Downhole video was first used in the Coalinga field in 1998. Since then, video technology has been used extensively to record images of casing damage, liner damage, wellbore plugging, and analysis of remediation procedures. In many cases, downhole video technology has become the logging method of choice due to its unparalleled ability to accurately assess the downhole environment. This said, downhole video technology is not applicable in all cases.
The first attempts to use camera technology in a wellbore occurred in the 1940’s at the request of a local pump manufacturer located in the San Joaquin Valley. The early attempts led to the capture of black and white pictures on stereoscopic slides that were used with a viewfinder to create a 3-D aspect. These early cameras were very large in diameter and limited (downhole video limitations) to depths of up to 1000 feet. Technology led to further developments in downhole video deployment in the 1960’s through development of coaxial cable capable of
handling the transmission of high frequency signals required for motion video. In the early 1990’s, an Electro-Opto logging cable was developed utilizing fiber optic technology1. This greatly enhanced the ability of the camera by addressing pressure constraints and opening up new applications in production logging.
The downhole video camera uses Electro-Opto fiber optic technology. This technology produces real time video at 30 frames per second with a working temperature of 257 F to 350 F, depending on tool diameter. The tool is made up of three basic components – the electrical chassis, the centralizer, and the “Backlight” camera. The light source is positioned above the camera in the same housing. This facilitates indirect illumination, as well as creates an unobstructed view of the wellbore. This coupled with a surfactant applied to the camera lens allows the operator to descend into the well through an
oil/gas column of several thousand feet and maintain the ability to image the wellbore where a clear fluid is the primary medium. This technology is routinely applied to pumping wells with minimal preparation. In many cases, by shutting in the well and allowing the fluids to separate, clear real time video can be achieved.
Today, downhole video technology is a viable diagnostic tool for many downhole applications. Downhole video technology has been used for numerous applications including mechanical inspection, open hole logging, formation damage analysis, fishing operations, as well as detection of fluid and sand entry.