Method of removing hydrogen sulfide from a subterranean geological formation with an imidazolate-based nanomaterial in an oil-based drilling fluid

A method of removing hydrogen sulfide from a subterranean geological formation, comprising:

• mixing a cobalt-imidazolate material with an organic liquid to form a drilling fluid suspension,
• wherein the cobalt-imidazolate material is present in an amount of 0.1 to 2.5 percent by weight of the drilling fluid suspension,
• wherein the cobalt-imidazolate material is a ZIF-67,
• wherein the organic liquid comprises one or more unsaturated oils,
• wherein the drilling fluid suspension has a pH of 10 or more,
• injecting the drilling fluid suspension in the subterranean geological formation,
• circulating the drilling fluid suspension in the subterranean geological formation and forming an oil-based mud;
• and
• scavenging hydrogen sulfide from the subterranean geological formation,
• wherein the hydrogen sulfide reacts with the cobalt-imidazolate material during the scavenging.