When inspecting oilfield surface equipment for integrity issues, the most comprehensive tool available is the combination of the human eyeball and brain. The ability to detect varying colors, textures, and features down to a submillimeter level is unsurpassed. Recording this visual inspection for records or further diagnosis by eye at the surface relies on the latest camera technology.
Video technology has evolved significantly with the advent of high-definition (HD) and 3-D cameras streamed from the helmet of an offshore worker direct to onshore for analysis and storage. Now some of the technology revolution in video technology that we all take for granted in our day-to-day lives is beginning to be deployed in the wellbore environment.
The idea of downhole cameras has been around for many years. The challenge of getting the technology in a camera phone to work at high temperatures and pressures and then transmitting the images back to the surface has meant, however, that the downhole cameras that have traditionally existed have had low functionality with poor quality – still capturing images in black and white. As a result, while occasionally useful for well integrity monitoring, these cameras were limited in their applications.
The latest downhole video technologies can now deliver full-color HD video either streamed to the surface or stored in memory, enabling the techniques applied at the surface to now be applied downhole.
Evolution of downhole video technology
Whether deployed on electric line, slickline, or coiled tubing, the latest generation of downhole video cameras can survey a complete tubing string to give an HD visual image of the tubing wall and completion hardware. Delivering these pictures to the surface requires the marriage of several leading-edge technologies.
Lighting must be provided downhole. Originally this might have been via an unreliable and inefficient filament bulb. Now cameras use LED technology that originated from a McLaren sports car. The camera lenses have to be able to sustain pressures up to 22,000 psi, minimize heat transmission, and pass the maximum light levels. The camera sensor must be able to sustain elevated temperatures for extended periods, which has been achieved using experience learned from the defense and space industries.