Systems and methods for capping a subsea well

Abstract

A method for capping a subsea wellbore comprises (a) identifying a subsea landing site on the BOP or LMRP for connection of a capping stack. In addition, the method comprises (b) preparing the subsea landing site for connection of the capping stack. Further, the method comprises (c) installing a capping stack on to the subsea landing site. Still further, the method comprises (d) shutting in the wellbore with the capping stack after (c).

1 . A method for capping a subsea wellbore, wherein a wellhead of the subsea wellbore is disposed at the sea floor, a subsea blowout preventer (BOP) is mounted to the wellhead, a lower marine riser package (LMRP) is coupled to the BOP, and a riser extends from the LMRP, the method comprising:
 (a) identifying a subsea landing site on the BOP or LMRP for connection of a capping stack;   (b) preparing the subsea landing site for connection of the capping stack;   (c) installing a capping stack on to the subsea landing site; and   (d) shutting in the wellbore with the capping stack after (c).   
     
     
         2 . The method of  claim 1 , wherein the LMRP has an upper end including a riser flex joint connected to the riser, and wherein the subsea landing site is a riser adapter of the riser flex joint. 
     
     
         3 . The method of  claim 2 , wherein (b) comprises removing the riser from the riser flex joint before (c). 
     
     
         4 . The method of  claim 3 , wherein the capping stack has a longitudinal axis, an first end, a second end comprising a mule shoe, and an annular flange axially adjacent the mule shoe;
 wherein (c) comprises:   (c1) inserting the mule shoe into the riser adapter;   (c2) axially advancing the mule shoe into the riser adapter until the annular flange of the capping stack engages a mating annular flange on the riser adapter; and   (c3) securing the annular flange of the capping stack to the annular flange of the riser adapter.   
     
     
         5 . The method of  claim 3 , wherein the capping stack comprises a body and a sealing mechanism, wherein the body has a central axis, a first end, a second end opposite the first end, a main bore extending axially from the first end to the second end, and wherein the sealing mechanism is configured to seal the main bore. 
     
     
         6 . The method of  claim 5 , wherein the capping stack comprises a BOP or a valve spool. 
     
     
         7 . The method of  claim 5 , wherein the capping stack further comprises a plurality of side outlets, each side outlet having a first end in fluid communication with the main bore, a second end distal the body, and a valve disposed between the first end and the second end, wherein each valve is configured to control the flow of fluid through the corresponding side outlet. 
     
     
         8 . The method of  claim 7 , wherein (d) comprises actuating the sealing mechanism to a closed position. 
     
     
         9 . The method of  claim 8 , wherein (d) comprises allowing each valve of the plurality of side outlets to remain in an open position during the actuating of the sealing mechanism of the capping assembly to alleviate pressure on the wellbore. 
     
     
         10 . The method of  claim 9 , wherein (d) comprises sequentially closing each of the valves of the side outlets to completely seal the wellbore. 
     
     
         11 . The method of  claim 5 , wherein (c) further comprises:
 (c1) connecting a transition spool to the riser adapter, wherein the transition spool comprises a longitudinal axis, a first end configured to be coupled to the body of the capping stack, a second end comprising a mule shoe, and an annular flange positioned axially adjacent the mule shoe;   (c2) connecting the capping stack to the transition spool after (c1).   
     
     
         12 . The method of  claim 11 , further comprising plugging an outlet of a mud boost line of the riser adapter. 
     
     
         13 . The method of  claim 11 , wherein (c1) comprises:
 positioning the transition spool laterally offset from the subsea landing site,   moving the transition spool into alignment with the riser adapter, and   urging the transition spool into engagement with the riser adapter; and   
       wherein (c2) comprises:
 positioning the capping stack laterally offset from the subsea landing site, 
 moving the capping stack into alignment with the transition spool, and 
 urging the capping stack into engagement with the transition spool. 
 
     
     
         14 . The method of  claim 5 , wherein the capping stack includes a guidance device at the second end of the capping stack. 
     
     
         15 . The method of  claim 14 , wherein (c) further comprises:
 positioning the capping stack laterally offset from the subsea landing site,   moving the capping stack into alignment with the riser adapter, and   urging the guidance device of the capping stack into engagement with the riser adapter.   
     
     
         16 . The method of  claim 1 , wherein the subsea landing site is a wellhead-type coupling at a first end of the BOP. 
     
     
         17 . The method of  claim 6 , wherein the capping stack comprises a BOP having a wellhead-type coupling at the second end, and wherein (c) comprises connecting the wellhead-type coupling of the capping stack to the subsea landing site. 
     
     
         18 . The method of  claim 5 , wherein (c) comprises using a perforated riser joint coupled to the capping stack to install the capping stack, and allowing hydrocarbons to flow through a plurality of holes in the perforated riser joint. 
     
