Active Magnetic Ranging While Drilling: Tool Function and Tests Results

A well intercept operation has the scope to drill into an existing well. Similarly, some infill drilling operations are conducted with the scope of avoiding interception with other wells. A prototype of a tool for Active Magnetic Ranging While Drilling (AMR) without the use of a separate wireline operation has been developed. The main scope of the current article is presenting the results of a series of prototype tests of this tool in test wells. The ranging tool emits a low frequency alternating current into the formation to reach the target well, and then run through that well's casings and back to the well being drilled. This electric current set up a variable magnetic field that is measured by the AMR tool determining the direction towards the target well as well as the distance. In case of drilling a relief well, 10 - 25 wireline runs are needed before the target well is intercepted. The present AMR tool is fully integrated in the drill pipe and, thus, no wireline operations are required, and all the tripping operations are avoided. A prototype of an active magnetic ranging tool on the drill pipe has been developed. This tool is outlined in the paper. Most focus will be given to a performance test conducted in a research well in Norway. Different pipes with controlled earthing are placed in neighbour wells to the well with the logging tool. The AMR tool was run in one of the research wells and the direction and distances to other target wells were measured. The set-up and the results of this logging operation that was conducted on the drill pipe is described in detail. It is described how the direction and distance between the two wells are measured using the tool.