Geopolymer cementing composition

A method of downhole cementing, the method comprising injecting a geopolymer cementing composition into a borehole in a subterranean geologic formation;

• and
• curing the geopolymer cementing composition,
• wherein the injecting is performed at a borehole temperature of greater than 150° F., and
• wherein the geopolymer cementing composition comprises class F fly ash particles, hematite particles, laponite particles and a binder,
• wherein the wherein the class F fly ash particles comprise:
• 50 to 62.5 wt. % SiO2,
• 25 to 35 wt. % Al2O3,
• 2.5 to 7.5 wt. % CaO,
• 2.5 to 7.5 wt. % Fe2O3,
• 0.5 to 3.5 wt. % TiO2, and
• 0.5 to 3.5 wt. % K2O;
• wherein the laponite particles comprise:
• 52.5 to 65 wt. % SiO2,
• 20 to 35 wt. % MgO,
• 1 to 4 wt. % Na2O, and
• 0.1 to 1.5 wt. % Li2O,
• wherein the binder comprises an aqueous alkaline solution, the aqueous alkaline solution comprising 1 to 8 mol/L of an alkali activator,
• wherein the alkali activator is one or more selected from the group consisting of KOH, NaOH, and Na2SiO3,
• wherein the bottom third of the cured cement has a density of X and a porosity of Y and the top third of the cured cement has a density of 0.75*X to 1.05*X and a porosity of 0.60*Y to 1.10*Y.