Downhole tool hydraulic retriever

A downhole tool hydraulic retriever, comprising:

• a stroking unit comprising a hydraulic cylinder, a piston body at least partially disposed within the hydraulic cylinder, and a piston rod extending from the piston body, wherein the piston rod comprises an inner bore for enabling flow of drilling mud from an upper end of the downhole tool hydraulic retriever to a lower end of the downhole tool hydraulic retriever;
• first and second pipe gripping mechanisms configured to translate axially with respect to each other;
• a pressure intensification module comprising sequencing valves and hydraulic distribution lines;
• and
• a connection mechanism configured to connect to a bottom hole assembly, wherein the connection mechanism is configured to block the flow of drilling mud through the inner bore of the piston rod and to direct the flow of drilling mud through the pressure intensification module when the connection mechanism is connected to the bottom hole assembly;
• wherein the pressure intensification module is configured to alternatingly direct pressure associated with the flow of drilling mud between the first and second pipe gripping mechanisms through the sequencing valves and hydraulic distribution lines of the pressure intensification module, such that the first and second pipe gripping mechanisms alternatingly apply an outward radial force.