Publications

Loss of annular integrity in a well can create sustained annulus pressure and loss of zonal isolation, both of which can significantly impair the productive capability and efficiency of the well. Effective remedial action must be based on a clear understanding of the underlying causes. It has previously been difficult or near-impossible to locate, explain and quantify the undesired fluid movements symptomatic of loss of annular integrity. Without this information, repair or control is at best a matter of informed guesswork or trial-and-error. An analysis technique is presented which uses ultrasound energy and thermal profiles, recorded in wells with and without simultaneous annular bleed-off. The log data, recorded in both depth and time domains, is integrated with other well data. History matching techniques of temperature modeling can deduce a quantitative estimate model of fluid movements in annuli. The analysis method has been applied successfully to a number of wells over the past year. An outline of the methodology and the overall results achieved for this group of wells are presented as brief case studies in this presentation. The correlation of acoustic data with temperature measurement has long been recognized as a useful integrity diagnostic, this paper will shows that the development of an ultra-sensitive ultrasound recording device combined with highly developed temperature modeling techniques can significantly improve annular integrity analysis. It is concluded that the technique offers a valid method for diagnosis of the cause and extent of annular integrity failure, which may then inform a more effective remedial strategy and subsequent action. The consequence must be a reduction in the risk to both safety and the environment for the upstream industry.