Patent ID: 6119772
Filing Date: 2000-09-19
Classification: E21B

Abstract:
A continuous flow apparatus for maintaining drilling fluid flow at high pressure in a drill string while adding or removing joints of drill string, the apparatus comprising:(a) a cylinder which defines an expandable chamber around a threaded connection of an upper joint and a lower joint of drill string;(b) an inlet for flowing drilling fluid into said chamber;(c) an outlet for flowing drilling fluid out of said chamber; and(d) a partition means for partitioning said chamber into an upper sub chamber and a lower sub chamber between a disconnected connection of said upper and lower joints, wherein(i) with said connection connected, drilling fluid flows at high pressure through said upper and lower joints and downward through said drill string,(ii) with said connection disconnected, drilling fluidflows at high pressure through said inlet into said lower sub chamber and through said lower joint and downward through said drill string,and flows at low pressure through said upper joint and through said upper sub chamber and through said outlet, and(iii) said chamber expands upon disconnecting said connection therebyallowing said chamber to be partitioned with said partition means,and compensating for a pressure differential between said upper sub chamber and said lower sub chamber.