What are the issues caused by changes in pressure of gas cap during well startup?
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With gas, the Joule Thompson effect may give temperatures far below 0 °C due to high pressure drop over production choke valves during startup. During shutdown of a well, the upper part of the well tubing, will cool down rapidly because the ambient formation temperature is near to the seawater temperature, if the tubing is not thermally insulated and the tubing is gas filled. This can give the following problems:
During depressurization, severe cooling may be caused by isentropic expansion (lost expansion work for the fluid at the entrance of the pipe which "pushes" i.e. does work on the fluid downstream, due to expansion ) in addition to the Joule-Thompson cooling. This may give temperatures below minimum design.
1.0 ScopeThis Specification defines the requirements for manufacturing, testing, inspecting, marking, and shipping of steel line pipe for gas and …