Reservoir Characterization Using 3d Obn Seismic Survey - Cheleken Asset Case Study

Abstract The Cheleken Area lies in the Turkmenistan sector of the South Caspian Sea, over an area of 920 Km2 and in water depth of 10 to 40 m. Located in a complex wrench faulted system orientated WNW-ESE from the Apsheron Peninsula in Azerbaijan to the Cheleken Peninsula in Turkmenistan, the cheleken fields have a large thickness of stack sand and shale reservoirs, with significant areal and vertical variation. The field is covered by legacy 3D OBC seismic data acquired and processed in 2004 and reprocessed in 2017 which served as a guide during the exploration and appraisal wells however it presented a lot of limitations in data quality and resolution. In 2022, another step change in data quality was achieved with the acquisition of the first ever Ocean Bottom Node seismic survey acquired in Turkmenistan. Using high-resolution seismic parameters leads to much better image quality and overcome the majority of subsurface challenges. The image quality enhancement over this area of shallow water depth was the results of good seismic survey design and a proper seismic processing workflow based mainly on a good velocity model building. The targets in the current oilfield are variable in depth and thickness and to end up with a better understanding and delineation of the several reservoirs in the studied area, a seismic inversion, as an important tool used in reservoir characterization, was carried out as well as a pore pressure prediction evaluation using seismic velocity. By combining well data and seismic data, we were able to predict rock properties away from borehole and get better understanding of the reservoirs extension. Seismic inversion and attribute techniques could be the solution to predict reservoir quality. During the current reservoir characterization study, we used seismic data, well logs, seismic velocity as well as the interpreted horizons to generate impedance data and describe vertically and laterally the different reservoirs in a proper way and minimize the risk for the future drilling activities.