Method and apparatus for setting an underwater drilling system

An underwater conductor pipe drilling system comprising:

• a conductor pipe having a head housing formed at the upper end thereof;
• a drill string disposed within said conductor pipe, said drill strng having a drill bit and underreamer on the lower end thereof, means for rotating said drill bit and underreamer, a lower latch sub disposed above said rotating means, and an upper latch sub axially spaced above said lower latch sub;
• an annular housing latch releasably mounted within said head housing of said conductor pipe and having said drill string adjustably extending therethrough, said housing latch including outer retractable pin means for releasably securing said housing within said head housing of said conductor pipe such that said drill string and said housing latch may be selectively released from said conductor pipe and inner retractable pin means for adjustably securing said drill string within said housing latch such that said drill string may be selectively adjusted from an extended position with said drill bit and underreamer extending below the lower end of said conductor pipe wherein said housing latch engages said upper latch sub to a retracted position with said drill bit and underreamer disposed within said conductor pipe wherein said housing latch engages said lower latch sub;
• said outer retractable pin means for releasably securing said housing latch to said head housing including at least one outer release pin selectively extendable radially outwardly from said housing latch to releasably engage said head housing;
• and
• said inner retractable pin means for adjustably securing said drill string within said housing latch including at least one inner release pin selectively extendable radially inwardly from said housing latch to selectively engage said upper latch sub and said lower latch sub of said drill string.

A method for setting an underwater conductor pipe system comprising the steps of:

• positioning a conductor pipe in surrounding relation to a portion of a drill string with the formation cutting means on the lower end of said drill string extending below the bottom of said conductor pipe, said conductor pipe supported from an upper latch sub disposed within said drill string, said conductor pipe connected to said drill string by a housing latch selectively detachably connected to the upper end of said conductor pipe, said housing latch selectively engaging said upper latch sub of said drill string;
• lowering said drill string with said conductor pipe thereon in a body of water;
• activating said formation cutting means of said drill string to drill a hole in the earth at the bottom of the body of water so that as the hole is drilled and said drill string is lowered, said conductor pipe is lowered into the hole;
• releasing the connection between said housing latch and said upper latch sub of said drill string;
• raising said drill string relative to said housing latch and conductor pipe until a lower latch sub disposed within said drill string intermediate said formation cutting means and said upper latch sub lockingly seats within said housing latch thereby retracting said formation cutting means into said conductor pipe and sealing between said drill string and said conductor pipe;
• cementing around the exterior of said conductor pipe in the drilled hole;
• releasing the connection between said housing latch and said conductor pipe;
• and
• recovering said drill string with said formation cutting means by extracting said drill string and said housing latch from said conductor pipe.

A method for setting an underwater conductor pipe system comprising the steps of:

• positioning a conductor pipe having a head housing at the upper end thereof in surrounding relation to a portion of a drill string with formation cutting means on the lower end of said drill string extending below the bottom end of said conductor pipe, said conductor pipe having an annular housing latch detachably disposed within said head housing of said conductor pipe, said housing latch selectively detachably connected to an upper latch sub disposed within said drill string wherein said annular housing latch is selectively detachably connected to said head housing of said conductor pipe by outer retractable pin means of said housing latch and said annular housing latch is selectively detachably connected to said upper latch sub of said drill string by inner retractable pin means of said housing latch;
• lowering said drill string with said conductor pipe thereon in a body of water;
• activating said formation cutting means of said drill string to drill a hole in the earth at the bottom of the body of water so that as the hole is drilled and said drill string is lowered, said conductor pipe is lowered into the hole until a guide base fixedly secured to the upper end of said conductor pipe engages the bottom of the body of water;
• retracting said inner pin means of said housing latch to detach said upper latch sub of said drill string from said housing latch;
• raising said drill string relative to said housing latch and conductor pipe until a lower latch sub disposed within said drill string intermediate said formation cutting means and said upper latch sub lockingly seats within said housing latch thereby retracting said formation cutting means into said conductor pipe, said lower latch sub including retractable dogs and an annular shoulder adapted to engage said housing latch, said inner pin means being extended to lockingly engage said lower latch sub within said housing latch;
• cementing around the exterior of said conductor pipe in the drilled hole;
• retracting said outer pin means of said housing latch to release said housing latch from said head housing of said conductor pipe;
• and
• recovering said drill string with said formation cutting means by extracting said drill string and said housing latch from said conductor pipe.