Most wells require additional energy to bring fluids to the surface as reservoir pressure declines. One solution is artificial lift, which provides energy to the well fluids to increase the production from a wellbore. A major component of Oxy's operations, artificial lift is installed in more than 21,000 wells which collectively produce approximately 9 million barrels of fluid per day – over 90 percent of Oxy's operated production.
Oxy continuously invests in new technologies and techniques to optimize production and extend the run life from artificial lift. The primary methods of artificial lift in use at Oxy are Beam Lift, Electric Submersible Pump (ESP), Gas Lift and Progressive Cavity Pump (PCP).
Beam Lift, the most common artificial lift method worldwide, consists of a beam unit (also called pumping unit, pump jack, sucker rod pump) on the surface, a downhole pump and rods that connect the two. This lift-type is the largest component of Oxy's artificial lift, both in terms of wells (approximately 17,000) and production (more than 40 percent).
Oxy operates a communication and computing system that enables surveillance, troubleshooting, optimization and control of beam wells from anywhere in the world. The majority of the wells are automated with pump-off controllers, with a growing number also using variable speed drives for improved control.
Electric Submersible Pumps (ESP) consist of an electric motor and pump suspended near the bottom of a wellbore and connected to a power supply at the surface. Such units are the workhorse of Oxy's artificial lift fleet when it comes to total fluid production. Approximately 2 billion barrels of fluid are lifted annually from over 3,000 wells using Oxy's ESPs. These are typically monitored and optimized through downhole gauges and surface controllers that automate the performance of the ESPs. Variable speed drives also are used to adjust the speed of the motors and pumps to accurately match the reservoir inflow to the well.
Gas Lift is installed in fewer than 1,000 Oxy wells but makes up a significant share of the company's operated production at nearly 20 percent. In this method, gas is injected into the fluid column in a wellbore, thereby reducing the column's density to the point where reservoir pressure is sufficient to produce the fluid to the surface.
Oxy operates approximately 100 gas-lifted wells offshore Qatar, where we model the surface network linked to the subsurface field production. Each individual well is modeled with its own unique wellbore characteristics, including deviation, downhole equipment and vertical lift performance curves. The production model then links all the wells and pipelines together to calculate accurate production rates consistent with actual daily production.
The model accurately predicts pressure responses throughout the system by utilizing data from bottomhole and wellhead pressures, flowline pressures and arrival pressures at the central production station. Combining the surface network model with an automated system for collecting real-time operating data provides a powerful tool for production optimization.
Progressive Cavity Pumps (PCPs) are in use across many of Oxy's business units. These pumps typically fill a niche in relatively shallow wells where beam pumps or ESPs aren't effective. The primary components are a rotor, rotating inside of an elastomeric stator. Oxy also uses metal to metal, rotor and stator combinations in the high temperature service of steam flood producers.
Control of these pumps typically is automated through downhole gauges measuring pressure and tied into a surface controller that controls the speed of the rotating rotor.