The Quartet downhole reservoir testing system, enabled by Muzic wireless telemetry, was only recently commercialized by Schlumberger in 2013.
Already, reports indicate the innovative system has more than proved its value in the field.
Quartet has been deployed in 22 field trials in locales around the world, including Egypt, Indonesia, Qatar, Brazil and Angola, in locales ranging from onshore to deep water.
The trials registered a 100 percent communication success rate in transmitting data from downhole to surface.
Quartet technology enabled by wireless telemetry was applied in Indonesia to meet a straightforward challenge: implement real time pressure transient analysis of bottomhole pressure (BHP) data to optimize well test operations conducted in a deviated offshore exploration well.
“The client sought a testing solution that would optimize operations because reservoir uncertainties and rig rates were high,” said Bengt Nilssen, testing services marketing communications manager at Schlumberger. “Wireless transmission of BHP and temperature data in real time was fundamental to attaining this goal.
“We proposed using Signature quartz gauges, which deliver high resolution pressure data, augmented even further with wireless telemetry,” Nilssen said. “This integrated approach enables bidirectional communication between the surface and downhole.
“Repeaters, installed at intervals in the test string, transmit wireless commands downhole and pressure and temperature data to the surface,” he noted. “Each gauge can be queried independently for both real time and historical data.”
Signature is one of four tools comprising the Quartet system. Each tool is considered to be equally applicable – yet not always required – in all environments.
Because the Indonesia field trial was not in deep water, a conventional packer was run instead of the CERTIS reservoir test isolation system, which eliminates the need for drill collars and slip joints.
“The Signature quartz gauges enabled by Muzic wireless telemetry successfully transmitted uninterrupted real time BHP and temperature data to the surface for seven days,” Nilssen said. “This helped the client truly understand what type of reservoir they were looking at.”
Brazil Case Study
Halfway around the world in offshore Brazil, the Quartet system was used to do its thing in a whole different environment.
We’re talking the ultra-deep water, pre-salt, which is known to test the skills and knowledge of the most seasoned operators.
“The challenge there was to quickly acquire real time well test data in the deepwater environment, while ensuring high data resolution and accuracy,” said Schlumberger’s John Reddington.
To enable the client to optimize its deepwater well operations, Schlumberger proposed a real time communication solution on a well in the pre-salt Santos Basin, more than 150 miles offshore Brazil, according to Reddington.
Water depth exceeded 6,500 feet.
“This is an excessively costly market,” he emphasized. “The ability to deploy the CERTIS system with wireless telemetry means we could run this system much quicker than a conventional string, retrieve it quicker and have access to the data in real time much faster to be sure the objectives were reached.”
Deploying the wirelessly enabled Signature gauges on the pre-salt well test allowed the client to interact with downhole equipment, manage wellbore events and refine the test in real time.
Running the wireless system in this well required less than six hours of rig time versus 20-24 hours when using a standard wireline system, according to Nilssen.
“We saved rig time by visualizing downhole data during flow periods,” he said, “and eliminating the need to rig up a conventional surface readout system.”
The Results Are In
The Signature quartz gauges transmitted wireless downhole data continuously for 568 hours to provide the data necessary to optimize the well test operations in real time.
Reddington noted that the optimized test enabled the client’s engineers to:
- Observe perforating guns’ effect on pressure and confirm dynamic underbalance.
- Compute productivity when the well was flowing.
- Validate that sufficient data were acquired during the initial and main buildup periods to end them earlier.
- Eliminate the need for a wireline run.
- Establish reservoir pressure after the initial post-perforating flow period.