The guar gum has gained wide usage especially in the crude extraction industry. Further research has shown that it can be modified to increase its effectiveness oil well fracturing.
The Hydraulic Fracturing Process and the Use of Fracturing Fluids
This is the process used to improve production from oil wells. It is mostly applied in fields which crude occurrence is from low permeability formations. When this process is applied, crude is able to move easily from the rock to the well where they can then be pumped to the surface.
Fracturing fluids are used to deliver the proppant (sand) as well as stabilize the sand particles which help to retain the fractures open. The rheological properties of the fracturing fluids are very important due to the need for quick flow and particle placement.
Hydrophobic Modification of the Guar Gum
Modification of this compound has led to new forms of fluids called hydrophobically modified polysaccharides. This has led to the development of polymers having hydrophilic and hydrophobic parts.
Hydrophobically modified guar has shown improved rheological characteristics as compared to the original product due to the random distribution of the alkyl chains in the solution.
The use of low molecular weight polymer which is made by controlled replacement of the polymer backbone has been helpful in the production of low molecular weight fracturing fluids. These fluids have been shown to exhibit very stable rheological characteristics which are good for pumping.
Cross Linking Characteristics
The cross linking agent is a major component of the fracturing fluids. Two processes can be used to achieve high viscosity. This can be done through escalating polymer concentration or by cross linking the polymer. Increasing the polymer concentration is not cost effective.
Low application of guar increases the viscosity of the fluid and subsequent addition of the borate ions assist in magnifying this viscosity.
This mixture is the most suitable because the flow rate is easily reversed my mechanical shear.
Substitution Patterns and Solubility Changes
Three hydroxyl groups are suitable for replacement on the D- mannose or the D galactose units in guar gum. Substitution of the hydroxyl groups allows for extension of the side groups which in turn alters the solubility characteristics. The most common derivatives of this substitution are the carboxyl methyl and hydroxyl propyl guar which show more solubility properties.
Gel Breaking Products in the Hydraulic Fracture Preservation Process
According to current research, carboxyl methyl guars have been proposed as good gel breakers in the final stages of the hydraulic fracturing process. These serve to maintain the viscosity of the solution during the pumping process and after the pumping is complete the viscosity breaks to that of water allowing only the sand particle to remain in the fracture and allow better fluid flow to the well.
Conclusion
The use of guar gum as a constituent in the hydraulic fracturing process is increasing every day. Substitution of the D mannose and D galactose units in the structure has made it possible for the solubility properties to be altered creating more better fracturing fluids.
This article has been posted by Biren Patel working at Agro Gums. Agro Gums is a guar and cassia gum manufacturing company offering high quality guar gum powder, fast hydration guar gum powder, cassia powder, guar splits and guar meal to satisfy the production requirements of various industries across the world.
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