Deep well pump for viscous oil

Claim 1

IN A DEEP WELL PUMP FOR PUMPING HIGHLY VISCOUS OIL, SAID PUMP BEING ADAPTED TO BE LOCATED AT THE LOWER END OF A STRING OF PRODUCTION TUBING AND ACTUATED BY A SUCKER ROD WITHIN SAID TUBING, THE COMBINATION OF: A SUB CONNECTED TO AND CLOSING THE LOWER END OF SAID TUBING TO CONFINE A COLUMN OF PRODUCTION FLUID THEREIN, SAID SUB HAVING AN AXIAL BORE OF RELATIVELY LARGE DIAMETER COMPARED TO THE DIAMETER OF SAID SUCKER ROD; A PLUNGER ACTUATING PISTON CLOSELY FITTING SAID BORE AND RECIPROCABLE THEREIN; CONNECTOR MEANS CONNECTING THE UPPER END OF SAID PISTON TO THE LOWER END OF SAID SUCKER ROD FOR REPEATEDLY RECIPROCATING SAID PISTON IN SAID BORE, EACH RECIPROCATION INCLUDING A SUCTION STROKE AND A COMPRESSION STROKE; STANDING VALVE MEANS PROVIDED IN SAID SUB PERMITTING AN UPWARD FLOW OF PRODUCTION FLUID THERETHROUGH INTO SAID PRODUCTION FLUID COLUMN BUT PREVENTING A REVERSE FLOW OF FLUID THERETHROUGH; RECIPROCATING PUMP MEANS HAVING A SUCTION AND COMPRESSION CHAMBER COMMUNICATING WITH THE LOWER END OF SAID STANDING VALVE MEANS FOR DRAWING PRODUCTION FLUID FROM SAID WELL INTO SAID CHAMBER ON THE SUCTION STROKE OF SAID PUMP MEANS AND FORCING FLUID FROM SAID CHAMBER UPWARDLY THROUGH SAID STANDING VALVE MEANS AND INTO SAID PRODUCTION FLUID COLUMN ON THE COMPRESSION STROKE OF SAID PUMP MEANS; AND MEANS FOR CONNECTING SAID PISTON TO SAID PUMP MEANS TO PRODUCE A SUCTION STROKE OF THE LATTER BY EACH DOWNSTROKE OF SAID PISTON AND A COMPRESSION STROKE OF SAID PUMP MEANS DURING EACH UPSTROKE OF SAID PISTON, SAID STANDING VALVE MEANS REMAINING CLOSED DURING THE DOWNSTROKE OF SAID PISTON WHEREBY A VERY SUBSTANTIAL NET DOWNWARD HYDROSTATIC PRESSURE IS IMPOSED UPON SAID PISTON BY THE FLUID HEAD OF SAID PRODUCTION COLUMN, IN ADDITION TO THE WEIGHT OF SAID SUCKER ROD, THEREBY SPEEDING UP THE DOWNSTROKE OF SAID PISTON AND INCREASING THE PRODUCTIVE CAPACITY OF SAID PUMP MEANS.