ROPS Wellbore Instability Case Study


• Target formation contained laterally variable fluvial deposits consisting of competent sands (pay zone) with unpredictable occurrences of unstable, fissile shales.
• Production lateral section drilled at 89-92° inclination and sub-parallel to bedding dip, increasing the risk of formation breakout, bedding plane instability and stuck pipe events (Figure 1). Typically, to maintain a stable wellbore, higher mud weights must be used and swabbing loads must be minimized, however geomechanical constraints in the area were limiting.
• No onsite personnel trained in identifying and reporting cavings relating to wellbore instability.
• Existing operational practices prioritized fast connections and tripping speeds, as a result previous wells experienced stuck BHAs and unsuccessful casing runs due to instability and poor management practices.

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