Welltec

Frontier Observatory for Research in Geothermal Energy

Devices Suitable for Sectional (zonal) Isolation Along Both Cased and Open-hole Wellbores Under Geothermal Conditions

Welltec®

Principal investigators:

Welltec® - Ricardo Vasques

Welltec® - Yosafat Esquitin

Welltec® - Soren Hallundbaek

Welltec® - Ryan Melander

Welltec® - Soren Hallundbaek

Oklahoma University - Ahmad Ghassemi

Oklahoma University - Catalin Teodoriu

Summary
The optimum means to achieve effective and controllable zonal isolation, aiming to reduce the risk of uncertain geological properties that will affect the production/injection of a geothermal well, is the use of a mechanical annular isolation system that creates effective sealing between the tool and the wellbore. Typical wellbore isolation devices are plugs and packers.

Conventional plugs and packers utilize elastomeric seals (i.e., HNBR, HNS, Swellable Compound, Aflas, FFKM, etc.), which can be a common failure under the high-temperature conditions experienced in EGS.

Welltec® has developed state of the art, all-metal annular sealing system “Welltec® Annular Barrier” (WAB®) for EGS. It works in combination with either a slotted liner, pre-perforated pipe, or with the Welltec® Flow Valve (WFVTM).

Our objective is to develop and deliver a game-changing solution, which enables our users to optimize the management and development of EGS.

Conventional methods such as slotted liners or pre-perforated pipe, in combination with Polished Bore Receptacles (PBR), will allow for selective zonal stimulation. However, it doesn’t offer the same flexibility as the WFV’s.

Conventional methods or enhanceds inflow control methods (WFV’s), in combination with the WAB®, create a productive and reliable life of the well system to achieve the ultimate zonal isolation for stimulation and production in EGS.

When utilizing the WFV’s in conjunction with the WAB®, each zone will be controlled independently, either open or closed, for the life of the well management. The advantage of the WAB® and WFVTM system compared with conventional methods is a controlled and effective stimulation and reservoir injection/production management throughout the life of the well.

The enhanced Welltec® system will allow users to reconnect via an injection string and “key” or straddle system for the future to re-stimulate a targeted zone(s). Within this project, we plan to upgrade and already commercial Welltec® WFVTM to EGS standards, differential pressure, temperature resistance, and durability at temperatures above 225°C for the life of the well.

To demonstrate the capability to seal both cased-hole and open-hole conditions. The team from the Oklahoma University (OU) will carry out a full 3D finite element modeling of:

• The WAB® system with wellbore wall rock.

• The isolation tool, including seal and sealability properties, of the novelwill, targeted the novel internal sealing system.

Additionally, small-scale block testing will be performed to test the performance of the system under stress and temperature perturbations. The study aims to identify the critical loads for each phase of the stimulation process (deployment, injection, production, standby).

During the intermediate and final stage, the Oklahoma University will also perform full-size testing on the prototype to measure the Stimulation Isolation Device (SID) contact stresses and uniformity as well as to physically prove the fatigue resistance.

The experimental testing will include strain gauge measurements and cyclic loading of the SID. A dedicated setup (available) will allow testing of various seal material and concepts to be used as an internal sealing element for the isolation tool.

Please see below for reports, data, and a video.

Overview Geology Water Chemistry/Ground Water Geophysics Earth/Fracture Modelling

Seismicity GIS Data/Maps R&D Projects Wells 16A&16B Stimulation Reports

Well 58-32 Well 78-32 Well 78B-32 Well 68-32 Well 56-32 Well 16A(78)-32 Well 16B(78)-32 Wells General

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