BHA Surge Relief System

Abstract

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.

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.   
     
     
         2 . The surge relief system of  claim 1 , further comprising:
 a second passage defined along the length of the tubular between the first end of the tubular member and the proximal end of the drill bit, the second passage in fluid communication with the first passage and having a third port defined in the exterior surface of the tubular member;   a second relief valve disposed in the second passage between the first and third ports   
     
     
         3 . The surge relief system of  claim 2 , further comprising:
 A third passage defined along the length of the tubular between the first end of the tubular member and the second port, the third passage in fluid communication with the first and second passages and having a forth port defined in the exterior surface of the tubular member; and   a third relief valve disposed in the second passage between the first and forth ports.   
     
     
         4 . The surge relief system of  claim 2 , wherein the first relief valve is adjacent the second port of the first passage and the second relief valve is adjacent the third port of the second passage. 
     
     
         5 . The surge relief system of  claim 3 , wherein the first relief valve is adjacent the second port of the first passage; the second relief valve is adjacent the third port of the second passage; and the third relief valve is adjacent the forth port of the third passage. 
     
     
         6 . The surge relief system of  claim 2 , wherein the first and second passages are in fluid communication with the annulus. 
     
     
         7 . The surge relief system of  claim 3 , wherein the first, second and third passages are in fluid communication with the annulus. 
     
     
         8 . The surge relief system of  claim 3  further comprising a fourth passage defined in the drill bit and isolated from the first passage, the fourth passage having a fifth port at the distal end of the drill bit and a sixth port between the distal end and the second end of the tubular member; and
 a fourth relief valve disposed in the fourth passage between the fifth and sixth ports. 
 
     
     
         9 . The surge relief system of  claim 2 , wherein the first and second passages are isolated from the annulus. 
     
     
         10 . The surge relief system of  claim 9 , wherein the annulus is in fluid communication with the distal end of the drill bit. 
     
     
         11 . The surge relief system of  claim 9 , wherein the elongated tubular member is a mud motor sub. 
     
     
         12 . 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, 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 between the distal end and the second end of the tubular member;   a first relief valve disposed in the first passage between the first and second ports;   a second passage defined along the length of the tubular between the first end of the tubular member and the proximal end of the drill bit, the second passage in fluid communication with the first passage and having a third port defined in the exterior surface of the tubular member;   a second relief valve disposed in the second passage between the first and third ports;   a third passage defined along the length of the tubular between the first end of the tubular member and the second port, the third passage in fluid communication with the first and second passages and having a forth port defined in the exterior surface of the tubular member;   a third relief valve disposed in the second passage between the first and forth ports; and   a non-return valve disposed in the internal annulus of the elongated member.   
     
     
         13 . The surge relief system of  claim 12 , wherein the first relief valve is adjacent the second port of the first passage; the second relief valve is adjacent the third port of the second passage; and the third relief valve is adjacent the forth port of the third passage. 
     
     
         14 . The surge relief system of  claim 13 , wherein the first, second and third passages are in fluid communication with the annulus. 
     
     
         15 . The surge relief system of  claim 14  further comprising a fourth passage defined in the drill bit and isolated from the first passage, the fourth passage having a fifth port at the distal end of the drill bit and a sixth port between the distal end and the second end of the tubular member; and
 a fourth relief valve disposed in the fourth passage between the fifth and sixth ports. 
 
     
     
         16 . The surge relief system of  claim 14 , wherein the first, second and third passages are isolated from the annulus. 
     
     
         17 . The surge relief system of  claim 16 , wherein the annulus is in fluid communication with the distal end of the drill bit. 
     
     
         18 . A drilling system disposed in a wellbore, the drilling system comprising:
 a drill string comprised of a plurality of elongated tubular members, the drill string having an exterior surface and further having an internal annulus;   a bottom hole assembly attached to the drill string, the bottom hole assembly 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, the internal annulus of the bottom hole assembly being in fluid communication with the internal annulus of the drill string;   a drill bit, the drill bit having a proximal end and a distal end, wherein the proximal end of the drill bit is attached to the second end of the elongated tubular member of the bottom hole assembly;   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 between the distal end and the second end of the tubular member;   a first relief valve disposed in the first passage between the first and second ports;   a second passage defined along the length of the tubular between the first end of the tubular member and the proximal end of the drill bit, the second passage in fluid communication with the first passage and having a third port defined in the exterior surface of the tubular member;   a second relief valve disposed in the second passage between the first and third ports;   a third passage defined along the length of the tubular between the first end of the tubular member and the second port, the third passage in fluid communication with the first and second passages and having a forth port defined in the exterior surface of the tubular member;   a third relief valve disposed in the second passage between the first and forth ports; and   a non-return valve disposed in the internal annulus of the bottom hole assembly or the drill string.   
     
     
         19 . The drilling system of  claim 18 , wherein the first relief valve is adjacent the second port of the first passage; the second relief valve is adjacent the third port of the second passage; and the third relief valve is adjacent the forth port of the third passage; the surge relieve system further comprising a fourth passage defined in the drill bit and isolated from the first passage, the fourth passage having a fifth port at the distal end of the drill bit and a sixth port between the distal end and the second end of the tubular member; and
 a fourth relief valve disposed in the fourth passage between the fifth and sixth ports.   
     
     
         20 . The drilling system of  claim 19 , wherein the elongated tubular member is a mud motor sub, and wherein the first, second and third passages are isolated from the annulus. 
     
     
         21 . A method of drilling a wellbore from an offshore floating platform, the method comprising the steps of:
 moving a drill string in a wellbore when operation of the drill bit is suspended, the drill string including a bottom hole assembly having an elongated tubular member with 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, wherein the proximal end of the drill bit is attached to the second end of the elongated tubular member of the bottom hole assembly; 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 between the distal end and the second end of the tubular member; a first relief valve disposed in the first passage between the first and second ports; a second passage defined along the length of the tubular between the first end of the tubular member and the proximal end of the drill bit, the second passage in fluid communication with the first passage and having a third port defined in the exterior surface of the tubular member; a second relief valve disposed in the second passage between the first and third ports; and a non-return valve disposed in the internal annulus of the drill string;   actuating the non-return valve to seal the annulus when the drill string is tripped into the wellbore;   actuating the first relief valve to allow wellbore fluid to flow therethrough when the wellbore fluid is subjected to a first pressure differential arising from uncontrolled vertical movement of the drill string in the wellbore; and   actuating the second relief valve to allow wellbore fluid to flow therethrough when the wellbore fluid is subjected to a second pressure differential higher than the first differential arising from uncontrolled vertical movement of the drill string in the wellbore.   
     
     
         22 . The method of  claim 21 , wherein flow through an actuated relief valve and associated passage is in a first direction when the vertical movement of the drill string is downward and flow through an actuated relieve valve and associated passage is in a second direction when the vertical movement of the drill string is upward.