     
         19 . The method of  claim 5 , wherein (c) comprises injecting a hydrate inhibiting fluid into the main bore of the capping assembly with a hydrate injection system, wherein the hydrate injection system comprises a flow line having an outlet in fluid communication with the main bore of the body. 
     
     
         20 . The method of  claim 1 , further comprising:
 (e) relieving excessive wellbore pressure after (d).   
     
     
         21 . A capping stack for containing a subsea wellbore, comprising:
 a body containing a sealing mechanism, wherein the body has a central axis, a first end, a second end opposite the first end, and a main bore extending axially from the lower end to the upper end, wherein the sealing mechanism is configured to seal the main bore; and   a transition spool having a central axis, a first end releasably connected to the second end of the body, a second end opposite the first end, and a flow bore extending axially between the first end and the second end, wherein the flow bore is in fluid communication with the main bore of the body;   wherein the transition spool includes an annular flange axially disposed between the first end and the second end of the transition spool and a mule shoe extending axially from the second end of the transition spool.   
     
     
         22 . The capping stack of  claim 21 , wherein the capping stack comprises a BOP or a valve spool. 
     
     
         23 . The capping stack of  claim 21 , wherein the first end of the transition spool comprises a wellhead-type connector. 
     
     
         24 . The capping stack of  claim 22 , wherein the BOP comprises one or more sets of opposed rams, wherein each set of opposed rams has an open position with the rams radially withdrawn from the main bore and a closed position with the rams extending radially into the main bore. 
     
     
         25 . The capping stack of  claim 22 , wherein the capping stack further comprises a plurality of side outlets, each side outlet having a first end in fluid communication with the main bore, a second end distal the body, and a valve disposed between the first end and the second end, wherein each valve is configured to control the flow of fluid through the corresponding side outlet. 
     
     
         26 . The capping stack of  claim 25 , wherein the plurality of side outlets are disposed between the valve spool and the transition spool. 
     
     
         27 . The capping stack of  claim 25 , wherein the second end of each side outlet comprises a connector hub, wherein a pressure control device is coupled to at least one of the connector hubs. 
     
     
         28 . The capping stack of  claim 24 , further comprising a pressure transducer configured to measure the pressure of fluid within the main bore of the BOP, wherein the pressure transducer is axially disposed below each of the sets of opposed rams. 
     
     
         29 . The capping stack of  claim 21 , wherein the mule shoe has a tapered end in side view and is configured to be inserted into a flex joint. 
     
     
         30 . The capping stack of  claim 21 , wherein the transition spool includes a plug extending axially from the annular flange, wherein the plug is configured for insertion into an outlet of a mud boost line. 
     
     
         31 . The capping stack of  claim 21 , wherein a guide pin extends axially downward from the annular flange, the guide pin having a frustoconical lower surface. 
     
     
         32 . A method for shutting in a subsea wellbore, wherein a wellhead of the wellbore is disposed on the sea floor, a subsea BOP is mounted to the wellhead, an LMRP is mounted to the BOP, and a riser extends from the LMRP, the method comprising:
 (a) removing the LMRP from the BOP subsea;   (b) lowering a second BOP subsea from a surface vessel to a position laterally adjacent the subsea BOP, wherein the second BOP includes a body having a central axis, an upper end, a lower end, and a main bore extending axially from the lower end to the upper end;   (c) maintaining the second BOP outside of a plume of hydrocarbons formed by the produced hydrocarbons during (b);   (d) moving the second BOP laterally over the subsea BOP after (b);   (e) lowering the second BOP axially downward into engagement with the subsea BOP after (d);   (f) securing the second BOP to the subsea BOP.   
     
     
         33 . The method of  claim 32 , further comprising:
 (g) shutting in the wellbore with the second BOP after (f).   
     
     
         34 . The method of  claim 33 , wherein the second BOP includes one or more sets of opposed rams;
 wherein each set of opposed rams has an open position with the rams radially withdrawn from the main bore and a closed position with the rams extending radially into the main bore; and   wherein (g) comprises closing at least one of the one or more sets of opposed rams.   
     
     
         35 . The method of  claim 33 , wherein the one or more sets of opposed rams comprises a first set of opposed rams and a second set of opposed rams disposed axially above the first set of opposed rams. 
     
     
         36 . The method of  claim 33 , wherein the BOP further comprises a plurality of side outlets, each side outlet having a first end in fluid communication with the main bore axially below the first set of opposed rams, a second end distal the body, and a valve disposed between the first end and the second end, wherein the valve is configured to control the flow of fluid through the side outlet; and 
     
     
         37 . The method of  claim 36 , further comprising:
 (h) monitoring the wellbore pressure during (g);   (i) relieving excessive wellbore pressure by opening the valve in one side outlet.   
     
     
         38 . The method of  claim 32 , further comprising:
 using one or more subsea ROVs to move the second BOP over the subsea BOP in (d).