Currently, with the increasing of the national energy demand and development intensity, drilling engineering have gradually attracted the global attention. In addition, oil and gas exploitation tends to be much deeper reservoirs in which pore-structures are complicated and pore-throat size diameter ranges from nano to micron meter, and bottom hole pressure and temperature are also higher than that under the normal condition, more and more drilling is in complex strata. To adapt the current situation, reserchers find the special nano-composite materials would be a best way, and the drilling technology with higher requirements has been put forward.<br/>In this work, inverse microemulsion copolymerization of acrylamide (AM), sodium allylsulfonate (SAS), and sodium 4-styrenesulfonate (SSS) initiated by redox initiators composed of persulphuric acid and sodium bisulfite, and stabilized by the mixed emulsifier system sorbitan monooleate (Span-80) and polyoxyethylene sorbitan monooleate (Tween 80) were examined as a function of the combination of hydrophilic (Tween 80) and hydrophobic (Span 80) emulsifiers, reaction temperature, AM/SAS mass ratio, SSS concentration, and initiator concentration. The physicochemical and thermal properties and the structure of this copolymer were also determined and discussed. The reaction rates for all runs of the experiments exhibited two intervals, which were typical of microemulsion polymerization. Mostly, modified nanoparticles (montmorillonite 1%wt~1.5%wt) were dispersed homogeneously into the copolymer matrix, in order to improve the performances of the new drilling fluid, such as high temperature resistance. The microstructure of the composites was characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and laser particle analyzer. The thermal stability and swelling rate of the composites was studied by thermo-gravimetric analysis (TGA).<br/>In a word, the nano-composite constrained high temperature drilling fluid significantly improved behavior properties of the traditional drilling fluid and obviously enhance oil and gas yield. This is an important technical breakthrough in petroleum engineering.

Preparation and characterization of a nano-composite constrained high temperature drilling fluid with water soluble AM-SAS-SSS copolymers by inverse microemulsion polymerization

253rd National Meeting (2017)

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