SURFACE PUMPING SYSTEMS
Surface pumps are used to transfer fluid. Applications and fluid types vary widely, including upstream oil and gas, midstream, and industrial operations. Common fluids include chemicals, hydrocarbons, water, and distillates. The American Petroleum Institute (API) has developed the ISO 13709:2009/API Standard 610 (API 610) as an international set of requirements designed to govern centrifugal pumps in the petroleum, petrochemical, and natural gas industries.
SUMMARY OF API 610 INTERNATIONAL STANDARD
API 610 covers three families of pumps including overhung, between bearing, and vertically suspended designs. This specification is extremely detailed with requirements for basic design, materials, bearings and lubrication, running clearances, pressure casing design, and pressure connections. It also covers accessories, inspection and testing, and vendor data to be provided with the equipment.
Generally speaking, these pump designs are very mature, and requirements within API 610 are based on lessons learned through decades of use. A primary goal of API 610 is reliability, as equipment of this type is required to have a minimum service life of 20 years, and must be designed to operate continuously for at least 3 years without interruption. This is primarily due to the critical nature of petroleum and chemical services, and the fact that these systems are not easily repaired.
THE REALITY OF USING API 610-RATED SYSTEMS
While the API 610 international standard goes a long way to protecting pump vendors, purchasers, the environment, and the public, it focuses on mature pump technologies. With most API 610 systems, users spend a great deal of time and money in efforts to maintain reliability and mitigate risk.
The bottom line is that API 610 pumping systems are complex and complicated. They are difficult to repair, often requiring lengthy downtime to service things like wear rings, impellers, and eroded cases. Whether carried out on site or in the factory, repairs for these complex systems are expensive, time consuming, and too often result in unacceptable levels of downtime.
A BETTER SURFACE PUMPING OPTION
In its introduction, the API 610 international standard states that vendors nor purchasers are prohibited from accepting alternative, engineered pumping solutions, particularly when they use innovative technologies.
Electrical submersible pumping (ESP) systems were developed to help oilfield operators lift more oil out of reservoirs that do not have enough pressure to push hydrocarbons to the surface. ESPs are efficient, rugged, and have been designed to stand up to harsh conditions like high temperatures, fluctuating operating pressures and flow rates, corrosive fluids, and abrasive solids.
Observing some of the problems and delays caused by positive displacement (PD) pumps and split casing pumps (now governed by the API 610 international standard), Baker Hughes saw an opportunity to use proven, effective ESP technology to eliminate many of those problems through design and engineering. The result was the HPump™ surface pumping system.
HPump Surface Pumping System
The HPump™ surface pumping system was designed to transfer fluids in upstream oil and gas, midstream, and industrial operations. This modular pumping system is an alternative to positive displacement and split case pumps.
The HPump system uses adapted CENtrilift™ ESP technology to deliver leak-free, lownoise fluid transfer. The multistage centrifugal pump is combined with a horizontal thrust chamber (HTC) and an industrial foot-mounted electrical motor in a single skid-mounted system. The HPump system is designed for easy transport, and its modular construction enables off-the-shelf component replacement. Common applications include water injection and disposal, CO2 transport and injection, amine transport for natural gas treatment, boiler feed in steam assisted gravity drainage (SAGD) wells, booster pumps, general fluid transfer, and pipelines.
The HPump system represents a paradigm shift in surface pumps. It consists of skidmounted components that can be easily changed, upgraded, repaired, and serviced. Instead of waiting weeks or months for repairs, Hpump components can be switched out in hours or days to mitigate the risk of excessive downtime. Many components are available off the shelf and can be delivered in just a few hours. And the flexible, engineered-for-growth design enables quick replacement and upgrades for common components like the pump, motor, HTC, couplings, and mechanical seals. This enables operators to quickly scale up or down depending on required flow rates and pressures. HPumps can also be configured in series to provide extra power or flow as needed.
A benefit of the simplified, modular HPump design is that it can significantly reduce ultimate fluid transfer costs. The pump is fully contained in a tubular (adapted ESP) housing, greatly simplifying pressure boundaries and protecting against leaks. And the HPump system offers significantly shorter lead times. Instead of the months it can take to have an API 610 system delivered and functional, an HPump system can be up and running in just a couple weeks. This is particularly advantageous when production requirements change rapidly, and when project schedules compress. The reliability of HPump components and ability to easily change them out also eliminates the time and cost required for third-party inspections, documentation, and witness hold points.
Differences between the HPump System and API 610 Systems
There are several key differences between the HPump surface pumping system and API systems. The HPump system does not have the same design characteristics or components as overhung, between bearing, and vertically suspended designs. As such, it is not subject to the same specific regulations covered by the API 610 international standard.
Many of the features and advantages of the HPump system are not addressed by the API 610 international standard, and many of the stated requirements simply do not apply and are not practical in an HPump system. The international standard was written to address pumps that predate HPump technology. The HPump system is derived from and built primarily using ESP downhole pumping equipment.
Capable of reliable operation in harsh, downhole, and even subsea environments, the HPump system features a smaller diameter and longer length than API 610 systems, and uses multiple stages operating at 2-pole speed. It has symmetric impellers/diffusers with little induced radial load. And it features fluid-lubricated bearings throughout the pump to support the shaft (proven to perform in non-traditional ESP fluids such as CO2, amine, NGL, and ammonia among others).
Unlike API 610 systems, the HPump system’s modular design enables replacement of the pump, motor, mechanical seal, and thrust chamber with minimal disturbance to other components on the skid. It also uses separate pump and thrust bearing shafts with a spline coupling connection to improve modularity. Note that our high-capacity HTCs use tilt pad bearings rather than ball bearings. Regardless of flow, pressure, and horsepower requirement changes, the HPump system can be easily upgraded with the appropriate component quickly. This is unheard of in API 610 systems.
The lower system and maintenance cost of the HPump system gives operators the opportunity to install multiple units at the same cost of a single API 610 system. Two HPump systems can operate in parallel to maintain partial capacity, with the second system standing by to provide full redundancy at all times.
HPump System Delivered Four-Year Run Time and Avoided Replacement Pumps
Location: Alberta, Canada
An oil and gas producer in Alberta, Canada required a surface pump to re-inject produced water. The disposal volume was 2,400 BFPD at 1,100 psi discharge. A competitor’s pump failed after only 30 days, caused by fluid starvation and accelerated pump wear. Key issues for pump selection were abrasion resistance, maintenance expense, and the ability to control the speed of the pump using a variable speed drive (VSD).
The operator chose a Baker Hughes 450-hp HPump™ horizontal surface pumping system capable of flow rates up to 24,000 BFPD and an Electrospeed™ VSD to control the pump speed based on tank level.
Since the pump was controlled off tank level, this allowed the operator more flexibility and increased uptime. With changing site conditions and varying amounts of produced fluid, a signal from the tank notified the VSD to increase or decrease the frequency based on the amount of fluid in the tank. This kept the pump within its operating range and eliminated cavitation.
In addition to a significant increase in run life, the HPump system offered higher efficiency and resulted in lower operating costs and increased uptime when compared to competitor pumps. The system prevented replacement pumps due to wear. The Baker Hughes ARMOR™ I internal stage coating along with our abrasion resistant technology were important for enhanced run life. ARMOR I is a fluoropolymer coating designed to prevent buildup of asphaltenes and scale as well as minimize abrasive wear.
With the Baker Hughes solution, the HPump system and Electrospeed VSD delivered a run life of more than 1,460 days.
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