Coring tool

A coring tool adapted to be mounted at a lower end of a drill string for cutting and catching a subterranean core, comprising:

• outer barrel means including a hollow drill bit disposed at a lower end of said barrel means and adapted to be rotated about a vertical longitudinal axis for cutting a core, and
• inner barrel means disposed coaxially within said outer barrel means and including:
• a jaw-carrier sleeve mounted for longitudinal displacement relative to said outer barrel means and including a downwardly facing stop surface, and a pair of pivotably mounted jaws arranged to be swung laterally inwardly from a rest position to a core catching position,
• a jaw closing sleeve having an upwardly and inwardly inclined lower surface arranged above and in a longitudinal path of travel of said jaws,
• said jaw carrier sleeve arranged to be upwardly displaceable relative to said jaw closing sleeve,
• a bearing ring disposed coaxially with and radially between said jaw-carrier sleeve and said outer barrel means at an elevation above said jaws, said bearing ring being operably connected to said jaw closing sleeve by means of radial keys passing through longitudinally elongate slots in said jaw-carrying sleeve, said bearing ring carrying bearing means permitting said outer barrel means to rotate relative to said inner barrel means,
• a driver sleeve disposed coaxially within said jaw carrying sleeve and extending downwardly past said jaws to radially cover said jaws during a core cutting operation and including an upwardly facing abutment face, said driver sleeve being arranged to be upwardly displaced relative to both said jaw carrying sleeve and said jaw-closing sleeve in response to the application of upward forces to said driver sleeve by a drill string to radially uncover said jaws and bring said abutment face into engagement with said stop surface to displace said jaw carrying sleeve upwardly such that said jaws are raised into contact with said inclined lower surface of said jaw closing sleeve and are subjected to a deflecting force therefrom which deflects said jaws from said rest position to said core-catching position,
• said jaw closing sleeve being operably connected to said outer barrel means through said bearing ring such that the weight of said outer barrel means is applied downwardly against said jaws through said jaw closing sleeve.

In a tool insertable into a well bore and including a lower section and an actuating section disposed above said lower section,

• said lower section including coaxially telescoping outer and inner portions, said inner portion being movable vertically relative to said outer portion,
• said actuating section disposed above said lower section and including an outer sleeve assembly operably connected to said outer portion, and an inner sleeve assembly disposed coaxially within said outer sleeve assembly and being operably connected to said inner portion for transmitting vertical forces thereto, said inner sleeve assembly defining a longitudinal fluid passage, and comprising:
• a tubular portion containing a plurality of radial slots and shoulder surface means extending at an acute angle relative to a longitudinal axis of said tubular portion,
• a plurality of radial dogs disposed in said slots and extending radially between said inner and outer sleeve assemblies and being radially movable between a radially outward locking position preventing upward movement of said inner sleeve assembly relative to said outer sleeve assembly and a radially inward unlocking position permitting said inner sleeve assembly to move upwardly relative to said outer sleeve assembly, and
• a dog release member disposed within said fluid passage and including:
• a surface arranged for blocking movement of said dogs from said locking position to said unlocking position,
• a plurality of flexible fingers each including a hook surface extending at an acute angle relative to said longitudinal axis and engaging said shoulder surface means to prevent downward movement of said dog release member, and
• a longitudinal fluid port having an upwardly facing seat adapted to receive a plug dropped from the ground surface for blocking said port until fluid pressure is sufficient to displace said hook surfaces from said shoulder surface means and move said dog release member downwardly to unblock said dogs and permit said dogs to be cammed radially inwardly in response to vertical movement of said inner sleeve assembly relative to said outer sleeve assembly.