CMOS X-ray Imaging Shores Up Oil and Gas Operations

Alana Achterkirchen, Rad-Icon Imaging, a Division of Dalsa Corp.

Current events have spotlighted the deep-sea oil and natural gas industry and have drawn attention to the importance of nondestructive testing (NDT) of critical oil and gas field equipment. For many reasons, leaks can occur over time if the infrastructure is not monitored carefully. There is an inordinately high cost of cleanup in the event of an oil leak or spill.

Until this point, the industry has relied largely on film-based radiographic systems to monitor the integrity of its equipment. However, many companies are beginning to adopt digital imaging technologies that have a long service life and a high degree of accuracy in taking high-resolution images of their pipes during the manufacturing process, during in-service operations above water and, eventually, underwater.

However, the process of gaining acceptance for a new testing method can be lengthy. One of the biggest challenges lies in validating the quality of the digital radiography panel. Often, the new approach must be qualified by three or four constituencies, including the company that performs the inspection, the company that manufactures the tubing, the company that buys the tubing and, ultimately, the company that insures the project.

As proven petroleum reserves continue to decline and worldwide oil demand continues to increase, most growth will be based upon improved recovery efficiencies from increasingly complex oil reservoirs such as this. Courtesy of Roxar.

The risks in this industry, which run high, are the result primarily of pipe manufacturing, joint welding, and pipeline corrosion or fatigue. From a metallurgical perspective, there is no such thing as a flawless part, so the question is whether the defects are at such an insignificant level that they will not eventually propagate a problem. Changing an NDT inspection system is not easy to accomplish, even if there are time, efficiency and inherent safety benefits in leveraging digital imaging versus film. However, the oil and gas industry has made progress, much of which is based on the pioneering work of the medical industry.

According to Jack Zsakany, general manager of Draka Engineered Specialties, digital radiography has had to overcome not only industry resistance to change but also fundamental resolution concerns and file storage standardization.

A subassembly of the CMOS x-ray imaging system is shown. Courtesy of Draka Cableteq PTM.

“With new technology such as digital x-ray panels, resolution can be much higher than traditional film,” Zsakany said. “This is tuned by one’s ability to see the same wire image quality indicator as film – no more and no less for purposes of product certification to a design standard. To counter any concern that radiographers might digitally alter images, DICONDE-formatted database storage includes the unaltered base image and applies the radiographer’s filters on top of that. One can always return to the original source image. DICONDE standardization of information fields and file storage has done a lot to gain credibility for digital radiography and also demystify the process.”

Increasing efficiency

Draka Engineered Specialties (formerly Pressure Tube Manufacturing, or PTM) of Bridgewater, N.J., is a wholly owned subsidiary of Draka Holding NV of Amsterdam, the Netherlands. Draka Holdings, a €2 billion enterprise, is the third-largest cable manufacturer in Europe and the eighth largest in the world. Its New Jersey facility produces austenitic and duplex stainless steel and nickel-base seam-welded tubing in outside diameter sizes from 1/8 to 5/8 in. Since 1910, Draka has manufactured wire products and, with the acquisition of PTM, the company now integrates these products into corrosion-resistant tubing in lengths up to 50,000 ft or more.

One of the company’s distinguishing capabilities is the manufacture of tube-encapsulated cable and pressure tube bundled together with multiple tubes to create a polymer-encapsulated “flatpack.” These flatpacks can be many miles in length and are installed in a gas or oil well for system monitoring and control (for example, communicating with downhole pressure and temperature sensors, controlling hydraulic valves and injecting chemicals).

Although the company has a long history of using film-based imaging for oil and gas well infrastructure, it sought to leverage digital x-ray imaging. The Draka team understood that the benefits of digital x-ray imaging would go beyond gaining efficiency and reducing expenses. On the plant floor, digital imaging also would simplify database cataloging and improve customer and supplier communications due to the ease of sending digital images versus film.

The Draka team sought bids from four digital x-ray suppliers, ultimately choosing Envision CmosXray LLC of Anchorage, Alaska. Envision knows the oil and gas business, has extensive technical expertise in digital imaging and understands the trade-offs in custom automation applications.

An x-ray image shows a pipeline joint weld. Courtesy of Envision CmosXray LLC.

