Nanomaterials and Technology Applications for Hydraulic Fracturing of Unconventional Oil and Gas Reservoirs: A State-of-the-Art Review of Recent Advances and Perspectives

Realizing the Rapid Release of Drag Reducers via pH-Induced Oil Phase Transition of Inverse Emulsion

As a key component of slickwater fracturing fluids, emulsion drag reducers play a vital role. The dissolving capacity of traditional emulsion drag reducers is improved by adding hydrophilic surfactants, which leads to poor stability of the emulsion drag reducer. In order to eliminate the contradiction between stability and release of the emulsion drag reducer, here, pH-responsive polymer emulsion was fabricated using the switching solvent (HA) and white oil as the continuous phase. Monomer emulsions exhibit obvious pH-responsive behavior. This is because the deprotonation of HA by pH stimulation leads to a change in the oil-water ratio of the emulsion, thereby facilitating the demulsification of emulsion. The remarkable stability of the monomer emulsion benefits the preparation of inverse emulsion polymers (P(AM-AA-AMPS)). The obtained P(AM-AA-AMPS) polymer emulsion features remarkable stability even after 15 days of storage. Importantly, the P(AM-AA-AMPS) polymer was released from the emulsion efficiently by pH stimulation instead of introducing an extra hydrophilic surfactant, which confirmed the improvement of polymer release by pH stimulation. The viscosity of the P(AM-AA-AMPS) polymer aqueous solution reaches a maximum value of 96 mPa s within 80 s at a pH value of 9.2. The release efficiency of P(AA-AM-AMPS) polymer emulsion is increased by 33% in comparison with that of traditional polymer emulsion (2 min). The P(AM-AA-AMPS) emulsion demonstrated remarkable drag-reduction performance by achieving a drag-reduction rate of 73% at a concentration of 0.05 wt %. P(AM-AA-AMPS) polymer emulsion with pH responsiveness eliminates the contradiction between the stability and release of emulsion drag reducers. Research based on pH-responsive P(AM-AA-AMPS) polymer emulsion provides other ideas for the development of quickly dissolving and long-term storage drag reducers, which is helpful for the development of low-permeability oil and gas resources.

Modified guanidine gel fracturing fluid system and performance optimization for ultra-deep and ultra-high temperature oil and gas reservoirs

The development of deep high-temperature oil and gas reservoirs gives rise to a rise in reservoir temperature along with the depth of the oil reservoir, thereby imposing higher requirements on the heat resistance of fracturing fluid. Guar gum fracturing fluid has difficulty tolerating temperatures exceeding 160 °C, thereby demanding the development of corresponding cross-linking agents, temperature stabilizers, and other additives to enhance the thermal stability of the fracturing system. Considering the distinctive characteristics of deep and ultra-deep reservoirs, such as extreme burial depth (exceeding 6000 m), ultra-high temperature (higher than 160 °C), and high fracturing pressure, an experimental modification of a guar gum fracturing fluid system was carried out, specifically tailored for ultra-high temperatures. The experiment identified and selected individual agents for ultra-high temperature fracturing fluids, including crosslinking agents, thermal stabilizers, flowback aids, and clay inhibitors. Through rigorous experimentation, these key agents for an ultra-high temperature fracturing fluid system have been successfully developed, including the optimal thickener GBA1-2, crosslinking agent BA1-1, anti-swelling agent FB-1, and gel breaker TS-1. The evaluation of diverse additive dosages has facilitated the development of an optimal guar fracturing fluid system, which exhibits outstanding high-temperature resistance while minimizing damage and friction. The outcomes of our experiments indicate that even after subjecting our ultra-high temperature fracturing fluid to 2 h of shearing at 170 s-1 at 180 °C, its viscosity remained above 200 mPa s-a distinct proof of its superior performance in withstanding high temperatures. This achievement represents a substantial progress in providing a suitable fracturing fluid system for the transformation and stimulation of ultra-deep and ultra-high temperature reservoirs, and also lays a solid foundation for further exploration and application in related fields in the future.

Unveiling the revolutionary role of nanoparticles in the oil and gas field: Unleashing new avenues for enhanced efficiency and productivity

Prominent oil corporations are currently engaged in a thorough examination of the potential implementation of nanoparticles within the oil and gas sector. This is evidenced by the substantial financial investments made towards research and development, which serves as a testament to the significant consideration given to nanoparticles. Indeed, nanoparticles has garnered increasing attention and innovative applications across various industries, including but not limited to food, biomedicine, electronics, and materials. In recent years, the oil and gas industry has conducted extensive research on the utilization of nanoparticles for diverse purposes, such as well stimulation, cementing, wettability, drilling fluids, and enhanced oil recovery. To explore the manifold uses of nanoparticles in the oil and gas sector, a comprehensive literature review was conducted. Reviewing several published study data leads to the conclusion that nanoparticles can effectively increase oil recovery by 10 %-15 % of the initial oil in place while tertiary oil recovery gives 20-30 % extra initial oil in place. Besides, it has been noted that the properties of the reservoir rock influence the choice of the right nanoparticle for oil recovery. The present work examines the utilization of nanoparticles in the oil and gas sector, providing a comprehensive analysis of their applications, advantages, and challenges. The article explores various applications of nanoparticles in the industry, including enhanced oil recovery, drilling fluids, wellbore strengthening, and reservoir characterization. By delving into these applications, the article offers a thorough understanding of how nanoparticles are employed in different processes within the sector. This analysis may prove highly advantageous for future studies and applications in the oil and gas sector.