元坝地区大安寨段二亚段页岩气储层孔隙度计算方法

Calculation method of shale-gas reservoir porosity for the second sub-member of Da'anzhai Member in Yuanba area

元坝地区大安寨段二亚段作为页岩气勘探的新层系,存在着储层孔隙类型复杂、非均质性强、实验分析数据少、孔隙度计算方法不明确的难点。在开展页岩气储层孔隙类型分析基础上,应用6种页岩气测井解释评价技术对储层孔隙度开展计算方法研究。通过分析可知,“核磁共振测井技术”不适用,“拟合模型法”没有办法建立模型,“ANN技术”、“KNN算法”、“声波时差法”和“骨架密度法”这4种技术方法的计算孔隙度的相对误差分别是13%、13%、0.4%和3.7%,其中“声波时差法”误差最小,说明解释精度最高。因此,认为“声波时差法”是目前计算大安寨段二亚段页岩气储层孔隙度最为合适的方法。研究成果推动了元坝地区大安寨段二亚段湖相页岩气的勘探部署。

As a new formation for shale gas exploration,the second sub-member of the Da'anzhai Member in the Yuanba area has the difficulties of complex reservoir pore types,strong heterogeneity,few experimental analysis data and unclear porosity calculation methods.Based on the analysis of shale gas reservoir pore types,six shale gas logging interpretation and evaluation techniques are used to study the calculation method of reservoir porosity.The results show that the“NMR logging technology”is not applicable,the“fitting model method”can not build a model,and the relative errors of the calculated porosity of the“ANN technology”,“KNN algorithm”,“acoustic transit time method”,and“skeleton density method”are respectively 13%,13%,0.4%,and 3.7%.The“sonic transit time method”has the smallest error,indicating the highest interpretation accuracy.To determine the porosity of the shale gas reservoir in the second sub-member of the Da'anzhai Member,it is believed that the“acoustic transit time method”is the most appropriate method.The findings of the study have encouraged lacustrine shale gas exploration and development in the second sub-member of the Da'anzhai Member in Yuanba area.