Paper: Subsurface Hydraulic Pumping Diagnostic Technique

Hydraulic pumping made its appearance as a method of oilwell artificial lift in the early 1930"s. Since that time this method has found wide acceptance, especially in deep, high volume pumping. Because the unit is located near the bottom of the well, understanding the operation and condition of the downhole unit can often be a problem for the producer. This paper presents a well-site analytical method using pressure and production data to determine useful information about the overall condition of the hydraulic pumping system along with the well's potential. Thus, by thoroughly understanding equipment and well conditions, the producer is in a better position to reach his goal of maximizing profit. The hydraulic pumping system analyzed in this paper consists of a downhole hydraulic reciprocating engine directly connected to a reciprocating pump which functions as a unit. There are many configurations of downhole units available such as tandem engines with single pumps, tandem pumps with single engines, tandem pumps with tandem engines, and a large selection of power ratios. Also, downhole tubular arrangements vary depending on application such as casing free, fixed casing, parallel and fixed insert. Since the operation is basically the same, the method discussed in this paper applies generally to all. Also of importance are the two types of power fluid arrangements, i.e. open and closed systems. The closed system keeps the power fluid separate from produced fluids as compared to the open system which mixes produced fluid and power fluid as they are discharged from the unit. Most systems are of the open type because of simplicity of design and reduced equipment costs. This paper discusses the open type only; but with minor modifications, the closed power fluid arrangement can be analyzed as well.