Patent ID: 9133690
Filing Date: 2015-09-15
Classification: E21B

Abstract:
1. A method for starting a subsea pump along an oil and gas flow line over a startup period of time while avoiding large pressure drops, comprising, in sequence: a. providing a subsea pump along a flow line in which fluid is flowing and a choke valve capable of being partially closed downstream of the subsea pump; b. partially closing the choke valve so that the choke valve has a choke valve percentage opening to restrict fluid flow through the choke valve; c. starting the subsea pump so that fluid flows through the subsea pump at a subsea pump flow rate and fluid flows through the choke valve downstream of the subsea pump at a choke valve flow rate less than the subsea pump flow rate; d. allowing fluid flowing in the flow line downstream of the subsea pump to be directed through a recirculation loop, wherein the recirculation loop comprises a recirculation pipeline and the recirculation loop intersects the flow line at a first location downstream of the subsea pump and upstream of the choke valve and a second location upstream of the subsea pump and the recirculation loop further comprises a recirculation valve having a recirculation valve percentage opening along the recirculation loop; e. over the startup period of time, increasing the choke valve percentage opening while decreasing the recirculation valve percentage opening; and f. opening a full bore valve in a bypass loop comprising a bypass pipeline, wherein the bypass loop intersects the flow line at a location upstream or coincident with the first location at which the recirculation loop intersects the flow line and a second location downstream of the choke valve, such that fluid is directed to flow through the bypass loop.