Optimized Stimulation Efficiency with Degradable Particulates in High-Anisotropy Carbonate Reservoirs: Comparative Study of Horizontal and Vertical Wells in Iraq

Highly anisotropic carbonates require unique stimulation fluid placement methodologies and one of the ways to improve this is by utilizing degradable particulate material, which will be the focus of this manuscript. The primary objective was to help improve stimulation efficiency and reduce the number of stages, overall treatment time, and requirement for prolonged workover rig operations. A comparative evaluation between horizontal and vertical well geometries was also conducted to assess particulate placement behavior and diversion effectiveness. Degradable particulates were introduced as a temporary diversion agent during acid stimulation treatments in a carbonate reservoir with high permeability contrast. The particulate blend was engineered to fully degrade under downhole conditions to eliminate post-treatment intervention and across multiple field applications on both vertical and horizontal wellsReal-time data from pressure response, surface rates, and fluid distribution confirmed diversion performance. Post-treatment production data and wellbore imaging tools confirmed fluid coverage and zonal activation. The degradable-particulate diversion workflow delivered marked improvements in stimulation efficiency for both vertical and horizontal high-anisotropy carbonate wells. After a baseline matrix-acid schedule, particulates were injected between stages to temporarily seal treated zones and force acid into bypassed intervals at matrix stimulation rates. Real-time surface pressure records rose from 15% to 60% after each diversion stage, followed by a pressure drop with the 15% HCl, confirmingimproved fluid penetration homogeneity and effective zonal isolation. Post-operation tests showed uplift in stabilized oil rates and an observed increase in average wellhead pressure versus pretreatment values, which demonstrated the direct impact of improved fluid placement and reservoir contact. Encouraged by these gains, a transition occurred from complex ported work strings that struggle to apply the technology to simple open-end tubing with bridge plugs, which streamlined operations and extended diversion reach in longer intervals. This optimized design cut workover rig time by 25%, reduced stage count by 40%, and removed the requirement for straddle packers. Field-wide rollout sustained production increases of 25 to 35% for the treated wells, which established degradable particulates as a cost-effective, low-footprint solution that helped improve stimulation coverage in complex carbonate reservoirs. How degradable particulate diversion can simplify stimulation workflows and maximize treatment efficiency in complex carbonate reservoirs is highlighted. It also provides valuable insights into particulate behavior in various wellbore geometries, which helps improve the design of future stimulation strategies in anisotropic formations.