Evaluation of using HEDTA chelating agent to clean up long horizontal heterogeneous sandstone wells without divergent

The removal of the calcium carbonate water-based filter cake and the associated formation damage after drilling is a very difficult task, especially in horizontal and extended reach wells. The horizontal section length could be 20,000 ft or more with different permeability distributions, which makes the damage caused by the drilling fluid vary from one section to another. The filter cake removal in heterogeneous long horizontal lateral needs diverters to distribute the cleanup fluid through the entire section. In this paper, a smart fluid (HEDTA of 20 wt% and pH 4, hydroxyethyl ethylenediamine triacetic acid trisodium salt) was evaluated to remove the damage caused by calcium carbonate weighted drilling fluid for the horizontal and extended reach wells without adding gelling agents. This fluid will react with the calcium carbonate in the filter cake and the calcium carbonate in the formation to produce high viscosity fluid that will divert the fresh flow through the less permeable sections in the horizontal well. Parallel coreflooding experiments were used to confirm the diversion ability of this chemical through two sandstone cores with different permeability. The results obtained showed that the viscosity of the stimulation fluid increased at least 3 times after the treatment of the sandstone cores and the parallel coreflooding showed good ability of diversion for the fluid. The experimental results were used to describe the process of diversion using this fluid mathematically. HEDTA chelating agent showed good ability to remove the damage caused by drilling fluid from different sandstone cores with different permeabilities.