Assembly and method for jarring a drilling drive pipe into undersea formation

A method for driving a drive pipe into a subsea formation, said method comprising:

• suspending the drive pipe from a drill string;
• moving at least one mass in a direction having an upward component and within the drive pipe;
• accelerating at least one mass relative to the drive pipe, wherein the at least one mass is accelerated within the drive pipe;
• transferring energy from the accelerated at least one mass to the drive pipe;
• isolating the drill string from energy from the accelerated at least one mass;
• and
• removing a core of formation from within the drive pipe after said transferring.

An impact tool for driving a drive pipe into a subsea formation, said impact tool comprising:

• at least one mass adapted to fit within the drive pipe;
• an accelerator of said at least one mass;
• a first body member mechanically communicable with said at least one mass;
• a second body member mechanically communicable with a drill string;
• an actuator of said first and second body members relative to each other;
• a detent of said first and second body members relative to each other;
• and
• a transferror of energy from said at least one mass to the drive pipe,
• wherein said transferror transfers energy after said at least one mass is accelerated by said accelerator, wherein said first body member is a sleeve and said second body member is a mandrel, wherein said actuator comprises at least one lift section between the sleeve and the mandrel, wherein said at least one lift section comprises a lift chamber defined by the mandrel and the sleeve, wherein overpressure within said lift chamber moves the mandrel and the sleeve relative to each other.

An impact tool for driving a drive pipe into a subsea formation, said impact tool comprising:

• at least one mass adapted to fit within the drive pipe;
• an accelerator of said at least one mass;
• a first body member mechanically communicable with said at least one mass;
• a second body member mechanically communicable with a drill string;
• an actuator of said first and second body members relative to each other;
• a detent of said first and second body members relative to each other, wherein said detent comprises:
• a detent chamber filled with a fluid, wherein said detent chamber is in mechanical communication with said first body member;
• a protrusion into said detent chamber, wherein said detent chamber has a first inside dimension in the proximity of the protrusion, wherein said detent chamber has a chamber section on opposite sides of said protrusion, each chamber section having a second inside dimension larger than the first inside dimension;
• a piston within said chamber and in mechanical communication with the second body member, wherein said piston has an outside dimension smaller than the first inside dimension of said detent chamber, whereby fluid flowing between chamber sections is constrained by the piston and the protrusion when the piston is adjacent the protrusion;
• and
• a transferror of energy from said at least one mass to the drive pipe, wherein said transferror transfers energy after said at least one mass is accelerated by said accelerator.

A system for driving a drive pipe into a subsea formation, said system comprising:

• a drill string suspendable from a marine vessel;
• a running tool attachable to said drill string, wherein a top of the drive pipe is connected to said running tool;
• at least one mass adapted to fit within said drive pipe;
• an accelerator of said at least one mass, wherein said accelerator is in mechanical communication with said running tool and said at least one mass;
• and
• a transferror of energy from said at least one mass to the drive pipe, wherein said transferror transfers energy after said at least one mass is accelerated by said accelerator.