Method for preparing repeated fracturing blocking agent based on selective gel breaker

Abstract

The invention discloses a method for preparing a repeated fracturing blocking agent based on a selective gel breaker. The method comprises the following steps of: (a) preparing polyacrylamide; (b) dissolving the prepared polyacrylamide; (c) adding a pre-crosslinker into the solution; (d) adding a second crosslinker into the solution; (e) adding the gel breaker into the solution, wherein the gel breaker is ammonium persulfate; and (f) reacting the mixed solution in an incubator, and thus obtaining a target product. By adopting the method, the repeated fracturing blocking agent required by the conventional oilfields can be successfully prepared; the method is simple and facilitates artificial operation; various performance parameters of the prepared repeated fracturing blocking agent are superior to those of the conventional pressure blocking agent, and a foundation is laid for the exploitation of the oilfields; and by selecting the proper gel breaker, the gel breaking performance of the product is improved.

Description

technical field [0001] The invention relates to a method for preparing a repeated fracturing plugging agent based on selecting a gel breaker. Background technique [0002] Low-permeability reservoirs in my country generally refer to reservoirs composed of oil layers with a permeability between 10-50×10-3μm2. With the continuous deepening of exploration and development, my country's low-permeability oil reservoirs account for an increasing proportion of the total proven reserves and produced reserves, and play an increasingly important role in maintaining and promoting the development of the petroleum industry. Big. Take China National Petroleum Corporation as an example. By the end of 2001, the proven oil reserves in place were 145×108t, of which low-permeability reserves were 44×108t, accounting for 30%; the produced oil reserves were 110×108t, of which low-permeability reserves were 21×108t , accounting for 19%; the remaining proven undeveloped petroleum geological reserv...

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Problems solved by technology

[0004] (1) The natural production capacity of the oil well is low, and it has industrial exploitation value only after fracturing;

[0005] (2) The law of seepage does not follow Darcy's law and has a starting pressure gradient;

[0006] (3) The natural energy is small, the pressure and output drop rapidly, and the primary recovery rate is low;

[0007] (4) The water absorption capacity of the water injection well is low, and the starting pressure and water injection pressure rise rapidly;

[0008] (5) The liquid production index of the oil well drops sharply after water breakthrough, making it very difficult to stabilize production

[0010] Oil, gas, and water wells after hydraulic fracturing, due to the limitations of fracturing technology, materials, equipment and tools at that time, were small in scale, improperly selected materials, and limited equipment power, etc., would lead to a significant reduction in the conductivity of hydraulic fractures and gradually Some of them are not effective due to improper well layer selection or operational reasons. At the same time, after long-term development, major oil and gas fields have entered the development stage of medium and high water cut periods, and it is becoming more and more difficult to achieve high and stable production. For this type of oil and gas Wells that require refracturing for high production and economic recovery

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