延川南气田基于测井参数的煤层含气量预测模型研究

    Study on prediction model of coal seam gas content based on logging parameters in Southern Yanchuangas field

    • 摘要: 煤层含气量的准确评价至关重要,含气量模型的预测精度亦随着煤层气勘探开发的进程逐渐变高。研究基于延川南气田煤层含气量的测井响应特征,利用MIV (Mean Impact Value)方法优选测井参数,引入BP神经网络与随机森林思想分别建立了煤储层含气量预测模型,将建立的模型与传统多元线性回归方法进行对比,并基于随机森林模型对研究区的含气量分布做简要阐述。结果表明:简单的多元线性回归模型预测结果较差,难以反映测井参数与煤储层含气量之间的复杂关系;BP神经网络模型与随机森林模型的预测精度有明显提升,其中,随机森林模型预测精度更高,更适用于研究区煤储层含气量的预测。基于随机森林模型预测可知,气田含气量的分布范围为4.84-21.83 m3/t,平均为11.63 m3/t,平面上煤层含气量由东南向西北逐渐升高,其变化规律与气田煤层埋深的规律大体一致,纵向上随着埋深的增大,煤含气量逐渐升高,且随着煤层埋深增大,含气量分布的离散程度增大。

       

      Abstract: The accurate evaluation of coal seam gas content is very important, and the prediction accuracy of gas content model is gradually improved with the process of coalbed methane exploration and development. Based on the logging response characteristics of coal seam gas content in Yanchuannan gas field, the MIV(Mean Impact Value) method is used to optimize the logging parameters, and the BP neural network and random forest ideas are introduced to establish the gas content prediction model of coal reservoir respectively. The established model is compared with the traditional multiple linear regression method, and the gas content distribution in the study area is briefly described based on the random forest model. The results show that the simple multiple linear regression model has poor prediction results, and it is difficult to reflect the complex relationship between logging parameters and gas content of coal reservoirs. The prediction accuracy of BP neural network model and random forest model has been significantly improved. Among them, the random forest model has higher prediction accuracy and is more suitable for the prediction of gas content in coal reservoirs in the study area.Based on the prediction of random forest model, the distribution range of gas content in gas field is 4.84-21.83 m3/t, with an average of 11.63 m3/t. On the plane, the gas content of coal seam increases gradually from southeast to northwest, and its variation law is generally consistent with the law of buried depth of coal seam in gas field. Vertically, with the increase of buried depth, the gas content of coal increases gradually, and with the increase of buried depth of coal seam, the dispersion degree of gas content distribution increases.

       

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