Circulation sub and method for using same

Abstract

A circulation sub including a tubular and a diverter valve are configured to continuously circulate fluid into a drill string. The tubular has a first end connectable to the drill string, a second end connectable to a pipe segment, and a port. The tubular has a fluid path for allowing the fluid to flow from the pipe segment to the drill string and a circulation path for allowing the fluid to flow from the port to the drill string. The diverter valve has a channel in selective fluid communication with the fluid path. The diverter valve is positionable between a flow through position for selectively allowing the fluid to flow through the fluid path and a diversion position for selectively allowing the fluid to flow through the circulation path whereby the fluid may continuously flow through the drill string.

What is claimed is: 
     
         1 . A circulation sub for continuously circulating a fluid through a drill string, the drill string positionable in a wellbore penetrating a subterranean formation, the circulation sub comprising:
 a tubular connectable to the drill string, the tubular having a fluid path and a circulation path therethrough and a port therein, the fluid path extending from an uphole end of the tubular to an interior of the drill string, the port extending through a wall of the tubular and to the fluid path; and   a diverter valve comprising a piston slidably movable in the tubular to selectively divert the fluid flowing through the tubular, the piston having a channel therethrough, a port end, and a flow end;   the piston positionable between a flow through position wherein the port end selectively blocks the port and the circulation path to allow the fluid to pass from the uphole end to the interior of the drill string, and a diversion position wherein the flow end selectively blocks the fluid path to allow the fluid to flow from the port to the interior of the drill string and prevent the fluid from flowing to the uphole end, whereby the fluid may be continuously passed from the tubular into the drill string.   
     
     
         2 . The circulation sub of  claim 1 , wherein the tubular has a hydraulic port to selectively allow the fluid to flow therein to move the piston. 
     
     
         3 . The circulation sub of  claim 1 , wherein the channel includes an offset piston tube. 
     
     
         4 . The circulation sub of  claim 3  further comprising an offset flow through tube, and wherein the flow end includes a piston seal surface to engage an end of the offset flow through tube. 
     
     
         5 . The circulation sub of  claim 1  further comprising a biasing member to bias the piston to the flow through position, and wherein the flow end includes piston flow paths therethrough. 
     
     
         6 . The circulation sub of  claim 5  further comprising an upper flow through tube, and wherein the flow end includes a seal portion to engage a seal of the upper flow through tube. 
     
     
         7 . A circulation sub for continuously circulating a fluid through a drill string, the drill string positionable in a wellbore penetrating a subterranean formation, the circulation sub comprising:
 a tubular connectable to the drill string, the tubular having a fluid path and a circulation path therethrough and a port therein, the fluid path extending from an uphole end of the tubular to an interior of the drill string, the port extending through a wall of the tubular and to the fluid path; and   a diverter valve comprising a gate valve having a gate flow port therethrough and a gate actuation surface thereon, the gate valve positionable about the fluid path and the circulation path to selectively divert the fluid flowing through the tubular;   the piston positionable between a flow through position wherein the gate actuation surface selectively blocks the port and the circulation path to allow the fluid to pass from the uphole end to the interior of the drill string, and a diversion position wherein the gate valve selectively blocks the fluid path and the gate actuation surface receives the fluid from the port to allow the fluid to flow from the port to the interior of the drill string and prevent the fluid from flowing to the uphole end, whereby the fluid may be continuously passed from the tubular into the drill string.   
     
     
         8 . The circulation sub of  claim 7  wherein the gate actuation surface comprises a sloped surface. 
     
     
         9 . The circulation sub of  claim 8  further comprising a circulation actuator to flow the fluid through the port and onto the sloped gate actuation surface to move the gate valve toward the diversion position. 
     
     
         10 . The circulation sub of  claim 7  further comprising a gate end to be engaged to move the gate valve toward the flow through position. 
     
     
         11 . A circulation sub for continuously circulating a fluid through a drill string, the drill string positionable in a wellbore penetrating a subterranean formation, the circulation sub comprising:
 a tubular connectable to the drill string, the tubular having a fluid path and a circulation path therethrough and a port therein, the fluid path extending from an uphole end of the tubular to an interior of the drill string, the port extending through a wall of the tubular and to the fluid path; and   a diverter valve comprising a drum having an offset flow tube to be selectively aligned with a flow through tube and a circulation tube in the tubular, the drum positionable about the fluid path and the circulation path to selectively divert the fluid flowing through the tubular;   the drum positionable between a flow through position wherein the offset flow tube is rotationally aligned with the flow through tube to selectively block the port and the circulation path to allow the fluid to pass from the uphole end to the interior of the drill string, and a diversion position wherein the offset flow tube is rotationally aligned with the circulation tube to selectively block the fluid path to allow the fluid to flow from the port to the interior of the drill string and prevent the fluid from flowing to the uphole end, whereby the fluid may be continuously passed from the tubular into the drill string.   
     
     
         12 . The circulation sub of  claim 11  further comprising a drum actuator to rotate the drum. 
     
     
         13 . The circulation sub of  claim 12 , wherein the drum actuator comprises a plurality of actuation gears for engaging a plurality of drum gears. 
     
     
         14 . The circulation sub of  claim 11 , wherein the flow through tube and the circulation tube are on the same side of the drum. 
     
     
         15 . The circulation sub of  claim 14 , wherein the flow through tube and the circulation tube are adjacent and parallel.