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

Abstract

This research presents a method for calculating stress ratio to
predict fracture pressure gradient. It also, describes a correlation and
list ideas about this correlation.
Using the data collected from four wells, which are the deepest
in southern Iraqi oil fields (3000 to 6000) m and belonged to four oil
fields. These wells are passing through the following formations: Y,
Su, G, N, Sa, Al, M, Ad, and B. A correlation method was applied to
calculate fracture pressure gradient immediately in terms of both
overburden and pore pressure gradient with an accurate results.
Based on the results of our previous research , the data were used
to calculate and plot the effective stresses. Many equations relating
horizontal effective stress and vertical effective stress are obtained for
each well and used to calculate fracture pressure gradient. Similar
equations are found for group of formations that calculate fracture
pressure gradient and to find the most accurate correlation among
them.