PH Responding Variable Viscosity Acid

1. System Characterizations

The new type of thickener used in PH responding variable viscosity acid will induce viscosity change when PH value changes due to the reaction between acid and formation rock and CaCl2 generation, and a tight reaction film is created on the rock surface when acid viscosity increases so that leakoff and acid-rock reaction rate can be dramatically lowered. In that way deeper acid penetration can be achieved, and acid sweeping radius and acid-fracking/acidizing stimulation effectiveness can be improved.

2. Property Indices

Properties		Indices
Thickener	Appearance	White or pseudo white powder
	Solid content, %	≥88
	Size, Mesh	≤50
	Solubility	Disperse and solvable in water or acid
Gelled Acid	Slow rate，%	＞90
	Friction reducing ratio, %	≥65
	Temperature tolerance, ℃	≤180

3. Application for Treatment

Mix with acid before use and make sure no “fish eyes” occurs during mixing. It is not necessary to warm the acid. Indoor mixing can be done with normal mixer. When whirlpool occur in the acid pour the dry powder around the whirlpool evenly to avoid particle cohesion. The process usually requires 30 minutes. After acid injection fracturing cleanser is used to take care of the acid-rock reaction film so the acidizing effectiveness can be obviously improved.