Stress Ratio Method to Predict Fracture Pressure Gradient in Southern Iraqi Deep Wells

Abstract

This research presents a method for calculating stress ratio topredict fracture pressure gradient. It also, describes a correlation andlist ideas about this correlation.Using the data collected from four wells, which are the deepestin southern Iraqi oil fields (3000 to 6000) m and belonged to four oilfields. These wells are passing through the following formations: Y,Su, G, N, Sa, Al, M, Ad, and B. A correlation method was applied tocalculate fracture pressure gradient immediately in terms of bothoverburden and pore pressure gradient with an accurate results.Based on the results of our previous research , the data were usedto calculate and plot the effective stresses. Many equations relatinghorizontal effective stress and vertical effective stress are obtained foreach well and used to calculate fracture pressure gradient. Similarequations are found for group of formations that calculate fracturepressure gradient and to find the most accurate correlation amongthem.