Role of cementation and compaction in controlling the reservoir quality of the Middle to Late Jurassic Sandstones, Jara dome, Kachchh Basin, western India. (14th September 2020)

• Record Type: Journal Article
• Authors: Quasim, Mohammad Adnan; Khan, Shaista; Srivastava, Vineet Kumar; Ghaznavi, Asma Amjad; Ahmad, Abul Hasnat Masood
• Other Names: Henrot A.‐J. guestEditor.; Bruch A. A. guestEditor.; François L. guestEditor.; Utescher T. guestEditor.
• Is Part Of: Geological journal. Volume 56:Number 2(2021)
• Page Start: 976
• Page End: 994
• Publication Date: 2020-09-14
• Subjects: diagenetic parameters -- Jara dome sandstone -- Kachchh Basin -- Middle to Late Jurassic -- reservoir potentiality; Geology -- Periodicals; 551
• DOI: 10.1002/gj.3989
• Languages: English
• ISSNs: 0072-1050

Abstract

Abstract : Thin‐section petrography, scanning electron microscopy (SEM) and X‐ray diffraction (XRD) analyses are applied to investigate the various diagenetic controls on the reservoir quality of the Ridge and Athleta Sandstone members (Chari Formation) of the Jara dome, Kachchh Basin, western India. The results show that the sandstones of Jara dome are quartz‐arenite to sub‐arkose, medium‐ to coarse‐grained, sub‐angular to sub‐rounded, poorly to moderately well‐sorted and having low‐ to medium‐sphericity. Diagenetic features such as mechanical compaction, pressure solution, cementation, and dissolution of unstable framework grains are analysed to synthesize the reservoir characteristics. The principal cementing materials are carbonates, iron oxides, silica overgrowth, and authigenic clays, mainly chlorite and kaolinite. Compaction and cementation are the controlling factors for the reduction in porosity and permeability of the sandstones. Dissolution of detrital feldspars is the main cause of porosity enhancement in these sandstones. The relationship between the intergranular volume (IGV) and cement volume indicates that cementation had played a more important role in the destruction of primary porosity than that of compaction. On the one hand, the ubiquitous development of carbonate cement advocates the loss in primary porosity at the early stage of diagenesis, while on the other hand it also prevented the further compaction of sandstone, thus preserving unfilled voids as primary porosity. Precipitation of carbonate cement is followed by development of pore‐lining and pore‐filling clayey cements. The pore‐filling kaolinite resulted in a considerable loss of porosity while the pore‐lining chlorite has helped in retaining the porosity by preventing syntaxial silica overgrowths. The reservoir quality of the studied sandstone is reduced by the authigenic clay cements, early carbonate precipitation and silica overgrowths, nonetheless, it is improved by the dissolution and alteration of unstable grains, in addition to partial dissolution of carbonate cements. The potential of the studied sandstone to act as a reservoir is strongly related to sandstone diagenesis. Abstract : The main diagenetic minerals in the studied quartz‐arenite and sub‐arkose types of the Jara dome sandstones are carbonates, iron oxide, silica overgrowth, kaolinite, and chlorite. The Jara dome sandstones of the Kachchh Basin experienced loss of primary porosity mainly due to compaction, although poikilotopic and pore‐filling blocky types of cementation also played a vital role in the reduction of porosity and permeability. The presence of carbonates and clay mineral has played a crucial role in loss of permeability of the studied sandstones. However, the patchy carbonate cements played an important role in the reservoir quality by slowing down the mechanical compaction and creation of secondary porosity by dissolution. Dissolution of feldspar grains and carbonate cements are the major contributor to the generation of secondary pores in the studied sandstones. This study helps to understand the variation in the pathways of diagenetic evolution and their impacts on the reservoir quality and heterogeneity of the Jara dome sandstones of Kachchh Basin that may help in subsequent hydrocarbon exploration and exploitation of energy resources.