To address the challenges encountered in drilling operations for high-temperature and high-salinity hydrocarbon reservoirs, this study successfully designed and synthesized a novel organic–inorganic core–shell structured fluid loss control agentDH. This material features rigid calcium carbonate nanoparticles as the core, encapsulated by a copolymer shell of acrylamide (AM) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS). This unique structure is designed to fundamentally enhance the thermal stability and salt tolerance compared to conventional pure polymer treatments, by restraining the curling and decomposition of polymer chains under extreme conditions. Characterization results confirmed the successful construction of the core–shell structure and demonstrated excellent thermal stability. Performance evaluation showed that DH maintains outstanding fluid control performance even after exposure to high temperature (200 °C), high salt concentration (15% NaCl), and multiple aging cycles. Compared to the base fluid, DH reduces fluid loss by over 95%. More importantly, its performance significantly surpasses that of conventional agents (e.g., PAC); under similarly harsh conditions where the latter fails (fluid loss >25 mL), DH stably controls the API fluid loss below 7 mL. Mechanism studies revealed that efficient fluid control is achieved because DH, with its uniform particle size distribution (matching filter cake pore sizes) and large specific surface area, effectively plugs filter cake micropores, thereby forming a compact, low-permeability filter cake. This study provides an innovative and effective solution for developing next-generation drilling fluid additives suitable for extreme operating conditions.

Low porosity and permeability of oil and gas reservoirs make it difficult to develop these resources. To address these problems, we developed and evaluated a novel, environmentally friendly waterproof locking agent, which was prepared using dimethyl silicone oil and octadecyltrimethylammonium chloride and characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and particle size measurement. The waterproof locking performance of the agent was evaluated in a low-permeability reservoir using surface tension and contact angle measurements, and thermodynamic calculations were performed. The average particle size or median diameter (D ₅₀) of a 1% mother liquor was 325 nm at 20 °C and 470.8 nm at 70 °C. The contact angle of clean water on the core surface increased from 10 to 110°. At 70 °C, the surface tension of water was reduced to 24 mN·m^-1, indicating good waterproof locking performance. The interaction parameters were calculated in accordance with the Langmuir adsorption theory. The increase in temperature from 20 to 70 °C reduced Γ_max from 4.59 × 10^-6 to 1.36 × 10^-6 mol·m^-2 and ΔG ^θ from -40.93 to -56.54 kJ·mol^-1. Thus, the adsorption behavior of the developed locking agent is believed to improve the productivity of oil wells.

Sulfur is an important constant element in the crust, with a mass abundance of approximately 0.03%, is mainly obtained as a by-product of hydrodesulfurization in petroleum refining. Although China produces over ten million tons of sulfur annually, its applications remain limited, and while sulfur is not flammable under normal conditions, its oxidizability and potential to catch fire under extreme conditions pose safety and environmental risks during storage. To address these issues, we developed a multicomponent polymerization (MCP) strategy using elemental sulfur, dicarboxylic acids, and diamines to synthesize functional polythioamides. This metal-free approach utilizes readily available raw materials and enables the efficient construction of structurally diverse polymers. Unlike previously reported MCP systems relying on aromatic monomers, our work employed aliphatic diamines and diacids, yielding polythioamides with rigid structures and excellent properties. Characterization by Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS). Adsorption studies demonstrated a strong affinity for Hg(II), with a maximum capacity of 187 mg·g⁻¹. SEM, XPS revealed clear morphological and compositional changes after Hg(II) uptake, confirming efficient adsorption. This work highlights MCP as a promising route for converting sulfur into functional polymers with high potential in wastewater treatment and environmental remediation.