INTELLIGENT WELLS USE valves or chokesin the reservoir section that can beoperated from the surface. For more than15 years, they have been used in fields

across the world for the more effectiveexploitation of resources through shut-off ofunwanted production, improved waterinjection placement, and modification tohydrocarbon inflow profiles to increaserecovery factors.

Currently available intelligent completiontechnology is controlled from the surfaceusing multiple hydraulic and / or electriccontrol lines which must pass through thewellhead into the completion annulus, alongthe length of the completion, through anypackers and into the reservoir section wherethe monitoring and control devices arelocated. While this technology has beensuccessfully implemented in low complexitywells, there are some limitations associatedwith the use of control lines. Such examplesinclude the compatibility with complex wellarchitectures, potential well integrity issuesdue to feedthrough connections, and thesignificant amount of hardware required whichcan make it uneconomical for marginal fields.

Shift from conventionaltechnologiesWireless completions equipment is becomingmore common, from DST testing to multi-node intelligent completions. The move fromconventional equipment with nocommunication mechanism, and moremodern control line based systems, to awireless system is ongoing and presentsseveral key advantages in efficiency,performance and safety.

All completions incur significant costs, butone of the key items, when used, is the

control line for downhole communication andactuation. Even single control line strings canadd significant cost to the project, while tripleor more bundles for hydraulic control can addover US$1 million to the project cost once theadditional hardware, man power and rig timeare included.

While control line systems typically requireincreased CAPEX, the alternative of aconventional completion system can often seethe savings on equipment nullified due toincreases in OPEX and deferred productionthrough increased intervention and poorreservoir performance.

Wireless intelligent well technology willextend the operating envelope for theadvanced completion to allow interval controlwhere currently this cannot be achieved.Independent valve assemblies without control

lines can be rotated in the well duringdeployment and function without physicalconnection to the surface. Single critical pointfailure modes are eliminated and inflow controlcan be achieved in the laterals of multilateralwells or at the furthest extent of a longopenhole lateral. Well construction costs arereduced as cost savings in control lines,downhole connection and completion timesare made, and basic top hole workovers canbe performed more simply and cheaplywithout affecting the advanced completionfunctionality. The addition of real-time datacan lead to informed decision making, whilethe ability to act immediately and withoutintervention leads to an optimal productionenvironment.

Wireless systems can help to provide ahybrid of the key features, whereby the

Tendeka’sPulseEight device

Tendeka, a leading provider of completion systems and production optimsation technologies, discusses the benefits of its PulseEight intelligent well technology for the digital oilfield.

Wireless intelligent completion

technology

Wirelesscompletions equipment isbecoming more common”

Technology

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Technology

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completion is kept simple allowing a quickand safe installation, but offers thecommunication mechanism required tomonitor and control wells effectively.

PulseEight technologyTendeka’s PulseEight intelligent welltechnology provides cable-free control andmonitoring solutions for a wide range ofapplications. Each independently actingdevice provides an infinitely variable chokeand seal with pressure and temperaturemeasurements for optimum control.

The all-electric system is microprocessordriven and can be programmed to function based on wirelessly transmitted instructions from surface or to respond autonomously to the well environment, for example detecting well shut-ins, changes in well pressure or metering mass flow rates.

The wireless communication uses a unique semi-duplex pressure pulse telemetry suitable for multi-phase fluid environments that utilises the existing wellhead equipment to interface with the downhole valve.

Once in the well, the PulseEight device can be actuated from surface using pressure pulse commands. These commands are typically generated using the surface choke, and the size of pressure change required can be establish prior to deployment using well modelling.

Flow from the reservoir enters ports in the tool and flows to surface. The device creates a downhole pressure response by briefly choking the flow, with the response being viewed at surface.

Six pressure pulses are identified on the surface recorder. The time between the pulses is analysed to give a unique binary code that is decoded to provide pressure and temperature readings as well as tool status information.

To communicate from surface down the

well to a PulseEight device, a number ofpulses are created at the wellhead. Eachdevice responds to a unique pulse sequenceand takes action to open, close or choke orto amend any variable.

In addition to this direct surface controlledoperating mechanism, PulseEight can beconfigured to work autonomously based onchanges in downhole conditions. Computermodels can be used to build the optimalinflow profile, and the PulseEight device canbe programmed to target a fixed dP throughthe valve. This computer model can be keptupdated with the downhole pressure datasent from the valve, and the valve’sprogrammed parameters can be adjustedwhile in hole to suit the update output fromthe model. This offers an additional benefitover hydraulic control line valves as autonomy

leads to faster decision making andimplementation of optimisation techniques.

Example application areasPulseEight can be used for variousapplications, such a s pressure/temperatureprofiling for improved reservoir understanding;variable interval control for reduced water cutand improved recovery factors; multilateralcontrol for efficient well construction andperformance; water and gas shut-off for rapidcontrol of high WC/GOR zones; remotebarrier for management of Frac hits;autonomous gas lift for optimal wellperformance; downhole regulator for optimalgas hydrate prevention; and autonomouscrossflow prevention during well shut-ins.

Delivering a robust and reliablesolution to marketThe uptake of new technology in the oilfieldtends to be slow due to the significantperceived risks with new technology and thefinancial cost of equipment failing downhole.To minimise the risks and deliver a reliablesystem to market, PulseEight has gonethrough a robust and staged qualificationprogram including component testing, systemtesting, and field testing.

Reliability of the design was ensured byusing internal components common to previoussystem offerings, while testing sequences weredesigned in accordance with appropriateindustry standard and regular input fromoperating companies along the way. The abilityto test the system in live well scenarios hasbeen invaluable in proving the communicationmechanism over long distances, and under flowregimes that would have been impossible torecreate in a lab environment.

While the immediate future for thistechnology will be to extend the operatingenvelope for intelligent completion technologyand address some of the applicationsmentioned in this article, the long-term aim forthe technology is to form part of a fully digitaloilfield. This would involve a set of ‘goal-seeking’ devices being installed in a well andcommunicate with each other, as well as withsurface, to provide a fully autonomous,optimal production environment. n

Flow from the reservoir enters ports in the tool and flows to surface

The long-term aimfor the technology is toform part of a fully digitaloilfield”

Six pressure pulses are idenitified on the surface recorder