Diesel invert emulsion hydrogen sulfide mitigating drilling fluid and method of drilling subterranean geological formation

A method of drilling a subterranean geological formation, comprising:

• driving a drill bit to form a wellbore into the subterranean geological formation thereby producing a formation fluid comprising hydrogen sulfide;
• and
• injecting a drilling fluid into the subterranean geological formation through the wellbore,
• wherein the drilling fluid comprises:
• 0.25 to 2 wt. % of a primary hydrogen sulfide scavenger, which is potassium permanganate, based on a total weight of the drilling fluid;
• an invert emulsion, comprising:
• a continuous phase comprising diesel, and
• a dispersive phase comprising water;
• 2 to 4 wt. % a primary emulsifier;
• 0.25 to 0.50 wt. % a secondary emulsifier;
• 4 to 6 wt. % a viscosifier;
• 0.4 to 0.7 wt. % at least one fluid loss prevention agent;
• 0.6 to 1.0 wt. % a pH adjusting agent comprising an alkali metal base;
• 0.25 to 2 wt. % a clay stabilizer comprising an alkali metal halide salt;
• 0.05 to 0.5 wt. % a filtration rate agent;
• and
• 1 to 3 wt. % a weighting agent;
• wherein the potassium permanganate present in the drilling fluid composition reacts with the hydrogen sulfide present in the formation fluid to produce a dispersion of manganese-containing particles which are at least one selected from the group consisting of manganese sulfide and manganese sulfate.

A drilling fluid, comprising:

• 0.25 to 2 wt. % of a primary hydrogen sulfide scavenger which is potassium permanganate;
• an invert emulsion, comprising:
• a continuous phase comprising diesel, and
• a dispersive phase comprising water,
• 2 to 4 wt. % a primary emulsifier;
• 0.25 to 0.50 wt. % a secondary emulsifier;
• 4 to 6 wt % a viscosifier;
• 0.4 to 0.7 wt. % at least one fluid loss prevention agent;
• 0.6 to 1.0 wt. % a pH adjusting agent comprising an alkali metal base;
• 0.25 to 2 wt. % a clay stabilizer comprising an alkali metal halide salt;
• 0.05 to 0.5 wt. % a filtration rate agent;
• and
• 1 to 3 wt. % a weighting agent;
• wherein the drilling fluid is configured to produce, upon contact with hydrogen sulfide, a dispersion of manganese-containing particles which are at least one selected from the group consisting of manganese sulfide and manganese sulfate.