Moving from 2D to 3D surveys was a big step in reservoir evaluation advancements. But there’s a new seismic technology on the block—4D seismic surveys.

3D surveys provide a static, three-dimensional image of subsurface structures. 4D surveys take that capability a step further, enabling companies to building on 3D seismic data while seeing changes over time.

Onshore and offshore operators have benefits from 4D seismic technology, which enables them to track changes in hydrocarbons for more informed decisions on well placement and production strategies.

Companies such as SLB and MicroSeismic Inc. have implemented 4D surveys in locating and estimating oil and gas reserves, as well as in reducing drilling hazards and optimizing production strategies.

In Saudi Arabia’s Ghawar Field, the world’s largest oilfield, oil is situated over the peak of the rock layers within an anticline. The formation makes drilling operations more prone to waterflooding, said MicroSeismic Founder, President and CEO Peter Duncan.

“What happens is sometimes that water will run around and hit a higher well and miss some of the hydrocarbons that are lower,” Duncan said.

Operators lean on 4D seismic surveys to monitor changes and track the movement of the waterflood, a practice that is now standardized across major oil fields, Duncan said.

“What 4D seismic can do is allow the lab to go back a year later, or two years later, or three years later and look at the changes in where hydrocarbons are and where the water is,” Duncan said.

This capability has led to increased production, extended field life and significant cost savings for E&Ps.

The technology is most valuable in actively producing fields where monitoring fluid dynamics can improve decision-making.

4D seismic technology is also gaining popularity offshore, said Bartosz Szydlik, SLB’s 4D geophysics lead. In the Gulf of Mexico, E&Ps are increasingly using 4D processing and 4D Full Waveform Inversion (FWI) to better understand reservoir history and optimize production plans.

Offshore Guyana, Exxon Mobil contracted a new 4D seismic study to aid its development of the prolific Stabroek Block. Exxon has plans to start a six-month 4D ocean bottom node survey to improve its understanding of offshore hydrocarbon reservoir management.

“One of our clients, a major oil and gas company, recently presented their production profile at the SEG [Society of Exploration Geophysicists] conference, showcasing significant gains from newly processed and interpreted 4D seismic data. Additionally, 4D technology is now being applied to dissimilar seismic acquisition geometries—an approach rarely used in the past—allowing for the efficient reuse of vintage data in a cost-effective manner,” Szydlik said.

But while 4D surveys have indisputable advantages, they don’t take 3D surveys completely out of the picture.

“3D seismic remains preferable in situations where time-lapse monitoring is unnecessary or impractical, such as during initial exploration or in well-characterized reservoirs,” Szydlik said.

Advances in optimization

The integration of artificial intelligence (AI) and machine learning (ML) add a new layer for MicroSeismic and SLB to use in data analysis.

ML algorithms are being applied to automate and accelerate data analysis, helping to identify patterns in time-lapse seismic data. This enables predictive capabilities for reservoir behavior, Szydlik said.

“Machine learning is mother’s milk to geophysicists who are trying to create these images of the subsurface. Images we can’t see,” Duncan said. “But what’s changed is the power of the computers these days now allowing us to automate some of these pattern recognition processes.”

One such advancement is the use of distributed acoustic sensing using fiber optic cables.

“Distributed acoustic sensing using fiber optic cables is explored for cost-effective, frequent monitoring of 4D seismic data,” Szydlik said.

This technology promises more continuous and real-time monitoring of reservoirs.

Recent breakthroughs in 4D processing and advancements in FWI have significantly improved the ability to detect complex production-related changes.

4D FWI can improve subsurface illumination challenges and non-repeatability between 3D surveys, ensuring consistent reservoir change imaging, Szydlik said.

“4D FWI directly estimates velocity changes, enhancing the quality of time-lapse seismic data,” he said.

What’s next for seismic?

MicroSeismic is growing its seismic services across oilfields. Its latest project is being implemented in Argentina’s Vaca Muerta Shale.

“We are starting to take our expertise we developed …. down into Argentina and the Vaca Muerta to help them bring that field online,” Duncan said, noting that the shale is behind in terms of the number of wells being drilled.

“It’s a different geological environment, there are some different challenges, but at the end of the day, geology is geology,” Duncan said.

The future of seismic surveys is set to be data- and AI-driven. Ongoing research and development is aimed at overcoming current limitations.

“Because of [MicroSeismic’s] technology, because of the way we can listen to the dynamics in the reservoir, we are perfectly positioned to take advantage of those opportunities and move into these new business areas,” Duncan said.

Both companies predict the future of seismic surveys supporting mineral exploration, carbon capture and storage and the geothermal industry.

“As the industry moves toward a more sustainable future, the continued development of 4D seismic technology will be instrumental in balancing efficient hydrocarbon recovery with the growing demand for low-carbon energy solutions,” Szydlik said.

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