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The Auger is an in-line, bulk gas : liquid separator, designed to remove a major proportion of free gas from well streams producing a largely de-gassed liquid phase and relatively dry gas. It should be viewed as a means to achieve partial separation of well streams to reduce downstream equipment requirements or de-bottleneck gas constrained systems. The Auger can be installed either as at surface or downhole. As an in-line device its dimensions and weight are very low compared to more conventional separator vessels and it’s installation, particularly as a retro-fit solution is simple and low cost.
The cost of a surface installed Auger is typically no more than 5% of the installed cost of a conventional separator scheme for the same duty.
The Auger technology is marketed and manufactured under a global licence from BP Arco.
downhole application:
The Auger can be used facilitate the use of gas from high pressure wells as a local source of lift gas for low pressure wells on the same remote well site. This removes the need for additional and expensive gas supply line and/or processing infrastructure. The advantage of downhole separation is that, by allowing the gas to flow up the annulus, a higher gas pressure can be achieved if the gas is not subjected to the frictional and heat pressure drops produced by the more viscous and dense liquid phase. If there is sufficient pressure at the wellhead, then a surface installation would attract most economic benefit.
surface and subsea application
The Auger offers a number of applications in topsides or subsea systems:
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conventional
separator de-bottlenecking - Bulk gas removal upstream of a gas constrained separator thereby increasing separator liquid capacity. For example, this might allow the introduction of satellite fluids into an existing separation train with minimal additional process equipment. |
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surface gas scrubbing – Replacement/downsizing of conventional gas scrubbers. Economic and space benefit by replacing or downsizing large conventional gas scrubbers with an Auger. |
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compact degassing capability for a cyclonic partial processing scheme – Pre-separation and Deoiling Hydrocyclones have a limited gas handling capability and an Auger provides a compact and economic solution to pre-condition the feed flow for these types of liquid/liquid separators. |
operating characteristics
The operating principle of the Auger separator is simple. Multiphase fluid enters axially at the base of the unit and is forced to rotate by a stationary double helical vane. The pitch of the vane controls the proportion of the inlet axial velocity converted to a tangential velocity component. The greater the tangential velocity, the greater the radial acceleration field it creates, and thus the higher the radial rate at which the liquid flows to the outer wall by virtue of the phase density difference. A fraction of the gas passes through ports located on the inner wall and is removed via the cross over tubing. The liquid and the remainder of the gas continue and exit axially at the top of the unit. The geometry of the liquid and gas outlets will depend on the application. For an Auger installed downhole, the dry gas fraction will be transferred to the tubing-casing annulus. For surface applications, the denser phase will be allowed to exit at the large diameter outlet at the top of the unit while the lighter phase component will be taken off via an elbow. This ensures that the pressure drop across the separator is minimised.
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auger separator separation
characteristics |
 Click image to enlarge |
The operating characteristics of the Auger depend on the pitch of the helical vane, diameter, length, gas cross over geometry as well as the liquid and gas flowrates. A spreadsheet based model has been developed from theory and experiment which predicts such parameters as pressure drop, radial acceleration field strength, radial settling velocity and residence time. In conjunction with other models that estimate the drop size distributions in two phase pipe flow, the model will also predict liquid carry over in the gas phase.
product range
Cyclotech has Auger designs up to 16” nominal pipe size and in pressure ratings up to ANSI 1500#. Materials of construction can be selected to match the surrounding pipework specification, with the Auger internals in Duplex Stainless Steel, (UNS S31803) or hardened Stainless Steel.
benefits
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No moving parts |
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No maintenance |
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Compact, in terms of space and weight |
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Insensitive to motion |
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Highly flexible construction |
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Low cost compared to conventional technology |
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Pipe installation - vessel design codes do not apply |
contact us if:
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You are intending to De-bottleneck a gas constrained process |
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You have a remote gas-lift application |
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You want to reduce the size of conventional gas : liquid separation equipment |
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You have downhole or subsea separation applications |
