First Application of Arresting Production Decline and Increasing Restimulation Effectiveness Using Fiber Diagnostics: A Case Study from North Kuwait
Authors: Al-Ajmi A. , Al-Kandary A. , Eid W , Abdelbaky A. , Alboueshi A. , Wakwak A. , Robles F. , Mousa Y. 
Published: November 2024

The Mauddud formation in Bahrah field located in north Kuwait is a low permeability carbonate formation with moderate to high oil viscosity. As the field development phase progressed, the field started suffering from production decline and reservoir pressure depletion due to lack of pressure maintenance. This work presents the entire process of identification of a potential candidate for multistage hydraulic re-stimulation including operational preparations, re-execution, and analysis of post-treatment results. The interest in restimulating wells has been driven by multiple factors—the desire to arrest the steep decline curves of wells, to fully drain formation and to increase the EUR of the well through achieving additional stimulated reservoir along the lateral completions.

The development strategy in Bahrah field was to drill horizontal wells and complete them with multistage stimulation sleeves and were operated by a ball-drop system from the surface. There are several reasons to consider restimulating a well, and without properly assessing the goal of a particular restimulation treatment, it can be difficult to discern which candidate wells are best positioned for economic success. After candidate selection, developing a solution phase that will accomplish the treatment's goal and overcome operational challenges to selectively close sleeves and open target sleeves, and to confirm and diagnose such functionality, but also address reservoir challenges such as restimulation of hydraulically fractured depleted and low-pressure reservoirs is one of the most important challenges. The Nitrogen (N2) Foamed acid, used in this methodology, is a finely dispersed mixture of nitrogen gas bubbles within hydrochloric acid liquid which increases the volume of the active acid, improves penetration, and diverts fluid from high permeability zones into low permeability zones. This in turn, enables to control fluid loss, maximize conductivity, and provide gas expansion to assist flowback.

This paper summarizes the candidate selection criteria, first application of restimulation design in Kuwait, operational procedures, diagnostics tools, well clean-up and production performance aspects of the N2 foam restimulation treatment. Success of this N2 foam restimulation technique is crucial for Bahrah field to overcome production decline and reservoir pressure depletion and effectively stimulate Mauddud formation, increasing the stimulated reservoir volume to continue rising field production capacity.

Based on the comparative valuation completed on the Bahrah wells, the use of energized fluids is shown to create significantly improved well performance over those wells fractured with non-energized fluids. Though the treatment costs for the energized fracture treatments were seen to be higher, the value of this incremental recovery surpasses the supplementary cost with no additional risk. Besides, there is potential to reduce the fracturing fluid liquid volumes with using N2 Foam treatments, thereby improving production while also minimizing ecological impact. The first application of this methodology is tuned to focus on the challenges of well procedures, formation technical complications, high-operational economics, and high potential from this depleted reservoir.