Brent Cope and David Gilmore, ChampionX Artificial Lift
Extended-reach horizontal well geometries and higher hydraulic fracturing stage counts have led to increased well productivities in tight oil plays across the Lower-48. However, lateral lengths in excess of 10,000 feet with complex fracture networks can also introduce more dynamic behavior and even more severe production declines over time, often exacerbated by tight oil formations that produce fluids with higher gas-to-oil ratios, sand and solids content, and water cuts.
Accommodating these factors while cost-effectively managing rapidly changing production rates and depleting natural reservoir pressures can be a major challenge for artificial lift, especially during the first few years. However, the combination of gas lift and plunger lift technologies provides a flexible lift solution capable of not only optimizing production at every phase of the well lifecycle, but also adapting relatively easily and quickly as wells transition from the early-, to mid-, to late-life stages.
The paper examines how leveraging gas lift, plunger-assisted gas lift (PAGL)/gas-assisted plunger lift (GAPL),and plunger lift at different points in the decline curve allows operators to take full advantage of the relative strengths of each method, including:
• Gas lift’s ability to mimic natural reservoir flow and efficiently handle varied production rates and well characteristics, including high GORs and solids.
• PAGL’s ability to increase reservoir drawdown, stabilize production, and reduce surging as production diminishes to where gas lift becomes inefficient.
• Plunger lift’s ability to carry accumulated fluids to surface at rates as low as a few bbl/d without an external power/energy source. The plunger also sweeps tubing of paraffin, scale, asphaltene, etc.
• GAPL’s ability to deliquefy loaded wells and produce liquids and gas from mature wells with little to effectively no natural reservoir drive.
This full lifecycle approach to managing tight oil well production encompasses three interrelated forms of artificial lift applied at distinct phases to collectively span the entire slope of the decline curve -- from IP to depletion:
• Gas lift in early life (maximum flow rates)
• PAGL through the mid-life plateau (moderate flow rates)
• Plunger lift and potentially GAPL in late life (minimum flow rates)
The paper provides engineering recommendations and operational practices to simplify transitioning wells from gas lift, to PAGL to plunger lift in response to changing production profiles as wells mature. It also details considerations for selecting surface equipment, downhole equipment, and automated digital controls capable of optimizing well production during gas lift, PAGL, and plunger lift/GAPL, without having to interrupt production or make capital investments to pull tubing or swap out components.
Case history data from wells in the Mid-Continent and Permian Basin are presented to illustrate the benefits of adopting an integrated gas lift -PAGL-plunger lift approach to artificial lift and production management over the full well lifecycle.
The purposeful application of gas lift, PAGL/GAPL, and plunger lift component technologies gives operators a single artificial lift equipment design capable of maximizing well performance at every point along the tight oil well decline curve. Ultimately, this translates into improved long-term production economics and the recovery of more reserves in less time.