Torsion resistant gap sub

A gap sub comprising:

• a female part having a female mating section;
• a male part electrically isolated from the female part, the male part having a male mating section and a gap section, the male mating section being inserted into a bore of the female mating section whereby the male and female mating sections overlap in an axial direction and are spaced radially apart from one another to provide a radial gap between the male and female mating sections wherein surfaces of the male and female mating sections facing one another across the radial gap comprise grooves, the grooves on the surface of the male mating section corresponding to the grooves on the surface of the female mating section, forming pairs of corresponding grooves;
• an electrically insulating collar positioned on the gap section;
• and
• a plurality of electrically-insulating bodies located between the overlapping male and female mating sections and spanning between each pair of corresponding grooves in the surfaces of the male and female mating sections such that the male and female parts are mechanically coupled together;
• wherein at least one of the surfaces of the male and female mating sections is formed such that opposing edges of at least one of the corresponding grooves have different elevations;
• and
• wherein at least one groove of at least one of the pairs of corresponding grooves comprises spherical cups formed in one wall of the at least one groove, the shape of the bodies shaped to conform with the spherical cups.

A gap sub comprising:

• a female part having a female mating section;
• a male part electrically isolated from the female part, the male part having a male mating section and a gap section, the male mating section being inserted into a bore of the female mating section whereby the male and female mating sections overlap in an axial direction and are spaced radially apart from one another to provide a radial gap between the male and female mating sections wherein surfaces of the male and female mating sections facing one another across the radial gap comprise grooves, the grooves on the surface of the male mating section corresponding to the grooves on the surface of the female mating section, forming pairs of corresponding grooves;
• an electrically insulating collar positioned on the gap section;
• and
• a plurality of electrically-insulating bodies located between the overlapping male and female mating sections and spanning between each pair of corresponding grooves in the surfaces of the male and female mating sections such that the male and female parts are mechanically coupled together;
• wherein at least one of the surfaces of the male and female mating sections is formed such that opposing edges of at least one of the corresponding grooves have different elevations;
• and
• wherein, at least one body of the plurality of bodies projects more deeply into the respective groove than into the respective corresponding groove of one of the pairs of corresponding grooves.