Diagenetic attributes of Badabagh Member sandstone of Jaisalmer Formation, western Rajasthan, India: implications toward reservoir quality

Abstract

The Badabagh Member sandstone is mainly quartz arenite, and its composition ranges from sub-arkose to sub-lithic arenite. Petrographic analysis, scanning electron microscopy (SEM), X-ray diffractometer (XRD), and quantitative measurements of reservoir properties were utilized to thoroughly examine the physical and diagenetic characteristics of the Badabagh Member sandstone. Mechanical compaction; the precipitation of calcareous, ferruginous, and silica cement; the creation of clay minerals; the breakdown and alteration of unstable clastic grains like feldspar and rock fragments; and grain fracturing are among the identified diagenetic properties. Primary porosity was greatly decreased by mechanical compaction and using authigenic cement, such as ferruginous, calcareous, and silica. Clastic grains and cement dissolved, resulting in secondary porosity. Porosity was estimated to have been 40% at first, then compaction decreased it to approximately 9.76%, and cementation further reduced it to 28.03%. Compared to compaction, cementation had a relatively greater effect on the reduction of porosity in the Badabagh Member sandstone. On the other hand, some primary porosity was preserved due to sporadic patches of calcareous cement and imperfect filling. Physical compaction, cementation, and grain ductility were primary contributors to reduced porosity and permeability, whereas clay coatings like kaolinite booklet-type coating, pore-lining chlorite coating around grains, and feldspar dissolution were instrumental in preserving reservoir quality by creating secondary porosity. The sandstone under study exhibits diagenetic processes that are intimately related to its reservoir potential.