Fracture-Gradient Prediction for Offshore Wells

Abstract

Summary A key parameter required in the design of offshore wells is the fracture gradient of the formations to be penetrated. Existing fracture-gradient correlations have been developed largely on the basis of empirical data gathered on land and in the nearshore marine environment. They have been extended to deepwater areas through an equivalent intergranular stress concept. In this study, offshore data from several operators were obtained and a new fracture-gradient correlation procedure, based on an assumption of an exponential decline in average porosity with depth in normally pressured formations, was applied. The technique is ideally suited for implementation on a hand-held calculator or personal computer.