Clean Fracturing Fluid System
Scope of Application
The clean fracturing fluid system is specifically designed for replacing the guar gum fracturing fluid system. It is suitable for the fracturing improvement in all kinds of formation as well stimulation, which includes tight sandstone, shale and carbonatite and the applicable temperature range is 20-160℃ .
Technical Principle
FC clean fracturing fluid, a new clean fracturing fluid, is researched and developed based on the theory that the structural fluid is formed by the molecular association.FC clean fracturing fluid, which comprises a main thickener and an auxiliary thickener auxiliary, can delay the thickening and be compatible with KCL.These agents utilize the molecular association which forms the supramolecular aggregate and then develops into the reversible space mesh structure in the solution to become structural fluid. this fracturing fluid has following features: good high viscosity ( η effective viscosity = η non-structural viscosity + η structural viscosity), temperature tolerance, salt resistance, shear resistance, static and dynamic yield value (structural viscosity) as well as viscoelasticity. The commonly used gel breaker can be used to break the gel with no (very few) residue.
System Performance and Characteristics
(1)System composition
Viscosifier + auxiliary viscosifier (when the formation temperature ＞ 100 ℃ , the high-temperature stabilizer is used.)
The viscosifier is a polymer surfactant while the auxiliary viscosifier is a poly compound.
(2)Efficient viscosifying capacity
The experiment indicates that the apparent viscosity of the solution dramatically increases with the concentration and when the concentration is 0.5%, the viscosity can increase to 100mPa•s.
(3)Good antibacterial stability
The experiment indicates that the clean fracturing fluid can be stored for a long period without damage from bacteria.
(4)Rheological characteristic
The system has relatively high consistency factor and flow characteristic index with very low yield stress.Moreover, the system is seldom infl uenced by the increasing temperature.
(5)Shearing Resistance:
(6)Shear thinning behavior:
The shear thinning behavior is the inherent feature of the structural fl uid, therefore, it can be solved during the fl ow process and the fl ow resistance can be signifi cantly reduced as long as the sand-carrying is well guaranteed.
(7)Residue and damage
The Influence of Gel Breaker for the Polymer Fracturing
(8)Suspended propant performance:
The experiment indicates that new clean fracturing fluid has reached the suspending propant ability of the conventional fracturing fluid when its viscosity is more than 30mPa.s.
(9)Technological advantages:
① The fracturing fluid carrying capacity can be fully satisfied
without crosslinking.
② It has better anti-shearing stability and the flow resistance can be reduced better compared to conventional fracturing fluid.
③ It has simplified formulation and the construction technology of water-based fracturing fluid.
Field Service Performance
The companys clean fracturing fluid system has been successfully applied to major domestic oil and gas fields for 25 wells and realized significant effect in increasing yield.For example: a well in Puguang gas field. In December 2009, because of the high temperature, low porosity, deep layer and low permeability of the reservoir (porosity: 2.5%; permeability: 0.014md), the clean fracturing fluid system was applied to the fracturing treatment for the purpose of minimizing the damage of the fracturing fluid to the formation ; after the fracturing, the output has reached 20,000m3/day from no output.
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