Abstract: A spacer fluid made of a viscosity thinner, a weighting agent, an antifoaming agent, and a non-ionic surfactant in a base aqueous fluid is disclosed. In some instances, the viscosity thinner is a sulfomethylated tannin, the weighting agent is barium sulfate, the antifoaming agent is a silicone, and the non-ionic surfactant is an ethoxylated alcohol. A method of treating a well bore annulus in preparation of introducing water-based cement slurry into a well bore using the spacer fluid is disclosed. A method of using the spacer fluid to position a first fluid into a well bore annulus of a well bore containing a second fluid is disclosed. A method for fluidly isolating at least a portion of a well bore annulus in a well bore containing an oil-based drilling fluid using water-based cement slurry and the spacer fluid is disclosed.

Abstract: A spacer fluid made of a viscosity thinner, a weighting agent, an antifoaming agent, and a non-ionic surfactant in a base aqueous fluid is disclosed. In some instances, the viscosity thinner is a sulfomethylated tannin, the weighting agent is barium sulfate, the antifoaming agent is a silicone, and the non-ionic surfactant is an ethoxylated alcohol. A method of treating a well bore annulus in preparation of introducing water-based cement slurry into a well bore using the spacer fluid is disclosed. A method of using the spacer fluid to position a first fluid into a well bore annulus of a well bore containing a second fluid is disclosed. A method for fluidly isolating at least a portion of a well bore annulus in a well bore containing an oil-based drilling fluid using water-based cement slurry and the spacer fluid is disclosed.

Abstract: A spacer fluid made of a viscosity thinner, a weighting agent, an antifoaming agent, and a non-ionic surfactant in a base aqueous fluid. In some instances, the viscosity thinner is a sulfomethylated tannin, the weighting agent is barium sulfate, the antifoaming agent is a silicone, and the non-ionic surfactant is an ethoxylated alcohol. A method of treating a well bore annulus in preparation of introducing water-based cement slurry into a well bore using the spacer fluid. A method of using the spacer fluid to position a first fluid into a well bore annulus of a well bore containing a second fluid. A method for fluidly isolating at least a portion of a well bore annulus in a well bore containing an oil-based drilling fluid using water-based cement slurry and the spacer fluid.

Abstract: A well cement composition for plugging a bore at the location for initiating sidetracking to bore a lateral well is formulated as a slurry of hydraulic cement that contains at least two, but preferably all three of the following additives: (1) a source of silicon dioxide, (2) fracturing proppants and (3) an expansion compound selected from the group consisting of 1%-5% crystalline silica and 60%-99% MgO or CaO, and their mixtures.

Abstract: A well cement composition for plugging a bore at the location for initiating sidetracking to bore a lateral well is formulated as a slurry of hydraulic cement that contains at least two, but preferably all three of the following additives: (1) a source of silicon dioxide, (2) fracturing proppants and (3) an expansion compound selected from the group consisting of 1%-5% crystalline silica and 60%-99% MgO or CaO, and their mixtures.

Abstract: A test apparatus for the measurement of expansion and/or shrinkage of a cement test sample during curing under pressure and temperature conditions that simulate downhole oil well conditions isolates the test sample from a first fixed volume of incompressible pressurized liquid using a flexible barrier that forms a wall of a first chamber in a pressure vessel assembly. The first chamber is sealed by a movable piston. A second pressurizing medium is contained in a second chamber on the opposite side of the piston, and is in fluid communication with a pump, whereby the piston is pressure-balanced between the first and the second medium. The piston moves in a bore of the vessel assembly in response to changes in the volume of the test sample during curing and the amount of linear movement of the piston is detected by a sensor system that measures, correlates and transmits any change in the position of the piston as a change in the sample volume for display and recording.