1. PUMPING APPARATUS ADAPTED TO BE INSERTED IN THE CASING OF AN OIL WELL FOR PUMPING OIL OUT OF THE WELL AND ALSO FOR PUMPING FLUID DOWNWARDLY INTO THE WELL UNDER PRESSURE, SAID APPARATUS COMPRISING REVERSIBLE PUMP MEANS OF THE PROGRESSING CAVITY TYPE HAVING ELONGATED HELICAL ROTOR AND STATOR MEMBERS AND ADAPTED TO EXTEND DOWNWARDLY IN THE WELL CASING, AND VALVE, MEANS CONNECTED TO SAID PUMP MEANS, SAID VALVE, MEANS INCLUDING A CHECK VALVE ADAPTED TO OPEN TO PERMIT OIL TO BE PUMPED UPWARDLY OUT OF THE WELL BUT REMAINING CLOSED WHEN FLUID IS BEING PUMPED DOWNWARDLY INTO THE WELL, AND A SPRINGPRESSED PRESSURE VALVE ADAPTED TO REMAIN CLOSED UNDER THE STATIC PRESSURE OF A FLUID HEAD THEREABOVE AND ADAPTED TO OPEN AT A PREDETERMINED EXCESS PRESSURE ABOVE SAID STATIC PRESSURE FOR PERMITTING FLUID TO BE PUMPED DOWNWARDLY UNDER PRESSURE INTO THE WELL BUT REMAINING CLOSED WHEN OIL IS BEING PUMPED UPWARDLY OUT OF THE WELL.