Study On Fracture Identification And Evaluation Base On Well Logging Data

With increasing exploration efforts, fractured sandstone oil (gas) fields have kept increasing. Compared to more tight fractured carbonate, identification and evaluation of fracture in sandstone based on well logging data is still a difficult problem.The response characteristics of fracture on the electric imaging and conventional logging data were analyzed by comparing to the rock cores. A set method of identification and process for sandstone fracture which was suitable for the workarea was developed.Fracture aperture, porosity and permeability is more important in oilfield development. This paper do a deeply studied for the evaluation model of the fracture aperture and fracture porosity based on the dual laterolog. Various fracture aperture and porosity models were theoretically analyzed. Although these models have different application conditions, but they are all based on fractured carbonate which matrix physical property is not good and laterolog conduction mechanism is different with the fractured sandstone, so these models do not have good result in fractured sandstone. Starting from the current propagation mechanism in fractured sandstone, the current path of fractured sandstone was analysed. Using the parallel model for matrix porosity and fracture porosity, the suitable modle for calculating fractrue aperture and porosity in sandstone was established.The methods and parameters in various electric imaging data process softwares were understood and summarized. On this basis, theoretical model of fracture permeability which is suitable for the workarea was derived. Combined with the actual data processing, the effectiveness of various methods for the workarea was analyzed. Finally, frature identification and parameters evaluation was completed for 20 wells on workarea. And the statistical laws of fracture density and occurrence in the workarea was also analyzed.