Advanced ESP and Completion Solution for a Remarkable Run Life in an Offshore-High Corrosive Environment
Authors: Aklefa E. , Ehbeash A. , Elhajjaji R. R. , Elhamali B. , Awedan H. , Abusnina S. , Anabtawi E. , Eltamimi M. , Entira I. , Hkoma M. , Jazwi O. 
Published: October 2023

Severe corrosive conditions in a deep offshore reservoir located in the Mediterranean Sea have had a detrimental impact on the run life of the electrical submersible pumps (ESPs) which are installed in a pilot project. The ESP systems initially deployed in seven wells demonstrated early failures within an average run life of around 300 days resulting in considerable costs for ESP replacements. This paper gives an in-depth review of an advanced ESP and completion system that was specifically designed for this challenging environment, as well as its successful implementation and improving the operational efficiency and reliability of the system.

In order to function efficiently in such an environment, an encapsulated pod system was employed to contain the ESP systems in all wells. To counteract deep flow decline and high gas oil ratio, a mixed stage pump type was utilized alongside a wide operative flow range. Multiphase Gas Handler (MGH) was integrated to avert any possible gas locking issue and can handle up to 75% of the free gas within the system. Moreover, the ESP string was coated with a special alloy that exhibited excellent mechanical strength under high temperature and CO2 partial pressure conditions. Optimized medium-voltage Variable Speed Drive (VSD) is being utilized to operate the ESPs, which is specifically engineered for offshore platforms and incorporates a built-in well controller and a data acquisition system.

The results of a thorough Dismantle, Inspection, and Failure Analysis (DIFA) have shown that the integrity of the insulation around the pod penetrator was compromised due to the high temperatures developed across the pump. This was believed to be caused by the ESP operating under low flow conditions. Accordingly, an upgrade was made to the pod connector, replacing it with a higher temperature-rated type in the second successful run. Additionally, MLE insulation material was upgraded using Polyether Ether Ketone which showed better corrosive resistant. The implementation of a real-time data transmission system enabled remote control, monitoring, and the optimization of operating conditions through multiple ESP diagnostic simulations. Furthermore, a mechanically-controlled flow isolation valve (MFIV) and a 7-inch Sealbore Packer were installed below the ESP, successfully mitigating formation damage, and reducing offshore rig downtime and associated costs. The enhancements implemented have resulted in exceptional performance of the ESP systems surpassing six years of continuous oil production.

The substantial reduction in operational expenditures and the implementation of ESP technologies have proven their reliability, allowing the installation of further 14 ESPs in other offshore wells. The implemented standardized equipment strategy is an integral part of the project, which was planned to cover full production range and offers multiple advantages, that include selection flexibility, effective activity planning, and prompt actions.