(41) A RE-INTRODUCTION TO OIL AND GAS WELL STIMULATION WITH CHLORINE DIOXIDE (CLO2)

Chlorine Dioxide (ClO2) has been used as a well damage removal and stimulation fluid since the late 1980’s. It was originally investigated as a means to remediate reservoirs of the permanently damaging effects of polymer, monomer, and polyacrylamide floods popular in the 1980’s across many conventional oilfields, including those in the Permian Basin of West Texas, U.S.A. Chlorine Dioxide is a strong oxidizer and highly effective biocide, very popular today for preparing frac waters and aiding in recycling produced waters, also to be used in fracturing.  Many petroleum engineers and oilfield production personnel are not aware of the chemistry, or services available to remove the damaging effects of polymers, polyacrylamide, frac gel, gel filter cake, biomass / biofilms, Hydrogen Sulfide (H2S), Iron Sulfide (FeS), Iron Oxide (Fe2O3), all species of bacteria including Sulfate Reducing Bacteria (SRB’s), and many other oxidizable particles that have plugged and otherwise damaged all types of wells.  Chlorine Dioxide has proven to be extremely effective in salt water disposal (SWD’s) and injection wells, but has also found an important role in vertical and horizontal producers having production challenges such as Iron Sulfide, due to the infiltration of SRB’s into the reservoir and the subsequent H2S, FeS, and H2S corrosion. This paper forms a summary of the ways Chlorine Dioxide, in conjunction with Hydrochloric acid (HCL), is used to remove wellbore damage, drastically reduce H2S levels, and overall, restore the well’s injectivity or productivity.  In addition, the paper outlines to the key aspects of treatment design to insure success while concentrating on practical field applications, as demonstrated in wells across the Permian Basin.