WorldWide Drilling Resource®

Environmental Monitoring by Thomas Kwader, Ph.D., P.G. WorldWide Drilling Resource ® Hydrogeologist Well Development - Optimizing Well Yield from Screened Wells in the November 2019 issue of WWDR on page 32, Tom Ballard wrote an excellent article on the importance of well development for ensuring long life of water wells. i agree with his entire article, but would like to stress a few key points that are critical during the design to ensure the long life of production water wells. 1) The well should be designed to maintain a pumping level to remain above the top of the screen, or remain inside the well casing in open-hole finish (rock) wells. Exposing the screen or open portion of the well to air promotes the growth of unwanted bacteria. The bacteria will then tend to plug the pore spaces near the well. 2) if maximum production is a priority, a “wire wrapped” type screen (with V-shaped slots) is preferred over slots which are cut into the pipe. The slot openings should be slightly smaller than the median formation grain sized to maximize flow to the well. 3) if a “gel” type drilling fluid is used to seal the walls of the producing formation during drilling, an additive to break down the mud cake should be used to remove the gel after the screen is set. Otherwise, full devel- opment may be difficult to achieve, and the specific capacity of the well may be severely compromised. 4) Choosing the correct development method. There are dozens of ways to develop a well, including - bailing, surging, overpumping, compressed air, etc. The most effective method of well development is by using a surge block, which involves moving the water both in and out of the screen. The objective of surging is to break down the mud cake and remove as much of the fine-grained materials and gel as possible at the borehole wall as soon as possible. Once a well begins to fail, unless you take action to try to rehab the well (which is not always effective), it will likely con- tinue to deteriorate with declining water levels and lower pumping specific capacities. These facts make initial well development critical for a long well life. Also, it should be noted that wells with high specific pumping capacities over time will use significantly less energy than poorly developed wells. Tom Tom Kwader may be contacted via e-mail to michele@ 19 WorldWide Drilling Resource ® MARCH 2020 ENV May Issue Deadlines! Space Reservation: March 25 th Display & Classified Ad Copy: April 1 st