Bidirectional fluid operated vibratory jar

A bidirectional fluid operated jarring apparatus, which comprises:

• a tubular body having an axially upper end defining a pipe connection and an axially lower end defining downwardly facing body hammer;
• a tubular knocker sub having an axially upper end axially movably connected to said lower end of said body for limited axial movement with respect to said body between retracted and extended positions, and an axially lower end defining a pipe connection, said knocker sub including an upwardly facing shoulder defining an upwardly facing anvil engageable with said body hammer, and said knocker sub including an inwardly extending downwardly facing internal shoulder defining a downwardly facing internal anvil and an axially spaced apart upwardly facing inwardly extending internal shoulder;
• a tubular mandrel having an axial flow passage therethrough axially movably mounted in said body and knocker sub, said mandrel including a mandrel hammer positioned within said knocker sub between said internal shoulders of said knocker sub, said mandrel hammer including an outwardly extending upwardly facing shoulder engageable with said downwardly facing anvil of said knocker sub when said knocker sub is in said extended position and an outwardly extending downwardly facing shoulder engageable with said upwardly facing internal shoulder of said knocker sub when said knocker sub is in said retracted position;
• means for forming a sliding seal between said mandrel and said body;
• means for urging said mandrel axially upwardly with respect to said body;
• and valve means for closing said mandrel flow passage whereby fluid pressure urges said mandrel axially downwardly with respect to said body and opening said mandrel flow passage upon predetermined axially downward movement of said mandrel with respect to said body thereby to allow said mandrel to move axially upwardly with respect to said body such that when said knocker sub is in said extended position upward movement of said mandrel causes said mandrel hammer to strike said knocker sub internal anvil and when said knocker sub is in said retracted position downwardly urging fluid force on said mandrel is transmitted to said knocker sub through said upwardly facing internal shoulder and said body is urged upwardly with respect to said knocker sub and upon opening of said mandrel flow passage said body hammer strikes said knocker sub upwardly facing anvil.