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Temperature Maintenance for Deep Water Multiphase Flowlines

IP.com Disclosure Number: IPCOM000240210D
Publication Date: 2015-Jan-13
Document File: 2 page(s) / 180K

Publishing Venue

The IP.com Prior Art Database

Abstract

Oil and gas production in deep water marine environments around the world require some method of transferring produced fluids to centralized production facilities that separate oil, gas, and water – i.e., the fluids that are often produced together from an oil reservoir. One method of transfer is through offshore multiphase flow lines usually laid on the sea floor over some distance. These lines operate at high pressures and fluids in them tend to cool from the reservoir temperature to the ambient seawater temperature as they move because of heat loss. This cooling can result in the production of hydrates and the precipitation of waxes. Both of these events may lead to flow assurance issues, and both can ultimately lead to complete loss of production as complete flow line blockage can occur. Current practices to limit these flow assurance problems include minimizing heat loss by using sophisticated insulation / heating systems, minimizing the length of flow lines, injecting chemicals into the flow line to control hydrate and wax formation, and providing dual flow lines to allow round-trip pigging from a surface platform. An alternative method to resolve these flow assurance issues may be to use direct contact heat exchange to keep multiphase flow lines warm.

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Temperature Maintenance for Deep Water Multiphase Flowlines

Oil and gas production in deep water marine environments around the world require some method of transferring produced fluids to centralized production facilities that separate oil, gas, and water - i.e., the fluids that are often produced together from an oil reservoir. One method of transfer is through offshore multiphase flow lines usually laid on the sea floor over some distance. These lines operate at high pressures and fluids in them tend to cool from the reservoir temperature to the ambient seawater temperature as they move because of heat loss. This cooling can result in the production of hydrates and the precipitation of waxes. Both of these events may lead to flow assurance issues, and both can ultimately lead to complete loss of production as complete flow line blockage can occur. Current practices to limit these flow assurance problems include minimizing heat loss by using sophisticated insulation / heating systems, minimizing the length of flow lines, injecting chemicals into the flow line to control hydrate and wax formation, and providing dual flow lines to allow round-trip pigging from a surface platform.

Concept Description

An alternative method to resolve these flow assurance issues may be to use direct contact heat exchange to keep multiphase flow lines warm. This can be done in at least three ways. One way is to install a small diameter bare tubing line inside a much larger flowline when the flowline is first installed. This tubing line can be clamped to the bottom of the flow line or simply lay on the bottom. This line will extend from the production facility to a desired location upstream in the production flow line (e.g., all the way to the well locations). The interior bare line will allow pumping of heated dead oil, heated lpg, heated water / steam, or some other heat-transfer fluid from the production facility to locations upstream in the multiphase production flow line where they can flow directly into the multiphase production flow line and back to the platform. The production facility will include equipment to heat the heat-transfer fluid to the desired temperature before pumping it into the tubing line.

This method will al...