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Techniques Get Exam in Field

Compare, contrast

Compare and contrast” is always a good thing when it comes to dealing with new seismic data acquisition technology.

This was the impetus for a program that recently took place in the Piceance Basin in western Colorado – a project designed by ConocoPhillips to test advanced acquisition techniques for possible future use in the Piceance.

The 14-square-mile acquisition project was completed in September.

“One objective was to compare digital 3-component sensor and geophone data,” said Duncan Riley, vice president at Global Geophysical Services, which implemented the program. “Using the Sercel 428 system, we acquired the program with traditional P wave geophones and an embedded patch of Sercel Digital Sensor Units (DSUs).

Image Caption

Global’s crew 445 recorded on 16,200 live channels while implementing a program designed to test advanced acquisition techniques in the Piceance Basin. Photo courtesy of Global Geophysical Services

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Compare and contrast” is always a good thing when it comes to dealing with new seismic data acquisition technology.

This was the impetus for a program that recently took place in the Piceance Basin in western Colorado – a project designed by ConocoPhillips to test advanced acquisition techniques for possible future use in the Piceance.

The 14-square-mile acquisition project was completed in September.

“One objective was to compare digital 3-component sensor and geophone data,” said Duncan Riley, vice president at Global Geophysical Services, which implemented the program. “Using the Sercel 428 system, we acquired the program with traditional P wave geophones and an embedded patch of Sercel Digital Sensor Units (DSUs).

“The DSU replaces a string of geophones,” Riley said. “Instead of an array of geophones you have a single DSU at each receiver location.”

Riley noted the DSU measures a vertical (Z) component like a traditional geophone, and it also measures two horizontal components – one in the X direction and one in the Y direction.

“The DSU uses three digital accelerometers to measure ground motion on all three axes,” Riley said. “The vertical measurement by itself is comparable to the P wave measurement you’d obtain from traditional analog geophones; recording horizontal motion along two other axes provides shear wave measurement.

“Comparison of P wave and S (shear) wave data facilitates determination of certain rock properties, which enhances interpretation and reservoir characterization,” Riley noted.

Deploying the DSUs along with the traditional geophone methodology assists in determining if replacing a string of geophones with a DSU is sufficient or not, or if there needs to be some geophysical design differentiation.

What Technology is Best?

Given that the project was testing different recording systems, ConocoPhillips and Global recognized advantages in taking the program a step further by tossing OYO Geospace’s new land node recording system – Geospace Seismic Recorder (GSR) – into the mix for actual use and testing along with a limited number of the new Fairfield land node recording system – ZLAND – for testing.

“We placed 400 channels of the GSR alongside traditional geophones and the DSUs so we would have an autonomous recording system measurement we could directly compare to a data set acquired with a wireline telemetry system,” Riley said. “We see autonomous systems providing great benefit in the future.

“The terrain where the systems were deployed was identical as was the source effort for acquiring the data,” he said. “All that was different was recording methodology.”

Riley noted the testing was over a smaller area of the field and, depending on the results, will help the client determine which technology is most appropriate for the area. It also will allow Global to evaluate and understand new technology before committing its capital.

In areas where radio signals may be unreliable, the GSR units can be used in the vibrators to acquire vibrator signals that might otherwise have been lost

“We not only use GSRs to acquire seismic data,” Riley noted, “at ConocoPhillips’ request, we also used them to record data from vibrator electronics such as ground force, base plate and reaction mass velocity data that’s used for data processing purposes post acquisition.”

Overall, this effort dedicated to testing new technologies is yet another testament to the high level of forward-thinking indigenous to the geophysical industry.

“It’s a story where these wonderful fundamentals are driving innovation and the progressive science and applied technology which we’re seeing a lot of,” said Global president Richard Degner.

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