避复杂的地质风险和工程风险,对高效勘探开发南方海相页岩气具有指导意义。

Comprehensive evaluation technology for shale gas sweet spots in the complex marine mountains,South China: A case study from Zhaotong national shale gas demonstration zone

The exploration and development of marine shale gas reservoirs in South China is challenged by complex geological and geographical conditions, such as strong transformation, post maturity, complex mountains and humanity. In this paper, the evaluations on shale gas sweet spots conducted in Zhaotong demonstration zone in the past six years and the construction of 500 million m³ shale gas production capacity in Huangjinba region were discussed, and the results of shale gas reservoir evaluations in China and abroad were investigated. Accordingly, it is proposed that another two key indicators be taken into consideration in the evaluation on shale gas sweet spots in marine mountains in South China , i.e. shale gas preservation conditions and pore pressure, and the research on ground stress and natural microfracture systems be strengthened. Then, systematic analysis was conducted by integrating shale gas multidisciplinary data and geological and engineering integration study was carried out. Finally, a 3D model, which was composed of “geophysics, reservoir geology, fracture system and rock geomechanics”, was established for shale gas reservoirs. Application practice shows that the geological engineering integration and the 3D reservoir modeling are effective methods for evaluating the shale gas sweet spots in complex marine mountains in South China. Besides, based on shale gas sweet spot evaluation, 3D spatial congruency and superposition effects of multiple attributes and multiple evaluation parameters are presented. Moreover, the short-plate principle is the factor controlling the distribution patterns and evaluation results of shale gas sweet spots. It is concluded that this comprehensive evaluation method is innovative and effective in avoiding complex geological and engineering risks, so it is of guiding significance in exploration and development of marine shale gas in South China.