Time lapse Seismic, a Journey Trough 20 Years of Seismic Challenges

Abstract

Abstract

Time-lapse seismic data have now proved to be very valuable for monitoring production and fluid injection in reservoirs. Overcoming the 4D acquisition and processing challenges in both quality and timing is still a key task for operators as 4D data deliverables must conform to challenging production and development deadlines.

This paper will review several case studies showing examples of 4D experiments with a wide range of technical difficulties and contexts. The case study fields are characterized by very different geological settings and development maturities

We shall start in the early 1990s with a naive 2D-on-2D trial from the North sea, and continue with a look at the precise and repeated monitoring of water injection and production for reservoir management and field development in the Gulf of Guinea turbidite reservoirs a decade later.

Following these early successes we will describe the actions taken to industrialize time lapse processing and thus drastically reduce the processing turnaround and costs.

In order to cope with the increase in processing challenges we developed efficient and innovative QCs that allow faster and more straightforward assessment of the 4D signal quality after each processing step.

The next step up in difficulty came with the use of 4D technology to monitor production phenomena in carbonates fields. Time-lapse seismic has been acquired on a field in Eastern Asia affected by significant subsidence effects which significantly complexify the 4D processing workflow. However the rise in the Gas Water Contact (GWC) was clearly observed, which allowed us to anticipate future water breakthroughs in the field.

More recently, Time lapse processing techniques applied to the overburden have enabled us to characterize very subtle geomechanical effects above heavily depleted reservoirs.

Looking ahead, we are now aiming to routinely apply 4D techniques in Middle east carbonate fields suffering from heavy multiple contamination; Land 4D will offer another set of challenges, the first of which being to achieve acceptable acquisition repeatability, where using permanent sources and receivers may be a major part of the solution.

Last but not least 4D in Sub Salt contexts adds imaging challenges to the difficulties of preserving the reliable and repeatable amplitudes needed for quantitative time lapse results assessment.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016