Artificial Lift for High-Volume Production Roy Fleshman Bartlesville, Oklahoma, USA Harryson Obren Lekic Houston, Texas, USA For help in preparation of this article, thanks to Rick Bailey and Duane Russell, Reda, Bartlesville, Oklahoma, USA; James Garner, Camco Products & Services, Houston, Texas, USA; Peter Schrenkel, Reda, Dallas, Texas; and Dave Bergt, Schlumberger Oilfield Services, Sugar Land, Texas. NODAL is a mark of Schlumberger. AGH (Advanced Gas Handler), CDPS (Cable Deployed Pumping System) and HOTLINE are marks of Reda. Camco EOR (Engineering Optimization Resources) is a mark of Camco Products & Services. Camco Products & Services and Reda are Schlumberger companies. Rod pumps bring oil to surface in many fields, but for better flow rates more than 100,000 w ells use subsurface electric pumps or inject external gas to lighten the fluid column. Specialized approaches are needed to optimize existing gas-lift or submersible systems and to design new installations for more complex applications. Less than a fourth of producing oil wells flow nat- urally. When a reservoir lacks sufficient energy for oil, gas and water to flow from wells at desired rates, supplemental production methods can help. Gas and water injection for pressure support or secondary recovery maintain well pro- ductivity, but artificial lift is needed when reser- voir drives do not sustain acceptable rates or cause fluids to flow at all in some cases. Lift pro- cesses transfer energy downhole or decrease fluid density in wellbores to reduce the hydro- static load on formations, so that available reser- voir energy causes inflow, and commercial hydrocarbon volumes can be boosted or displaced to surface. Artificial lift also improves recovery by reducing the bottomhole pressure at which wells become uneconomic and are abandoned. Because reservoir pressure declines and more water is produced late in field life, artificial lift is generally associated with mature oil and gas developments. However, driven by activity in deep water and areas that require construction of complex wells, the mature state of hydrocar- bon exploitation worldwide has increased demand for high lifting rates to produce oil quickly and efficiently at low cost. Offshore and in difficult international regions, artificial-lift techniques accelerate cash flow, generate profits sooner and help operators realize better returns, even in wells that flow naturally. Rod pump, gas lift and electric submersible pumps are the most common artificial-lift systems, but hydraulic and progressing cavity pumps are also used. Each is suited to certain lifting requirements and operational objectives, 1. Brown KE: The Technology of Artificial Lift Methods, vol. 2A. Tulsa, Oklahoma, USA: PennWell Books, Inc., 1980. Spring 1999 49 but there is overlap between systems depending on subsurface conditions, fluid types, required rates, well inclination angles, depths, comple- tion configurations, lift-system hardware and surface facilities. Lift optimization to get the most fluid from a well or field at the lowest cost offers opportuni- ties for substantial production gains in new wells or mature fields. When selecting and designing lift systems, engineers must consider reservoir and well parameters, but field development strategies should be factored in as well. Artificial-lift selection is specialized and often tedious, but guidelines provide the relative appli- cability of each method (previous page) . 1 Artificial-lift technology is well established, but new developments continue to play a role in solving problems and meeting production chal- lenges. Recent improvements reduce lifting costs through system components that resist hostile environments, optimize power usage and improve reliability. Alternative means of deploying lift systems allow profitable production from previ- ously uneconomic wells or fields. Traditional arti- ficial-lift limits are expanded by using more than one lift method in the same well, such as gas lift or jet pumps combined with electric submersible pumps and progressing cavity pumps driven by electric submersible motors. This article reviews basic lift systems, discusses high-volume artifi- cial lift and presents selection, design and opti- mization strategies along with new gas-lift and submersible technology. < Artificial-lift selection. Making artificial-lift decisions is primarily a process of choosing the lift methods most applicable to expected sur- face, reservoir, production, fluid and operational conditions. This table provides applicability values and selection criteria or conditions for the basic forms of artificial lift. To choose a method that meets production requirements, select the range that applies— good to excellent (1), fair to good (2) and not recommended or poor (3)— for key criteria, tally these values and weigh the results.