Geonavigation of Horizontal Wells in the Barnett Shale: How to be Successful

Ken Bowdon

The Barnett Shale is one of the most significant onshore domestic gas plays within the past 30 years. The importance of the play does not rest solely upon the large reserves that have been proven within the Barnett Shale but more so because the Barnett play strengthens the hope that shale gas plays across the country may also be as prolific. There is little doubt now that Horizontal Drilling has played a most significant role in the play’s success and that the success of future Shale Gas plays will also depend upon the utilization of Horizontal Drilling. The question of geonavigation in the Barnett is evolving from an option to a necessity, as in every horizontal play that has arisen. The argument begins; “The zone is thick so it doesn’t matter where the well is in the reservoir”; “The frac will reach what we do not drill”; “There is little to no faulting”; “There is little structure so it is easy to stay in zone”; “Geonavigation increases the cost”. The world is always more complex than our models indicate, therefore as a horizontal play develops it is invariably recognized that there is a “sweet-spot” in the reservoir; fracs don’t always behave as our models predict; the formation is considerably more faulted with more structural complexity than previously imagined; faulting does affect well performance; the drainage area of the wells is different than expected; and the most expensive horizontal well is not the well that cost the most but the one that is in zone least. Geonavigation is one of the keys to success in every horizontal play. The Barnett Shale is no exception.