Innovative Application of Solid Degradable Particles Mitigates Plug Failure and Efficiently Enhances Acid Fracturing Plug and Perf Operation

Abstract

Abstract This methodology presents an efficient implementation of solid degradable particles to address zone isolation failures in plug and perforation (Plug and Perf) acid fracturing operations, thereby facilitating proper zone stimulation without the need for subsequent well interventions using coiled tubing or wireline. The novel approach centers on the utilization of multi-modal, self-assembling, and self-degradable solid particles to temporarily seal the void space created by an unset ball in a mechanical plug situated between two fracturing stages. The methodology encompasses techniques for identifying isolation failures from various perspectives and outlines the necessary adjustments to transition from conventional solid degradable particle usage to align with this new approach. Additionally, a comprehensive method is presented for readers to replicate this solution in similar scenarios. Effective stimulation of tight gas carbonate formations, particularly in high-temperature, high-stress, sour environments with reservoir heterogeneity, poses significant challenges. In addition to meticulously studying reservoir properties to select the appropriate acid blend and diverters for stimulation treatment, the completion strategy plays a pivotal role in augmenting stimulated reservoir volume. While Plug and Perf operations have proven to be an effective solution for zone isolation, they entail additional time and costs when interventions are needed, such as addressing an unset ball within the plug. This study focused on a horizontal well with two acid fracturing treatments, considering similar formation properties, perforation strategies and treatment fluid volumes. Based on these comparable parameters, a series of analysis were conducted to validate communication between stages through the mechanical plug. Subsequently, the methodology involved the design and efficient pumping of an appropriate solid degradable pill to isolate the path to the previously stimulated zone. Several indicators of its effectiveness were observed, including a significant pressure increase once particles began bridging and sealing off the path within the plug, an overall higher-pressure response between stages, and a substantial difference in instantaneous shut-in pressure (ISIP). These observations corroborated the effectiveness of stage isolation achieved using self-degradable solid particles, ultimately resulting in the treatment of the new non-stimulated zone. The innovative application of solid degradable particles presented herein represents a forward-thinking solution that enhances the efficiency of Plug and Perf operations. It obviates the need for additional wireline interventions to set new plugs and contributes to improved reservoir stimulation coverage—a critical factor for the commercial recovery of hydrocarbons in carbonate tight gas reservoirs.