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In order to solve the problem of poor dispersion and stability of mixed metal hydroxide (MMH), a kind of mixed metal hydroxide-like compound (MMHlc) gel was synthesized for use as the base mud in drilling fluid instead of bentonite gel. Na2CO3, Na2SiO3, and C17H33CO2Na were used as precipitants to form MMHlc with larger interlayer spacing and smaller particle size. MMHlc was synthesized by the coprecipitation method at 25 °C with a metal molar ratio of Mg:Al:Fe = 3:1:1. The performance evaluation of the treated drilling fluid showed that MMHlc (S2) synthesized using Na2SiO3 as the precipitant had the characteristics of low viscosity, low filtration, and a high dynamic plastic ratio at 25 °C, which fully met the requirements of oil field application, and it maintained its excellent properties after being aged at 250 °C for 16 h. Linear expansion and rolling recovery experiments showed that the S2 sample had excellent rheological properties and good inhibition. X-ray diffraction and FT-IR experiments showed that S2 had the most complete crystal structure, its interlayer distance was large, and its ion exchange capacity was strong. The thermogravimetric experiment showed that the S2 crystal was stable and the temperature resistance of the crystal could reach 340 °C. Zeta potential, particle size analysis, SEM, and TEM results showed that S2 is a nanomaterial with a complete morphology and uniform distribution. The drilling fluid of this formula had the characteristics of low viscosity, low filtration loss, and a high dynamic plastic ratio, and it met the conditions for oil field application. Considering these results, the new MMH prepared by our research institute is a drilling fluid material that can be used at ultra-high temperatures and can provide important support for drilling ultra-deep wells. [ABSTRACT FROM AUTHOR]

In the past two years, several horizontal wells with ultra-long horizontal intervals were completed in Changqing oil and gas field. The longest horizon interval reached 4466 m, which set a record of the longest onshore horizontal well in Asia. There were a lot of difficulties such as high friction, mudstone collapse, and sand carrying that puzzled the drilling of wells with ultra-long horizontal intervals. To solve these problems, some key treatment agents were screened to form a novel water-based drilling fluid system (CQSP-RH). The yield point and extreme pressure lubrication coefficient of the novel system were 18 Pa and 0.058, respectively. The filtrate volume of the novel system was only 1.9 mL at room temperature and was 12 mL at 120 °C. When the cuttings were rolled for 16 h at 120 °C, the primary recovery of them could reach 98.64%. Subsequently, the novel system was applied to wells with ultra-long horizontal intervals. The friction resistance between drilling tools and sidewall was controlled within 500 KN; the solid contents of drilling fluid was controlled within 10%. The results proved that the novel system have superb properties and tremendous potential to drill deeper horizontal wells. [ABSTRACT FROM AUTHOR]

Polyacrylamide and its derivatives are commonly used as viscosity enhancers in water‐based drilling fluids, but they have limitations in terms of salt resistance and temperature resistance. In this study, a novel cationic functional monomer, 4‐allylaminocarbonyl‐1‐dodecylpyridinium bromide, was introduced into the molecular chains of an acrylamide and acrylic acid copolymer in order to improve its temperature resistance and salt tolerance. Results showed that the apparent viscosity of a 2000 mg/L copolymer solution was 440.4 mPa s at a shear rate of 7.34 s−1, decreasing to 23.5 mPa s at 510 s−1 before recovering to 49.2 mPa s when the shear rate returned to 170 s−1. After 16 h of aging at 120°C, a brine drilling fluid containing 1% of the copolymer showed an apparent viscosity retention rate of 70%, likely due to the formation of a stable net structure between the copolymer's molecular chains and clay particles. These results suggest that the copolymer could be an excellent candidate for use as a viscosity enhancer in drilling fluids. [ABSTRACT FROM AUTHOR]

Solid-free drilling fluid has more advantages as a new type of drilling fluid compared with traditional drilling fluid, such as improving drilling efficiency, protecting oil and not having clay particles clog the oil and gas layer. In this study, Zn/Cu/Fe-doped magnesium–aluminum hydroxide (Mg-Al MMH) was prepared using the co-precipitation method and evaluated in solid-free drilling fluid. The inhibition mechanism of synthesized hydroxide was analyzed by X-ray diffraction, laser particle-size analysis and thermogravimetric analysis. The samples were directly used as drilling fluid base muds for performance evaluation. The results showed that the linear expansion rate of 4% M6-Fe was only 12.32% at room temperature within 2 h, that the linear expansion rate was 20.28% at 90 °C and that the anti-swelling rate was 81.16% at room temperature, indicating that it has a strong inhibition ability at both room temperature and at high temperatures. Meanwhile, the possibility of multi-mixed metal hydroxide as a drilling fluid base mud is discussed in this study. We found that 4% M6-Fe exhibited low viscosity, a high YP/PV ratio and high temperature resistance, and its apparent viscosity retention rate reached 100% rolled at 200 °C for 16 h, with a YP/PV ratio of 2.33. [ABSTRACT FROM AUTHOR]

In this paper, mixed metal hydroxide (MMH) was prepared via MgCl2 and AlCl3 by the co-precipitation method and characterized by XRD, TGA laser and particle size analysis. The inhibitory effect of MMH on the swelling of clay was evaluated by linear expansion, mud ball, laser particle size analysis, X-ray diffraction analysis and TGA. The linear expansion experiment showed that MMH with a ratio of Mg:Al = 3:1 displayed a strong inhibitory effect on bentonite expansion when 0.3% MMH was added to the drilling fluid, demonstrating better inhibition than 4.0% KCl. Within 48 h, only a few cracks were visible on the mud ball surface in the 0.3% MMH suspension, which indicates that MMH can inhibit wet bentonite for deep hydration. X-ray diffraction and particle size analyses of bentonite were conducted before and after MMH was added to illustrate the inhibition. MMH also displayed high temperature resistance in water-based drilling fluid as a shear strength-improving agent, and its dynamic plastic ratio and shear force were stable after aging at 200 °C for 16 h. [ABSTRACT FROM AUTHOR]

With the increasing amount of drilling of directional wells and large‐displacement wells, high torque and high resistance have become critical problems. Therefore, high‐performance and environment‐friendly lubricants for water‐based drilling fluid are urgently needed. In this paper, poly(ethylene glycol) 2000 (PEG) was used as a lubricant, and the lubricity, inhibition, compatibility and temperature resistance of the PEG lubricant were investigated. The results show that 0.1% (mass ratio) PEG in water‐based drilling fluid can reduce the friction coefficient of mud cake by 44.5%. This PEG also has certain inhibition and temperature resistance. As PEG is used with other drilling fluid additives, the compatibility was good and the lubricity of drilling fluid can be improved effectively. The lubricating mechanism of PEG was explored and the results showed that the hydrophobic alkane chains in the PEG molecules were adsorbed on the surface of bentonite, forming a hydrophobic film on the friction surface, thereby forming a lubricating layer. Field application in Sulige Gas Field showed that the PEG lubricant has good lubricity and can meet the technical requirements of corresponding horizontal wells. © 2020 Society of Industrial Chemistry [ABSTRACT FROM AUTHOR]