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Seismic Targets: Sweep the Pools

Maximum Recovery Is Goal

This is not your father's world of seismic.

In other words, seismic is no longer only for explorationists hunting for new discoveries, traps and hydrocarbons. Today the technology can help a project from conception all the way through the life of the field.

In short, reservoir quality seismic is expanding the data's scope to every phase of a project to reduce risk and uncertainty.

What exactly is reservoir quality seismic?

That's a good question with no definitive answer — but here's a start: Reservoir quality seismic can encompass newer techniques such as 4-D or time lapse seismic and multi-component seismic, but the term also applies to advances that have dramatically improved the quality and resolution of more traditional 3-D seismic.

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This is not your father's world of seismic.

In other words, seismic is no longer only for explorationists hunting for new discoveries, traps and hydrocarbons. Today the technology can help a project from conception all the way through the life of the field.

In short, reservoir quality seismic is expanding the data's scope to every phase of a project to reduce risk and uncertainty.

What exactly is reservoir quality seismic?

That's a good question with no definitive answer — but here's a start: Reservoir quality seismic can encompass newer techniques such as 4-D or time lapse seismic and multi-component seismic, but the term also applies to advances that have dramatically improved the quality and resolution of more traditional 3-D seismic.

The goal of these technological advances is to define and derive changes in reservoir properties such as saturation, porosity, permeability and pressure based on seismic data, according to Stephen Pickering, marketing manager for reservoir services with WesternGeco.

"The advantage of seismic data over measurements that can be taken in the wellbore is that seismic sees throughout the whole reservoir," Pickering said. "Technologies such as multi-component seismic, which measures both the pressure and shear waves … allow us to define some rock properties from seismic and relate those directly to the well information."

Making Improvements

Traditional 3-D seismic advances also are driving reservoir quality seismic applications.

Pickering said more closely spaced streamers and a higher number of sensors per streamer are yielding better sampling and improved imaging. Contractors also are towing streamers at shallower depths, which allows for better resolution.

"In addition, today we have more advanced techniques to remove noise from the data," he said, "and navigation technology allows us to place the boats in the same place time after time, making the data more repeatable."

A major problem with 4-D seismic in the past was the repeatability of the seismic surveys.

"Historically we were not able to precisely match a survey to a previous acquisition, so there were differences in the rock geology and noise, in addition to hydrocarbon production, which made it difficult to pinpoint just the fluid movements," he said. "We had the concept of 4-D but we were using old 3-D tools.

"Today we are developing tools specially designed for 4-D reservoir-quality seismic," he said, and they "address all the issues of better sampling, higher resolution, less noise and streamer steering for repeatability."

Other Benefits

Other oilfield operations, such as drilling and logging measurements, also can benefit from seismic data, according to Pickering.

"Seismic technology today can predict such things as geohazards, shallow water flows and over pressure," he said. "Also, seismic can now be used to geosteer the bit to land the well in the optimum part of the reservoir. After a well is drilled seismic can now be used to optimize production over time, which is the domain of 4-D seismic.

"From discovery through to the end of production oil companies are interested in only one thing — getting the most oil out of the ground safely using the fewest wells possible at the lowest cost," he said. "When an operator has a high level of confidence in the seismic data and can drill fewer appraisal wells to accurately quantify reserves, that significantly impacts costs and the time to first production."

During development reservoir quality seismic can aid in well placement and design; during the production phase it can help maximize recovery.

"Late in field life if an operator can turn off certain wells to stop the influx of water based on time lapse seismic they may be able to extend the life of the field and improve hydrocarbon recovery," Pickering said.

The major oil companies are leading the effort in reservoir-quality seismic, and, as a result, calibrated and quantified seismic measurements will be the "industry direction of the future."

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