When injecting into multiple wells simultaneously, stagnation zones can develop preventing effective reagent delivery. Figure 1 shows the simulated EOS Pro distribution in a homogeneous aquifer when EOS Pro is injected into all the wells in a biobarrier at the same time. Simultaneous injection creates gaps in the biobarrier where converging streamlines prevent effective distribution.

Figure 1. Simulated EOS Pro distribution in biobarrier during simultaneous injection.

Luckily, there is a simple method to solve this problem. Split the wells into two groups, with every other well in Group A, and the remaining wells in Group B. Inject into all the wells in Group A first, then inject into the Group B. During the Group A injection, stagnation zones will develop midway between the A wells, where the B wells are located. During injection into the B wells, EOS Pro will be distributed throughout the stagnation zone. Figure 2 shows simulated contact efficiency for a biobarrier in a heterogeneous aquifer versus pore volumes of dilute emulsion injected. Switching from simultaneous to alternating injection can increase contact efficiency by up to 10% with little additional cost.

Figure 2. Simulated EOS Pro contact efficiency for simultaneous and alternating injection of biobarrier wells.​

For more ideas on how to improve contact efficiency and reduce costs, check out the article on Emulsified Vegetable Oil (EVO) for Anaerobic Bioremediation on ENVIRO.wiki.

Did you know our head of Research and Development, Dr. Robert “Bob” Borden, was instrumental in creating ENVIRO.wiki?  This site contains a wealth of information for our industry, all at no cost!  Check it out!