Abstract
The behavior and survivability of electric submersible pumping systems (ESPs) used for hydrocarbon production vary from one condition to another. Sour environment is generally known to bring about stress cracking of some sort in well completion assembly. Regrettably, the pattern and correlation of the survivability of ESPs to partial pressure remains unclear. Therefore, this paper sets to assess the contributions of partial pressures to ESP systems durability and survivability in a sour environment. An assessment of the relationships of different ESP systems in such environment with naturally occurring element of varying partial pressure is conducted and discussed in the paper. Weibull two-parameter distribution function approach in addition to extensive literature review were applied to understand and represent the contributions of sour fluid partial pressures on ESP’s durability and survivability that operated in hydrocarbon environments. The partial pressures of naturally occurring element - hydrogen sulphide, was conducted and determined to exhibit varying behavioral patterns, and contributions to the durability and survivability of electric submersible pumps in contact with the well fluid. The results obtained were matched with the Bathtub curve to identify the reliability patterns common to ESP assembly completion strings because of the fluid partial pressures. From the analysis, the varied partial pressures considered had different effects on the survivability of ESP systems operating in the various environments. The patterns of the ESP systems in the sour fluid environment cut across three main regions of Bathtub-curve performance patterns, which defined early survivability pattern, and normal or constant operating survivability pattern, and the wear-out survivability pattern. ESP performance and survivability patterns were observed to vary as the partial pressures increased while normalizing at certain levels partial pressures plateauing at about 200 psi. Finally, the naturally occurring sour fluid’s partial pressure had normalizing effects on ESPs as the run-lives increased. The paper adds to the body of knowledge in the oil and gas industry by bringing to clarity the contributions of partial pressures on ESP systems performance and survivability patterns used in sour hydrocarbon environment.
