Centrealoil--Variable viscosity acid acidizing

For the lower Paleozoic carbonate reservoir, through the acidizing stimulation,  acid etched fracture with a certain length and high conductivity can be formed, communicate and connect the seepage channel and gas storage space, especially for low permeability reservoir, in order to achieve the purpose of build long slit and filtration reduction, the development of acid fracturing technology is from the matrix acidizing to current gelling acid acidification, variable viscosity acid acidizing technology.

Give priority to with the United States Lubrizol AMPS, the linear polymer by microwave polymerization technology is a new variable viscosity acid system ,which is specially used for deep well and high temperature acidizing, to overcome the disadvantage of the ordinary gelling acid large fluid loss, short penetration distance, uneven acid distribution ,difficult flowback.

The system has the characteristics of high temperature resistance, good gelling properties. The base fluid viscosity of system at 20~50mPa.s(adjustable),after entering reservoir as temperatures rise, under the action of activator, the system is rapidly crosslinked and formed acid gel, the viscosity of gel is more than 1000mPa.s.Acid gel begin to temporarily block acid soluble main channels, its the effect of fluid loss is more than 5 times that of gelling acid, and force the fresh body acid to enter the low permeability zone, form a new acid soluble channel and continue to move forward, so as to achieve the goal of long distance, deep penetration, more acid soluble channel acidification. As the acid rock reaction, when the concentration of the residual acid decrease to less than 10%, the system begin to break, the gel breaking liquid without residue and the viscosity of it is the same as water. Acid fluid after gel breaking is corroded again the sealing reservoir, can be formed a large number of acid soluble channels in the reservoir, expand oil and gas seepage area.

Characteristics:

①The system filtration is little and less acid fluid dosage.

②The gel breaking liquid of system has no residue, little influence on fracture conductivity.

③The reaction rate of acid rock in the system than ordinary gelling acid is delayed by 3~5times.

④The system in the reservoir can play the role of automatic steering and temporary plugging acidizing.

⑤It is advantageous to the long distance and deep penetrating large acid fracturing construction.

⑥It is suitable for the reservoir temperature (90-120℃) carbonate reservoir acidizing reconstruction.

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