The present disclosure describes methods and systems for downhole well integrity reconstruction in a hydrocarbon reservoir. One method for downhole well integrity reconstruction in a hydrocarbon reservoir includes: positioning, a laser head at a first subterranean location, wherein the laser head is attached to a tubular inside of a wellbore; directing, by the laser head, a laser beam towards a leak on the wellbore; and sealing the leak using the laser beam.

A downhole tool includes a top sub-assembly that couples to a downhole conveyance and a housing. The housing includes a bore that extends through the housing from the top sub-assembly to a downhole end of the housing opposite the uphole end, and a plurality of compartments fluidly coupled to the bore. The downhole end of the housing including a tapered portion. At least one of the plurality of compartments includes at least one piston configured to extend away from the housing to forcibly expand at least a portion of a wellbore tubular based at least in part on a fluid pressure in the at least one compartment. The tool includes at least one hydraulic swage coupled to the housing and configured to expand to forcibly expand at least the portion of the wellbore tubular based at least in part on a fluid pressure in the bore.

A downhole tool includes a top sub-assembly that couples to a downhole conveyance and a housing. The housing includes a bore that extends through the housing from the top sub-assembly to a downhole end of the housing opposite the uphole end, and a plurality of compartments fluidly coupled to the bore. The downhole end of the housing including a tapered portion. At least one of the plurality of compartments includes at least one piston configured to extend away from the housing to forcibly expand at least a portion of a wellbore tubular based at least in part on a fluid pressure in the at least one compartment. The tool includes at least one hydraulic swage coupled to the housing and configured to expand to forcibly expand at least the portion of the wellbore tubular based at least in part on a fluid pressure in the bore.

An expansion tool includes a housing and a hydraulic power section for stroking a first expander on a pulling mandrel through a bore of an expandable outer clad, the expansion tool including a ratcheting reaction assembly, having a ratchet rack and a ratcheting component thereon, that engages a proximal end of the outer clad to prevent axial movement of the outer clad as the first expander is drawn through a portion of the bore of the outer clad to expand the outer clad. The ratcheting reaction assembly remains engaged with the proximal end of the outer clad as the housing is repositioned uphole to permit staged expansion of the outer clad using the first expander. The expansion tool improves sealing and structure integrity of the expanded outer clad within the casing by maintaining the outer clad in a position throughout the staged expansion process.

A patching construction method using a hydraulic variable-grade expansion tool for blocking during is provided, which includes a conversion joint, a supporting central pipe, a supporting ring, an expansion pipe, pressure gradient piston subs, double female thread connection subs, T-shaped limiting subs, a tapered centering sub, double male thread central shafts, split supporting subs, an expansion cone, a piston sub with male and female threads, a T-shaped ball compressor, a lower U-shaped pressing sleeve, a ball-seat fixing sleeve, a reciprocating spring, a sealing ball seat, a sealing ball, a tapered guide sub, etc. A patching construction method using a hydraulic variable-grade expansion tool for blocking during, omits the conventional expansion cone sealing manner, and designs a variable pressure gradient expansion tool, so that achieves the objectives of low pressure, large expansion force and reliable sealing, avoids drilling out bottom sealing joint, and reduces the risk of expansion failure.

A first aspect of the invention provides a gas or oil well tubing having an annular packer mounted thereon, wherein the annular packer is formed from an eutectic alloy. By prefabricating the annular packer on the tubing it can be placed in situ from the outset and thus can be active by melting at any time to form a eutectic seal quickly and easily. An annular packer with by-pass conduits is also provided to enable cement to be pumped past the annular packer when it is in situ. The annular packer is further provided with conduit clearance means to clear cement from within the conduits.

A first aspect of the invention provides a gas or oil well tubing having an annular packer mounted thereon, wherein the annular packer is formed from an eutectic alloy. By prefabricating the annular packer on the tubing it can be placed in situ from the outset and thus can be active by melting at any time to form a eutectic seal quickly and easily. An annular packer with by-pass conduits is also provided to enable cement to be pumped past the annular packer when it is in situ. The annular packer is further provided with conduit clearance means to clear cement from within the conduits.

Systems and methods for removing and replacing a first sealant in a subterranean well include a running sub located at an end of a running string. A helical guide port extends through the running sub. A port exit of the guide port is at a downhole end of the guide port and extends through a sidewall of the running sub. An inner assembly is extendable through the guide port. A head assembly is located at a drilling end of the inner assembly. The head assembly is sized to pass through the port exit and is oriented to drill a helical path within the first sealant radially exterior of the inner casing and form a void.

Systems and methods for removing and replacing a first sealant in a subterranean well include a running sub located at an end of a running string. A helical guide port extends through the running sub. A port exit of the guide port is at a downhole end of the guide port and extends through a sidewall of the running sub. An inner assembly is extendable through the guide port. A head assembly is located at a drilling end of the inner assembly. The head assembly is sized to pass through the port exit and is oriented to drill a helical path within the first sealant radially exterior of the inner casing and form a void.

A sealing tool for conveyance within a tubular member within a wellbore extending into a subterranean formation. The sealing tool includes a mandrel and a eutectic sealing material disposed about the mandrel. The eutectic sealing material has a eutectic temperature at which the eutectic sealing material melts. The sealing tool also includes means for heating the eutectic sealing material to at least the eutectic temperature. The eutectic sealing material is transferred onto an inner surface of the tubular member by activating the heating means to heat the eutectic sealing material to at least the eutectic temperature to melt the eutectic sealing material.