Real-Time Borehole Breakout Identification Utilizing Ultrasonic Amplitude Images in a Slim Borehole

Abstract

AbstractWellbore deterioration and breakouts can be mitigated by following proper drilling practices and drilling fluid optimization techniques. While conventional LWD tools can help in identifying borehole breakouts, advanced ultrasonic amplitude images can be utilized to identify borehole breakout intervals and additionally determine their widths to enable safe mitigating actions while drilling. Ultrasonic amplitude images depend on impedance contrast to reliably identify borehole shape and features.Breakout identification depends on the contrast in properties between the formation and the mud, and historically density and photoelectric images have been used for this purpose. Using ultrasonic imaging tools, breakout can be identified using azimuthal variations in measured amplitude. The ultrasonic imager can be used to determine the orientation of breakout intervals with improved resolution compared to conventional tools, and the image can be transmitted to surface through mud-pulse telemetry. Pre-planning is critical to optimize the tool settings, including the firing voltage and frequency.Pre-well modelling combined with real-time data is critical for drilling the well safely, and a pre-well geomechanics study provided an optimum mud-weight window based on offset-well analysis. The ultrasonic imager provided high-definition images for mud-weight optimization and gave insight into breakout width and direction in real time. In combination with other real-time measurements, the image was utilized to help stabilize the borehole and avoid hole deterioration by identifying the zones experiencing extensive wellbore damage. Time-lapse analysis provided critical information for understanding how such deterioration developed over time.This is the first application of amplitude images in a slim borehole for real-time geomechanics. The data helped with optimizing the mud weight and provided critical information for optimizing the completion design and anticipating problematic intervals. The acquired data was further utilized to study the effectiveness of pumped bridging material and together with time-lapse data will provide critical information to improve future wells in similar environments.