Method of drilling and completing wells

A method of drilling a borehole from a cased hole comprising:

• (a) positioning a stationary string in said cased hole, said stationary string having detachably attached thereto a drilling assembly, said drilling assembly having a drill bit at an end thereof for drilling the borehole;
• (b) conveying a secondary string in the cased hole, said secondary string adapted to detach the drilling assembly from the stationary string and attach it to the secondary string, said secondary string further adapted to activate the drilling assembly to cause the drill bit to drill the borehole when said drilling assembly is detached from the stationary string;
• and
• (c) activating the drilling assembly by utilizing the secondary string to drill the borehole past the cased hole.

An assembly for completing a well in a subterranean reservoir, the well containing a cased hole portion with production tubing placed concentrically therein, said production tubing attached to an isolation safety member for isolating the well from a reservoir pressure, the assembly comprising:

• (a) a secondary string adapted to be positioned in the stationary string at a first position;
• (b) a completion assembly attached to said secondary string for completing said well, said completion assembly including a perforating device for perforating the well;
• and
• (c) a detachment member, operably associated with said completion assembly, said detachment member enabling detaching said completion assembly from said secondary string and attaching the completion assembly to said stationary string at a second position spaced apart from the first position.

An assembly for completing a well, said well containing a cased hole portion, the assembly comprising:

• (a) a production string disposed concentrically within said cased hole portion, wherein said production string is attached to an isolation safety member for isolating the well from a reservoir pressure;
• (b) a completion assembly, operably connected to said stationary string, for completing said well to a target reservoir and wherein said completion assembly contains a perforating device;
• and
• (c) a lowering device, attached to said stationary string, for selectively lowering said completion assembly to a first and a second spaced apart position in said well.

A method for forming a wellbore, comprising:

• (a) positioning a stationary string at a desired position within the wellbore, the stationary string having a detachable assembly which is adapted to perform a desired downhole operation in the wellbore;
• (b) positioning a secondary string in the stationary string, said secondary string having a device attached thereto for detaching the assembly from the stationary string and for attaching the assembly to the secondary string;
• (c) detaching the assembly from the stationary string and attaching it to the secondary string;
• and
• (d) moving the secondary string so as to move the assembly to a second position in the wellbore;
• and
• (e) operating the assembly to perform the desired bottomhole operation at the second position.

A method for forming a wellbore, comprising:

• (a) positioning a stationary string at a desired position within the wellbore, the stationary string having a detachable bottomhole assembly containing
• (i) a perforating device for perforating the wellbore formation,
• (ii) a device for preventing sand from entering from the wellbore into the stationary string,
• (iii) a packer for providing a seal between the stationary string and the wellbore formation;
• (b) activating the perforating device to perforate the wellbore;
• (c) detaching the bottomhole assembly from the stationary string by a secondary string and attaching it to the secondary string;
• (d) repositioning the bottomhole assembly so as to place the debris preventing device adjacent the perforations in the wellbore;
• and
• (e) sealing a region on either side of the perforations in the wellbore by the packer.

A method for drilling a wellbore, comprising:

• (a) drilling an initial portion of the wellbore;
• (b) positioning a first string at a desired position within the initial portion of the wellbore, the first string having attached thereto a bottomhole assembly for performing a desired downhole operation, the first string further having a first device that enables a second string having a second device to detach the bottomhole assembly from the first string and attach it to the second string within the wellbore;
• (c) detaching the bottomhole assembly from the first string and attaching it to the second string;
• (d) moving the second string in the wellbore to position the bottomhole assembly at a second position in the wellbore;
• and
• (d) operating the bottomhole assembly to perform the desired operation at the second position.