Schlumberger today introduced the IriSphere* look-ahead-while-drilling service at the Offshore Technology Conference. The new service provides the industry’s first application of electromagnetic (EM) technology for detecting formation features ahead of the drill bit in oil and gas wells.
The service uses EM-based resistivity measurements more than 100 ft [30 m] ahead of the drill bit, which are then compared to a prepared model that incorporates offset and other data to reveal a true downrange representation of the formation while drilling. This enables operators to make proactive decisions rather than reacting to measurements at or behind the bit while drilling wells.
“IriSphere service was created in response to the needs of our customers for risk reduction, improved drilling efficiency and optimal casing point selection,” said Tarek Rizk, president, Drilling & Measurements, Schlumberger. “Knowing what conditions lie ahead of the bit while drilling enables operators to reduce uncertainties and minimize costs by identifying geological features and deciding which actions to take before encountering them.”
More than 25 field trials were conducted with the IriSphere service in Asia, Australia, Latin 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.
Offshore Western Australia, one customer used the IriSphere service in an unexplored part of a field to detect the reservoir 62 ft [19 m] ahead of the bit while drilling and determine reservoir thickness to be 82 ft [25 m]. This avoided the need to drill a pilot hole, and subsequent coring operations were optimized based on data acquired while looking ahead of the drill bit.
IriSphere Look-Ahead-While-Drilling Service
Continuous resistivity ahead of the bit delivers improved casing-point selection and reduced drilling risks
IriSphere look-ahead-while-drilling service combines deep directional measurements with advanced automated inversion to accurately detect formation features ahead of the bit and land wells while managing drilling risks, optimizing casing placement and coring location. The look-ahead capability is delivered while drilling in real time by using multifrequency transmitter and multireceiver directional subs. Electromagnetic (EM) signals are sent from the transmitter into the formation and retrieved by the receivers to enable the enhanced look-ahead sensitivity and resistivity profiles.
Operators can now drill ahead with confidence and reduce drilling uncertainties in real time. Applications include ahead-of-the-bit detection of formation features with potential pressure differentials for integration in a standard pore pressure prediction workflow. Penetrating a high-pressure reservoir might result in stuck pipes, lost circulation, and other potential wellbore instability issues.
IriSphere service provides drillers with real-time mud properties management and enables optimized casing design and contingencies planning. Unlike the current geostopping technology available in the industry, IriSphere service can differentiate between a thin high-resistivity stringer and a target reservoir. Consequently, premature casing seating or coring location is avoided.
IriSphere service enables the driller to see far in front of the bit while drilling, providing enhanced formation tops mapping, improved landing capability, and better drilling hazard avoidance. The same workflow is applied to determine the reservoir bottom, completion optimization, and salt navigation, including salt entry and exit.
BENEFITS
- Higher drilling efficiency
- Lower risk and reduced contingencies
- Proactive hazard management and avoidance
- Improved casing sections through reduction, optimization, or elimination
- Increased ROP
- Fewer BHA trips out of hole
FEATURES
- Deep look ahead of the bit exceeding 100 ft [30 m]
- Cloud-enabled automated solution
- Hole size availability from 55/8 in to 16 in
An operator drilling an appraisal well in a new block offshore Western Australia faced several challenges. The field had a complex stratigraphy because it was on an anticline and was composed of siltstones between discontinuous sand bodies.
The operator needed to confirm the presence and thickness of the reservoir in an unexplored part of the field, which was characterized by a lack of markers above the reservoir and several meters of seismic uncertainties. A conventional approach would have required the customer to confirm reservoir thickness by drilling a pilot hole and then performing a sidetrack for coring operations. Use look-ahead service to map the reservoir ahead of the bit The IriSphere service uses deep electromagnetic resistivity with a depth of investigation proportional to spacing of multiple receivers on the BHA. It is dependent on the formation resistivity environment to map features ahead of the bit, thus resolving seismic uncertainty while mitigating drilling risks.
This was crucial to help the operator improve coring operations by confirming the thickness and presence of the reservoir section. Maximized reservoir exposure to improve accuracy in landing the well A rotary BHA was fitted with proprietary imaging- and logging-while-drilling technologies that incorporated the EcoScope* multifunction loggingwhile-drilling service† and the sonicVISION* sonicwhile-drilling service as well as the IriSphere service. It revealed the reservoir top at about 19-m [62.33-ft] TVD ahead of the bit, and the 25-m [82.02-ft] reservoir thickness was ascertained at 7-m [23-ft] TVD ahead of the bit. This enabled the operator to avoid drilling a pilot hole and reduced overall drilling risks.
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