元素俘获测井在库车深层致密砂岩中的应用

库车前陆盆地深层砂岩气藏表现为低孔隙度特低渗透率特征,由于钻井取心少,评价复杂岩性储层存在困难。元素俘获测井(ECS)利用矿物成分获取地层岩性和骨架参数,能够指导评价复杂岩性地层。利用元素俘获测井获取的元素干重百分比,建立反演矿物模型求取矿物的含量。用ECS测井资料获得的矿物含量计算地层变骨架密度(地层骨架密度随深度变化而变化),再计算地层孔隙度,其孔隙度结果与岩心孔隙度基本吻合,验证了ECS测井技术求取地层孔隙度方法的可靠性。对库车前陆盆地深层7口井已知数据的验证,提高了地层孔隙度的解释精度。实践表明,ECS测井技术用于求取塔里木盆地库车深层致密砂岩地层中的储层参数,取得了很好的应用效果。

Applications of Elemental Capture Spectroscopy Log to Sandstone Reservoirs with Deep Layer in Kuqa

Sandstone gas reservoir with deep layer in kuqa depression is characterized by super-low porosity and permeability which has few drill cores, there is some difficulty to evaluate formation with complex lithologies.Quantitative determination of mineral from elemental capture spectroscopy (ECS) logging is used to obtain two parameters:formation lithology and formation matrix, which proposes new avenues for evaluating complicated lithological formations.Firstly, element concentrations are obtained by ECS logging technology.Secondly, mineral content is calculated in formation based on mineral inversion model.Thirdly, mineral content is used to calculate the formation grain density, which will increase the accuracy of the calculation of reserve parameters, like porosity, etc.During the validation process, the available data of 7 wells with deep layer in Kuqa depression are used.And the log interpretation shows calculated formation porosity is accurate.In general, variable formation grain density is calculated based on mineral content.Then, porosity is calculated.And the ECS interpretation porosity results are matched with those of core analysis.The results show that the method for calculating formation porosity is very reliable.The practice shows that logging interpretation of porosity has been done on practical logging data from reservoir with deep layer in Kuqa depression in Tarim oilfield by ECS logging, which has good results.