Reservoir Exploitation Case Study: Marine 4D
Minimize Risk without Compromising Data Quality
Time-lapse 4D programs are used worldwide to improve oil recovery by mapping changes in fluid movement over time. Towed streamer 4D surveys are especially challenging to execute safely and efficiently due to the difficulty replicating prior surveys – costing 30-50% more. To detect subtle reservoir changes, repeating source and receiver positions is critical, but challenging due to variability introduced by ocean currents. If the positions are far enough apart the area has to be re-shot. This re-shooting process, known as infill, can add 15% of the survey cost and increases survey duration.
Dynamically Manage the Survey to Optimize Operations
As a proponent of time-lapse seismic for reservoir monitoring, a major E&P company operating in the North Sea collaborated with us to improve the efficiency of their 4D surveys without compromising data quality. Our survey design experts modeled multiple acquisition scenarios, and working with our client, selected the survey plan and technology configuration that would result in the best balance of image quality and cost. Our approach prioritized survey lines that provided the most unique subsurface coverage. Advanced prediction software forecasted when ocean currents provided the best chance of acquiring these priority lines. As each line was acquired, source and streamer steering technologies made adjustments to ensure the source and receiver positions aligned as closely as possible to the survey plan. Throughout acquisition, we re-calculated the unique coverage contribution of each line so only the ones that made a difference to data quality and resulting image were acquired. Two of our marine acquisition technologies – Orca command & control software and DigiFIN lateral streamer control – provided the foundation for infill reduction via streamer steering. In addition, the prediction and streamer steering technology enabled safe acquisition around in-field obstructions in conditions that would have otherwise aborted the operation.
Reduced Acquisition Costs and Improved Repeatability
The combination of our survey planning and on-board Acquisition Optimization Specialists managing our advanced technology in real-time reduced infill, costs and cycle time while improving repeatability. By prioritizing the lines that provided the most unique coverage and predicting when the ocean currents were optimal, the sail line count was reduced by over 20%. No new in-fill lines needed to be acquired, which further reduced cycle time and saved the E&P company millions in acquisition costs. Our advanced marine technologies have proven instrumental in helping the E&P industry safely acquire high quality seismic data over obstructed producing fields with high vessel traffic, rigs, and offshore loading facilities.