Apparatus and method for melting metal in the annulus of an oil or gas well and thereby sealing the annulus to prevent shallow gas leakage and the like. Conveniently, eutectic metal is positioned within the annulus between the production and surface casing of the well and above the well cement. An electrical inductive tool is lowered into position and used to provide the necessary heat to melt the metal. The electrical inductive tool may be removed following the sealing of the annulus. Radioactive tracers may be used with the eutectic metal to confirm the desired location for the melt to occur.

Method and apparatus for melting a material and squeezing the melted material through casing perforations into a fault within the cement or formation of an oil or gas well. A heating tool carries solid material which is melted at depth within the well and adjacent to the casing perforations. The liquefied material is forced through the perforations and into the formation or the well cement. When the material cools and solidifies, the faults become sealed.

A method of centralizing tubulars prior to cementing and subsequent expansion involves using a plurality of telescoping cylinders whose leading or trailing end is closed and which are extended by applied internal pressure in the tubular or some mechanical means. The tubular is expanded from its interior with the cylindrical telescoping members still extended. The cement is pushed all around the tubular due to the centralizers. After the cement is delivered the expansion of the tubular pushes the telescoping members into the borehole wall.

A closed loop heat transfer system located on the surface near the wellhead for transporting hot fluid through a tubing located in the annulus between the well casing and the outer surface of the production string. The tubing extends down along the production string to a coil submerged in the oil reservoir in the vicinity of the production pump and back to the surface for reheating and recirculation. The tubing provides heat transfer from the hot fluid to the production fluid, as well as the downhole pump and the region of the oil reservoir surrounding the pump. The system is preferably operated to transfer enough heat to the oil to prevent paraffins from coagulating and forming deposits on the production string or sucker rods, if used. The higher temperature lowers the viscosity of the oil and increases oil production.

A method, apparatus and system for detecting seismic waves. A sensing apparatus is deployed within a bore hole and may include a source magnet for inducing a magnetic field within a casing of the borehole. An electrical coil is disposed within the magnetic field to sense a change in the magnetic field due to a displacement of the casing. The electrical coil is configured to remain substantially stationary relative to the well bore and its casing along a specified axis such that displacement of the casing induces a change within the magnetic field which may then be sensed by the electrical coil. Additional electrical coils may be similarly utilized to detect changes in the same or other associated magnetic fields along other specified axes. The additional sensor coils may be oriented substantially orthogonally relative to one another so as to detect seismic waves along multiple orthogonal axes in three dimensional space.