Diagenetic Controls on the Early to Late Bathonian Fort Member Sandstone of Jaisalmer Formation, Western Rajasthan

Abstract

AbstractPetrographic analysis, Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) were used to examine the various diagenetic controls on reservoir quality of the Fort Member Sandstone (FMS), Jaisalmer Formation in western Rajasthan. Diagenetic processes include mechanical compaction, cementation, pressure solution and dissolution of framework grains. The main diagenetic cements are carbonate, ferruginous, silica cement and authigenic clays. Cements occur as coatings around the detrital grain boundaries, pore fillings and pore linings. Compaction and cementation are common factors responsible for the reduction of porosity and permeability. The dissolution of detrital feldspar grains was the main drive for porosity enhancement in the FMS. The corroded contacts between successive carbonate phases and quartz grains, followed by the dissolution of carbonate cements were also responsible for the secondary porosity. The main porosity preservation in the FMS is due to scattered patches of carbonate cement, which prevented the compactional collapse of the framework. The relationship between the intergranular volume (IGV) and cement volume indicates a minor role of compaction in destroying the primary porosity. The widespread occurrences of carbonate cement suggest that the FMS lost a significant amount of primary porosity at an eodiagenetic stage. In addition to carbonate, authigenic clays like chlorite and kaolinite occur as pore-filling and pore-lining cements. The pore-filling chlorite resulted in a considerable loss of porosity, while the pore-lining chlorite may have helped in retaining the porosity by preventing the precipitation of syntaxial silica overgrowths. Paragenetic sequences are established to understand the pathways of diagenetic evolution and their impact on reservoir quality of the FMS.Please check and confirm if the authors and their respective affiliations have been correctly identified. Amend if necessary.Confirmed the respective authors affiliations and correctly identified.KeywordsDiagenesisReservoir qualityFort Member Sandstone (FMS)Jaisalmer formation