Evaluating the effectiveness of 3D-seismic in Northwest Paluh Tabuhan field: A case study

The effectiveness of 3D-seismic is controlled by four factors: the physical properties of reservoirs, the seismic frequency content, the field parameter design, and the goals to be achieved, provided that the collected data be processed and interpreted appropriately. By understanding the first and second factors, one can design the third factor optimally, and also estimate the effectiveness of 3D-seismic. This paper proposes a concept of 3D-seismic effectiveness measurement based on the dominant seismic wavelength and the thickness of reservoirs. The concept enables one to estimate the effectiveness of a 3D-seismic project and even to prepare actions to improve the effectiveness. To check the validity, the concept is applied to a case study of Northwest Paluh Tabuhan Field in North Sumatra Basin. The purpose of the 3D-seismic survey in this field was to better understand the detailed geological interpretation which enables one to effectively drain the field and to delineate the extension of the field. Using the above mentioned proposal, it was estimated that the 3D-seismic survey would be 54% effective or 72% conditionally effective. The interpretation of seismic data provided satisfying structural maps, however, it was unable to map the lateral distribution of the objective reservoirs. It was evident that the 3D-seismic data was ineffective in achieving the goal. This ineffectiveness, more specifically the inability of seismic data to show the lateral distribution of objective reservoirs, occurred due to the limited thickness of the reservoirs and the frequency content of seismic data. The results of interpretation meets the estimation derived from the concept of effectiveness. The concept proposed for onshore 3D-seismic survey is applicable to offshore data as well.