4D seismic surveys occur with comparison of 3D surveys results that made in same place and same conditions in time axis. 4D data provides to movement of hydrocarbon interface, Also high scale petroleum companies use this data for drilling and storage activities at future.
4D seismic technologies have existed for quite some time; the first 4D seismic survey was acquired in 1981 onshore Canada. Today, 16% of Q-Marine single-sensor seismic surveys are related to the monitoring of reservoir production. One reason for the growth of seismic reservoir monitoring programs is that, in the last five years, the industry has responded to 4D seismic imaging challenges through a number of significant enhancements in repeatability. This, combined with innovations in 4D analysis and interpretation, has caused time-lapse seismic technology to become an integral part of the business process of many oil companies [1].
Within this method, Safety, quality, turnaround and value are raising. Acceptance of this method is being improved today. As Safety; Spreading control and repetitive seismic surveys are safely provided by this method. Improving the 4D signal-to-noise ratio thereby enhancing the ability to detect weak 4D signals and allowing predictions of changes in fluid saturation and pressure.
Advances in technology, especially 4D processing, have allowed us to produce more precise 4D seismic differences and transform these into the context of reservoir engineering. With proper calibration and petrophysically constrained inversion techniques we are now able to derive quantitative estimates of changes in reservoir properties such as fluid saturation and pressure [2].
4D seismic data acquisition in congested oilfields and in areas with strong and rapidly changing currents is challenging because the reduction of non-repeatable noise in these complex operational environments is more difficult. To successfully acquire 4D seismic data in fields with strong ocean currents, multiple platforms, and other obstructions, we have developed technology that helps in operating safely and efficiently in these fields.
The market players are Statoil, Exxon Mobile, Shell, Chevron and additionally Petrobras.
Finally I want to give some important success stories which used of this technique.
- Statoil’ s “NARNA” Project
- Statoil- Schlumberger’ s “Gulfax” Project
Petrobras is will be active player of this sector soon. Today Petrobras’ Marlim field, in the Campos basin off the shore of Brazil, provides one of the best examples of how 4D seismic technology can be incorporated into reservoir management decisions. The use of WesternGeco’s 4D imaging capabilities at the field enabled improved dynamic and static modeling, which enabled the oil, gas and water movement through reservoirs to be monitored with greater accuracy and ensured that reservoir behavior can be predicted with more confidence in the future.
REFERENCES
[1] Schlumberger Limited, Internet Access: http://www.slb.com/
[2] CGG Veritas, Internet Access: http://www.cggveritas.com/
Statoil Company, Internet Access: http://www.statoil.com/en/Pages/default.aspx
Orkun TEKE- Dokuz Eylül University Geophysical Engineering Department, 35160, Tınaztepe- İzmir- Turkey
Contact: orkunteke@gmail.com
