Modeling Naturally Fractured Basement Reservoir: A case Study from Melut Rift Basin, Southeast Sudan

Abstract

In the fractured basement reservoirs, hydrocarbon is entrapped in the fractures network within the basement rocks. Fractured basement reservoir has become new target of the exploration activity in Sudan since the discovery of hydrocarbon-hosted in fractured basement reservoir. The objective of this study is to identify fractures within the basement reservoir in the study area and then develop a 3D fracture model. To achieve this goals, fractures were studied in different scales using well- log and 3D seismic data. Analysis of these data includes fracture orientation, density, aperture, and other fracture parameters. Compatible and parallel NW-SE, NNW-SSE to N-S, WNW- ESE to E-W and NE-SW fractures trends were observed from the two sets of data. The large and medium scale fractures (faults) were interpreted from seismic data manually and automatically using seismic attributes (Variance cube and ant-tracking) and then modeled deterministically. For the small fractures (sub-seismic scale), seven fracture sets were proposed based on the fractures interpreted from Formation Micro-Imager (FMI) of five wells with link to the tectonic history of the study area and then modeled stochastically. The different fracture sets were modeled separately to generate several discrete fractures network (DFN) groups. These steps were followed by upscaling of the fractures on the 3D geological model and then used to generate the permeability, porosity and sigma factor to describe the connectivity. Identifying and modeling fracture types and patterns can aid the oil exploration and development in the Melut rift basin and in other basins with similar geological and structural settings.

AAPG Datapages/Search and Discovery Article #90194 © 2014 International Conference & Exhibition, Istanbul, Turkey, September 14-17, 2014