Method for managing hydrates in subsea production line
First Claim
1. A method for managing hydrates in a subsea production system, the system having a production facility, an umbilical line for delivering displacement fluids from the production facility, at least one subsea production well, and a single production line for delivering produced fluids to the production facility, comprising:
- producing hydrocarbon fluids from the at least one subsea production well and through the single production line;
shutting in the flow of produced fluids from the at least one subsea well and the production line;
depressurizing the production line to substantially reduce a solution gas concentration in the produced hydrocarbon fluids;
repressurizing the production line to urge any gas remaining in a free-gas phase in the produced fluids within the production line back into solution; and
displacing production fluids within the production line by moving the displacement fluids from a service line within the umbilical line and into the production line, the displacement fluids comprising a hydrocarbon-based fluid having a low dosage hydrate inhibitor (LDHI).
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Abstract
A method for managing hydrates in a subsea production system is provided. The production system includes a host production facility, a control umbilical, at least one subsea production well, and a single production line. The method generally comprises producing hydrocarbon fluids from the at least one subsea production well and through the production line, and then shutting in the production line. In addition, the method includes the steps of depressurizing the production line to substantially reduce a solution gas concentration in the produced hydrocarbon fluids, and then repressurizing the production line to urge any remaining gas in the free gas phase within the production line back into solution. The method also includes displacing production fluids within the production line by moving displacement fluids from a service line within the umbilical line and into the production line. The displacement fluids preferably comprise a hydrocarbon-based fluid having a low dosage hydrate inhibitor (LDHI).
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Citations
23 Claims
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1. A method for managing hydrates in a subsea production system, the system having a production facility, an umbilical line for delivering displacement fluids from the production facility, at least one subsea production well, and a single production line for delivering produced fluids to the production facility, comprising:
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producing hydrocarbon fluids from the at least one subsea production well and through the single production line; shutting in the flow of produced fluids from the at least one subsea well and the production line; depressurizing the production line to substantially reduce a solution gas concentration in the produced hydrocarbon fluids; repressurizing the production line to urge any gas remaining in a free-gas phase in the produced fluids within the production line back into solution; and displacing production fluids within the production line by moving the displacement fluids from a service line within the umbilical line and into the production line, the displacement fluids comprising a hydrocarbon-based fluid having a low dosage hydrate inhibitor (LDHI). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for managing hydrates in a subsea production system, the system having at least one producing subsea well, a jumper for delivering produced fluids from the at least one subsea well to a manifold, a single, insulated production line for delivering produced fluids to a production facility from the manifold, and an umbilical for delivering chemicals to the manifold, the method comprising the steps of:
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placing displacement fluids into a service line within the umbilical, with the service line being tied back to the production facility and the umbilical being in selective fluid communication with the manifold, the displacement fluids comprising a hydrocarbon-based fluid having a low dosage hydrate inhibitor (LDHI); producing hydrocarbon fluids from the at least one producing subsea well and through the single production line; shutting in the flow of produced fluids from the at least one subsea well and through the production line; depressurizing the production line to substantially reduce a solution gas concentration in the produced hydrocarbon fluids; shutting in the flow of produced fluids from the at least one subsea well and through the production line; pumping additional displacement fluid into the service line in order to increase pressure in the production line, thereby pressurizing the production line to urge any remaining free gas phase in the produced fluids in the production line back into solution; pumping further displacement fluid into the service line and into the production line, thereby at least partially displacing produced fluids from the production line without use of a pig; pumping further displacement fluid through the service line and into the production line in order to more fully displace the produced fluids from the production line so as to displace the produced fluids before hydrate formation begins.
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Specification