Logging Evaluation Of Igneous Reservoir In The Western Margin Of Junggar Basin

Compared with conventional reservoirs,igneous reservoirs have complex and varied lithology,developed fracture and complex reservoir space.So we analyze the geological characteristics,summary the four characteristics,and analyze the relationship between four properties of the Carboniferous igneous rock in the western margin of Junggar Basin.Then we study lithology identification,reservoir parameter calculation and fluid property identification,and we have achieved good effect.Lithology identification is a fundamental but difficult work.We first study the petrological characteristics of igneous rocks and its lithology classification scheme.We use cross-plot method,discriminant analysis,support vector machine to identify lithology based on conventional log data.We compare the application effects of three methods and we find support vector machine performs better.We also use ECS and FMI to identify lithology basing on both rock composition and structure.We believe that this method has a more solid physical foundation.Fractures are well developed in this area of igneous reservoirs,so it is reasonable to use the Dual Porosity Model as a theoretical reservoir model.Correspondingly reservoir parameter evaluation content becomes calculations of matrix parameters,matrix porosity,fracture porosity,effective porosity,water saturation and permeability.We use a variety of cross-plots to determine the matrix parameters comprehensively.On this basis,we calculateφS,φN,φD,and it is worth noting that we useφS as the approximation of matrix porosity.We have established models of effective porosity at the different lithologies based on core porosity data.We also study the calculation of fracture porosity based on Laterolog data and FMI.We analyze the conductive models that proposed for fracture reservoirs currently,such as the dual porosity conductive model and the Li Ning conductive model.And we use Laterolog data to calculate water saturation.We study on the application of the cross-plot,P¹/2/2 method,Bayes stepwise discriminant analysis method in fluid identification and also introduce the application of NMR in fluid identification briefly.We find P^1/2 and Bayes are better than the first method.