Joe DUM Clegg, Consultant
High rate rod pumping continues to be an important artificial lift method in many fields around the world. Just what are the production limits and the loads for the largest rod pumping units? A comparison of the largest convention unit, air balanced unit, an improved geometry unit. and an ultra long stroke pumping system shows the potential production limits at various pumping depths. The key element in design is not to overload the sucker rods so that frequent fatigue failures occur. Also to prevent premature failures, do not overload the unit gear box and structure rating. The common goal in selecting. installing and operating any artificial lift system is to make the highest present value profit (PVP) -- net discounted income. All factors must be considered in picking the correct type, kind and size of lift method. Close attention to the various attributes of each lift method is recommended. The designer should consider the initial installation costs, possible production rates, and operating costs. The most difficult of these factors to obtain is the operating cost for the lift conditions to be encountered. Operating cost estimates must be made for typical fixed and variable costs plus the cost for energy and pumping repair and maintenance costs. Cost data from an analog field are most beneficial. Once the designer has the basic cost data, an overall economic analysis can then be made for the various artificial lift methods. Thus, by a combination of proper selection, design, and operating practices, near maximum profits will be realized.