The unconventional reserves are vital future energy resources and globally augmented interest endeavours the discovery of gas and oil-rich shales. The Kommugudem Formation, Krishna Godavari Basin was evaluated based on sample laboratory and well log studies from six wells deciphering mineralogical and organic geochemical parameters to provide an understanding of hydrocarbon potential and brittleness. Kommugudem Formation constitutes Type III kerogen dominantly with high total organic carbon (TOC) and T max indicating the presence of high organic matter. The mean vitrinite reflectance indicates mature to post-mature shale majorly in the gas generation window. Fourier transform infrared spectroscopy functional group investigation revealed the presence of aromatics and aliphatics with a higher degree of abundance owing to higher TOC content. The basic well logs recorded in the studied region are used to estimate the continuous TOC and porosity of the formation and corroborate with laboratory core data. Petrographic, X-ray diffraction, and field emission scanning electron microscopy studies revealed the presence of dominantly siliceous mineral matter with relatively lower clay and carbonates. Organic mudstone classification indicates formation is dominantly silica-dominated lithotype and clay-rich siliceous mudstone. Microfractures and micropores are observed in mineral and organic matter that may act as storage sites for hydrocarbons. Kommugudem Formation on the basis of mineralogy indicates compositional analogy with brittle zones of Barnett Shale Formation. The high mineralogical brittleness index of the Kommugudem Formation indicates good conditions for hydraulic fracturing. The present investigation demonstrates excellent hydrocarbon generation potential and good brittleness in wells A and B while C, D, E, and F have relatively lower potential and may have low gas and oil sources.K E Y W O R D S hydrocarbon potential, Krishna Godavari Basin, mineralogical brittleness index, shale gas 1 | INTRODUCTION Shale gas reserves are a globally prospective energy source and in India, shale gas resources exploration is in the emerging stage. India has an estimation of 96 Tcf of risked, technically recoverable shale gas reserves with the most likely shale gas reserves in regions of Cambay,
Lower Gondwana Kommugudem Formation of the Krishna‐Godavari (KG) Basin in the eastern coast of India records the deglaciation sequences of the Early Permian and is characterized by well‐preserved sandstone—shale—coal cyclothems. Kommugudem shales from six deep borewells of the KG Basin were studied for the organic petrological and geochemical compositions. The objective was to elucidate its source rock properties and depositional settings, which provide significant insights on the shifts in the Gondwanan palaeoenvironment and its climatic controls during the Early Permian. Maceral identification reveals the abundance of vitrinite that is distinctive to organic‐rich Permian Gondwana sediments. SiO2 enrichment with the dominance of quartz and clay minerals suggests moderate to strong weathering with palaeoclimate shift from cold, arid to hot, and semi‐arid during the Early Permian. The occurrence of higher short and mid‐chain alkanes with predominant n‐C18 and important biomarker ratios suggest a transitional fluvio‐marine environment of deposition, which is also supported by the enrichment of redox‐sensitive trace elements. Prevailing anoxia enhanced the preservation of organic matter, despite reduced primary productivity, as indicated by low P/Ti ratios. A depleted δ13Corg (mean = −21.55‰) in the shales, distinct to the interglacial period, reflects the changes in pCO2 of the Early Permian atmosphere. Sedimentary biomarkers, carbon isotopes, and trace elements explicate the palaeoceanographic conditions and sea‐level changes, indicative of marine influence in the dominantly fluvial regime. The deposition and preservation of organic‐rich sediments under anoxic (possibly euxinic) water‐column took place, forming the prolific Pre‐trappean Lower Gondwana Kommugudem source rock in the KG Basin.
<div> <p>The Permian-aged Kommugudem Formation has been identified as a potential candidate in the prospective Krishna Godavari basin for future shale gas exploration. Brittleness and hydrocarbon potential based on geochemical and mineralogical evidence is characterized from the conventional cores in the study area. According to petrographic, SEM, and XRD analysis, the shale is primarily composed of quartz, clays (kaolinite, chlorite and illite), siderite, muscovite, pyrite, and feldspar. The Mineralogical Brittleness Index (MBI) ranges from 60 to 80 percent, suggesting that the Kommugudem shale is a likely good fracking candidate. Natural microfractures in Formation can increase hydraulic fracturing performance by acting as hydrocarbon migration conduits and hydrocarbon storage sites. The low chemical maturity index of Kommugudem samples indicates an abundance of detrital minerals formed near provenance without significant recycling. Due to the insoluble nature and diagenetic immobility, the Nb and Th enrichment identified in Kommugudem samples further supports a possible detrital source of the quartz. Clay-sized microquartz cement seen in a few samples may bind silt-sized detrital quartz and promote brittleness. The development of recrystallized microquartz cement is also caused by the illitization of smectite clay, as evidenced by XRD data revealing the presence of illite. The mineralogical brittleness index does not take into account the mineral texture or the kind of clay mineral related. As a result, such computations must be used with caution. Kommugudem Formation is composed of Type III kerogen in admixture with Types II-III, with high TOC and Tmax predicting substantial organic matter concentration in the dry and wet gas windows. RockEval and FTIR examinations revealed that two wells had good hydrocarbon generation potential for oil and gas sources, while the other wells had comparatively lesser hydrocarbon potential. Brittleness appears to be substantially reliant on lithological heterogeneity, according to the proposed assessment. The examined area possesses lithological variability, and the Kommugudem shale shows compositional similarities to brittle sections of the Barnett and Marcellus shale plays. According to the integrated characterization, shale has high organic content and is brittle in nature. This comprehension is critical if the shale is to be considered for further investigation.</p> </div>
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