Collaborative VSP acquisition to optimize imaging for field development

The DTEK Oil and Gas-operated Machukhske gas condensate field in the Poltava region, central Ukraine, is a Tournaisian ramp carbonate structure in a high pressure and high temperature environment.

The initial surface seismic interpretation of the top carbonate reservoir north of the M-55 well did not fit with the expected geological model. The surface seismic data showed a very steep northern edge, where geologically a gradual ramp had been expected. This interpretation would significantly impact the drilling plans for the area. The area had little well control and the surface seismic data suffered from limitations owing to acquisition geometry; therefore, the well was targeted for Vertical Seismic Profile (VSP) acquisition. The main objective was to provide high resolution imaging along the top carbonate structure to help better understand or resolve the conflict between the surface seismic interpretation and expected geology.

This co-ordinated, flexible and collaborative VSP solution proved cost-effective and successful. Calibrated velocities, high-resolution images and additional information from the VSPs provided a crucial structural update to the interpretation and resolved several issues related to the depositional model.