Patent GB-1367961-A (GB)
Title: Apparatus for drilling and belling underground holes
IPC: E21B3/02
Filed: 1972-06-26
Abstract: 1367961 Boring earth &c SMITH INTERNATIONAL Inc 26 June 1972 [1 Sept 1971] 29905/72 Heading E1F An underreamer bucket 500 (Fig. 28) comprises a cylindrical body 504, having recesses 522, and a cutting bottom 546, blades 508, 509 normally retracted into the recesses and pivoted to the body adjacent the upper ends of the recesses, operating means 510, 511, 512 for extending the blades in unison, a member 514 reciprocable in the body and coupled to the body so as to extend the blades when moved upwardly. The body is connected to a tube 552 and to the bottom which is arranged to cut when the head is rotated in one direction, the blades being arranged to cut when the head is rotated in the other direction. The blades are pivoted to the body by pins 700 and to the arms 510, 511 of the operating means, the frame 512 of the operating means being pivoted to the arms and reciprocated in the body by the member 514. The frame has rollers 688 (Fig. 17) engaging the tube 552, and rods 692 running in grooves 543 (Fig. 16) formed in the body. Each blade has picks 615 carried by holders 614, and the bottom may carry a pilot bit. The bucket has lifting holes 584, 586. The bucket is used in the construction of cast piles which form the legs of a marine drilling platform. Casings 50 (Figs. 2b, 2c, 9a, 9b) are each driven into the sea bed at an inclination to the vertical from a barge, a casing being located at each leg position. A template carrying a drilling derrick and auxiliary apparatus is supported on the casings (Fig. 1, not shown) and the bracket is operated in conjunction with a drill string to drill out the soil from each casing, to extend each hole beyond the end of each casing, and to underream the extended holes. When the bucket is through the casing a sampler is lowered down a pipe 206 in the string and through the bucket to test the soil prior to under reaming. Each hole is filled with concrete and reinforced to form a leg. The string (Figs. 2a, 2b) comprises a swivel 100, a kelly 200, and alternating drill string sections 300, 400 supported by stabilizers 375 and connected to the bucket shaft 506 (Fig. 2c). The swivel (Fig. 3a) comprises a non- rotary housing 104 supporting a rotary centre pipe 112 through which drilling mud flows upwardly to an elbow 106 discharging to a mud tank. Air for gas-lifting the mud in the pipe 112 flows through port 156 in the housing to an annular chamber 152 and downwardly through ducts 158, 159 attached to the housing. Hydraulic fluid from stationary pipes 166 passes to rams 210 mounted on the ktlly through pipes 234 rotating with the kelly. The kelly comprises a tubular casing 220 (Fig. 3b) having longitudinal ribs (not shown) engaging complementary recesses in the rotary table (not shown), and pipes 204, 206 forming continuations of the pipe 112 and the duct 159 res-  pectively. The rams reciprocate a blade actuating rod 209 connected to the member 514, a finger 291 connected to the rod indicating the position of the blades. Each drill string section 300 (Fig. 9a) comprises a pipe 302 for upward flowing mud and connected to the pipe 204, pipes 304 and an enclosing casing 306 having four openings 308, which facilitate lifting of the section. The rod 209 reciprocates in one of the pipes 304 and the gas lift air from the pipe 206 flows downwardly through the other of the pipes 304. Each drill string section 400 (Figs. 9a, 9b) comprises a pipe 402 forming a continuation of a pipe 302, and pipes 404 connected to the pipes 304, and a casing 410 having holes-416 for lifting, holes 418 connecting the interiors of the pipe 402 and the gas lift air pipe 404 so that gas lift air may be injected into the pipe 402 to give the upward flow of mud. The bucket has a shaft 506 connected to the lowest drill string section, the shaft having the pipe 552 which forms a continuation of the pipe 402, and pipes 696, 694 continuing the pipes 404.