If necessity is the mother of invention, then persistence is what feeds the inventor’s soul. The trial-and-error nature of the discovery process eventually ends with a “eureka!” moment. For Bill Quinlan, a professional engineer with Horizontal Lift Technologies, that moment came while at work in a tight formation development.

“The idea for the dual gas-lift system came from a horizontal well development that we drilled in Michigan,” Quinlan said. “We drilled several 4,000-ft [1,219-m] laterals to open a fairly tight dolomite formation enough to make production economically feasible.”

The original development plan for the wells incorporated the use of conventional gas lift to aid with production. Over time, however, it became apparent that another solution was needed.

“Gas lift helped increase production but didn’t help reduce the steep decline rates,” he said. “Within a year, the wells needed additional help or the field would likely be abandoned.”

According to Quinlan, it was obvious that lift gas needed to be efficiently applied within the lateral portion of the wells. The question was how.

“After brainstorming different ways, I came up with a two-step approach that uses a specifically designed packer,” he said.

The packer enables an upper lift-gas stage to unload the well low into the curve and a second dedicated stage that delivers lift gas to the end of the lateral. In so doing, velocity across the entire lateral completion length “is enhanced, energizing and moving the produced fluid back to the curve so it can be efficiently produced out,” he said. “In doing that, we added about 40% to 50% additional recovery from the field.”

Complexities of well design and how horizontal wells are drilled contribute to production issues, he added.

“The highs and lows where the bit has drifted up and down during drilling create, essentially, a structure within the lateral wellbore,” he said. “The dual gas-lift system enables you to overcome these wellbore issues by adding velocity to every foot of the well-bore such that it combats the potential for liquid to load within any portion of that lateral. As a result, every foot of the completion interval that’s capable of production is brought into production.”

The beauty of gas lift is that it is very adaptable. The dual gas-lift system, Quinlan said, adds another layer of adaptability.

“Gas-lift rates to the vertical and curved portion of a well can be adjusted. With the dual gas-lift system, you are also able to adjust dual gas-lift rates within the lateral,” he said. “You have two independent dedicated fluid streams for gas lift to enable you to adjust to production changes within the well.”

The system has been used throughout Michigan, with its most recent success being in the Trenton-Black River formation. Quinlan has found the response in those wells to be “fantastic.”