BHA Surge Relief System

摘要

Disclosed embodiments include a surge relief system for a bottom hole assembly (BHA) and drill bit on an offshore drill string. One embodiment includes flow passages and external ports arranged to manage flow of wellbore fluids during sudden movements of the BHA and drill bit caused by waves. A first relief valve in the first flow passage is disposed to activate at a predetermined pressure to allow flow therethrough. Additional flow passages and pressure relief valves may be sequentially positioned along the length of the BHA/drill bit system to further assist in a managed bleed of pressurized fluid through the surge relief system. The sequential pressure relief valves may have activation pressures that sequentially increase or decrease.

主权项

1. A surge relief system for a drillstring, the surge relief system comprising:
an elongated tubular member having a first end, a second end and an exterior surface, and further having an internal annulus extending between the first and second ends; a drill bit, the drill bit having a proximal end and a distal end and an exterior surface, wherein the proximal end of the drill bit is attached to the second end of the elongated tubular member; a first passage defined in the drill bit, the first passage having a first port at the distal end of the drill bit and a second port in the exterior surface of one of the tubular member or drill bit between the distal end of the drill bit and the first end of the tubular member; a first relief valve disposed in the first passage between the first and second ports; and a non-return valve disposed in the internal annulus of the elongated member.