Successful Completion of the First Ten Multistage Acid Fracturing of an Oil Producer in Saudi Arabia

Abstract

Abstract Challenges have arisen when developing a relatively tight oil reservoir in Saudi Arabia using conventional matrix stimulation techniques to improve well productivity. The oil producer wells responsiveness to matrix stimulation was not adequate to supply the estimated oil production capacity due to the tightness carbonate reservoir formation. In order to get better well productivity in this low permeability environment, open hole with multistage frac completion using swellable isolation packers was chosen to develop this reservoir. This paper discusses the challenge journey of first ten multistage job from the well drilling and completion stage, design and lab optimization of the fracturing fluids, modeling of the optimized fracture geometry, onsite well QA/QC of each stage fracturing fluids. In addition, step rates test regression approach prior each stage for fracturing gradient calculation, pre and post fracturing injectivity test, and finally analyzing the flowback samples for four days. A ten multistage acid fracturing was performed on an oil producer well that was drilled as a single lateral into the oil tight carbonate reservoir. The well was completed with a ten sleeve multistage fracturing and eleven oil swellable packers. These packers showed excellent zonal isolation with no communication observed during the fracturing operation. The job resulted in a well producing 9 folds of production, with a water cut range less than 10 %. The four days flowback samples analysis revealed the need for longer cleaning up time. A successful approach was achieved using multistage acid fracturing technique. Lessons learned from this job planning and execution shed the importance of previously steps for future acid fracturing jobs in similar oil fields.