Sedimentology, Diagenesis and Reservoir Quality of the Bentiu Formation in the Fula Sub-Basin, Muglad Basin, Sudan

Abstract

Summary The factors controlled reservoir quality in the Bentiu Formation are: 1) sediments depositional processes; 2) diagenetic processes; and 3) burial depth. As a result, the porosity and permeability of the studied samples vary significantly due to these factors. Based on a detailed sedimentological and petrographical analyses, the following general conclusions are made: The coarser to medium grained sandstones with lower total clay content have higher porosity and permeability than sandstones with highest clay content, suggesting that clay content is a major control in porosity and permeability. Quartz overgrowths, pyrite, siderite and iron oxide together with kaolinite and chlorite are the major cement minerals observed in the studied Bentiu sandstones. These minerals migrate/ disaggregate into pore spaces and throats, thereby causing a decrease in porosity and permeability. With increasing the burial depth, the mounts porosity and permeability decrease due to compaction and cementation (quartz overgrowths).