In connection with upstream and midstream oil and gas production, pumps perform a large variety of services enabling gathering and processing of hydrocarbons and their derivates for the benefit of industrial users and consumers. These pumps are traditionally divided into two categories or principles: hydrodynamic and positive displacement pumps.
These two technologies have both different and sometime complementary use in oil and gas production and processing. They hydrodynamic pump – the more commonly used – is the traditional single stage or multistage centrifugal pump. It is applied primarily to handle lighter hydrocarbons and water, typically at higher flow rates. The positive displacement pump services more viscous and gas entrained liquids at higher pressure and often under difficult suction conditions. Special types of positive displacement pumps include high pressure piston pumps used in drilling and hydraulic fracking operations.
We are publishing a series of blogs that will focus on the application of rotary positive displacement pumps and, more precisely, the rotary screw pump. Much of what is to be discussed could apply to gear pumps, van pumps, lobe pumps, progressive cavity (PC) pumps, piston & plunger pumps, all of which are a part of the positive displacement pump family.
The oil and gas industry is facing increasing demands for operational flexibility, increased performance and better efficiency. Screw pumps are now playing a larger role in areas that have traditionally been dominated by centrifugal and reciprocating pumps. This is due in large part to the technology innovations and product improvements by screw pump manufacturers.
The screw pump has become more commonly used as the industry increasingly moves towards producing more difficult assets with hydrocarbons at higher viscosity. Additionally, oil and water emulsions and associated gas make it possible to add late life production and added total recovery.
Presently, both twin-screw and three-screw pumps are operating with success in upstream and midstream applications with condensates, multiphase and high gas entrainment fluids as well as with heavy crude and crude oil/water emulsions.
The oil and gas industry is gearing up to produce, transport and refine more non-traditional grades of hydrocarbons. The huge recoverable deposits of heavier and unconventional grades of crude oil from all over the world – specifically in Canada, California, other parts of the US, Mexico and South America – play an increasingly important role in the future.
Typically, the crude oil from these areas is highly viscous, often requiring blending with a diluent or heating using steam or other means of treatment. This is just to get the oil to flow from the wellsite to the processing facility. On the other side of the spectrum, the production of lighter oils from shale and tight oil demands pumps that can handle oils with low vapor pressure, gas entrainment and flashing problems.
The gas tolerant screw pump technology has emerged as a viable alternative to other technologies and is often called upon to meet many of these challenges. The use of screw pumps where liquids with high gas fractions are produced – also known as multiphase production – is a fast-growing area.