Companies Piggyback on Monitoring Technology to Save Money in Oil Patch

Microseismic Monitoring

After the first round of seismic acquisition in early 2013, passive microseismic monitoring began for a four-month period.

“The idea was to detect seismicity related to production as they turned on the field,” Duncan explained. “This is a sub-salt play. It’s very deep. We were monitoring and did not detect any events at the reservoir level. We did see events, though, and they were much deeper below the reservoir.”

The peculiar location of the events prompted Petrobras to continue monitoring to try and determine the nature of the relationship to the microseismic events and the producing reservoir.

In Duncan’s eyes, the events appear to be related to a deep fault that could have been reactivated with the production of the field.

Duncan noted a nebulous connection between the reservoir and the fault. “Is water going into the reservoir, or is it being recharged? These are things an operator needs to know because they might affect production.”

Exercising Caution

Acknowledging the “technological savvy” of Petrobras, Doug Foster, a senior scientist and geophysicist at the Institute for Geophysics at University of Texas at Austin, explained to Rigzone that many operators are beginning to up their investments in monitoring, whether they be in the form of large seafloor arrays or located downhole.

“There is an emerging realization that we need to monitor things better,” he said. “People are looking at more downhole monitoring tools with fiber optic sensing devices, which are slowly replacing geophones.”

Using fiber optic sensors is essentially like “strapping a heart monitor on someone and listening to what’s going on,” Foster explained. “Microseismic monitoring infers what’s happening by listening small to earthquakes. Downhole fiber optics can directly measure what’s flowing into the well.”

“Tracking fluid movement is everyone’s goal,” Foster added. “You want to know where things are moving both in the reservoir and in the overburden – what’s happening above the reservoir.”

Several years ago, operators were more concerned about movement in the reservoirs. Today, there is more sensitivity toward movement in areas around a reservoir.

“You only want hydrocarbons in the borehole. You don’t want them anywhere else, as that can cause problems, including serious leaks,” Foster said. “The Macondo accident has heightened the awareness of things that can go wrong outside of a reservoir.”


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