Experimental Investigation of Formation Damage Caused by Wellbore Fluids Using Glass Micromodel

Mohammadi, Mostafa | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52691 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Mahani, Hassan
  7. Abstract:
  8. During all operations in oil and gas reservoirs, it is possible to cause formation damage. These damages can greatly reduce the rate of production. One of the major damages that can seriously affect the performance of a reservoir is the damage caused by drilling fluid. The main purpose of this thesis is to study the main mechanisms of formation damage caused by water-based drilling fluid using a glass micromodel for the first time. An accurate understanding of the mechanisms of formation damage can provide a good understanding of the selection of the type and concentration of materials used, as well as appropriate methods to control and eliminate damages. for controlling the drilling fluid properties, silica, alumina and titanium nanoparticles at different concentrations were used. First, the rheological and filtration properties of all drilling fluids were measured, then simulation of cutting transport by Landmark software was performed as a guide for designing micromodel experiments. In micromodel experiments, the micromodel is first saturated with oil and then the drilling fluid is injected. Hydrochloric acid is then injected into the micromodel as a cleaning fluid. Finally, oil is injected into the micromodel on the other hand.The results of rheology and filtration experiments show that silica, alumina and titanium nanoparticles can improve the plastic viscosity, yield point, filtration volume and mud cake thickness. In the simulation of cutting transport, silica and alumina nanoparticles perform the best cutting transport because of their best effect on the rheological properties of drilling fluids. In the micromodel experiments, various damages occur during injection drilling fluid into the micromodel and the oil produced from the micromodel. During the injection of the drilling fluid, the solid particles of the drilling fluid are damaged by deposition in the porous media. Then, when the acid is injected, the acid is placed between the solid particles of drilling fluid as well as on the micromodel surface. During the oil production, acid and oil in these areas mix and form emulsions. The observations and results of micromodel experiments show that silica nanoparticles have the best performance in reducing formation damage including emulsion acid-in-oil, emulsion on the micromodel surface and solid particle deposition due to their higher specific surface area. In low pH drilling fluid, the main cause of formation damage is the emulsion formed between the solid particles of drilling fluid. Silica nanoparticles by plugging mechanism prevent this damage. When using a high pH drilling fluid, the damage varies with low pH drilling fluid. In low pH drilling fluids, solid particles and emulsion acid-in-oil cause damage, but in high pH drilling fluids, in addition to both damages, emulsions on the micromodel surface and water block play a major role. With the addition of silica nanoparticles, the formation of damage is significantly reduced, and only the solid particles of drilling fluid are responsible for the micromodel permeability reduction. Although the use of alumina and titanium nanoparticles did not have a significant effect on the results of the filtration test, the results of micromodel experiments show that different concentrations of these nanoparticles can have a significant effect on the type and severity of induced damages. The optimum concentration of nanoparticles obtained from the simulation of cutting transport can be different from the optimum concentration obtained from micromodel experiments, which indicates the importance of considering the porous media in computation
  9. Keywords:
  10. Formation Damage ; Drilling Fluid ; Glass Micromodel ; Wettability ; Pore-Scale Model ; Pore Scale Simulation of Fluid Flow ; Anionic Nanoparticles

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