WorldWide Drilling Resource

Environmental Monitoring by Thomas Kwader, Ph.D., P.G. Well Development Can Make or Break a Well O f t e n t i m e s when we are drilling a new wel l in an “unknown” area, it’s difficult to estimate the specific capaci- ty or well yield, espe- cially if we are drilling by the mud rotary method. Well development is an important part of drilling every well. If the mud and gel are not sufficiently removed from the well, the true well yield cannot be deter- mined. There is no doubt many boreholes have been abandoned because they did not appear to have a sufficient amount of water to complete the borehole as a well. A quick “lesson learned” story: About 20 years ago, one of my industrial clients tried to save some money and pulled an eight-inch submersible pump out of a well with a crane he had on-site. They ended up ripping the stainless steel screen and had to have a new well. Of course, the new well was awarded to the lowest bidder. The company, from another state, was not familiar with the sand and gravel formations of the site and mixed up a heavy, viscous, gel-based mud which really plugged the formation. The well screen and casing were set, and drilling mud pumped out. The well was drilled 30 feet away from the last well, which was a very productive well, producing about 20 gallons per minute (gpm), per foot of drawdown. This new well, drilled exactly to the same specifications as the original well, was pumping dry at the total depth of 130 feet. After a day of pumping water in and out of the well, the well could still be pumped dry at 20-30 gpm. The second and third day was not much better. The mud gel was still strong and not breaking down. After using some chlorine and mud dispersant, the well began producing the same amount of water as the original well. Once the gel started to breakdown, the specific capacity increased dramatically. Moral of the story - developing a well, which includes breaking down the “mud-cake” and using a surge block to move the “fines” (clay) into the borehole and out of the well by surging may be the most important part of the drilling process. You don’t know how good your well is until you have fully developed the fine material out of the borehole that was “packed” there by the drilling process. Tom Tom Kwader may be contacted via e-mail to michele@worldwidedrillingresource.com 33 WorldWide Drilling Resource ® AUGUST 2017