Laserfiche WebLink
%-`]-I q9S 3:32Af l FROf 1 • • <br /> F_ I <br /> JTSC-OPS Fax:y16-1�h-5(Sa May 14 i.y� I 2 r. u4 <br /> decommissioning operations and in most situations, should be <br /> avoided. Perforating an entire well casing from bottom to top and <br /> placing grout in the casing, with or without being pressurized, is <br /> a very common procedure that is too routinely used for <br /> decommissioning wells. For most wells in sedimentary environments, <br /> this procedure should be thoroughly evaluated and probably <br /> reconsidered before being implemented. To achieve proper results <br /> for any decommissioning technique requires that permeable (as well <br /> as impermeable) zones be identified because they may hinder the <br /> sealing process. Permeable geologic materials generally accept <br /> grout and/or sealing slurries targeted for emplacement adjacent to <br /> aquitards. some permeable geologic materials are capable of <br /> accepting so much grouting material that they will severely limit <br /> the sealing operation. <br /> Construction and design criteria are <br /> lthe second <br /> most <br /> important <br /> considerations for decommissioning <br /> Of filter <br /> pack materials, screen slot openings, and casing in a borehole must <br /> be determined before sealing agents are installed. Unfortunately, <br /> construction details for many wells are not available from well <br /> owners, DWR, or local governmental agencies. The absence of <br /> construction records complicates the decommissioning procedure <br /> usually requires that downhole remote sensing survevs be performed. <br /> However, even if records are available, a downhole video camera <br /> survey should always be performed to check condition of the casing; <br /> prior to aerforzaing a down-hole video survey, the casing should be <br /> vigorously brushed and left idle for at least 24 hour so that <br /> particulate material will settle. common geophysical logging <br /> techniques 'what provide for establishing geologic control and well <br /> nd casing <br /> construction details include cement bond (sonic) , gamma, a <br /> cellar locator. <br /> A simple effort exercised by many individuals to decommission wells <br /> has been to fill them with miscellaneous debris including rocks, <br /> bricks, metal, wood, and earth materials_ intoe the well 1 but efforts prevent <br /> unwanted solid objects from being pp <br /> do <br /> from migrating into the subsvxtace or <br /> nothing to halt fluids <br /> preventing cross contamination of ground water. The removal of <br /> `ill-types of material from a well shouto bu$ matt ualya£ ddre %a <br /> because the most sinple te=nlque is YP <br /> circulation apparatus. Reverse-circulation techniques will remove <br /> and if casinis w6aki it 'May <br /> all water from inside casing <br /> water tab e e Mud rotary drilling is <br /> collapse, especially below <br /> the best technique for removing foreign debris from wglls- <br /> Wells with Extensive Filter Packs <br /> Many Wells are constructed using extensive filter packs which act <br /> as conduits to vertically pass ground water and, if present, <br /> coatamxnakion. To ptoperly daCC;=i.ssion these typ®!s Of well' <br /> without Q0zkP1ete1y drixlih4 out =nstt"ctian materials requires <br /> pe�rrarc4tinq the oakinq wd�acsn ea aguitards, pa"ar placement, and <br /> -rem ie e grouting sections of the w,e11 in lifts with time <br /> pvessur <br /> provided for cement curing. Special effort must be provi.Bed for <br />