The production phase in the unconventional wells of the Powder River basin is very dynamic and changes based on the total volume of fluids produced and the gas-to-liquid ratio. These dramatic changes in production that occur within a few weeks or months make it impractical to use a single artificial lift method effectively throughout the life of a well. Samson Resources sought to maximize early production on their horizontal wells in the Powder River basin by installing ESP systems shortly after the completion of the well rather than flowing the wells naturally until they loaded up and then installing artificial lift. The result has been improved cash flow for the company.

All ESP systems include downhole pressure sensors that measure pump intake pressure and other parameters. Samson uses the pressure data to manage the drawdown and accelerate production early in the lives of the wells. Wide ranges of operating conditions exist while drawing down the reservoir from above to below the bubblepoint. Below the bubblepoint, events of 100% gas flow frequently occur, resulting in challenging pumping conditions. Based on the development of the field so far, toe-up wells have more gas influx problems than toe-down wells.

A special configuration of ESP systems with redundant gas separation and gas handling devices, including a multiphase axial pump, was used. This configuration has been proven to effectively manage the drawdown by reducing the pump intake pressure (PIP) from 4,000 psi to between 200 to 400 psi, followed by an extended period of sustained production at a target of 100- to 200-psi PIP. The ESP is kept in operation until the production declines to between 150 to 250 bbl/d, at which point the well is put on rod pump for the remainder of the life of the well. The first ESP systems were pulled in operable condition after 7 months of operation. Upon retrieval from the well, the downhole components of the ESP systems were inspected, tested, and repaired, if necessary, at the manufacturer’s assembly, repair, and testing (ART) Center for reuse in the next wells.

The gas handling technology installed allowed the operator to optimize production early in the well life cycle. The timely artificial lift conversion from ESP to rod pump reduced capex and opex by transferring the ESP system to another new well and replacing it with a rod pump, leading to more efficient well operations at the lower rate during the remaining well life cycle.