Water Well Journal
Issue link: http://read.dmtmag.com/i/529509
the smaller diameter screens. The length of screen is based on forma- tion samples and overall design of the well. 3. The leader is made of Schedule 40 steel or stainless steel that is the same diameter as the screen. It can be any length but is usually 5 to 10 feet long. It serves three purposes: a. It provides maximum exposure of the screen without the problems of pulling the outer liner too far (fudge factor). b. It provides an area where you can attach the screen packer and the "nubbins" for the secondary packer without losing screen production. c. It provides an area to attach the centering guides to assure the exact location of the screen and leader for installation of the pri- mary K-packer. 4. The secondary screen packer is welded to the leader and serves as a seal between the screen and the pri- mary K-packer assembly. The "nub- bins" below the packer serve to set the screen in the well via the setting tool. 5. The liner packer or primary K-packer is designed with a right hand external "J" hook to lock the upper packer to the screen packer. Once the gravel pack is in place, the casing is pulled back to expose the screen, and devel- opment has been completed, the upper packer is set with a tool using a left handed "J" hook. This allows you to turn out of the internal "J" hook with the tool, which will lock the primary K-packer onto the sec- ondary K-packer with the external J-hook in a simultaneous motion. This is referred to as a double inverted J-hook assembly. Once this is completed, the setting tool is removed. The primary K-packer is made up of three pieces: • External J-hook cut from steel pipe to form the notch of the "J." It is large enough to slip over the leader, yet seal to the secondary packer. • Concentric bell reducer to connect the J-hook to the primary packer made of steel and usually welded together. • Standard figure K-packer to seal the upper K-packer assembly to the inner liner. There are three specialty tools re- quired to pull the screen, install the gravel pack, and place the primary K- packer assembly. They are: • Pulling tool. This tool is used to pull the screen out if necessary. It should be made up with the sump assembly to assure it fits the J-hook of the sump assembly. It can be adapted to either National Pipe thread (API) or to rotary drill rod thread (which is usually stronger). • "Hat". This gravel packing tool allows you to set the screen via the J-hook assembly on the secondary packer, and provides a way to install the gravel pack without filling the screen with sand. The packing tool just fits over the secondary packer. Water is run on the inside of the set- ting pipe and sand is added. The sand and water run out of the setting pipe just above the "hat" and allow for the placement of the sand without prob- lems of bridging. The amount of sand needed can be calculated, but constant checking between the screen and inner liner is required to assure proper placement of the sand. The gravel packing tool has a right hand J-hook that can be turned 1/8th turn to release the tool. • Setting Tool. The setting tool is used to place the primary figure K-packer. It is constructed so that the tool keeps the primary K-packer from tipping, which would make it difficult to in- stall. Once in place it is turned 1/8th turn to release prior to removal. Design Is Key The key to success in any production well is the proper design of the screen. The cable tool method offers the benefit of allowing you the time required to per- form a sieve analysis on the samples, to determine the screen design and cost changes, to wait for production of the screen, and to get the screen and proper gravel pack to the site for installation. In this case, it took two weeks to design, manufacture, and deliver the screen to the site. Most rotary or open hole drift wells would not open that long. The ro- tary or auger method would require in- stallation of a test hole while waiting for proper screen design, manufacture, and delivery. In late June, we performed a pump test on this municipal well. The test on Well No. 11 showed a production rate of 4000 gpm with a yield of 160 gallons per foot of drawdown—a solid producer for the city of Maple Grove. Contractor Roger E. Renner, MGWC, is part of the family firm of E.H. Renner & Sons Inc., Elk River, Minnesota. He is a certified Master Groundwater Contractor. WWJ Twitter @WaterWellJournl WWJ July 2015 51 Exceeding Drilling Expectations, Daily. s l l i r t d s e n fi e th r fo e c r u o s r u o Y e d i w d l r o w e l b a l i a v a l a c i n h c te o e G l ta n e m n o r i v n E l a m r e th o e G l xpectations Daily a m r e th o e G l l e W r te a W / M n o ti c u tr s n o C r e g u A y r ta o R c i n o S s k c u tr T P C s r e m m a h to u A m p i u q e ty l a i c e p S g y. n i n i s t n e m 3 6 4 4 . 4 0 4 . 0 0 8 . 1 m o c . s e i g o l o n h c te l r a m Exceeding Drilling Expectations, Daily.