“We eliminated the pilot hole,” Wibowo says. The IriSphere service’s EM-based deep directional resistivity measurements are integrated with offset and other data to provide a resistivity profile ahead of the bit, delivering an accurate downrange representation of the formation while drilling.
The tool enables the customer to make proactive drilling decisions rather than reacting to measurements at or behind the bit, Wibowo says.
She emphasizes that pre-job modeling is crucial to understanding reservoir issues and sensitivities to determine how far ahead the customer has the ability to look. It’s also key to properly space the transmitter and receivers when planning the bottom hole assembly (BHA) to obtain the desired sensitivity, she said.
“The further we space the transmitter and receivers, the further our signal propagates,” she says.
To date, she says, the largest distance between the transmitter and receiver has been 160 feet along the drillstring, which made it possible to see 100 feet ahead of the drill bit.
The system uses one transmitter combined with one, two or three receivers. The system applies to hole sizes ranging from 5 5/8 inches to 16 inches.
With more than 100 measurements available in real-time, IriSphere uses state-of-the-art inversion to invert for a high-resolution 1D formation profile in resistivity ahead of the bit, according to the company.
In developing the tool over the course of five years, Schlumberger conducted more than 25 field trials in Asia, Australia, Latin America, North America and Europe. These trials included successfully detecting reservoirs and salt boundaries, identifying thin layers and avoiding drilling hazards, such as high-pressure formations that can lead to wellbore stability issues. The tool has also been used onshore to detect a high-pressure environment.
The development team – which includes a number of experts in deep directional resistivity – engineered the system in response to customer requests to be able to look ahead of the drill bit in order to reduce drilling risks, improve efficiency and place casing in specific locations.
“Knowing the conditions that lie ahead in real time and continuously enables the customer to reduce drilling uncertainties,” Wibowo says.