David H. Johnston, ExxonMobil Exploration Co., will give his American Association of Petroleum Geologists Distinguished Lecture, “4-D Seismic in the Deep Water – Challenges and Rewards,” at 12 p.m. April 8 in Room 281 of the Green Center at the Colorado School of Mines, Golden, Colo. This presentation will show how ExxonMobil uses 4-D seismic technology in deepwater reservoir management and discusses some of the challenges faced in its application.


Time-lapse or 4-D seismic data has proven value in reservoir management, increasing reserves and recovery by locating bypassed and undrained hydrocarbons and optimizing infill well locations and flood patterns. Four-D seismic can also decrease operating costs by reducing uncertainty in the reservoir geologic model and flow simulation, optimizing completions and minimizing the number of dry holes. Time-lapse is simply the use of multiple seismic surveys shot over a producing field. Changes in the seismic response typically occur because of production-induced changes in saturation and pressure. Successful 4-D projects have been carried out in a wide range of geographical areas, geological settings and depletion scenarios.


To maximize the value of a 4-D seismic project, planning for 4-D is a critical part of an overall field lifecycle strategy. In exploration, assets can be screened for potential 4-D application. Early in development planning, 4-D seismic models based on reservoir flow simulations and geologic models are used to estimate the magnitude and interpretability of the 4-D response, evaluate optimal survey repeat times, and assess potential business impact. Once the field is under production, effective 4-D project execution requires collaboration among asset team geoscientists, engineers and field operations with geophysical acquisition and processing specialists.


ExxonMobil’s experience in West Africa and the Gulf of Mexico demonstrates that the deepwater production environment presents unique opportunities and challenges for 4-D projects. Issues range from the impact of surface facilities on data quality to contending with ongoing field operations. In addition, aggressive drilling schedules dictate a rapid turnaround of 4-D data. But these fields have high drilling and well intervention costs, and 4-D seismic may be the only available field-wide reservoir surveillance tool.


For more information, call 303-273-3938.



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