Capsule design for the capture of reagents

A method of using a gas control additive to provide gas migration control in a wellbore, the method comprising the steps of:

• mixing the gas control additive with a cement to form a cement slurry, where the gas control additive is formed by the steps of:
• mixing a first solvent, a first monomer, and a surfactant to produce a continuous phase;
• mixing a second solvent, a second monomer, and a scrubbing agent to produce a dispersed phase;
• mixing the continuous phase and the dispersed phase to form a mixture having an emulsion such that the dispersed phase is dispersed as droplets in the continuous phase, where an interface defines the droplets of the dispersed phase dispersed in the continuous phase;
• forming a polymer on the interface of the droplets, such that the polymer forms a semi-permeable membrane around a core, where the core contains the dispersed phase, such that the semi-permeable membrane around the core forms the gas control additive;
• and
• settling the gas control additive from the mixture;
• and
• separating the gas control additive from the mixture using a separation method;
• introducing the cement slurry into the wellbore;
• and
• reacting the scrubbing agent with an antagonistic gas to produce a helper byproduct, where the antagonistic gas migrates from a hydrocarbon-bearing formation into the wellbore and permeates through the semi-permeable membrane to the core of the gas control additive.

A gas control additive for providing gas migration control in a wellbore, the gas control additive comprising:

• a semi-permeable membrane comprising a polymer, the semi-permeable membrane forming a shell with a core, such that the core contains a scrubbing agent, the semi-permeable membrane operable to allow an antagonistic gas to permeate through the membrane into the core;
• and
• the scrubbing agent, the scrubbing agent operable to react with the antagonistic gas that permeates into the core to produce a helper byproduct,
• where the polymer comprises subunits derived from a first monomer including a di-functional amino group and subunits derived from a second monomer including a tri-functional acid chloride.