Abstract
The utilization of electrical submersible pumps (ESP) in oil production has been established in the energy industry. Many factors play major roles in selecting the optimum ESP design to maximize oil production and prolong the system run life. One of these factors is the percentage of free gas present at the pump intake while ESP is operating. Oil wells with a high gas-oil ratio (GOR) percentage could experience challenges while operating the ESP and would frequently trip due to unstable production. Furthermore, introducing free gas into the pump could significantly deteriorate ESP pump performance and can lead to mechanical damage due to degradation or electrical damage due to significant overheating. A conventional mixed-flow ESP system can handle up to 20% free gas at the pump intake, while ESPs with axial-flow gas handlers with ESP packer applications could manage up to 50% free gas. Both options were proven inefficient while operating in a higher GOR environment. One of the available solutions is to utilize a gas separator and gas handler with the ESP system to separate the free gas and flow it to the surface through tubing casing annuals (TCA). This technology is commonly used with packerless completion to enable flow through TCA. A novel approach is required to use gas separators with downhole packers.
This study introduces a novel approach by employing a dual-string configuration with ESP systems and downhole packers. This configuration facilitates the utilization of gas separators and handlers, effectively mitigating the adverse effects of free gas on ESP performance. The main string accommodates the ESP and gas separator, while the secondary string remains accessory-free, ensuring efficient cable deployment and system integrity. Moreover, modifications to packers, hangers, and clamps facilitate safe installation and operation.
Simulations analysis indicates significant improvement to ESP performance after following the indicated novel approach. The ESP is able to operate with higher free gas volume fractions (GVFs) at the pump intake while sustaining higher flow rates. This can help in reviving several high GOR wells that could not flow with the conventional ESP system and gas handlers. furthermore, ESP run life is expected to improve significantly due to the reduction of ESP trips caused by flow instability.
The deployment of ESPs with gas separators and handlers is proven to be an excellent success in wells without downhole packers for significantly enhancing the production of high GOR oil producers requiring artificial lift. This study presents a novel approach to safely deploy gas separators and gas handlers with ESP systems while utilizing downhole packer in order to increase well deliverability and confirms the advancement of the emerging technology as opposed to the conventional ESPs that cannot withstand high gas fractions.
