+ SPECIALIST COMPLETIONS - Zenith Oilfield Technology Ltd

SPECIALIST COMPLETION SYSTEMS (Cont.)Zenith have the engineering know-how tomake certain the completion will integratecorrectly with your ESPs. Our team haveextensive experience in ensuring the completiondesign is fit-for-purpose to meet yourproduction requirements.BESPOKE SYSTEMSOne of Zenith’s keystrengths is our ability todesign bespoke completionsystems to your specificrequirements.Zenith’s design director is a recognisedworld leader in ESP completion design;responsible for the industry introduction ofthe highly successful bypass and dual ESPsystems with approximately 3,000 of hissystems installed to date worldwide.DUAL ZONE ESP SYSTEMSFor multiple zone wells that require control of zonal contribution (fig. 4)Dual zone completions enable production from multiple zone wells. A dedicated ESP foreach zone gives independent control of draw-down. This allows improved zone management,prevents cross-flow between zones, allows improved water management and enablesindividual production well tests on each zone independently. If used effectively duringfield planning, these systems can decrease the number of wells required to be drilled.Dual zone systems are available in two configurations:Commingling SystemsCombines production from dedicated ESPs for upper and lower zonesThe lower ESP is housed in a sealed pod which is stabbed into a permanent packer thatisolates the upper and lower zones. Production from the lower zone is produced by theESP inside the pod. The upper ESP is installed above the pod using a bypass system. Thelower zone is produced via the bypass tubing and its production commingled with productionfrom the upper zone at the Y-block. Zones can be produced either simultaneously orindependently by running upper, lower, or both ESPs. Cross-flow between zones duringproduction shut-down can be prevented, and well tests of individual zones can be carriedout to provide improved well testing. This is achieved by running each ESP individuallythereby producing only the relevant zone for testing.Dual Concentric SystemsDedicated ESPs for upper and lower zones that isolate zone contribution to surface productionfacilitiesThe dual concentric system is similar to the commingled system described above but producesthe zones independently to surface using concentric production strings. This systemis particularly useful where complete isolation of production zones is a requirement. Fluidfrom the lower zone is produced to surface through a flow crossover tool which routes thefluid through the inner production tubing string. Fluid from the upper pump flows throughthe inside of the flow crossover tool and to the surface through the annulus between the innerand outer production strings. The two separate production strings exit the well througha concentric well head that allows flow through two separate production flow lines.DUAL BACK-UP WITH WIRELINE ACCESSFor wells with high workover costs or difficult access that require wireline access below(fig. 5)In the event of an ESP failure, a back-up ESP already deployed in the well can be immediatelyturned on to maintain production. The second ESP is suspended below the upper ESPwith a bypass assembly. The bypass tubing provides a production path for the lower ESPwith the third leg allowing wireline access for logging operations.Normally the upper ESP is run first to prevent temperature effecting the backup systemrunlife. The lower ESP can be appropriately sized to accommodate changes in well performancesuch as decreasing reservoir pressure or increasing water cut.