Oil and gas well downhole equipment and service tools, namely, machines used to re-pressurize and chemically treat reservoir pore-space by injecting pressurized fluids to dislodge and mobilize trapped hydrocarbons; and machines used to de-pressurize the wellbore to pull dislodged hydrocarbons and produced-fluids from adjacent reservoir pore-space into the wellbore for artificial lift pumping to the surface