Greg Davall, plant manager for Draka, said, “We were initially concerned about the distance between Anchorage and Bridgewater, N.J. However, in the bidding, design and fabrication processes, we found Envision to be more responsive than other suppliers on the East Coast.”

When Ky Holland, general manager, and John Cope, vice president of Envision, got the call from Draka, they arranged for Draka to see an Envision system installed at Ethicon Inc., a division of Johnson & Johnson, based in New Jersey. This system performs NDT imaging on laser-drilled microholes at the end of suture needles used in heart surgery.

The digital solution

Envision provides complete digital imaging solutions and also film-to-digital retrofits for oil and gas companies looking for semiautomated inspection systems for their pipelines’ weld joints. The company’s CMOS Tubing Inspection Cabinet (TIC) is the highest-resolution system available for small tubing inspection. The mobile shielded system incorporates a computer-controlled, microfocus x-ray tube; a high-resolution CMOS digital x-ray detector from Rad-icon Imaging; and a rotational movement system for capturing images between 0° and 180°.

The RadEye1 and RadEye100 CMOS x-ray sensors are shown. Photo by Carter Dow Photography of San Francisco. Courtesy of Rad-icon Imaging.

Rad-icon’s CMOS x-ray detector has a 4 x 4-in. image area, a 20- to 160-kV response, a spatial resolution of 50 μm (10 line pairs per millimeter) and a dynamic range of 12 bits. Controlled by Envision’s EnSpect image-capture software, the detector comprises a matrix of more than 4 million pixels, each containing a photodiode to collect signal, an amplifier to read out the signal voltage, and two switching transistors to address and reset the pixel. The image area is divided into eight segments, which are scanned in parallel to minimize readout time and increase the effective pixel rate. The image is scanned in a rolling shutter process, starting at the center of the active area and proceeding simultaneously to the top and bottom edges. All clock and control signals required to scan the image are generated on-chip.

Envision’s TIC is designed for imaging weld joints for deep-sea oil and gas applications. Hookups to wellheads at 5000 to 6000 ft require a massive infrastructure to control underwater oil and gas facilities. High-pressure specialized tubing as long as 10,000 ft is used to connect hydraulic controls in oil valves. These tubes are manufactured from rolls of various grades of stainless steel in short segments, which are taken out to sea by barge, then hooked up to the oil-drilling platform. Each segment is welded to form the long pipeline, and these joints require NDT imaging to ensure the integrity of the joint.

To inspect tubing and valves, the x-ray detector is placed on one side of the joint weld, an image is taken, and the detector is rotated 120° to take three views of the weld before moving on to the next weld. All of this takes approximately 30 seconds. A technician receives the digital images within seconds, evaluates the weld and, if it’s deemed solid, more tubing is uncoiled.

“Our Tubing Inspection Cabinet produces astounding images of joint welds leveraging high-resolution CMOS x-ray panels,” Holland said. “If your operation requires a significant number of NDT inspection images over several months, a digital inspection system would quickly pay for itself and would also increase the output of your plant.”

The net result

Draka’s design goals included reducing actual x-ray time from approximately 1 min each for three shots plus the time to load film packs and mechanically reposition the source, to less than 30 s to capture three digital x-ray images with 120° rotation around the joint weld. Within a minute, the images are displayed on a screen. Technicians can evaluate the image on the spot and either decide to move to the next joint weld or send the file electronically across campus for further evaluation.

The more traditional film-based process can take up to 45 min to load a film cassette, capture an image, develop the film, unhook the entire assembly mechanism and start the mechanism up again to capture the next image. Technicians would have to walk across campus with the film if further evaluation were deemed necessary.

Draka has optimized production focal length and integrated automation, and it is in the process of production hardening with lead shielding. “In manufacturing, we’re very excited about the potential for expanding digital x-ray beyond this initial application,” Davall said. “The oil and gas industry is recognizing that digital x-ray imaging has its place and can deliver everything we need at a cost-efficient price. Our customers demand cost-effective and efficient operations with the highest quality and safety.”

Meet the author

Alana Achterkirchen is the director of business development and marketing for Rad-icon Imaging, a division of Dalsa Corp. of Sunnyvale, Calif.; e-mail: sales@rad-icon.com.