Novel selective water shutoff agent for oil well water shutoff
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A water plugging and selective technology for oil wells, applied in the direction of drilling compositions, chemical instruments and methods, etc., can solve the problems of oil phase permeability and other problems, and achieve good pumpability, good dispersibility, and simple construction technology Effect
Inactive Publication Date: 2012-01-25
SOUTHWEST PETROLEUM UNIV
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Many existing technologies can form polymer gels with high strength and good thermal stability in various complex oil
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Embodiment 1
[0034] 1. Preparation of polymer gel and selective water blocking agent
[0035] Weigh 10g of acrylamide monomer, add 0.01g of cross-linking monomer trimethylolpropane trimethacrylate into 100g of deionized water and stir evenly, pass nitrogen gas for 30min, add 0.005g of initiator ammonium persulfate, and heat at 60°C The reaction was carried out for 5 hours in a water bath environment to obtain the gel particle matrix—polymer gel.
[0036] The synthesized polymer gel is dried in a 65°C constant temperature box and then mechanically pulverized to prepare submillimeter-millimeter gel particles. Due to the relatively large particle size of the mechanically pulverized particles, it is suitable for large Water plugging in medium and high permeability reservoirs. Use the formation water of an oilfield (total salinity is 9180.24mg / l, Ca 2+ , Mg 2+ Each ion concentration is 200 mg / l) to configure a selective water blocking agent, the following is the mass percentage: 2.0% gel parti...
Embodiment 2
[0057] Micron-sized gel particles are first prepared by inverse emulsion polymerization, and the steps are as follows:
[0058] 1) Weigh 8.38g of sodium 2-acrylamide-2-methylpropanesulfonate monomer and slowly add it to 14g of deionized water, and adjust the base with sodium hydroxide to neutralize to a certain extent;
[0059] 2) Weigh 20g of acrylamide monomer and 1.2g of polyoxyethylene sorbitan monooleate (Tween-80) into 15.6g of deionized water, and stir evenly;
[0060] 3) Weigh 30g of kerosene and 6g of sorbitan monostearate (Span-60), stir evenly, then pour the mixed solution into a three-necked flask for polymerization;
[0061] 4) Stir the mixture in the three-necked flask at high speed (600-1000rpm);
[0062] 5) Mix the solutions in the first two steps evenly, and sequentially add 0.2g of chelating agent ethylenediaminetetraacetic acid and 0.03g of crosslinking monomer ethylene glycol diacrylate;
[0063] 6) Add the mixed solution in 5) to a three-necked flask wit...
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Abstract
The invention relates to a novel selective water shutoff agent for oil well water shutoff, belonging to the technical field of tertiary oil recovery. The water shutoff agent is a composite system of gel particles with the mass concentration of 0.5-5% and a cross-linking agent with the mass concentration of 1-2%, which is prepared by using oilfield injection water; and the water shutoff agent is applicable to water plugging of an oil well at a temperature of 60-120 DEG C. The gel particles are formed by an acrylamide monomer or compounding the acrylamide monomer with a temperature resistant and salt-resistant auxiliary monomer and a cross-linking monomer through copolymerization; the cross-linking monomer is an ester monomer which has a double-bond structure and is easy to resolved when being heated, the expanding and resolving time of the cross-linking monomer at different temperatures can be controlled through adjusting the concentration of the cross-linking monomer, and bulk polymerization or inverse emulsion polymerization is adopted as a polymerization method. In the invention, basically no gel is formed on an oil layer, and high-strength gel can be formed on a water layer, thus defects in the prior art are overcome, the error shutoff phenomenon easily caused by the traditional polymer bulk gel in the oil layer is reduced to the greatest extent, and the capacity of an oil well suffering from water shutoff is ensured.
Description
Technical field: [0001] The invention relates to a polymer gel water shutoff agent for water shutoff in oil wells, which can realize selective water shutoff in the true sense, and belongs to the field of oil field chemistry. Background technique: [0002] Excessive water production in oil wells will lead to a decline in oil production, and at the same time will increase the treatment costs of a large amount of produced water such as lifting and separation, resulting in huge economic losses. Other problems such as increased pipeline corrosion rate caused by produced water, reservoir emulsification plugging or fouling, etc. also arise. Some physical and chemical water control and water blocking methods have been effectively applied. For the physical method, special workover equipment is required in operation, especially on the offshore platform due to space limitations, it is inconvenient to implement and will increase the cost. The chemical method does not require workover ...
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