Predicting Subsurface Sand Fracture Stress in the Niger Delta?s High-Pressure Environment: Insights from Oil-Well Drilling Experience

A comprehensive understanding of fracture stress characteristics at greater depths is indispensable for drilling high-pressure deep exploration wells without operational complications. Pore pressure and fracture gradient are the two natural limits that most affect drilling costs and safety. The difference between the fracture gradient and pore pressure determines the safe drilling margin. Without accurately predicting pore and fracture pressures, serious wellbore challenges-including kicks, blowouts, lost circulation, and instability-pose a serious threat to drilling. Experience from the Deep well, part of the renewed HP campaign in the Niger Delta, indicates that field leak-off tests are best used at the well-planning stage, while the porosity-effective stress approach offers a viable alternative for real-time fracture-stress prediction in high-pressure reservoirs. Precise quantification of fracture stress is imperative for safe drilling and achieving the geological objective. Hard data from the Deep well support this assertion.