GB991280A - Method and apparatus for drilling an underwater well - Google Patents

Abstract

991,280. Wells; sinking well piping by jetting. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. Sept. 11, 1963 [Sept. 13, 1962], No. 35871/63. Heading E1F. An underwater well is drilled from a platform 11 at the surface 12 of the water by lowering a foundation pipe 21 from the platform to the formation by guide lines 30, 31 attached to the pipe, and sinking the pipe to the desired depth in the formation whilst removing the formation material within the pipe. Weights 22 -- 24 are placed on the pipe to sink it, and material is removed from the interior of the pipe by a pipe string 26 provided with a jetting head 27. The weights and pipe string are removed and a pipe cutter 44 (Fig. 3) is lowered to the pipe 21 on a running string 45, the cutter being detachably positioned within a guide cage 46 which slides down the guide lines. The cage remains on top of the pipe whilst the cutter is lowered and manipulated to sever the pipe section 21a which is removed along the guide lines with the cutter and cage (Fig. 4). A drill string 48 having its bit 49 detachably positioned in the cage is lowered into the pipe, the cage remaining on the pipe or being removed by means of a line 41 during the ensuing drilling. After the hole 50 is drilled (Fig. 8), the string and bit are removed and casing 52 is guided by the cage and guide lines into the pipe and hole on a running string 53, a flange 54 on the casing finally resting on the pipe. When the casing is positioned the string 53 is used to cement the casing to the pipe and the formation. The guide cage (Fig. 13) has slots 60 and channels for the lines, the lines being held in the channels by pins 62. The cage is attached to the cutter, bit or casing 52 by projections 63, 64, the projections 64 pivoting on downward pressure to release the cutter, bit or casing.