低阻砂岩气藏测井饱和度计算方法——以准噶尔盆地玛河气田为例

为了解决准噶尔盆地南缘地区低阻油气藏饱和度计算数值不准问题,以玛河气田古近系紫泥泉子组低阻砂岩气藏为例.通过孔渗、岩电、铸体薄片、阳离子交换容量等实验数据,研究分析阳离子交换量、阳离子当量电导、阳离子交换容量、胶结指数、饱和度指数等参数的变化规律,建立适用于低阻砂岩气层含水饱和度计算的变参数的Archie饱和度模型和Wax-man-Smits(W-S)饱和度模型,并进行实例井验证,获得良好效果.研究结果表明:在低阻砂岩气层中,常规的Archie模型适用于胶结指数、饱和度指数较小的纯产气或电阻率较低的水层,但在气水同层中解释效果较差;而通过变参数的Archie与W-S模型计算出的含水饱和度值均满足同一段储层下部含水饱和度大于储层上部的规律特征,其结果数据与岩心分析、气测试结果相吻合.两种饱和度计算新模型对低阻砂岩气藏储层饱和度的解释精度和流体识别的准确度提高方面具有重要指导意义.

Calculation Method of Logging Saturation in Low Resistivity Sandstone Gas Reservoir: Case Study of the Mahe Gas Field in Junggar Basin

In order to obtain the saturation calculation model method of low resistivity oil and gas reservoir, this paper takes the sandstone gas reservoir of Paleogene Ziniquanzi formation in Mahe gas field in the southern margin of Junggar Basin as an example, establishes Archie model with variable parameters and W-S saturation model with consideration of temperature change through experimental analysis of porosity and permeability, rock electricity, cast thin section and cation exchange capacity, and analyzes cation exchange capacity CEC and cation exchange capacity Based on the variation law of equivalent conductivity B, cation exchange capacity QV, cementation index m and saturation index n, the calculation method of water saturation suitable for low resistivity sandstone gas reservoir is established. The results show that: in the low resistivity sandstone gas layer, the conventional Archie model is suitable for the water layer with low pure gas production or low resistivity, but the interpretation effect is poor in the same layer of gas and water, and the water saturation values calculated by the variable parameter Archie and W-S model meet the characteristics of the lower water saturation and the upper water saturation of the same reservoir, and the results are consistent with the core analysis and gas testing The results are consistent. The two new saturation calculation models have important guiding significance for effectively improving the accuracy of reservoir saturation interpretation and fluid identification in low resistivity sandstone gas reservoirs.