Exploration • Drilling • Field Services
Te specially designed X-ray detector has six individual area detector tiles. Te tiles are arranged azimuthally around the source tube. Each tile has its own pinhole to direct the scattered photons onto the detector. Te six tiles provide the tool with
a good overall field-of-view while maintaining high spatial resolution. Te pinholes ensure that the field-of-
view of each pixel encompasses a narrow region of space. Although these regions overlap slightly for neighbouring pixels, each pixel views a well-defined portion of the object surface. Measurements of backscattered radiation are converted into three- dimensional renderings or two- dimensional images of the object using an innovative fluid-based surface reconstruction technique. Visuray has designed and built the VR90, a wireline tool that incorporates the thermoionic X-ray tube with the necessary imaging system components. Both the tool and its operating procedures are designed to operate at ambient temperatures of up to 150°C (300°F) and withstand pressures up to 1380 bar (20000 psi).
Te tool has a maximum outer diameter of 9.2 cm (3⅝ in) and a length of 8.38 m (27.5 ft). Te tool can be run on all types of electric wireline and either centred or eccentred in the well, and is compatible with tractors, strokers, and coiled tubing. Example images
from operating the tool in a laboratory setting demonstrate the ability of the tool and technique to create reconstructions of objects in a variety of normal production fluids including clean water, saline water, oil, and fluids with suspended rust particles. Te images also demonstrate the millimetre-scale resolution and accuracy of the tool. Altogether, this represents a versatile tool with the capabilities to provide useful information in challenging well management scenarios and do so while saving time, reducing cost, improving safety, and minimising environmental risk. l
Fig. 3. Well intervention decisions are not easy to make. The VR90’s downhole X-ray backscatter imaging techniques provide high-resolution data.
Kenneth Søndervik is with Visuray in Randaberg , Norway.
www.visuray.com
For more information ✔ at
www.engineerlive.com/iog
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