井下的眼睛：VR90对修井洞若观火

Oil and gas wells often fail to produce to their true potential thanks to malfunctioning downhole hardware or debris in the well. Because of the opacity of most well fluids, oil companies have had no reliable means of imaging a well’s physical condition. Visuray’s VR90 tool uses ground-breaking X-ray technology to provide precise downhole images irrespective of well fluid. The improved visibility allows oil companies to plan well interventions that address these issues precisely and efficiently.

The objective was to image and unambiguously diagnose the status of a downhole safety valve so the operator could plan future workover operations. Visuray’s VR90 X-ray imaging tool acquired multiple downhole measurements and provided valuable information for the client. The results demonstrate the VR90’s unique ability to obtain dimensionally accurate downhole X-ray images in opaque well fluid environments and in offshore operations.

VR90 is 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). The tool has a maximum outer diameter of 9.2 cm (3 5/8 in) and a length of 8.38 m (27.5 ft). The 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. The 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.

‘To our knowledge, this was the first time an X-ray tool has ever been run in an offshore well. The job went safely and smoothly, and in fulfilling the customer requirement we’ve proven the reliability of the VR90 tool and service,’ says Sergey Feoktistov, Sales Director Europe. ‘As Visuray’s downhole X-ray diagnostic service gains credibility and visibility, we look forward to expanding our operations worldwide and enabling our customers to optimize well interventions and save operating costs.’

Retrieving downhole hardware is often achieved by engaging a mandrel with overshot or spear. If both techniques fail to retrieve a fish, the operator is left with quite a challenge. An impression block can be run, but this generally proves unreliable. The operator can proceed directly to milling, but this is time-consuming, costly and destructive.

Instead, the operator can run the VR90 X-ray diagnostic service to determine the cause of the failed fishing attempts.

The image (right) obtained at Visuray’s test facilities shows a case where the mandrel has been crushed, and hence the spear tool would not fit inside nor the overshot around the mandrel. Additionally, the VR90’s dimensionally-accurate images allow the operator to design a custom fishing tool and quickly retrieve the hardware without destroying it.

A unique and compact X-ray source emits X-rays that probe the volume immediately below the tool. Measurements of the backscattered radiation are then converted into 2D and 3D images using an innovative fluid-based surface reconstruction technique. By using X-rays rather than other conventional methods, the VR90 tool works in any downhole production fluid, however opaque.

APPLICATIONS

• Inspection of downhole equipment such as valves and mandrels;
• Classification and quantification of wellbore restrictions;
• Determination of shapes and dimensions of dropped objects;
• Identification and characterization of collapsed or split casing;
• Providing input for design of customized fishing tools.

BENEFITS

The VR90 is now available to provide services. It is a downward-viewing imaging tool that:

• Works in all production fluids, and can image sand-covered objects -– saving time and money by eliminating the need to displace well fluid, clean up or chemically
• condition the well;
• Operates at temperatures up to 212°F/100°C* and pressures up to 20,000psi / 1,380bar – providing answers in previously inaccessible environments;
• Uses inherently safe, electronic X-ray sources – simplifying logistics;
• Produces real time answers online – enabling well-informed decisions anywhere in the world;
• Works centered or eccentered in the well – for extra operational flexibility;
• Runs on all types of electric wireline and is compatible with tractors and strokers.

made or selected and the fish is retrieved.

Today, the Visuray team has grown to more than 50 professionals from about 20 countries, offering the VR90 commercial service to allow oil companies to see inside their wells, while charting a path forward to improve oil and gas well integrity, and eliminate radioactive materials from the oilfi eld.