页岩气田储层含气性测井评价——以四川盆地涪陵页岩气田J区块为例

Gas-bearing property evaluation by petrophysical logging in shale gas reservoirs: a case study in J area of Fuling shale gas field, Sichuan Basin

  • 摘要: 页岩储层岩性较复杂、储集空间类型多样,现有的含气性测井综合评价方法体系还不够完善。为深化四川盆地涪陵页岩气田J区块页岩储层含气性评价认识,应用密度-中子叠合法、自然伽马-去铀伽马叠合法、铀-钍比值法开展含气储层定性识别,并对吸附气、游离气、孔隙度、含气饱和度等含气性参数进行了测井定量预测研究。在多参数对比研究的基础上,优选了有机碳含量、孔隙度、含气饱和度、硅质含量、埋深为影响含气性测井评价参数,采用灰色关联分析法构建出储层含气性测井评价指数GQ,建立了含气性评价标准,即Ⅰ类含气储层GQ ≥ 0.57,Ⅱ类含气储层0.37 < GQ < 0.57,Ⅲ类含气储层GQ ≤ 0.37。该方法应用于J区块表明,含气性参数定量预测模型精度较高,且含气性评价标准可以对储层含气性进行有效的评价和分类,具有很好的推广前景。

     

    Abstract: The lithology of shale reservoirs is complex and the types of storage porosity are diverse. The existing gas-bearing property evaluation system by petrophysical logging is not perfect. In order to deepen the understanding of the gas-bearing capacity evaluation of shale reservoirs in J area of the Fuling shale gas field in the Sichuan Basin, the density-neutron curve superposition method, natural gamma-de-uranium gamma curve superposition method, and uranium-thorium ratio method are applied in qualitative recognition. Quantitative logging research was carried out on gas-bearing parameters such as adsorbed gas, free gas, porosity, and gas saturation. Based on the multi-parameter comparative study, organic carbon content, porosity, gas saturation, siliceous content, and burial depth are selected as the logging evaluation parameters that affect gas-bearing properties. A logging evaluation index (GQ) for gas-bearing capacity is constructed using fuzzy correlation analysis. The gas-bearing evaluation criterion is established, that is, GQ ≥ 0.57 for type Ⅰ gas-bearing reservoirs, 0.37 < GQ < 0.57 for type Ⅱ gas-bearing reservoirs, and GQ ≤ 0.37 for type Ⅲ gas-bearing reservoirs. The application of this method in J area shows that the accuracy of the quantitative prediction model for gas-bearing parameters is high, and the gas-bearing evaluation criteria can effectively evaluate and classify the gas-bearing properties of the reservoir.

     

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