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Improving Temperature Stability of Drilling Fluids Polymers Using Nano Particles

Halali, Mohamad Amin | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48425 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ghotbi, Siroos
  7. Abstract:
  8. Water base drilling fluids are the most common drilling fluids in oil and gas operations and biopolymers are the requisite additives used in such kind of fluids frequently. Unfortunately, at harsh conditions of HPHT the polymers undergo thermal degradation which cause serious loss in fluid rheological and filtration properties. Accordingly, this will induce operational pitfalls and tremendous cost. The power of economy along with environmental regulations force us to search for reasonable chemically benign additives to fulfill this need. Nanoparticles are the most promising additives proposed in this study to address this challenge. Regarding their unique exclusive properties, they are able to attenuate the temperature dependency of the system and on the other side of the coin, mechanically speaking, the suspension system will be governed by interactions potentials such as interparticle electrostatic and van der Walls forces which depend significantly on the particle size, shape, and interparticle distance. CNT can form super micelle aggregates with the existing surfactant and on the other hand, existing biopolymers can either be physically adsorbed on the surface of highly active CNTs or interact by themselves to engender firm chains above their critical concentration. As a result, a robust three-dimensional network called supermicellar aggregates is developed with respect to presence of biopolymers, surfactant and CNTs, simultaneously. All in all, such reasons evince higher rheological properties and better filtration features. Cabon nano tubes and magnesium oxide are the desired nanoparticles applied in this study. The stability of nanofluids is perused form various facet and angles including rheological and filtration properties, shale stability, zeta potential and thermal conductivity. The results were amazingly convincing since the presence of nano particles could reduce the filtration at high temperatures even by 95% and it also had conspicuous effect on shale stability, zeta potential and thermal conductivity. Furthermore, the effect of nanoparticles and surfactants concentration were investigated, separately. In this study, both physical and mechanical approaches have been applied to serve uniform dispersion of nanoparticles. i.e., adding surfactants and using ultrasonic bath, respectively. At last, experimental data were fit to most outstanding rheological models to determine the best models describing the behavior of our nano system. It was clarified that the Sisko and Mizhari-Berk models enjoy the highest accuracy among the others. Moreover, a correlation is developed in this study relating the viscosity of nano fluid to shear rate, temperature and nano particles concentration. The model exposed high accuracy regarding high value of average correlation factor which was 0.994
  9. Keywords:
  10. Drilling Fluid ; Surfactants ; Stability ; Nanoparticles ; Biopolymer ; High Pressure High Temperature (HPHT)

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