During well intervention activities, one of the biggest challenges faced is uncertainty about the downhole hardware. Carrying out interventions without understanding the state of downhole equipment can be time-consuming, expensive and ultimately unsuccessful. There are several diagnostic techniques available to assess the state of downhole hardware, but none offer an efficient and reliable solution, particularly if the well fluid is opaque. Recently, an X-ray based wireline tool was introduced for providing downhole imaging, regardless of the well fluid. We will present a case study in which this new tool was run in a brine-filled onshore gas storage well in the Netherlands.
The technique uses X-rays produced by the wireline tool that backscatter from the well fluid to reconstruct the surfaces of objects in the well. The reconstructions are displayed as two-dimensional images, three-dimensional interactive renderings, or even 3D printed models. To inspect an object, the tool is run into the well to tag the object of interest. Images are then acquired and sent to the surface in real-time for viewing and analysis. Imaging can be conducted in any fluid, including oil, brine, oil/water mixtures, drilling muds, and other fluids with a large amount of suspended particulates, as well as through some solid materials. The tool is currently undergoing field testing.
We present a case study from a well in the Netherlands. During a coiled tubing intervention, the coiled tubing became stuck and disconnected downhole, leaving behind a bottom-hole assembly (BHA). Before attempting to retrieve the BHA, the client wished to verify the size and integrity of the coiled-tubing (CT) disconnect. Due to a large amount of sediment and debris in the well, the well fluids were murky and laden with particulates making it difficult to run an optical camera. The new X-ray imaging tool was run, and clear images were obtained, providing measurements with millimeter-scale accuracy of the inner- and outer-diameter of the CT disconnect. The images also revealed an unanticipated cylindrically-shaped object inside the disconnect. Post-facto offsite testing indicated that this object was likely a casting of a tube that had run through the CT disconnect and was formed from a cake of waxy material and metal shavings. The X-ray imaging results verified the client’s fishing plan and they successfully retrieved the fish on the first attempt.
The new X-ray wireline tool provides dimensionally-accurate images of downhole equipment in a manner that is quick and reliable without the need for fluid displacement or well clean-up. Additionally, visualization of objects in 3D in real-time provides a unique perspective that improves understanding of the state of downhole hardware. Altogether, this reduces the uncertainty and concomitant risk associated with well interventions, resulting in a higher success rate, less downtime, and lower cost.