Carbon-nanotube-polymer nanocomposites enable wellbore cements to better inhibit gas migration and enhance sustainability of natural gas reservoirs

Abstract Polymers coupled with carbon nanotubes to form polymer-nanocomposite particles are useful additives for gas wellbore cements in enabling them to better inhibit formation gas migration through cemented annular spaces. Successfully installing a cement sheath around steal casing in natural gas wells is a challenge due to substantial variations in subsurface pressures and temperatures with depth. It is essential for wellbore cements to achieve adequate bonding with the rock formations and casing to prevent the formation of micro-annuli that provide potential upward migration routes for formation gas. More elastic cements are able to provide adequate strength and flexibility are better suited to this task. Carbon nanotubes synthesized in a methyl methacrylate polymer matrix to form a polymer-nanocomposite display excellent properties as wellbore cement additives. Such additives improve the rheology, mechanical strength, flexibility, and bonding abilities, while reducing fluid losses, of the treated cements. The nanocomposite latex structure inhibits the formation of micro-fissures during the transient conditions through which the cement passes from a liquid to a solid state. Significantly, these polymer-nanocomposite additives also reduce shrinkage, porosity, and permeability of treated cements. Such features make it ideally suited to better inhibit gas migration in the annular wellbore space. Sealing the annular spaces of wellbores with such cements offers the potential for longer-lasting wells that are less prone to suffer from gas leakage over time. Banner headline Gas wellbore cements dosed with polymer-nanocomposite additives, including carbon nanotubes, offer the potential to better inhibit gas migration upward through the cemented annular space. Such additives are able to improve the rheology, mechanical strength, flexibility, and bonding abilities, while reducing fluid losses, of the treated cements. Their reduced shrinkage, porosity, and permeability enable them to bond more effectively with the rock formation, inhibit the formation of micro-annuli and better isolate formation gas.