Investigation of volcanic rock quantitative fracture evaluation and reservoir classification based on the logging method - an example from Nanpu Sag

Abstract

Multi-stage development results in complex lithology and variable pore structure in volcanic reservoirs. Therefore, it is difficult to calculate fracture porosity and determine the volcanic reservoir type. In this study, we use the deep volcanic rock of the Nanpu No. 5 structure as an example to use a matrix porosity logging evaluation model in different lithology reservoirs. Dual Laterolog has a large detection range and is sensitive to fractures. Therefore, the relationship between igneous fracture and logging response characteristics is analysed via numerical simulation. Then, the method used for calculating fracture parameters was verified by combining formation MicroScanner image (FMI) logging technology with Dual Laterolog. For accurate reservoir classification, a fracture porosity less than 0.0005 is ineffective since the formation fluid cannot be transported. The quantitative fracture evaluation of volcanic rock reservoir was completed based on calculation model. The agreement with the actual production proved the effectiveness of the method. [Received: September 9, 2022; Accepted: December 30, 2022]