基于录井资料的储层流体性质识别新方法——以川西地区须家河组储层为例

A new method for the mud logging identification of reservoir fluids:A case study from the Xujiahe reservoirs in the western Sichuan Basin

传统录井资料解释技术在成因机理、检测精度、解释模型等方面缺乏相应的理论指导,因此没有可靠的评价模型与评价标准,从而造成录井资料解释可靠性差的结果。针对目前勘探开发目标多样化的发展趋势,以及各类复杂油气藏、深层油气藏、薄互层、非常规油气资源的钻探现状,基于数理统计技术,以录井色谱分析的天然气组分数据为基础数据集,根据变量空间中欧氏距离与马氏距离对多元变量相互之间影响的不同反应能力,分析了采用不同空间距离算法的流体识别模型在识别气层与水层方面的不同能力,所构建的判别模型在四川盆地川西地区上三叠统须家河组气藏进行了应用,模型预测准确率在83%以上。进而结合识别模型自身的特点,进一步提出了一个优化模型,与欧氏模型、马氏模型相比较,对储层流体性质的识别能力得到进一步提高,预测准确率为97.22%。同时对传统的气测解释技术也提出了一个基于严格数学意义上的评价方法,并对新建识别模型和传统模型进行了对比分析。

For lack of robust theoretical guidance in the respect of genetic mechanism, inspection accuracy and interpretation model, and without any reliable evaluation models and standards, the traditional interpretation techniques of mud logging data produces results with poor reliability. At present, drilling targets are getting more diversified, and fluid identification becomes challenging for complex reservoirs, deep reservoirs, thin interbedded reservoirs and unconventional reservoirs. In view of this, based on mathemati- cal statistics technologies, the natural gas component from the mud logging chromatographic analysis was first taken as the basic data set; the different response abilities were then analyzed of Euclidean distance and Mahalanobis distance to multiple variables in variable space. Additionally, the different abilities were discussed of spatial distance-based fluid identification models in identifying gas and water layers. Finally, a new identification model was built and applied in the fluid identification of the Upper Triassic Xujiahe reser voirs in the western Sichuan Basin, achieving a coincidence rate of above 83%. In combination with the characteristics of this new model, an optimized model was further built and also compared with the Euclidean model and Mahalanobis model. The optimized model was more powerful in fluid identification and the accuracy of prediction results reached up to 97.22 %. Meanwhile, a mathe- matics-based evaluation method of traditional mud logging interpretation was proposed and a comparative analysis of the optimized model and traditional model was also performed.