Putting positioning errors in their place - A new method for survey design overcomes repeatability issues

摘要

When the idea of 4-D seismic as a reservoir imaging and monitoring method was first debated in the mid 1990s, a key concern was the question of repeatability, particularly in the case of surveys carried out using towed streamers. Was it really possible to return to exactly the same offshore location as the baseline survey and be able to accurately replicate all the circumstances of the original acquisition operation? In the marine environment, currents, tides, weather and different equipment are just some of the variables that have to be considered. Yet if the seismic imaging was to show inter-pretable differences in the reservoir over time during production, then it was crucial that such changes could be measured accurately without any fear of distortions from extraneous factors.