Integrated Workflow of Acid Stimulation Evaluation and Selection for Productivity Enhancement in Carbonate Rocks

Abstract

Most oil fields worldwide are stored in carbonate rocks, which vary in rock and fluid properties. Heterogeneity, thickness, and depth play vital roles in the selection of specific acid stimulation to improve the productivity and injectivity of the wells from near-wellbore damaged formation resulting from overbalance drilling. This paper describes the integrated workflow that guides petroleum engineers in the selection of optimum acid stimulation techniques and technologies for a specific field. Specifically, this work discusses the stimulation strategies in the form of a stimulation workflow that considers various aspects to achieve the stimulation objectives. The stimulation objectives are also streamlined for the well objectives, which mainly consider the well completion approach. Considering the well completion and well objective, the stimulation strategies highlight the conveyance selections, fluid selections, and the methodologies. Guidelines are provided as examples for fluid specification. Some comparisons of the stimulation fluids are also shown to consider the advantages and disadvantages of each application. Example simulation and case studies show various applications in UAE. Numerous new technologies and different acid types have been tested worldwide on different carbonate rocks whereas very limited information exists on a tailored acid stimulation workflow that can be fit to the needs of a specific field. The developed workflow is an integrated holistic guidance based on worldwide best practice of acid stimulation and can facilitate and guide technical expertise for production and cost optimization in different oil and gas fields. The latest stimulation technologies are highlighted for the reference on the case studies.