Prof. (Dr.) Atul Kumar Varma studied various coal/ lignite basins. He along with his students has investigated Permian coal basins of Raniganj,Barjora, Birbhum, Jharia, Giridih, East Bokaro ,West Bokaro, South Karanpura ,Daltonganj, Auranga,Talchir, Ib valley, Korba, Mand-Raigarh, Sohagpur , Singareni . He has also studied Tertiary coal basins of Makum and Darrangirri. He has also examined Panandhro, Cambay, Palana and Neyveli lignite basins with his students. Besides these he has studied Silesian coal basin of Poland during his doctoral studies. He could find that the natural conditions (under which coal is formed i.e. sedimentation conditions, coalification course and shaping of coal quality) affect the conversion of inertinitic coals during coal liquefaction and coking. He has suggested degree of conversion for inertinite rich coal and enumerated petrographical factors on hydrogenation of inertinite rich coal. Prof. Varma has given petrographical caking ratio (PCR) to understand the role of microlithotypes (association of macerals) on caking property. Prof. Varma has done also coke petrography. He was able to suggest petrographical structural ratio (PSR) to indicate role of organo-petrographic constituents on formation of reactive constituents of coke. In addition, Prof. Varma has applied thermogravimetric investigations in predictions of coal behaviour during coal liquefaction and coking properties including pyrolytic carbon formation. Puzzling differences in reactivity of coal have been explained with petrographic characteristics of coal formation in various depositional conditions viz. limnic and paralic facies. He has also done hydrogenation petrography. He has suggested that mean vitroplast reflectance is a significant parameter and it may indicate formation of various organo-petrographic components. Prof. Varma has studied coal seams of Northern part of Cambay Basin, Gujarat for exploration of coal bed methane. He has enumerated geologic and petrographic controls on the coal bed methane. He has suggested petrographic seam gas estimate (PSGE) for estimation of coal bed methane. Prof. Varma along with his students was able to point out total carbon content through colour manifestations which may be important for shale gas exploration. He emphasized the importance of sorption dynamics for shale gas and also indicated role of clay minerals in methane gas adsorption – desorption. Prof. Varma assessed organic richness and hydrocarbon generation potential of Raniganj Basin Shales of West Bengal. Prof. Varma characterized coal and shaly-coal samples petrographically from Ib Valley Basin, Odisha for sorption properties. Along with many scientists of the world, he has also contributed in Microscopical characterization of carbon materials derived from coal and petroleum and their interaction phenomena in making steel electrodes, anodes and cathode blocks. Prof. Varma along with his co-workers presented petrographic insights of organic matter conversion of Raniganj basin shales of West Bengal and also indicated Langmuir volumes of shales. Prof. Varma had also given coalbed methane-produced water quality and its management options in Raniganj basin, West Bengal. Prof. Varma has provided FTIR, XRF, XRD and SEM characteristics of Permian shales of India which may be significant for shale gas development in India. Prof. Varma has also indicated petrographic controls on combustion behaviour of inertinite rich coal and char and fly ash formation, He has also reported vitrosphere in char for the first time. Prof. Varma also carried geological and petrographic investigations of rider seams for roof/side fall which may help in strata control. Prof. Varma has helped in devising electro-chemical method for determining the susceptibility of Indian coals to spontaneous heating. Besides these, Prof. Varma has carried X-ray diffraction studies of some structurally modified Indian coals and also tried to see their correlation with petrographic parameters. From the above, it appears that, Prof. Varma has contributed in various fields of coal and lignite geology, petroleum geology, coal and organic petrology, coal bed methane, shale gas, coal conversion, coke petrography, hydrogenation residue petrography, coal combustion and solvent extraction. Prof. Varma has recently studied geochemistry of trace and rare earth elements and yittrium (REY) present in coal.