Water resources consultant, Woodward-Clyde Consultants, Denver, Colo.
Pages: 13 Published: Jan 1981
Many factors affecting fluid injection through wells involve clogging of the well and injection zone. Extensive field research carried out in the Grand Prairie Region of Arkansas, supported by special laboratory testing, involved the injection of surface waters into native waters of the local aquifers. The principal causes of clogging were found to be gas binding or air entrainment in the injection zone, suspended particles in the injection fluid, bacterial contamination of the injection zone by the injection fluid and subsequent clogging by bacterial growths, mechanical jamming of the injection zone and gravel pack around the well caused by particle rearrangement when the direction of fluid movement into and through the injection zone is reversed, and chemical reactions between the injection fluid and the native groundwater or the particles in the injection zone. The results indicated that the efficiency of the injection well could be reduced by as much as 50 percent by such factors and that treated injection fluid therefore would be advisable.
Other problems in operating an injection well included the effects of injecting fluid of a different temperature and viscosity and the interpretation of fluid-level changes in the injection zone during the injection tests because most clogging was found to take place within a few feet of the injection well.
Laboratory tests were used successfully to make preliminary estimates of the hydraulic characteristics of the injection zone prior to field testing of those properties. Laboratory experiments also showed that a permeability reduction of as much as 45 percent resulted from compaction of the gravel pack caused by surging action during well development and from the pumping and injection tests.
water injection, injection wells, well completion, groundwater recharge, recharge wells, water
Paper ID: STP27656S