Self-powered downhole injection systems and methods for operating the same

A downhole injection system configured for use with a wellhead assembly and a wellbore, the downhole injection system comprising:

• a pumping chamber configured to be in selective communication with the wellhead assembly, the pumping chamber defining:
• a wellhead pressure portion defining a wellhead pressure inlet configured to be in selective communication with the wellhead assembly and a wellhead pressure outlet configured to be in selective communication with the wellhead assembly, wherein the wellhead pressure portion is maintained at a wellhead pressure;
• and
• a chemical portion configured to be in selective communication with the wellbore;
• a wellhead pressure inlet valve configured to be positioned between the wellhead assembly and the wellhead pressure portion, wherein the wellhead pressure inlet valve is positionable between an open position, in which wellhead material may flow from the wellhead assembly to the wellhead pressure portion through the wellhead pressure inlet valve, and a closed position, in which the wellhead material may not flow from the wellhead assembly to the wellhead pressure portion through the wellhead pressure inlet valve;
• a supplemental pump in selective communication with the wellhead pressure portion of the pumping chamber;
• and
• a supplemental pump valve positioned between the supplemental pump and the wellhead pressure portion of the pumping chamber, wherein the supplemental pump valve is positionable between an open position in which fluid from the supplemental pump can pass to the wellhead pressure portion through the supplemental pump valve, and a closed position, in which the fluid from the supplemental pump is restricted from flowing to the wellhead pressure portion through the supplemental pump valve.