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Summary Based on the low hydration heat demand of cement slurry system used in deep water cementing, novel materials, namely, microencapsulated phase change materials (MPCMs), were synthesized and used to control the heat evolution of cement slurry by physical means. Here, the temperature profiles and hydration heat of cement slurry system were tested by using the developed semiadiabatic test apparatus. Firstly, the MPCM containing low melting paraffin wax with urea formaldehyde resin shell was synthesized by in situ polymerization. Then the properties of MPCM, such as structure, encapsulation efficiency, acid and alkali corrosion resistance, phase change properties, and thermal stability, were characterized by a series of methods. As a result, it was confirmed that the MPCM could be introduced and used to control the heat evolution of cement slurry system. Secondly, the synthesized MPCM was introduced into cement slurry system to control the heat evolution, and an intelligent cement slurry system, which could be used in the cementing of gas hydrate formation, was prepared. The highlight of current study is that the heat evolution of cement slurry system was successfully controlled by the synthesized MPCM through physical means. Besides, this study provides some guidance for the research and development of deep water oil and gas resources.

During this study, paraffin wax with low melting point was encapsulated in a urea-formaldehyde resin to prepare a novel microencapsulated phase change material (Micro-P6) for temperature regulation and thermal energy storage. The structure and properties of Micro-P6 were characterized by using Fourier transform infrared spectroscopy, differential scanning calorimeter, laser particle size analyzer, thermogravimetric analysis, contact angle analysis, and scanning electron microscope. The results indicated that the chemical structure of Micro-P6 meets the designed core-shell structure; and the paraffin wax with low melting point was successfully encapsulated by using urea-formaldehyde resin; and the Micro-P6 shows a spherical structure and rough surface, and the average size is 8.0-10.0 μm. Then, the performances of Micro-P6, such as core content, mechanical property, thermal conductivity and durability, were tested. Based on above characterization and performance test, it was indicated that the synthesized Micro-P6 could be used in the field of cementing and construction for temperature regulation and thermal energy storage. The applications of Micro-P6 in the field of cementing and construction will be completed in our next study.

Based on the requirement of the synthesized polymer resistant to higher temperature and lower cost demand of water-based drilling fluid system, a novel polymer, which named poly(AMPS/AM/SSS), was synthesized using acrylamide (AM), 2-acrylamido-2methylpropanesulfonic acid (AMPS), and p-styrenesulfonate (SSS). At first, the molecular structure was investigated through Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance hydrogen spectroscopy ( 1 H-NMR) and element analysis. Simultaneously, the molecular weight and distribution was obtained by gel chromatography method. Moreover, the thermal stability was produced by thermal analysis (TG). Secondly, the poly(AMPS/AM/SSS) was introduced into water-based drilling fluid system. As a result, it was shown that the use of poly(AMPS/AM/SSS) significantly improved the filtration performance of drilling fluid system. When the adding amount is 1.2 wt %, the FL API of drilling fluid system is 9.20 mL. Moreover, it was found that the flow curve of water-based drilling fluid systems are more fitted to the Herschel-Bulkley flow model. Besides, the temperature resistance of water-based drilling fluid system was obviously improved. Furthermore, it was confirmed that the cost of water-based drilling fluid system was significantly reduced. During this study, the filtration mechanism of the synthesized poly(AMPS/AM/SSS) was studied by adsorption analysis, Zeta potential method, and morphology analysis.

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