借你一双慧眼 看透固井水泥完整性

ConocoPhillips and Statoil Petroleum have signed a joint-sponsorship-development agreement with Visuray Technology to fund development of a downhole cement-integrity-evaluation technology. The new technology, known as the VR360 Diagnostic Cement Evaluation Tool, will have the capability of evaluating cement integrity even behind multiple casing strings. The tool will provide a full-3D cement map and will complement traditional ultrasonic measurements, which are highly sensitive to the cement bond between the cement and the inner casing wall.

Recent regulatory focus on deepwater wells initially stimulated the development of the technology, but as decommissioning and abandonment of mature wells grows in importance because of economic, regulatory, and environmental concerns, the tool’s potential in such settings spurred the effort to establish the agreement.

The goal of the joint industry project, which became effective in mid-December 2017, is to deliver a number of prototype tools for downhole deployment with a range of external diameters. The project is expected to last 3 years, during which time other oil companies may consider joining the project. The prototypes will be tested in both oil and gas wells.

The VR360 tool will be based upon a suite of X-ray technologies developed by Visuray known as the Downhole X-Ray Platform. Visuray’s first tool from the platform, the VR90 Downhole X-Ray Diagnostic Tool, has been used globally in well-inspection applications. The VR90 service uses an X-ray imaging technique that works in even opaque fluids. Its X-ray backscattering technology can work in any borehole fluid. X-ray forward-scattering is sensitive to the density of the material through which it passes. Because the X-ray source is orders of magnitude brighter than conventional radioisotopes, forward-scatter technology can be used to probe the well environment through multiple casings. The resulting reconstruction of the object’s surface can be displayed as both a 2D surface map and a 3D object with millimetric dimensional accuracy.

VR360

 The VR360 diagnostic cement evaluation tool is designed to provide a much-needed step change in cement evaluation. Cement integrity is the most important factor in well safety throughout the life of the well.

Harnessing Visuray’s Downhole X-ray Platform®, the VR360 diagnostic cement evaluation tool is a second-generation Visuray service that radiates X-ray photons radially outward from the tool axis to evaluate cement integrity and detect mechanical anomalies, even in double casing strings. The service will be available in 2019.

The VR360 service overcomes many of the limitations of current cement evaluation technology. It is the first direct measurement of cement distribution, with the ability to evaluate even the most advanced, lightweight oil-well cements, thereby making it superior to current ultrasonic technology. While regulatory focus on deep-water well integrity initially stimulated this development, an increasing focus on the safe abandonment of wells in depleted fields has opened a new and important market for the service.

Significant industry funding has already been secured to accelerate the commercial development of the VR360 diagnostic cement evaluation tool. Key milestones in its technical development have also been reached with full-scale tests in realistic single- and dual-casing well environments, proving the tool’s ability to directly evaluate cement distribution and determine mechanical integrity.

HOW THE PLATFORM WORKS

Conventional X-ray imaging – for example in security or medical applications – involve placing the object to be scanned between the X-ray source and detector. This physical configuration isn’t possible in an oil well. Therefore Visuray scientists developed an alternative solution called “fluid-based surface imaging” that uses an X-ray source and detectors positioned on the same side of the target object.

The technique relies on X-ray scattering within the fluid separating the target object from the X-ray source. Fluids scatter X-rays strongly, so an increase in scattered and detected X-rays means more fluid present in the field of view and correspondingly more distance to the target object. Visuray uses this effect with high-pixel resolution to reconstruct the target object in 2D and 3D with millimetric accuracy.Wherever the well and whatever its condition, the Downhole X-Ray Platform’s family of services will see what’s happening and deliver quality images 100% of the time.

CHALLENGE CONVENTION

Five distinct technological developments and innovations lie at the heart of the Visuray Downhole X-Ray Platform:

• First is a range of custom-designed photon-counting X-ray detectors, which include dense, pixelated arrays derived from technology developed in the medical industry, combined with customized compact photomultiplier/scintillator detectors that are used in the oil industry.
• Second is a range of powerful X-ray sources that have been specially miniaturized and designed for high output.
• Third is a compact, ultra-high voltage power supply enabling the source to emit high-energy X-rays.
• Fourth, is a family of heat exchangers and downhole coolers used to control the temperature of the sources and detectors.
• Fifth is patented data analysis and processing techniques that convert the acquired digital data into 2D and 3D images.