2d seismic reflection data interpretation, petro physical Analysis, colored inversion and facies analysis of Fimkassar area, upper indus basin, Pakistan using-seismic and Well log data

Abstract

The study area (Fimkassar and Turkwal oil fields) is located in the Central Potwar Bas in, Distri ct Chakwal, Punj ab, Pakistan. T urkwal deep-O 1 is being operated by Pakistan Oil Field Limited (POL). T urkwall deep-O 1 is an explora tory well and is suspended. Effective reservo i r at fi e ld I ies within the Sakesar and Chorgali format ions. Organ ic rich shales of the Paleocene (Patala Formation) can be co ns idered as the source of the a rea. Both structura l and stratigraphic traps are present in the Potwar Bas in. Structu ral traps have been deve loped due to th in-skinned tectonics, which has produced anticlines, pop-up and positi ve nower stru ctures above Pre- Cambrian sa lt. This whole section has been severely de formed by intense tecton ic activity during the Himalayan. For petrophys ica l evaluation of T urkwal deep- 01 well two formations (Chorgali Formation and Sakesar Limeston e) are tested for the assessment of hydrocarbon saturation. T he results suggest th at both Chorga li and Sakesar Formations are more producing as compared to Nammal Formation which is less productive because of a lternating shale limes tone li tholog ies. Patala Formation is fo und to be mature source rock with in some well s of study area, while Naillmal Formation cons ists of immature organ ic content. T he lower part of Sakesar Formation shows indication of maturity or reservoir shale. Structurally in T urkwal deep-O I well there is a thrust fau lt confonned by repetition of the strata in vvhich older rocks lay over younger rocks. T he thickness of both the Chorga li Formation and Sakesar Limesto ne decreases from SW to NE. Seismic inve rsion res ul ts are also demonstrating that Chorga li act as a rese rvoir. The post stack color inversion is performed to confirm the leads location. On inverted section Chorgali shows low value of impedance i.e. strong ind icator for the presence of hydrocarbons. Sei smic facies res ults shows that there a re three lithologies limestone, limesto ne inter bedded with shale and shal e. This is because the values of logs used are obta ined only f rom reservoir . T he reservoir is Chorgali and it is limestone it confirms our interpretation as in hydrocarbons resisti vity va lues should be hi gh and the dens ity valu e should be less .