Abstract: Magnesium oxysulfate cement compositions and methods for controlling and preventing fluid and gas flow through a wellbore are described. The compositions and methods may be implemented to provide a barrier to fluid and gas flow between casings or in other operations such as squeeze operations. Magnesium oxysulfate cement compositions may include an admixture of magnesium oxide, magnesium sulfate trihydrate and water. When admixed with water, the compositions rapidly transition from a flowable state to a solid state with formation of little or no gel strength before the transition and further have a near-linear relationship between the time required for the transition to occur and the composition temperature at which the transition occurs enabling the user to determine the time within which the transition will occur. Additives, such as accelerators and inhibitors can be added to modify the time in which the compositions make the transition from flowable state to solid state.

Abstract: Magnesium oxysulfate cement compositions and methods for controlling and preventing fluid and gas flow through a wellbore are described. The compositions and methods may be implemented to provide a barrier to fluid and gas flow between casings or in other operations such as squeeze operations. Magnesium oxysulfate cement compositions may include an admixture of magnesium oxide, magnesium sulfate trihydrate and water. When admixed with water, the compositions rapidly transition from a flowable state to a solid state with formation of little or no gel strength before the transition and further have a near-linear relationship between the time required for the transition to occur and the composition temperature at which the transition occurs enabling the user to determine the time within which the transition will occur. Additives, such as accelerators and inhibitors can be added to modify the time in which the compositions make the transition from flowable state to solid state.

Abstract: Compositions for controlling wellbore fluid and gas invasion including methods for using the compositions. The compositions are initially flowable slurries preferably comprising about 70 to 30% by weight of magnesium oxychloride and about 70 to 30% by weight of water. The compositions undergo a rapid phase transition to form a substantially solid mass with a near-linear relationship between the time required for the phase transition to occur and the composition temperature at which the phase transition occurs thereby permitting accurate determination of the set time. The method includes use of the composition to control the loss of fluids and gases from the wellbore.

Abstract: The disclosure is directed to a composition for controlling wellbore fluid and gas invasion including methods for using said composition. The composition of the invention is a flowable slurry preferably comprising about 70 to 30% by weight of magnesium oxychloride and about 70 to 30% by weight of water. The composition is a flowable slurry at composition temperatures below about 60° C. and sets to form a substantially solid mass upon reaching a composition temperature of about 60-68° C. The phase transition is rapid, thereby limiting or avoiding formation of gel states which contribute to incomplete wellbore seals. The rapid set of the slurry further avoids invasive contamination of earthen formations surrounding the wellbore. The composition has a near-linear relationship between the time required for the phase transition to occur and the composition temperature at which the phase transition occurs.