Electrical submersible pumping (ESP) remains the preferred artificial lift method for high rate production when technically viable. ESP, on the other hand, is sensitive to downhole conditions and pumped fluid. Sour fields, in particular, are considered as a major challenge for producing facilities and well completion elements. Reservoirs producing fluids with hydrogen sulfide (H2S) present a special challenge to ESP systems.
This paper uses ESP field observations and pulled equipment findings from many dismantle inspection and failure analyses (DIFAs). The findings confirmed H2S behavior and root causes of electrical and mechanical failures within multiple ESP components. The outcome of these investigations and the recommended system upgrades to enhance ESP reliability in corrosive environments will be illustrated.
Critical ESP system materials will deteriorate and fail when subjected to sour environments. H2S can penetrate the pump’s cable insulation, attack the copper, and react to form copper sulfide, resulting in electrical failure. It can also permeate the seal bags and o-rings, diffuse in the seal dielectric oil, and attack the bronze and copper components in the seal and the motor. To improve reliability, a new version of motor lead extension (MLE) using three individually armored connectors and a seal with H2S sacrificial anode scavenger inside each chamber were introduced. The improved design encapsulated the insulated conductors individually within metal tubes made of high nickel alloy. The tubes can be terminated individually at the motor and above the production packer with proven swage type connectors.
By utilizing high nickel alloy tubes as barriers against H2S and removing all connections below the packer, the H2S effect has been eliminated. On the other hand, the seal with H2S passive scavenger will retain most of the H2S in the dielectric oil before it reaches the motor. These novelty technologies resulted in a threefold improvement, leading to longer up time, less workover jobs, and more sustainable production.