Electromagnetic gap sub assembly

An apparatus for use with an EM telemetry system, comprising:

• a housing;
• a mandrel;
• a dielectric material disposed between the housing and the mandrel;
• a first non-conductive gap ring disposed between the housing and the mandrel;
• a seal assembly disposed between the housing and the mandrel, wherein the seal assembly comprises:
• a sleeve made from a relatively high strength, high temperature plastic;
• and
• at least one elastomer sealing element disposed between the sleeve and the housing and at least one elastomer sealing element disposed between the sleeve and the mandrel.

An apparatus for use with an EM telemetry system, comprising:

• a housing comprising a first section and a second section coupled by a threaded connection;
• a mandrel comprising a first section and a second section coupled by a threaded connection;
• a dielectric material disposed between the housing and the mandrel;
• and
• a first non-conductive gap ring disposed between the second section of the housing and the second section of the mandrel;
• and
• a first seal assembly disposed between the second section of the housing and the first section of the mandrel, wherein the first seal assembly comprises:
• a first sleeve made from a relatively high strength, high temperature plastic;
• and
• at least one elastomer sealing element disposed between the first sleeve and the second section of the housing and at least one elastomer sealing
• element disposed between the first sleeve and the first section of the mandrel:
• and
• a second seal assembly disposed between the second section of the housing and the first section of the mandrel, wherein the second seal assembly comprises:
• a second sleeve made from a relatively high strength, high temperature plastic;
• and
• at least one elastomer sealing element disposed between the second sleeve and the second section of the housing and at least one elastomer sealing element disposed between the second sleeve and the first section of the mandrel.

An apparatus for use with an EM telemetry system, comprising:

• a housing;
• a mandrel;
• a dielectric material disposed between the housing and the mandrel;
• a first non-conductive gap ring disposed between the housing and the mandrel;
• a first compression ring disposed between the first gap ring and the mandrel;
• and
• a second compression ring disposed between the first gap ring and the housing.