A DAS VSP Pilot Survey for 3D Imaging and 4D Monitoring at the Culzean Field, UKCS

Summary A DAS borehole seismic programme was acquired at the Culzean field, UKCS, during 2019. The goal of the survey was to provide a dataset that could be used to analyse potential and limitations of the DAS method for 4D monitoring and 3D imaging. The acquisition consisted of fixed offset, walkaway, walkabove and 3D VSP surveys, each acquired with a surplus of shots to evaluate acquisition methods for attenuation of noise. Noise records were subsequently taken in each well once production flow was established. These were added to the survey data to simulate records that would be acquired with the field in operation. The survey showed that the DAS VSP method yields data of comparable quality to conventional VSP data when recorded in noise-free wells and can produce quality data for all survey geometries. However, production related noise significantly reduces data quality, and is the key limitation of the method. The data are continuing to be analysed to determine the limitations and benefits of the DAS method for 4D monitoring and 3D imaging at Culzean and nearby fields, to examine the role of production noise on data quality and to derive acquisition and processing strategies to overcome this noise.