Maximum reservoir contact and extended reach wells have been widely used to maximize the well productivity. The horizontal section could be 6000 ft or more in those wells, which make the damage caused by the drilling fluid varied from one section to another in the long horizontal section. The process of diversion of the stimulation fluid in carbonate wells with the same features has been performed using Viscoelastic surfactant (VES) and polymers based hydrochloric acids. In sandstone wells we cannot use either VES or polymers because there is no enough calcite to react with these fluids to produce the gel diverting materials. Also, VES could be adsorbed on the sandstone surface and cause more damage to the formation, and the use of HCl in sandstone formations has been proved to be more damaging than removing the damage.

In this paper we will introduce a smart fluid that can be used to remove the damage caused by calcium carbonated weighted drilling fluid from the maximum reservoir contact (MRC) and extended reach wells without adding any gelling materials. This fluid will react with carbonates in the sandstone formation and will produce high viscosity that will divert the flow through the less permeable part in the horizontal sections. The proposed fluid is HEDTA (hydroxyl ethylene diamine tri acetic acid). Sandstone cores were used in the coreflooding experiments, and the stimulation fluid viscosity will be measured before and after the flooding. Parallel coreflooding technique was used to confirm the diversion ability of this chemical through two sandstone cores with different permeabilities.

The experimental results showed that the viscosity of the stimulation fluid increases at least 3 times after the treatment of the sandstone cores and the parallel coreflooding showed a good ability of diversion for the fluid. The experimental results were used to describe the process of diversion using this fluid mathematically in this. HEDTA chelating agent showed good ability to remove the damage caused by drilling fluid from different permeability contrast set of cores.

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