Method of drilling wellbore into subterranean geological formation

A method of drilling a wellbore into a subterranean geological formation, comprising:

• drilling the subterranean geological formation to form the wellbore;
• and
• circulating an invert emulsion drilling fluid into the wellbore during the drilling to suspend cuttings formed during the drilling,
• wherein the invert emulsion drilling fluid comprises:
• diesel;
• a primary emulsifier;
• a secondary emulsifier;
• a brine comprising water and a polished brine sludge (PBS) powder comprising halite in an amount of 55 to 75 wt. %, calcite in an amount of 25 to 40 wt. %, and brucite in an amount of 2 to 6 wt. %, based on the total dry weight of the PBS powder;
• at least one viscosifier;
• at least one weighting agent;
• and
• at least one alkali,
• wherein the invert emulsion drilling fluid has an oil-to-water volume ratio of 90:10 to 70:30;
• and
• wherein the invert emulsion drilling fluid does not comprise calcium chloride,
• wherein the subterranean geological formation is a shale formation and the invert emulsion drilling fluid does not expand shale adjacent to the wellbore.