Oilfield services company Schlumberger has introduced the TerraSphere high-definition dual-imaging-while-drilling service
The new service provides the industry with the first application of a logging-while-drilling dual-physics imager for oil-based mud for drilling oil and gas wells.
It incorporates electromagnetic (EM) and ultrasonic measurements that enable multiple high-resolution borehole images in nonconductive mud. This reveals enhanced details for geological, petrophysical and geomechanical interpretation to uncover subtle variations in the subsurface caused by stratigraphic or structural properties that impact wellbore stability.
The real-time transmission of images with these enhanced details enables drillers to make better-informed decisions during the near-wellbore stress interpretation process.
Tarek Rizk, president, drilling and measurements, Schlumberger, said, “Drillers have been unable to visualise, in real-time, subsurface features when drilling with oil-based mud.”
“The TerraSphere service delivers geological and geomechanical data that saves not only logging time and related rig costs, but also reduces the potential risk for loss circulation of drilling muds into formation fractures,” he added.
More than 30 field trials were conducted with the TerraSphere service in the Gulf of Mexico, Middle East, North Africa, the North Sea and US land. These trials included successful imaging for structural and stratigraphic analysis, revealing breakout fractures that enabled drillers to avoid mud loss.
The new service acquired additional and higher definition data, reducing subsequent operational time and improving net-to-gross ratio in the payzone.
In the North Sea, a customer used the TerraSphere service in a complex reservoir in Balder Field, according to Schlumberger. Dual imaging while drilling delineated sand injectites in the reservoir and removed ambiguity from conventional logs, providing more accurate characterisation through increased reservoir coverage to maximise production potential. The resolution captured by ultrasonic images is now refined to millimetres, previously possible only with wireline imagers.
