Drillpipe Conveyed Cased Hole Logging: New Technology and Mode of Conveyance for Cement and Casing Inspection

Abstract

Abstract Casing and cement are probably the two most critical components for good well integrity through the life of a well. Understnding the condition and annular coverage of both is essential for many subsequent operations and may also, in many locations, be a regulatory requirement. Therefore, a good knowledge is needed of the internal dimensions of the casing, the ovality, the thickness of the casing, the level of corrosion or wear, and the material in the annular space behind the casing. As the industry moves towards a significant amount of mature fields there is a push towards accessing new reservoir exposure from within existing production infrastructure. This is leading to a significant increase in the number of re-entered wells, often in highly deviated wellbores. Sidetracking off an existing cased well requires a good understanding of the condition of the casing and cement. It is now often the case that casing and cement evaluation operations are required several times on the same well. Historically these measurements have only been available on wireline. What we shall describe in this paper is the development and early field results of a pipe conveyed equivalent. The best description of this is to consider it the analog of a logging while drilling tool, but specifically designed for cased hole interpretation and furthermore for casing inspection and cement mapping. The fact that we run drillpipe in the well on numerous occasions gives us the opportunity to acquire this critical data, often in parallel with existing operations, or acquiring it in real-time during the rig operation we are using the data for. We will demonstrate how this tool was designed, and some of the key differences between this and a wireline conveyed tool. These differences presented some specific challenges that needed to be overcome, not only in the mechanical design of the tool, but also in the way it handles and processes data downhole. We will then show, through case histories, some of the data sets acquired and their comparison with wireline for qualification of the tool. The field results will show the full range of measurements which this tool is capable.