Conventional front-mounted, rotary crank-balanced pumping units were compared with front-mounted pumps to determine the comparative electric energy requirements. The wells studied were divided into groups of identical make, API ratings, strokes per minute and stroke length. Monthly production and power consumption were averaged for a six-month period and kilowatt- hours per barrel of fluid per 1,000 ft of depth were calculated and plotted against fluid production per day. The front-mounted units consumed an average of 36.8 per cent less electric power than did the conventional units when the strokes per minute were scaled evenly. Design modifications of the front-mounted units are discussed and dynagraph cards are used to illustrate the work loads.
A number of major oil companies have made comparative field tests of the front-mounted, rotary crank- balanced pumping unit (Fig. 1) and various conventional beam-type pumping units (Fig. 2). These tests were generally made using one type of unit on a given well for several days then replacing it with the other type unit for the same length of time. The daily production, electric energy used and inch-pounds of torque required were all noted during these exacting tests. Obviously a study of this type requires more time and money than are generally available to most companies. Another method of comparing the conventional beam- type pumping unit with the front-mounted, rotary crank- balanced pumping unit, based on electric energy consumed per barrel of fluid pumped, is discussed in this paper. The wells under study were divided into groups of identical make, API ratings, strokes per minute and stroke length:
conventional 160D units operating at 16.5 X 64 in. strokes/min;
conventional 160D units operating at 16.3 X 64 in. strokes/min; and
front- mounted 114D units operating at 16.7 X 64 in. strokes/ min.