Choosing the most efficient artificial lift system is critical to maximizing production in a field. The producer should analyze the operating depth, production volume, temperature, and fluid properties when selecting an artificial pump method. The progressing cavity pump (PCP) is a form of artificial lift that provides additional energy to increase the flow of hydrocarbons to the surface. The product line is comprised of a series of pump models that vary in volume and pressure capabilities in order to maximize production.
A major attribute of PCPs is the ability to efficiently produce viscous and solid-laden heavy fluids. They are capable of functioning in a variety of difficult well environments including: high viscosity, sand, and gas. Baker Hughes PCP systems are supported by engineering, technical, manufacturing, and application experts – ensuring robust, application specific solutions for the most challenging of wells.
Basic Function
The progressing cavity pump is a positive displacement pump that uses progressing sealed cavities to move fluids to the surface. PCPs provide a non-pulsating flow that reduces the risk of emulsifying fluids and by theory these pumps will not gas lock. The combination of the progressing cavity design coupled with high grade materials of construction make the pump ideally suited for producing viscous and/or abrasive fluids.
Progressing cavity pump consists of a helical rotor inside a double helical elastomeric stator. This geometry creates cavities that progress a fixed volume of fluid through the pump as the rotor turns inside the stationary stator. From this theory, the pump does not generate pressure, it withstands pressure. This pump will continue to push fluid until it reaches its mechanical limits.
The point at the bottom of each cavity where the rotor and stator seal the fluid in the cavity is known as the seal line. As the rotor turns, these seal lines follow the profile of the stator, pushing the fluid cavities up the pump. The fluid travels up the pump as one cavity closes and the next opens. Higher fluid volumes are handled by increasing the size of the cavity. The intake and discharge opening areas are constant throughout the rotation of the rotor meaning there is the exact same amount of fluid entering and that there is exiting, giving you a non-pulsating flow.
The Baker Hughes Rod Driven Progressing Cavity Pump, RDPCP, has unique features that differentiate it from the ESPCP. With an RDPCP there is no longer a need for the expensive downhole motor, GRU, seal, and flexshaft since RDPCPs are surface driven. They utilize a prime mover attached to a drivehead that transfers rotational energy to a rod string that turns the rotor downhole. This enables easier troubleshooting since the majority of moving parts are on the surface. P
The RDPCP system includes drivehead equipment options to suit a wide variety of applications with power requirements from 5 to 300 horsepower. The rugged durability of the driveheads makes them applicable in severe environments, including cold weather and desert conditions. Baker Hughes driveheads internalize as many of the vital components as possible to reduce the possibility of damage during installation or maintenance operations. This concept also serves to protect the drivehead from external environmental conditions that can prematurely age exposed equipment. RDPCP systems are applicable in conventional oil and gas applications, waterflood source wells and gas well dewatering operations.
Basic Applications
The rod driven progressing cavity pump (RDPCP) system can be designed to handle sand/abrasion, high gas content, and high viscosity fluid.
Sand and abrasion will wear both the rotor and stator. The rotor and stator used in a particular application will depend on the quantity, angularity, hardness, and size of the solids. Small particles can get stuck in the elastomer and will eventually wear away the rotor. Because wear is proportional to the squared of speed, operating the pump at a lower rpm will increase run life. High differential pressure in the pump will also increase the wear rate. For this reason, if there is a high solid content, the pump should be overstaged (i.e. longer) which will reduce the pressure differential seen in the seal lines. For reference, 10 to 30% sand is considered a high solid content so an overstaged pump is recommended.
Contrary to other forms of artificial lift, PCPs thrive in viscous fluids. The thick fluid allows the rotor/stator fit to be looser, which puts less stress on the elastomer, giving the pump a longer run life. Additionally, in viscous applications the elimination of a sucker rod string accommodates a larger flow area in the production tubing string, lowering flow losses and increasing system efficiencies. Baker Hughes progressing cavity pump systems offer an option where operations demand reliability, repeatable efficiency and an attractive total cost of ownership. The PCP line is comprised of a series of pump models that vary in volume and pressure capabilities in order to maximize production. A selection of elastomers provides additional versatility of application.
Features and benefits
RDPCP Pros:
Thrive in viscous fluid
No downhole motor, GRU, seal, or flexshaft,
Applicable in severe environments
Higher Efficiency
Bear higher BHT than ESPCP
RDPCP Cons:
Limited wellbore deviation
Head loss from rods
typically not used for depths exceeding 6,500 feet
Application Case
Case 1
An operator in Alberta, Canada used a competitor’s rod driven progressing cavity pump system. The horizontal heavy oil well produced for two years but increasing gas levels and difficulties with well draw down required a change.
Based on a history of 90-day average run lives and poor efficiencies, this Canadian well was a good candidate for the Baker Hughes 65-B-3600 PCP pump with LT2000 elastomer. The over-staged pump is designed to handle large amounts of free gas and increase overall system efficiencies by displacing the gas from inside the pump to the annulus. The increase in efficiency allowed the well to be drawn down, providing better inflow of the heavy viscous oil.
With the Baker Hughes RDPCP system, annual revenue jumped from USD 1.6 million to USD 2.1 million and run life rose from 90 days to more than 225 days. Pump efficiency rose from 45% to 85% and production increased from 46 BOPD at 165 rpm to 58 BOPD at 110 rpm. Due to the extended run life and increased system efficiency, the customer installed 25 additional Baker Hughes systems.
Case 2
A customer in California had a heavy oil field that was experiencing extremely high fluid levels in all of its wells. Conventional rod lift pumping units were running at a rate of 10 strokes per minute but were not producing enough to lower the fluid levels. After looking at available data, a conversion well was selected which produced 301 BWPD and 3 BOPD while maintaining a fluid level of 1,542 feet over pump (FOP).
Baker Hughes designed a rod driven progressing cavity pumping (RDPCP™) system equipped with a LIFTEQ™ drivehead —the industry’s most robust drivehead line— manufactured to precise standards with rugged durability for the most severe environments. With the combined advantages and efficiencies of the RDPCP system, Baker Hughes was able to increase water production from 301 BWPD to 1,145 BWPD. Oil production increased from 3 BOPD to 17.4 BOPD while dropping the fluid level from 1,542 to 200 FOP.
石油圈
