Hydraulic thruster

An expansion system for expanding a casing patch inside a casing of an oil or gas well, comprising:

• a motor;
• a pump, wherein the pump is driven by the motor;
• a hydraulic thruster comprising:
• a cylinder comprising two cylinder pistons,
• a shaft comprising a shaft piston,
• a first pressure chamber, a second pressure chamber, and
• a fluid disposed within the first pressure chamber, within the second pressure chamber, of partially within both the first pressure chamber and the second pressure chamber, wherein the shaft piston is disposed within the cylinder, between the two of cylinder pistons to form the first and second pressure chambers;
• an expansion device coupled to the shaft;
• and a casing patch, wherein the expansion device is in communication with the casing patch;
• wherein upon axial manipulation of the shaft via circulation of the fluid by the pump, the expansion device is displaced in a direction which causes the expansion device to radially expand the patch.

A method of expanding a patch inside a casing of an oil or gas well, comprising:

• (A) providing an expansion tool assembly by coupling a hydraulic thruster system comprising a motor, a pump, and a hydraulic thruster to an expansion system comprising an expansion device and a patch, wherein a shaft disposed within the hydraulic thruster is connected to the expansion device;
• (B) deploying the expansion tool assembly into an oil or gas well;
• (C) pumping a fluid from at least one first pressure chamber disposed within the hydraulic thruster into at least one second pressure chamber disposed within the hydraulic thruster via the pump and motor, wherein the fluid passes through a first and second fluid passage disposed within the shaft;
• (D) allowing the transfer of fluid to axially displace the shaft and the expansion device to which the shaft is connected;
• (E) expanding the patch radially inside a casing of the oil or gas well as a result of the axial displacement of the shaft.