In deep oil and gas operations, as well as in carbon capture, utilization, and storage, the temperature resistance of polyacrylamide is becoming increasingly critical. This paper investigates the temperature resistance of polyacrylamide from both microscopic and mesoscopic perspectives. Molecular dynamics simulation results indicate that the incorporation of sodium p-styrenesulfonate can increase the radius of gyration of polyacrylamide at high temperatures (increased by 2.97% at 180 °C) and decrease its diffusion coefficient (decreased by 33.94%) in water, effectively enhancing its temperature resistance. However, the decrease in hydrogen bonding was 17.39%. Additionally, the spatial network structure of the polymer obtained from scanning electron microscope images is parameterized using ImageJ software. The average values of area, perimeter, and width increased by 6.5%, 97.52%, and 275.86%, respectively, compared to the initial values, while the average value of skeleton width increased by 61.48% and 412.6%, respectively. Parameters such as pore area and width, along with an increase in fluctuation level, lead to a decrease in viscosity. The parameterization of the spatial network structure serves as a bridge between material structure and performance and also expands the application of spatial network structures in fields such as materials science and chemistry.

In order to get rid of the dilemma of gas well fluid accumulation in the gas field, we propose an innovative scheme of using Laval nozzle as a downhole atomizing nozzle for atomized drainage gas extraction. First, the preliminary design of the atomizing nozzle is carried out by combining the actual production situation of the gas field with the working principle of the Laval nozzle. Second, the single-phase flow of gas inside the Laval nozzle as well as the law of GLP (gas–liquid two-phase flow) was studied through CFD (computational fluid dynamics) numerical simulation calculations, focusing on analyzing key parameters such as flow rate, LVF (liquid-phase volume fraction), and pressure. The results show that the GLP field has similar characteristics to the single-phase flow field of gases, in which the flow velocity can be as high as the supersonic speed of 1060 m/s. However, the instability of the flow is enhanced, and the turbulent kinetic energy and energy dissipation are significantly increased. Inside the nozzle, LVF was maintained at a stable level of 0.008 34%, which verifies the feasibility of the Laval nozzle for downhole applications. Finally, the optimal structural parameters of the atomizing nozzle were obtained using the maximum volume fraction of the liquid phase, the effective conversion efficiency of the energy, the pressure change, and the change of the Mach number as the evaluation criteria: the length of the contraction section was 70 mm, the expansion angle was 10°, the expansion scale was 9.6 mm, and the Mach number of the outlet cross section was 2. This study provided theoretical guidance and practical basis for the field application of the Laval nozzle on the atomized dewatering gas extraction tool, and it also provided a good basis for future research and technological development.

The efficient development of carbonate rock reservoirs with rich oil and gas resources has become a hot topic and a focal point in the current oil and gas industry. The development of carbonate rock oil and gas reservoirs differs from that of sandstone reservoirs. Although gas flooding, water flooding, and chemical flooding have been carried out in recent years, the development is still unsatisfactory, and the on-site application of technologies such as nanoparticles is on the rise. For the future development of acid fracturing technology, accurate reservoir geological description, core printing based on additive manufacturing technology, the development of new acid fracturing techniques, and the research and development of acid fracturing equipment will have great research potential and economic value in the development of carbonate rock oil and gas reservoirs. Under the development background of high-temperature deep reservoirs, this paper comprehensively reviews unconventional acidizing fracturing fluids in carbonate rock oil and gas reservoirs. We introduce the main components, corresponding mechanisms of action, current research achievements, and advantages of promising acid fracturing fluids, including thickened acids. We focus on the application and limitations under harsh conditions of high temperature and high salinity while also focusing on the development of thickened acid fracturing technology. The thickening agent is the core of a thickened acid solution. Therefore, this article fully reviews the structure, sources, advantages and disadvantages, as well as the current development status of biological, cellulose, and synthetic polymer thickeners. Synthetic polymers, low-molecular-weight polymers, and small-molecular compound crosslinkers provide clues for temperature and salt-resistant thickeners and also promote the development of tight reservoirs.

The failure of thickeners at high temperature results in gelled acid acidification fracturing. To solve the problem, 8 kinds of polymers were synthesized by free radical polymerization of aqueous solution using AM, AMPS, NaAMPS, MAPTAC, DTAB and NVP as raw materials. The polymer was characterized by infrared spectroscopy and viscosity-average molecular weight, and the temperature resistance, rheology, salt resistance and shear resistance of the polymer solution were compared, and the mechanism was analyzed. The results show that the viscosity of GTY−2 is 181.52 mPa·s, and the viscosity loss rate is 56.89% at 180 °C and 100 s⁻¹, and its temperature resistance is the best. Meanwhile, the viscosity retention rate of GTY−2 is 84.58% after 160 min shear, showing the strongest shear resistance. The viscosity loss rate of GTY−1 in 20% hydrochloric acid solution is 80.88%, and its acid resistance is stronger than that of GTY−2. Moreover, due to the amphiphilicity of DTAB, the molecular hydration film becomes thicker, and the salt resistance of GTY−2 is lower than that of GTY−1. The experimental results show that GTY−1 and GTY−2 have good temperature resistance, salt resistance, acid resistance and shear resistance, and can be used as thickeners for acid fracturing with thickened acid to improve the effect of acid fracturing under high temperature conditions.