Revitalizing a High-Temperature Tight Oil Reservoir: Successful Stimulation Using Single-Phase Retarded Acid and Pinpoint Abrasive Jet

This paper details the successful stimulation of a high temperature tight oil reservoir using single-phase retarded acid and pinpoint abrasive jet technology. Despite multiple prior attempts to improve injectivity, including pre-commissioning acid treatments, the well remained non-productive and shut in. The objective was to restore injectivity and achieve sustainable production through an innovative and tailored stimulation approach. The well, completed as a horizontal oil producer with a 6" open-hole section, initially underwent a pre-commissioning treatment with 15% HCl via coiled tubing, which failed to enhance injectivity. In 2025, a new stimulation plan was developed, supported by core sample testing to identify the fluid system with the highest solubility power and optimal Pivot. The treatment began with an acid wash using 28% HCl to improve reservoir accessibility. This was followed by 20% HCl single-phase retarded acid, specifically formulated to control the acid-carbonate reaction rate, enabling deeper wormhole penetration and permeability enhancement. The stimulation treatment achieved remarkable success, with injectivity improving 2.2-fold. The operation was conducted in 35 stationary stages using pinpoint abrasive jet technology, ensuring precise acid placement in low-permeability zones. The initial acid wash with 28% HCl effectively removed near-wellbore damage and provided initial improvement in injectivity allowing placement of the main treatment, while the single-phase retarded acid delivered deeper wormhole penetration into the reservoir, enhancing connectivity and bypassing existing formation damage. A significant outcome was the well’s immediate flow of hydrocarbons post-treatment, without the need for nitrogen lifting assistance. This highlights the effectiveness of the tailored stimulation approach in revitalizing a well that had previously failed to respond to conventional acidizing treatments. Post-treatment analysis confirmed that the combination of advanced acid systems and pinpoint abrasive jet technology successfully addressed the severe injectivity challenges, resulting in sustained improvements in reservoir connectivity and production. The results demonstrate that such an integrated approach offers a highly effective solution for enhancing the performance of tight reservoirs where conventional methods have failed. This study reports the first successful application of single-phase retarded acid in combination with pinpoint abrasive jet technology in this field. The approach offers a replicable and efficient solution for overcoming injectivity challenges in similar low-permeability reservoirs where conventional acidizing treatments have proven to be inefficient.