Shearing sequence for a blowout preventer

Abstract

The present disclosure relates to a system that includes a body surrounding a bore, a first ram disposed adjacent a first end of the body and coupled to a first actuator, a second ram disposed adjacent to a second end opposite the first end of the body and coupled to a second actuator, and a controller communicatively coupled to the first and second actuators. The controller is configured to actuate the first actuator to direct the first ram toward a tubular string disposed in the bore, such that the first ram aligns the tubular string with a first shearing portion of the second ram when the first ram is in an actuated position, and to actuate the second actuator, after actuating the first actuator, to direct the second ram toward the tubular string such that the first and second rams completely cut the tubular string.

1 . A blowout preventer system, comprising:
 a body surrounding a bore configured to enable fluid flow between a wellhead and a drilling riser;   a first ram disposed adjacent a first end of the body, wherein the first ram is coupled to a first actuator;   a second ram disposed adjacent to a second end opposite the first end of the body, wherein the second ram is coupled to a second actuator; and   a controller communicatively coupled to the first actuator and the second actuator, wherein the controller is configured to actuate the first actuator to direct the first ram toward a tubular string disposed in the bore, such that the first ram aligns the tubular string with a first shearing portion of the second ram when the first ram is in an actuated position, and wherein the controller is configured to actuate the second actuator, after actuating the first actuator, to direct the second ram toward the tubular string such that the first ram and the second ram completely cut the tubular string to seal the bore.   
     
     
         2 . The blowout prevention system of  claim 1 , comprising a sequencing valve configured to direct hydraulic fluid toward the first actuator and configured to block a flow of hydraulic fluid toward the second actuator when a first pressure of the hydraulic fluid in the first actuator is below a first threshold pressure. 
     
     
         3 . The blowout prevention system of  claim 2 , wherein the first threshold pressure corresponds to a second pressure of the hydraulic fluid in the first actuator when the first actuator is in the actuated position. 
     
     
         4 . The blowout prevention system of  claim 2 , comprising a piloted check valve configured to direct the hydraulic fluid from the sequencing valve toward the second actuator and configured to block the hydraulic fluid from flowing toward the sequencing valve from the second actuator when a third pressure of the hydraulic fluid in the first actuator meets or exceeds the first threshold pressure. 
     
     
         5 . The blowout prevention system of  claim 4 , wherein the piloted check valve is configured to direct the hydraulic fluid from the second actuator toward the sequencing valve when a fourth pressure of the hydraulic fluid in the second actuator reaches a second threshold pressure. 
     
     
         6 . The blowout prevention system of  claim 2 , comprising a pump configured to drive the hydraulic fluid through the sequencing valve. 
     
     
         7 . The blowout prevention system of  claim 1 , comprising a sensor configured to send feedback to the controller pertaining to a pressure of a fluid at the wellhead, wherein the controller is configured to compare the feedback to a threshold value. 
     
     
         8 . The blowout prevention system of  claim 7 , wherein the controller is configured to actuate one or both of the first and second actuators only when the feedback meets or exceeds the threshold value. 
     
     
         9 . The blowout prevention system of  claim 1 , wherein the first ram comprises a second shearing portion comprising a linear geometry and the first shearing portion of the second ram comprises an indented geometry. 
     
     
         10 . A system, comprising:
 a bore extending between a wellhead and a drilling riser;   a tubular string disposed in the bore and configured to direct a fluid between the wellhead and the drilling riser;   a blowout preventer coupled to the wellhead, wherein the blowout preventer comprises a body surrounding the bore and the tubular string;   a first ram of the blowout preventer positioned on a first side of the bore, wherein the first ram comprises a first shearing portion and is coupled to a first actuator;   a second ram of the blowout preventer positioned on a second side of the bore opposite the first side, wherein the second ram comprises a second shearing portion and is coupled to a second actuator; and   a controller coupled to the first actuator and the second actuator, wherein the controller is configured to actuate the first actuator to direct the first ram toward the tubular string and configured to actuate the second actuator to direct the second ram toward the tubular string after actuating the first actuator.   
     
     
         11 . The system of  claim 10 , comprising a hydraulic circuit configured to flow a hydraulic fluid to and from a hydraulic accumulator, the first actuator, and the second actuator. 
     
     
         12 . The system of  claim 11 , wherein the hydraulic circuit comprises a sequencing valve configured to direct hydraulic fluid toward the first actuator and to block a flow of the hydraulic fluid toward the second actuator when a first pressure of the hydraulic fluid in the first actuator is below a first threshold pressure. 
     
     
         13 . The system of  claim 12 , comprising a piloted check valve configured to direct the hydraulic fluid from the sequencing valve toward the second actuator and block the hydraulic fluid from flowing toward the sequencing valve from the second actuator when a second pressure of the hydraulic fluid in the first actuator meets or exceeds the first threshold pressure. 
     
     
         14 . The system of  claim 13 , wherein the piloted check valve is configured to direct the hydraulic fluid from the second actuator toward the sequencing valve when a third pressure of the hydraulic fluid in the second actuator reaches a second threshold pressure. 
     
     
         15 . The system of  claim 10 , wherein the first shearing portion of the first ram comprises a linear geometry and the second shearing portion of the second ram comprises an indented geometry. 
     
     
         16 . A method, comprising:
 actuating a first ram of a blowout preventer toward a tubular string disposed in a bore of the blowout preventer, wherein the first ram is disposed on a first side of the bore;   aligning the tubular string with a first shearing portion of a second ram disposed on a second side of the bore opposite the first side; and   actuating the second ram toward the tubular string and the first ram, such that the first ram and the second ram cut the tubular string to seal the bore.   
     
     
         17 . The method of  claim 16 , wherein actuating the first ram of the blowout preventer toward a tubular string disposed in the bore of the drilling riser comprises directing hydraulic fluid through a sequencing valve and toward a first actuator coupled to the first ram. 
     
     
         18 . The method of  claim 17 , wherein directing the hydraulic fluid through the first sequencing valve and toward the first actuator coupled to the first ram comprises blocking the hydraulic fluid from flowing toward a second actuator coupled to the second ram when a pressure of the hydraulic fluid in the first actuator is below a threshold pressure. 
     
     
         19 . The method of  claim 18 , wherein actuating the second ram toward the tubular string and the first ram such that the first ram and the second ram completely cut the tubular string to seal the bore comprises directing the hydraulic fluid through the sequencing valve toward the second actuator coupled to the second ram when the pressure of the hydraulic fluid in the first actuator meets or exceeds the threshold pressure. 
     
     
         20 . The method of  claim 16 , wherein aligning the tubular string with the first shearing portion of the second ram disposed on the second side of the bore opposite the first side comprises guiding the tubular string along an inner diameter of the bore, such that the tubular string is aligned with the first shearing portion and a second shearing portion of the first ram with respect to a longitudinal axis.