Abstract: The present disclosure relates to cement compositions including Portland cement and volcanic ash. An exemplary cement composition includes about 10 wt % to about 85 wt % of Portland cement, and about 10% by weight of cement (BWOC) to about 70% BWOC of volcanic ash.

Abstract: A method of repairing wellbores includes setting a plug to isolate a wellbore flowpath within a plurality of concentric casing strings, milling a window through a radially innermost casing string of the plurality of concentric casing strings, via a casing milling tool, and radially outward towards one of a plurality of cement columns, cleaning out one of plurality of a cement columns between two of the concentric casing strings to expand the window radially, inserting a solid eutectic alloy into the wellbore flowpath above the plug, heating the solid eutectic alloy, via a heater inserted within the wellbore flowpath, to melt the eutectic alloy and allow the melted eutectic alloy to flow into the window, solidifying the melted eutectic alloy to form a solidified eutectic plug within the window, and drilling out the solidified eutectic plug to restore the wellbore flowpath through the eutectic plug.

Abstract: A method of repairing wellbores includes setting a plug to isolate a wellbore flowpath within a plurality of concentric casing strings, milling a window through a radially innermost casing string of the plurality of concentric casing strings, via a casing milling tool, and radially outward towards one of a plurality of cement columns, cleaning out one of plurality of a cement columns between two of the concentric casing strings to expand the window radially, inserting a solid eutectic alloy into the wellbore flowpath above the plug, heating the solid eutectic alloy, via a heater inserted within the wellbore flowpath, to melt the eutectic alloy and allow the melted eutectic alloy to flow into the window, solidifying the melted eutectic alloy to form a solidified eutectic plug within the window, and drilling out the solidified eutectic plug to restore the wellbore flowpath through the eutectic plug.

Abstract: The present disclosure relates to cement compositions including Portland cement and volcanic ash. An exemplary cement composition includes about 10 wt % to about 85 wt % of Portland cement, and about 10% by weight of cement (BWOC) to about 70% BWOC of volcanic ash.

Abstract: Compositions and methods including a polyaramid-reinforced cement. The polyaramid-reinforced cement may comprise a cement at 100% by weight of blend (bwob); a polyaramide polymer at 0.01% weight of the cement (bwob) to 80% bwob; and water at 30% bwob to 70% bwob. The polyaramid-reinforced cement may be used to produce a cement structure within a wellbore.

Abstract: A method includes running a eutectic alloy system downhole in a wellbore including a first casing string and a second casing string therein, activating a differential valve tool within the second casing to generate a primary annular seal within a casing-casing annulus defined between the first casing string and second casing string, pumping a flushing fluid into the casing-casing annulus above the primary annular seal via a first ported collar, melting a eutectic alloy blanket into a molten alloy within the flushing fluid in the casing-casing annulus via a heater, solidifying the molten alloy to establish a supplemental seal above the primary annular seal in the casing-casing annulus between the first casing string and second casing string, and pumping cement into the casing-casing annulus above the supplemental seal to form a cement column in the casing-casing annulus via a second ported collar.

Abstract: A method of testing and a tester apparatus to determine the axial stress and strain of cements under the temperature and pressures encountered by cement during use in wellbore environments. Using these stress and strain measurements, the Young's Modulus may be established for a material at the encountered temperature and pressure of the wellbore. By combining static tensile strength testing and elasticity measurements of cements, Young's Modulus values for different cement compositions under stresses that are similar to the conditions occurring in an actual wellbore are possible.

Abstract: A method of testing and a tester apparatus to determine the axial stress and strain of cements under the temperature and pressures encountered by cement during use in wellbore environments. Using these stress and strain measurements, the Young's Modulus may be established for a material at the encountered temperature and pressure of the wellbore. By combining static tensile strength testing and elasticity measurements of cements, Young's Modulus values for different cement compositions under stresses that are similar to the conditions occurring in an actual wellbore are possible.

Abstract: The storable, low-density, hydraulically-active, cementitious slurry of the invention is suitable for cementing within a subterranean formation for oil or gas wells. The low-density slurry comprises a hydraulically-active cementitious material, a set retarder, a plasticizer, glass or ceramic micro-spheres, and a strengthening agent. Further the slurry is substantially free of a suspension agent. The storable, low-density, hydraulically-active, cementitious slurry is made by adding glass or ceramic micro-spheres to a hydraulically-active cementitious material, adding a strengthening agent to the microsphere containing composition, and mixing the resulting composition with water, a set retarder, and a plasticizer to generate a slurry, wherein the set retarder is present in an amount sufficient to allow storage of the slurry.

Abstract: A method of testing and a tester apparatus to determine the axial stress and strain of cements under the temperature and pressures encountered by cement during use in wellbore environments. Using these stress and strain measurements, the Young's Modulus may be established for a material at the encountered temperature and pressure of the wellbore. By combining static tensile strength testing and elasticity measurements of cements, Young's Modulus values for different cement compositions under stresses that are similar to the conditions occurring in an actual wellbore are possible.

Abstract: The storable, low-density, hydraulically-active, cementitious slurry of the invention is suitable for cementing within a subterranean formation for oil or gas wells. The low-density slurry comprises a hydraulically-active cementitious material, a set retarder, a plasticizer, glass or ceramic micro-spheres, and a strengthening agent. Further the slurry is substantially free of a suspension agent. The storable, low-density, hydraulically-active, cementitious slurry is made by adding glass or ceramic micro-spheres to a hydraulically-active cementitious material, adding a strengthening agent to the microsphere containing composition, and mixing the resulting composition with water, a set retarder, and a plasticizer to generate a slurry, wherein the set retarder is present in an amount sufficient to allow storage of the slurry.