Pump technology continues to evolve as market demands spur improved performance in virtually every component of artificial lift systems. Additionally, equipment is now being applied in ‘harsher environments (higher GORs, temperatures, fluid viscosities and more corrosive conditions, etc.) and continual improvements are demanded. These challenges have presented many opportunities for innovation and expanded applications.
Manufacturing Inroads
Today, industry pump providers continue strong R&D efforts to deliver additional value. Metallurgical advancements in materials and coatings, manufacturing improvements, innovative design, better engineering and an expanded knowledge base of field operating conditions have led to numerous developments. Through the use of modern engineering programs, stress loading on pumping unit components can be measured and manufacturing improvements are made on a regular basis to enhance the life expectancy of equipment. New features are constantly being tested and designed for improved lift performance and production power. Providers also employ modern manufacturing techniques for building better products using NC machines, 3D drafting that transfers to the foundry and CFD software and analysis before final designs are executed.
At Weatherford, rod pumping advancements have continued in gauging technology along with major strides in metallurgy and coatings. Advancements in component design and looser fit plungers are now precluding solids interference resulting in longer run times and fewer failures.
In the ESP market, Jack Semon, Global Marketing Manager for Wood Group ESP says manufacturers have doubled ESP system run lives in the last 10 years primarily due to system-design engineering expertise and improved equipment/well maintenance procedures. One example is the use of soft starters to change motor torque through reduced voltage that isn’t detrimental to the equipment.
Niche Markets Develop
To maximize production across a wide range of reservoir conditions, service providers continue to find unique solutions. Schlumberger has developed the REDA Maximus ESP system. The system significantly reduces the early run failures of conventional ESPs and arrives onsite preshimmed and prefilled with oil from a controlled environment, eliminating these difficult tasks at the wellsite with rig-time savings during installation. The REDA Maximus system is ideal for extreme cold-weather operations.
A niche for beam pumping also continues to grow. According to Lufkin’s DeWayne Atwell, “We’re seeing deliquification of gas wells or dewatering gas wells as a prominent and growing market involving 50% of our installations today. You may have a well 10-15,000 ft deep and if you can remove 20 barrels a day of water to improve gas production, it may be economical.” Also, a growing number of coal bed methane, gas shale or other forms of unconventional type gas producing wells are being equipped with beam pumping systems.
Downhole Flexibility More Common
In some wells, the coning and entry of water causes the fluid volume to increase over time. Weatherford’s VP Elastomers Bill Lane states, “For this reason some customers are moving toward technologies which allow pump sizes to be easily changed. Reciprocating rod pumps and progressive cavity pumps are now available in “insert” configurations whereby the pumps can be easily replaced without having to pull the production tubing. Hydraulic pumps are pumped down the tubing into position and return by reversing the flow, so sizing can be changed easily. Gas lift valves orifices can be changed to adjust flow rates. Some companies even offer adjustable orifice valves that can be changed remotely from the surface.”
New Applications
In other new applications, Jim Pipes, Hydraulic Global Business Unit Manager from Weatherford, indicates that piston pumps are being used as downhole disposal pumps for multiple reservoirs. Jet pumps for producing gas wells are also seeing growth because of their ability to reduce wellhead backpressures. The further deliquification of gas wells including removing fracturing fluids from gas reservoirs, dewatering CBM reservoirs, and the need to maintain water head off depleted gas wells have all spurred involvement in lift technologies to provide solutions. High water cut wells are more economic at today’s oil prices. In the past, 50% of water to oil was a threshold. Now 80% wells are not uncommon.
Another opportunity for lift technologies is the ability to produce from multiple zones simultaneously using complex completion jewelry and the remote activation of completion components to facilitate this.
With the dynamics of the industry, there is additionally a market shift towards heavy oil caused by 1) continued depletion of medium and lighter oils as demand for oil usage increases, and 2) improved technologies for producing heavy oils. Lift technologies are also focused on this need.
ESP Advances
Electrically driven downhole pumps have advanced considerably during the past decades but operators still want them to produce larger volumes from greater depths. The ability to do this is mostly limited by horsepower. Thirty years ago 600 HP was an unusual application. Today, 600 HP is common and the industry has in some cases delivered 1600 HP units. Operators project a need for 2000 HP in the near future, when technology is available.
The ability to operate at higher bottomhole temperatures (BHT) is also a growing requirement for ESPs. In the past, a BHT of 230º F was the practical upper limit for most systems. Today, a BHT of 280º F is common and some specialized ESP systems are operating above 400º F.
ESPs have improved steadily in their ability to handle higher Vapor to Liquid Ratios as gas-handling technologies have made major strides. The GOR (gas/oil ratio of wellbore) is one issue where progress has been made. Centrilift introduced gas separators in the 70s and its third generation GasMaster® now features several new technologies that raise the total flow rate through the separator into the pump while providing improved efficiency to separate free gas before it gets to the pump. A new MVP® multi-vane pump design with a steep vane exit angle, a split vane and oversized balance holes, now allows for more flexibility in gas handling and better pumping efficiency in fluids with high gas contents.
The ability to handle abrasive fluids has also improved says John Bearden of Centrilift. “When you use a pump, you’re pumping whatever flows in the wellbore. Frac sands, natural sands, and abrasive particle quartzites tend to wear out a pump when you’re rotating at 3600 RPM. Materials advancements on the abrasives handling side of our systems have really helped. A few years ago, we introduced the Centurion® pump line with abrasion technology. We replaced softer cast materials with harder carbide materials. We now have carbide on carbide. Hard on hard. The main trade off with carbides is always cost vs. performance. Some pumps are expensive, but not in comparison to the money spent to pull, trip a unit/pump and in terms of lost production.”
Another advancement is the development of “variable speed drive” technology to improve ESP control rate flexibility by adjusting motor speed and thus, the volume range. When well conditions change, this capability lowers costs by eliminating the need to resize the pump. Variable speed drives also provide the optimum flow rate to avoid pump off and cycling problems, extending pump life.
