Field Experience Using Flow Positioned Ditch Magnet Systems - Contribution to Efficient Drilling

Abstract

The presence of magnetic debris in the drilling fluid has a detrimental effect on the drilling process. The BHA compass becomes shielded and most Logging While Drilling operations are affected. Magnetic particles will be present whenever no efficient method to remove these are used. The following text shows how removal of such contamination contributed to successfully drill 6624m horizontal 8 ½" section of in one run on with high average ROP on a North Sea field. Benchmarking of the flow positioned magnets with simpler systems has shown that it may be several times as effective in removal of magnetic debris than competing systems. Furthermore, this removal significantly eased the directional control during drilling. For the particular well the removal of magnetic debris was very effective. It was stated that due to the improved directional control they did not observe the severe whirl typically expected in long tangent sections. Directional control is known to be affected by the magnetic particle content in the drilling fluid. Neither was there any need for changing any logging tools during drilling. Such changing of logging tools is not uncommon because of agglomeration of metal on the measurement ports. Also, the lifetime of the turbine in the MWD increased partly because of less metallic debris in the drilling fluid. In the article it is summarised the experience of operating the ditch magnets along with an outline of the drilling performance. The amount of removed steel is quantified. The effect on directional drilling is assessed. At the same time, the workload to clean the magnets properly is shown as well as the need for the crew to operate the system properly.