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4D seismic technology

During production, changes in reservoir pressure, temperature and fluid saturation can cause changes in the physical properties of the reservoir rocks themselves.

We can track these changes by repeating 3D seismic surveys over time to create a time-lapse or "4D” seismic image. The interpretation of 4D seismic data helps ensure optimum and responsible oil and gas recovery from our existing fields.

Time-lapse seismic technologies developed and applied by ExxonMobil, including 4D full wavefield inversion, result in high-definition images of seismic changes that enable us to interpret changes in a reservoir with more certainty. Integrated with conventional field production data and reservoir models, 4D seismic methods help increase the productivity of ExxonMobil’s production assets as a result of the improved decision-making derived from the data.

Photo — In 4D seismic maps such as this one from a West Africa oil field, each region in the map represents an area of change in the reservoir over a period of time. Here, blue represents water movement and red indicates an increase in gas. Knowing how the fluid content of a reservoir changes during production is crucial to efficiently extracting its resources. In this case, water is injected into the reservoirs to help maintain pressure, resulting in greater oil recovery and reducing the need for additional drilling.

ExxonMobil has applied 4D seismic technology over a wide range of geographical areas, geological settings and production scenarios – from monitoring water and gas sweep (see image) in our deepwater Angola production wells to the thermal recovery processes used at the Cold Lake heavy oil field in Alberta, Canada. Our experience has demonstrated that 4D seismic methods can improve our understanding of the reservoir by identifying its distinct compartments and mapping the most permeable fluid flow pathways. The data can be used to locate unproduced oil and gas, increasing the efficiency of existing wells and reducing the need for additional wells and drilling.