In today’s dynamic downhole environments, operators require intelligent solutions to help them get the most out of their artificial lift strategy. ESPs play an important role in the production of oil and gas from unconventional resources, and precise equipment sizing is a key factor for ensuring long-term success. Whether producers have a target ESP lifespan for their application or adhere to a “run it until it fails” approach, right-sizing these systems to achieve the target production and minimize electrical costs is critical to shortening the payback on each well.
So what are the issues that make artificial lift sizing for horizontal wells so much more challenging than other applications? There are 3 main obstacles that application engineers have to take into account when projecting system performance and conducting ESP sizing for unconventional applications.
- Production decline
- Oil-to-water ratios change over time
- Transient gas
Download the Guide: Sizing for the Well Life Cycle
The capabilities of ESP sizing software like Zone have advanced in strides beyond the basic design processes used 20 years ago. The fast-paced, complex production environments operators experience today require adaptive and predictive technologies to stay two steps ahead of the curve, and sizing for these conditions is more complex than ever. In this guide, you’ll gain a better understanding of just how ESPs can fit into your artificial lift stack without being shortsighted.
Unconventional wells are unique in that they initially produce at high flow rates and rapidly decline over time. As a consequence of fracking the well with huge volumes of fluid, flowback water and formation water are produced along with oil, resulting in recovery ratios that can exceed 10 barrels of water for every one barrel of oil. Over time, however, the total amount of fluid in the formation decreases as the well is produced, resulting in a lower flow rate through the pump. If the ESP is sized at the high end of this range, it will be operating at a lower efficiency later in the well’s life cycle. Therefore, producers must take a strategic approach with ESP sizing to achieve their desired run-life while optimizing asset recovery.
Oil-to-Water Ratios Change Over Time
As production volumes decline over the life of the well, the oil-to-water ratio decreases as well. Therefore, the fluid properties of the production mixture change. This difference in fluid density affects both the intake pressure at the pump and the horsepower required to keep the ESP running efficiently. By proactively sizing the motor and the pump to account for variations in the fluid chemistry, operators and service companies can avoid motor problems and remain responsive to these conditions.
Finally, unconventional wells tend to produce significant amounts of gas, and this problem can increase over time as the flow rate declines and pressure in the formation decreases. Gas becomes trapped by undulations in the lateral leg of the well, forming large gas slugs that can interrupt the flow of fluids through the pump. Factoring this transient gas into the ESP sizing can lead to preventative solutions that extend system run life and avoid failures down the road.
With advanced sizing software like Zone®, you can use predictive scenarios to make more informed decisions and leverage ESPs across the life cycle of your well.