Controlling the heat evolution of cement slurry system using microencapsulated phase change materials

Abstract

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.

Novel cement slurry containing micro‐encapsulated phase change materials: Characterization, application and mechanism analysis

“…As shown in Figure A, it was found that there is no chemical reaction between GO and UF, which belong to physical blending. Besides, as shown in Figure B, the results demonstrated that the paraffin wax was successfully encapsulated by UF or UF@GO, then, it was also found that the chemical structure of Micro‐P1 was not changed by GO, because the infrared spectra are basically the same . Therefore, GO distributed uniformly in the wall structure of Micro‐P1 only by inter‐molecular force or hydrogen bond …”

“…The thermal control mechanism of Micro‐P1 on heat evolution was investigated by phase change properties, infrared spectrum, X‐ray diffraction, thermal stability and scanning electron microscope analysis. The composition of cement slurry as presented in Table , at first, the phase change properties of mixtures (cement and Micro‐P1) was tested, and then the cement slurry was cured at 20°C for 24 hours, the IR, XRD, SEM, TG and DSC distribution curves of cement hydration products were measured and obtained …”

“…Natural gas hydrates are essentially a potential new energy source, and the reserves are very large . However, in the development process of marine resources, hydrates put forward higher requirements for cement slurry . Namely, in order to avoid hydrates decomposition, there is a requirement that the cement slurry must have low temperature rise and low heat of hydration.…”

“…Besides, the inert materials can achieve the same effect, such as silica sand. However, the mechanical strength was affected . Moreover, recently, the phase change material (PCM) was used, the heat evolution was effectively regulated, but, the permeability and porosity of cement stone were affected by the melted PCM .…”

“…However, the mechanical strength was affected. 11,12 Moreover, recently, the phase change material (PCM) was used, the heat evolution was effectively regulated, but, the permeability and porosity of cement stone were affected by the melted PCM. 17 At present, the micro-encapsulated phase change material (MPCM) was introduced and investigated.…”