Results of exploration and evaluation of 4D effects based on repeated 3D seismic survey in aquatorial part of gas and condensate field

Seismic monitoring (4D seismic survey) of developed oil fields is a new direction in seismic survey. It is designed to solve the main task of field development – maintaining production rates while enhancing the oil recovery factor. Seismic monitoring of reservoir systems is series of 3D seismic surveys, spaced in time in order to receive the dynamic image of processes within the reservoir. This article focuses on this promising direction and based on a real practical example. In 2008, 3D seismic surveys were conducted in aquatorial part of oil and gas condensate field, using the standard methodologies available then. This data formed the basis for the geological and hydrodynamic models of the field. Today, this field is in the stage of deep development of reserves. To assess, forecast, and involvement in development of new promising reservoirs in deeper intervals, a repeated 3D survey with improved observation system parameters was carried out in 2017. As a result, two sets of data were collected for the same area, nine years apart. This created the prerequisite for evaluating 4D effects on the reservoirs that had been in operation throughout this period. To isolate the expected effects, 2D seismic-geological modeling was performed, and the seismic data were processed using a unified processing schedule. This article presents the results of data processing and analysis. The potential of using repeated 3D seismic surveys in aquatory for field development monitoring is demonstrated.