Fracture Gradient Prediction: Applicable to Safe Drilling and Underground Storage Operations

This study aims to implement pore pressure and three fracture gradient prediction strategies for the Koppeh-Dagh sedimentary basin using petrophysical and measured downhole pressure data along with the drilling events of the drilled well in the field. These strategies will help to ensure safe drilling, optimal design of fluid injection pressure (in EOR or underground storage operations), hydraulic fracturing, and completion operations for future wells in this area. This study estimated pore pressure using Eaton's most widely publicized method, and fracture gradient prediction was based on the Hubbert and Willis, Matthews and Kelly, and Ben Eaton methods. Downhole pressure test data calibrated the predicted pore pressure. Overburden stress and Poisson's ratio were calculated using density and sonic logs, respectively. Then, the three fracture pressure gradient strategies were examined based on available data, and the obtained results were compared with the drilling-related data and events. The Ben Eaton model-based fracture gradient prediction strategy delivered the most accurate results