Patent ID: 7757771
Filing Date: 2010-07-20
Classification: E21B

Abstract:
1. A method of preparing a subsea well for an inflow test, the method comprising the steps: a) providing on a work string a wellhead seal unit comprising a tubular body having an axial through passage, and a sleeve mounted on the tubular body though which the tubular body can move relative to the sleeve, an outer surface of the sleeve having an engagement surface against which one or more rams of a blow-out preventer are sealingly engageable; b) lining up surface pipe arrangements to take well returns through one or more choke lines in the blow-out preventer; c) sealing rams of the blow-out preventer against the engagement surface of the sleeve around the work string in order to provide a seal between the blow-out preventer and the work string in a subsea well bore; d) pumping fluid lighter than downhole fluid/mud though the work string to displace the downhole fluid/mud, while taking returns through the choke line; e) holding back pressure on the choke line to maintain a bottom hole pressure throughout the displacement; and f) bleeding off back pressure through the choke line via a choke valve to reduce the bottom hole pressure to perform an in-flow test.