Geomechanical Aspects of Brown Field Development Drilling in the South Arne Chalk Field, North Sea

In early 2016, a mature field development program was completed on the South Arne field. This North Sea chalk field thus increased the existing 20 well stock with a further 11 injectors and producers. Drilling was getting increasingly challenging up to the start of the campaign. The challenges originate from strong production induced pressure variations in the 100 Bar range within a well and 200 Bar between wells. In addition, parts of the field have seen production induced compaction. Mitigation of these issues has required significant variation from one well to another in how these should be drilled, and a main vehicle for success has been application of managed pressure drilling (MPD). Examples of pre- and post-drill mud-windows will be given and a well where compaction effects were significant in the reservoir section is discussed in the abstract. The drilling campaign was successful by broadly adhering to the plan, delivering the desired reservoir sections, and getting completions to bottom. The success is due to deployment of MPD, significant focus on geomechanical analysis, and strong cooperation between drilling, geomechanics, and related disciplines.