When it comes to downhole geology, little things matter.
Those “things” would include the realm of microseismic measurements, because as unconventional plays and hydraulic fracturing become the norm throughout the industry, the need for microseismic imaging grows in importance. [PFItemLinkShortcode|id:13689|type:standard|anchorText:See related story|cssClass:asshref|title:See related story|PFItemLinkShortcode].
Companies large and small are constantly developing, testing and using this technology, hoping to add value to today’s efforts.
One of those companies recently spent two years developing a new microseismic surface acquisition system – a development they say is ready for prime time.
In field tests, Schlumberger’s MS Recon system improved the sensitivity to smaller microseismic events by boosting the signal-to-noise ratio more than two-fold compared to a conventional system, according to company representatives.
“The new microseismic surface acquisition system addresses the challenges of detecting small microseismic signals emitted during hydraulic fracturing at the surface and near-surface locations,” said Joseph Elkhoury, who was the company’s vice president and general manager of Microseismic Services, when the new system was announced earlier this year.
Detecting more microseismic events also aids decision-making, he said.
The company first looked at conventional systems and ways to improve performance based on what new challenges were being faced by operators in the field.
Time and money savings also were major concerns; as microseismic measurements are increasingly used in completion evaluation and field development decisions, companies expect improvements that will reduce survey costs and enhance the results’ utility, according to marketing manager Michael Donovan.
“We decided to engineer a new system and include (our) proprietary technologies in sensor design and system electronics to improve the microseismic signal to noise ratio,” he said.
“We also sought to create a system that was easy to deploy, provided flexibility when utilizing different surface array geometries and supported real time data transmission,” he added. “MS Recon product development took about two years from concept to the first fully commercial job.”
A Flexible System
The system features a proprietary geophone accelerometer and ultra-low noise electronics to produce a wide range of signal detectability.
The nodal-based wireless acquisition system also provides flexibility in designing and deploying the surface and near-surface arrays. GPS-synchronized data are acquired continuously and transmitted to a real-time operations support center.
“Our expectations were fully met regarding the ease of deployment and centralized data collection,” said Uwe Rinck, operations manager, regarding their Texas field trials monitoring fracture treatments in a horizontal shale completion.
“The time to lay out MS Recon over a similar cable based system was reduced by 25 percent on the first job,” Rinck added.
“We also have flexibility in deploying the sensor arrays to meet specific logistical or technical customer challenges,” he said.
Signal quality is enhanced by using the geophone accelerometer, which has a broad frequency response across the range of interest and is designed to improve signal capture, he said.
The engineering design of the electronics improved signal-to-noise ratio when used in the lowest possible noise environments, Rinck said.
“While full-scale side-by-side trials are not practical, we have collected smaller amounts of ‘conventional’ system data alongside MS Recon,” he said. “The data analysis tells us that the signal quality meets the expectations we had for improving frequency content and fidelity, which is then further enhanced during data pre-processing steps such as grouping, stacking and noise suppression.”