DRILLING JAR SYSTEM WITH CHECK VALVE Russian patent published in 2017 - IPC E21B31/113 

FIELD: oil and gas industry.

SUBSTANCE: method comprises creating a drill string containing a drill pipe, a jar and a check valve disposed between the drill pipe and the jar containing a mandrel slidably mounted in the sleeve, flowing of mud through the drill pipe and the check valve, and selective throttling of the mud through the check valve to create a differential pressure through the check valve to create an axial force on the jar, so as to force the mandrel to move relative to the sleeve. The differential pressure creates an axial force transmitted to the jar, which facilitates the "loading" or firing of the jar. In one embodiment, the check valve throttles the downward flow of fluid to create a downward compression force on the jar, in another embodiment, the check valve throttles the upward fluid flow to create an upward tensile force on the jar. The ascending and descending fluid flow can be alternately throttled to for alternate firing of the jar in the ascending and descending directions. A bypass valve may be included in the drill string to create a mud flow path when it can be otherwise blocked by a foreign object in the wellbore.

EFFECT: increasing efficiency of the jar operation and reliability of the release process from the sticking of the drill pipe.

24 cl, 13 dwg