Effects of Hydroxy Ethyl Cellulose in Oil Drilling
Hydroxy Ethyl Cellulose has thickening, suspending, dispersion, water retention and other outstanding performance and are widely used in many industrial sectors. Especially in the oil fields, HEC performs very well in drilling, completion, workover and fracturing processes. It is mainly used as a thickener in brine, in addition to many special applications.
1. Salt Tolerance
Hydroxy Ethyl Cellulose has excellent salt tolerance of the electrolyte. As Hydroxy Ethyl Cellulose is a non-ionic material, in the aqueous medium it will not get ionized, or produce precipitated residues due to the occurrence of high concentrations of salts in the system, resulting in a change in the viscosity.
Hydroxy Ethyl Cellulose has a thickening effect on many monovalent and divalent electrolyte solutions of high concentration, while anionic cellulose derivatives such as CMC can produce salting effects on certain metal ions. In oilfield applications, Hydroxy Ethyl Cellulose is completely free from the effects of water hardness and salt concentration. It can even thicken the heavy liquids containing high concentrations of calcium ions and zinc ions. Only the aluminum sulfate can have a precipitation effect on it. Hydroxy Ethyl Cellulose has better thickening effects in such strong electrolytes as fresh water and saturated heavy liquids of NaCl, CaCl2 and ZnBr2, CaBr2.
2. Viscosity and Shear Rate
The water – soluble Hydroxy Ethyl Cellulose can be dissolved in hot or cold water to produce the viscosity and form fake plastics. When the surface activity of its aqueous solution get improved, it is easy to form bubbles.
In general oilfields, Hydroxy Ethyl Cellulose with high viscosity is used. Its solution is non-Newtonian, with high pseudoplasticity, and the viscosity can be influenced by the shear rate. At low shear rates, the molecular arrangement of Hydroxy Ethyl Cellulose is irregular, resulting in the chain entanglement of high viscosity and the increase in viscosity; at high shear rate, the molecular arrangement changes into the directional arrangement with the flow direction, reducing the resistance to flow and resulting in the increase of viscosity along with increase of the shear rate.
3. Other Properties
1). Hydroxy Ethyl Cellulose has excellent water- loss reducing performance, and API tests have shown this performance.
2). Hydroxy Ethyl Cellulose has good compatibility. The water-soluble HEC in solution can be mixed with the majority of the water-soluble resins, and can form a clear, homogeneous, viscous solution.
3). Hydroxy Ethyl Cellulose has the temperature effect. As the solution temperature rises, its viscosity will decrease. And this process is reversible.
4). When Hydroxy Ethyl Cellulose is degraded by the enzyme catalysis, the viscosity of the solution will be affected and decreased (especially in the dilute solution state). Read more
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