Perforating string with longitudinal shock de-coupler

A shock de-coupler for use with a perforating string, the de-coupler comprising:

• first and second perforating string connectors at opposite ends of the de-coupler, a longitudinal axis extending between the first and second connectors;
• at least one biasing device which resists displacement of the first connector relative to the second connector in both of first and second opposite directions along the longitudinal axis, whereby the first connector is biased toward a predetermined position relative to the second connector;
• and
• at least one energy absorber which, in response to displacement of the first connector a predetermined distance, substantially increases force resisting displacement of the first connector away from the predetermined position.

A shock de-coupler for use with a perforating string, the de-coupler comprising:

• first and second perforating string connectors at opposite ends of the de-coupler, a longitudinal axis extending between the first and second connectors;
• at least one biasing device which resists displacement of the first connector relative to the second connector in both of first and second opposite directions along the longitudinal axis, whereby the first connector is biased toward a predetermined position relative to the second connector;
• and
• first and second energy absorbers which substantially increase respective forces biasing the first connector toward the predetermined position in response to displacement of the first connector a predetermined distance in each of the first and second opposite directions.

A perforating string, comprising:

• a shock de-coupler interconnected longitudinally between first and second components of the perforating string,
• wherein the shock de-coupler variably resists displacement of the first component away from a predetermined position relative to the second component in each of first and second longitudinal directions,
• wherein the shock de-coupler comprises at least first and second perforating string connectors at opposite ends of the decoupler, and at least one biasing device which resists displacement of the first connector relative to the second connector in each of the longitudinal directions, whereby the first component is biased toward the predetermined position relative to the second component,
• wherein the shock de-coupler further comprises at least one energy absorber which, in response to displacement of the first connector a predetermined distance, substantially increases force resisting displacement of the first component away from the predetermined position, and
• wherein a compliance of the shock de-coupler substantially decreases in response to displacement of the first component a predetermined distance away from the predetermined position relative to the second component.