Time-lapse seismic (4D seismic) technology

a reservoir dynamic monitoring technology rapidly developed in recent years

has become a new tool for reservoir management

and has widely been applied in many oilfields

especially offshore oilfields. The application of this technology is continuously enlarging and the accuracy is continuously increasing with the deepening of study on petrophysical properties and the development of relevant technologies. Currently

time-lapse seismic technology is used to monitor changes of oil recovery

oil displacement efficiency and fluid front

to identify areas with bypassed oil

as well as to monitor sealing capacity or leakage of faults. The key to seismic acquisition is to improve repeatability and signal-to-noise ratio. New technologies

such as cross equalization

normalization and bin parameter recombination and the principle of synchronous processing of new and old data

are applied so as to ensure that the final seismic differences are the only results of fluid flow changes in reservoirs. Based on direct interpretation

reversion and property analysis

seismic history match and dynamic reservoir description are developed as seismic interpretation technologies and are used in combination with other subjects and technologies to reduce non-uniqueness of interpretation. Remarkable progresses have also been made in respect of lowering investment risk of projects and feasibility study. The application conditions and limitations of the technology should be considered when carrying out time-lapse seismic projects. With the deepening of research on time-lapse seismic techniques and enriching of experiences

time-lapse seismic reservoir monitoring will progress more rapidly and will more widely be applied.