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论述了在南海西部盆地高温超压储层中利用测井资料定性识别及定量评价气体类型时遇到的问题。储层中同时含有CH_4、CO_2以及地层水时,导致该类储层测井响应特征变化复杂,尤其是CO_2溶于水后形成的附加导电性变化规律不清晰,导致基于电阻率测井响应的评价方法对CO_2的定性识别和定量计算变得异常困难。为此,利用CH_4与CO_2在中子、密度测井响应存在的差异特征,构建一个经孔隙度、含气饱和度校正的识别参数(NDS-Sg),利用该参数可以对气体类型进行有效的定性识别;基于CH_4和CO_2在热中子扩散及减速方面的差异特征,首次采用中子测井长短源距计数率建立了气体组分定量计算模型。定性识别及定量计算结果与测试结果吻合良好,证实了方法的可靠性。
The problems encountered in the qualitative identification and quantitative evaluation of gas types by logging data in the high-temperature overpressured reservoirs in the western South China Sea Basin are discussed. When the reservoirs contain both CH 4, CO 2 and formation water, the logging response characteristics of these reservoirs are complex, especially the additional conductive properties formed when CO 2 is dissolved in water are unclear, resulting in the change of resistivity logging response The method of qualitative evaluation and quantitative calculation of CO_2 becomes very difficult. Therefore, by using the difference characteristics of CH4 and CO_2 in neutron and density log responses, a porosity and gas saturation correction identification parameter (NDS-Sg) is constructed, which can be used to validate gas types Based on the difference characteristics of CH4 and CO2 in the diffusion and deceleration of thermal neutrons, a quantitative calculation model of gas composition was established for the first time using the counting rate of neutron well spacing. Qualitative identification and quantitative calculation results are in good agreement with the test results, confirming the reliability of the method.