The extraction process of Tarim oil field in Xinjiang is accompanied by a large amount of oily sludge generation, which seriously restricts the progress of oil and gas development and causes serious pollution to the environment due to its large production, complex composition, and difficult treatment. Nanomaterials combined with ultrasound have been demonstrated to be a promising method for the disposal of hazardous oily sludge. In this paper, a magnetic material Nano-β-CD@Fe₃O₄ was prepared by hydrothermal method and surface modification method. Nano-β-CD@Fe₃O₄ can be intelligently enriched at the oil–water interface and oil-solid interface, and it can be stably dispersed to form nanofluid under the action of ultrasound. Nano-β-CD@Fe₃O₄ can cause changes in oil composition when it is exposed to ultrasound, resulting in the decrease of viscosity and increase of fluidity. The experimental results of treating oily sludge in Xinjiang Tarim showed that the best treatment effect was achieved when the concentration of Nano-β-CD@Fe₃O₄ was 0.5 %, the ultrasonic frequency was 60 Hz and the temperature was 60℃. This solution can reach 90.17 % oil removal efficiency within 45 min, and the secondary oil removal efficiency of Nano-β-CD@Fe₃O₄ recovered by magnetic separation could still reach 85.65 %. This efficient oily sludge treatment method proposed in our study provides valuable information for the development of oily sludge treatment technology.

In the drilling process of Tarim Oilfield, a representative of ultra-deep oil and gas reservoirs, there are many problems of wellbore stability/instability caused by the development of a large number of micro-fractures. According to the nano-plugging mechanism, rigid nano-SiO₂ and deformable nano-paraffin emulsion are added to the drilling fluid to improve the plugging rate. The effect of nanomaterials on the mechanical properties of limestone in the Karatal Formation was evaluated through a triaxial mechanical experiment, and it was found that rigid nano-SiO₂ can have a better plugging effect under high formation pressure. It can increase the compressive strength of the limestone core by 10.32% and the cohesion of the core by 12.19%, and the internal friction angle of the core was increased from 25.67° to 26.39°. The internal structure of the core after nano-blocking was observed using CT scanning, and the fracture distribution state of the core before and after plugging and the fracture characteristics of the core under the pressure gradient were obtained, which confirmed that nano-SiO₂ can effectively solve the fracture problem of deep limestone caused by micro-fractures.

The paper is proposed to introduce nanoemulsion into the ultra-drilling completion fluid system to improve the plugging performance. The pressure conduction method was used to evaluate the plugging properties of tight sandstone, the evaluation results showed that the fluid loss of ultrafine drilling and completion fluid with nanoemulsion was reduced to 6.3 mL, and the pressure difference between the upstream and downstream reaches 0.29 MPa Plugging Property of ultrafine drilling and completion fluid with nanoemulsion is double higher than without nanoemulsion, and was 2.96 times higher than only nanoemulsion. The nano-emulsion and micro-nano solid particles in the ultrafine drilling fluid can seal the plugging layer after entering the pore throat, it can play a role in retarding pressure transmission and filtrate intrusion, and enhancing the plugging effect. The experimental results provide a certain reference value for the follow-up study of the sealing properties of the nanoemulsion.

To address the insufficient long-term stability of kill fluids in ultra-deep, ultra-high-temperature wells in the Tarim Oilfield, this study systematically evaluates the adaptability of high-density kill fluids under high-temperature and prolonged static aging conditions, with a focus on identifying dominant settling mechanisms. The correlation between the microstructure and macroscopic properties of kill fluids was elucidated through particle size distribution analysis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and rheological characterization. A quantitative grading criterion for settling stability was established using settlement values and the falling rod method. Key findings demonstrate that low-density kill fluids (1.4–1.6 g/cm³) retained rheological stability after 20 days of aging at 220 °C, fulfilling the ≥20-day operational requirements for ultra-deep well testing. In contrast, high-density systems (1.9 g/cm³) exhibited severe particle aggregation after 15 days under identical conditions, with the yield stress-to-plastic viscosity ratio dropping below 0.10 and suspension capacity deteriorating. The apparent viscosity of ultrafine barite-weighted kill fluid increases with temperature, and its settling value is positively correlated with aging time and temperature. The settling mechanism of ultrafine barite-based kill fluids was attributed to reduced surface charge density caused by the decarboxylation of polyacrylate dispersants, which diminished interparticle electrostatic repulsion. The developed “settlement value vs. falling rod time” correlation model and grading criteria lay a theoretical foundation for optimizing kill fluid formulations and evaluating field performance in ultra-high-temperature wells, offering critical engineering insights to ensure safe deep hydrocarbon testing operations.

The southwest area of Tarim has good potential for exploration and development, but the geological conditions of Yingsha block are complicated and complex conditions occurred frequently in drilling operations. There were 11 times lost circulation, which ranged from N2a to E1a and the lithology ranged from mudstone and sand-mudstone interbeds to gypsum rock, and the drilling cycle is up to 719 days, which seriously restricts the exploration and development of oil and gas resources. In this paper, the rock mineral composition and physical and chemical characteristic profiles of the whole well have been established for the well drilled in this area. The characteristic profiles show that quartz (21.4%~57.4%) and clay minerals (17%~44.9%) are the main layers in the lower strata (5069 m-7015 m) drilled in Yingsha. The clay minerals are dominated by illite (58%~85.75%) without smectite. The highest proportion of illite/smectite formation is 25%, the highest expansion rate is 23.87%, and the lowest recovery rate is 3%. Therefore, the stratum has strong hydration and dispersion characteristics. The average porosity of 4064 m-6666.5 m is 1.86%-6%, and the formation cracks are well developed. The wellbore instability mechanism in Yingsha is the good physical property of the sandstone, the development of cracks and micro-cracks in the lower strata, the broken strata, and the strong hydration and dispersion ability. The performance evaluation of KCL-Polysulfonate drilling fluid used in Yingsha shows that the recovery rate increases to more than 80% when the amount of KCL is 7–10%. With the introduction of paraffin nano-emulsion, the filtration loss is reduced by 30%, and the inhibition and plugging performance of drilling fluid is further improved.

Ultra-deep dolomite formations exhibit pronounced mechanical heterogeneity governed by mineral composition, inter-particle cementation, and observation scale, complicating their mechanical characterization. Because intact downhole cores are difficult to obtain, a mesoscopic numerical framework that reproduces and classifies such behavior is needed. A two-dimensional mesoscopic model of Cambrian ultra-deep dolomite from the Tarim Basin was developed using the combined finite–discrete element method, incorporating mineral composition from X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy. A Weibull-distribution discretization scheme was introduced to represent matrix and cementation heterogeneity separately. Sensitivity analyses examined three factor groups: mineral composition and spatial distribution, matrix and cementation shape parameters, and mesh size as the observation scale. Accordingly, a three-level graded characterization framework was proposed, in which the compositional level governs strength magnitude; the structural level governs the elastic modulus, pre-peak nonlinearity and failure mode; and the scale level governs response representativeness and convergence. Quantitative grading indicators and threshold ranges were extracted for each level. Triaxial validation against laboratory experiments at confining pressures of 0 to 220 MPa confirmed strength and stress–strain response consistent with the proposed grading. The model and framework offer a transferable methodological reference for the mesoscopic mechanical evaluation of ultra-deep heterogeneous dolomite.