Pulsed-power drilling fluid property management using downhole mixer

A downhole drilling system comprising:

• a drill bit;
• and
• a drill string coupled to the drill bit, the drill string including a plurality of subassemblies, at least one subassembly including a downhole mixer comprising:
• a housing having an uphole end and a downhole end;
• a channel to convey a drilling fluid through the housing, the channel including an entrance proximate the uphole end and an exit proximate the downhole end;
• and
• a flow restrictor positioned in the channel between the entrance and the exit, wherein the flow restrictor comprises an elongational flow orifice having a fixed diameter to manage an electrical property of the drilling fluid by creating a pressure drop between the entrance and the exit to increase shear stress in the drilling fluid;
• wherein the elongational flow orifice has a length L and at least a first diameter D1, a second diameter D2, and an average inner diameter D, wherein the length L is at least two times the average inner diameter D.

A method comprising:

• inserting a drill string into a wellbore, the drill string including a plurality of subassemblies, at least one of the subassemblies including a downhole mixer comprising:
• a housing having an uphole end and a downhole end;
• a channel including an entrance proximate the uphole end and an exit proximate the downhole end;
• and
• a flow restrictor positioned in the channel between the entrance and the exit, the flow restrictor including an orifice having a fixed diameter;
• conveying, by the channel of the downhole mixer, a drilling fluid through the at least one subassembly, the drilling fluid having an electrical property;
• shearing, by the flow restrictor of the downhole mixer, the drilling fluid, wherein the shearing increases shear stress in the drilling fluid and manages the electrical property;
• receiving, by a drill bit coupled to the downhole mixer, the drilling fluid from the exit proximate the downhole end, the drill bit including a first electrode and a second electrode;
• and
• in response to the drill bit receiving the drilling fluid:
• generating, by the drill bit, an electrical arc between the first electrode and the second electrode, the electrical arc associated with the electrical property of the drilling fluid;
• directing, by the electrical property of the drilling fluid, the electrical arc into a rock formation at a distal end of the wellbore;
• and
• causing, by the electrical arc of the drill bit, the rock formation at the distal end of the wellbore to fracture.