Published: 07/31/2014
Published: 07/31/2014
Unexpectedly extreme mud losses occurred while a difficult intermediate section of a deepwater Gulf of Mexico well was being drilled. The operator wanted to understand the cause of the losses and extent of their occurrence to effectively plan the trajectory for the bypass well.
Rt Scanner triaxial induction service calculates vertical and horizontal resistivity (Rv and Rh, respectively) from direct measurements while simultaneously solving for formation dip at any well deviation. Measuring at multiple depths of investigation in three dimensions avoids the biases introduced in conventional resistivity logging by formation heterogeneity and inclined layers. Processing provides information on formation anisotropy, dip and cross-bedding, and geometry. New vertical fracture detection processing calculates the vertical fracture indicator (VFI) and fracture orientation to support advanced structural interpretation.
Data from Rt Scanner service across the estimated loss zone was processed to characterize the fractures by VFI and dip. It took only 24 h for the vertical fracture detection processing and to make an in-house presentation by Schlumberger petrotechnical experts. With this information, key decisions could be confidently taken for handling the losses and planning the bypass trajectory.
Analysis of the vertical fracture detection processing showed that the likely drilling-induced petal fractures were more abundant and widespread across a zone that was much larger than was originally thought. Understanding the generation and extent of the loss zone enabled selecting a kickoff direction for the bypass well that successfully avoided recurrence of the fracturing.
“With the help of the Rt Scanner fracture analysis, we were able to establish the orientation and direction objective for our bypass well. Without this analysis, we would have kicked off without accurately knowing if we would be drilling into the same fracture system, creating large mud losses, as we did previously.”
Operations Geologist
Challenge: Determine the cause and extent of extreme unexplained losses during drilling to avoid their recurrence in drilling a bypass well trajectory
Solution: Conduct innovative vertical fracture detection processing of data from Rt Scanner triaxial induction service to indicate fractures and determine dip
Results: In only 24 h, diagnosed orientation and magnitude of the likely drilling-induced petal fracturing as much more extensive than originally thought for designing the bypass well trajectory and successfully avoiding the loss zone to not waste the USD 7.8 million cost of the bypass
