WorldWide Drilling Resource

67 WorldWide Drilling Resource ® JUNE 2013 Rehab vs. New Well Replacement Decisions by Edd Schofield Johnson Screens We recently had a question raised by a salesman asking if anyone knew of a cost benefits analysis program when operating an aging well versus that of drilling a new well. The question is an age-old one, and one with numerous ramifications regard- ing the cost of operating an inefficient well. The related costs of rehabbing the well (an expensive decision) might not have any real guarantees attached to the work as opposed to simply dip- ping into the budget and coming up with the funding to drill a completely new well. There have been numerous studies evaluating dozens of related factors pertaining to a well’s present status and its overall operational life expectancy. Those factors are all weighed and an “expected service life” and designation is given to each individual well. This grading system of groundwater wells can help management make educated guesses as to how and when to budget future well rework with that of ultimate well replacement decisions. In the past 25 years, all in the same territory, I am now beginning to see well failures of LCS (low-carbon steel) where initially SS (stainless steel) completion material was recommended. At the time, decisions for LCS were made on a cost- effective basis; yet 25 years later, the cost savings has become a real expense. Regardless of the various promises of superior corrosion resistance with certain special “alloy mixes”, low-carbon steel is still low-carbon steel, and those various exclusive mixes of LCS which promised higher corrosion resistance are now be- ginning to fail just as you would expect any LCS-based steel to do so over time. There are numerous studies pub- lished today reporting wells completed with stainless steel last longer than those of (any) LCS alloy mixture, and all these studies conclude the cost difference be- tween wells completed in SS versus LCS are realized in as little as seven years! The use of stainless steel is an investment in a production well and not a cost - as had been believed years ago. The fact that well sighting today, especially in urban areas, comes at great expense, pumping facilities and trans- mission lines are not easy to replace or reroute, so we need to do the best job possible up front and invest in the best possible well completion materials from the start. As far as reworking an older well, one has to look at all related costs such as land, permits, cost to drill, and all material costs. Older wells in serious, obvious decline do not always guaran- tee a successful return to full production when a major rehab is completed. New wells offer more efficient well operation, but they come at a significant expendi- ture. Opting to rehab a well can typically buy some time, so you have to compare all the upfront rehab costs along with the prospect of operating an inefficient well with that of making an investment in a new, more efficient well. Edd admin@ worldwidedrillingresource.com " ; # 511-,(2 0) 20'5&43 %9 4+(3( ,/( $/5)$&452(23 ; 08 029'0/ # ! : : $8 $,- 3$-(3 *,6(/3,/4(2/$4,0/$- &0. "(% ,4( 777 *,6(/3,/4(2/$4,0/$- &0.