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Blocking method adopting fluid gel for producing blocking valve by formation temperature to block gas reservoir

A technology of formation temperature and gel, which is applied in sealing/seal, chemical instruments and methods, earthwork drilling and mining, etc., can solve problems such as uneven gel, high gel cost, and poor water retention performance, so as to avoid premature Low consumption, simple process, good water retention performance

Active Publication Date: 2013-10-23
BC P INC CHINA NAT PETROLEUM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] 1. In the existing patent documents, there is no disclosure of the method of using the above-mentioned gel for plugging;
[0008] 2. The existing gel formula is relatively complicated, the gel cost is high, and the pressure resistance and sealing are not enough;
[0009] 3. The existing gel formula has poor water retention performance after being gelled, and lacks better water retention monomers in the gel;
[0010] 4. The cross-linking agent only uses potassium persulfate or ammonium persulfate, which belongs to the water-soluble inorganic peroxygen gel initiator. This type of initiator is greatly affected by temperature, that is, the reaction must be initiated at a certain temperature and the reaction is easy to occur. Inhomogeneous gel, local dehydration
[0011] 5. In the existing patent literature, the method of mechanically breaking the gel with the drill bit is used to unblock the gel, but for the gel with viscoelasticity, mechanical breaking is difficult to achieve

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach

[0044] As the best implementation mode of the present invention, its method is as follows:

[0045] S1: Mix the gel cross-linking system and the gel initiator evenly without fish eyes in the solution to form a fluid solution; there are no restrictions on the device used for mixing, and any device commonly used in this field can be used, such as a stirring pump .

[0046]S2: After the fluid solution is prepared, the fluid solution is pumped into the wellbore. Under the surface temperature, the gel is not gelled, so it is easy to pump in. Pump in according to the design amount of the construction well, and the fluid reaches the required wellbore depth. Or stop the pump near the formation, because the temperature of the formation is much higher than that of the surface, when the reaction temperature of the gel initiator is reached, the copolymerization and crosslinking of the monomer and the cross-linking agent will be initiated to form a gel, which will seal the connection betwe...

Embodiment 2

[0079] As another preferred embodiment of the present invention, its components and proportioning ratio are:

[0080] 6% of acrylamide and 2% of sodium acrylate, and 0.5% of N,N'-methylenebisacrylamide, using the gel initiator azobis(dimimidylpropane) dihydrochloride (V44), the rest is For water, at 70°C, the gelling viscosity is 30,000 mPa.s after 30 minutes, and the maximum sealing pressure is 2.5MPa / 100m after gelling in a 5-inch casing. All the other are with embodiment 1. After the gel is formed, inject 2.5% ammonium persulfate breaker aqueous solution into the casing. The total amount of ammonium persulfate breaker is 1% of the total weight of the gel crosslinking system. At 70°C, break the gel after 1 hour. The apparent viscosity of the breaking liquid is 20mPa.s.

Embodiment 3

[0082] As another preferred embodiment of the present invention, its components and proportioning ratio are:

[0083] Acrylamide 8% and acryloyloxyethyltrimethylammonium chloride 2%, and N,N'-methylenebisacrylamide 0.5%, using water-soluble oxidation-reduction gel initiator potassium persulfate 0.3% and Sodium bisulfite is 0.2%, and the rest is water. At 40°C, after 40 minutes, the gelling viscosity is 20,000mPa.s. After gelling in a 5-inch casing, the maximum plugging pressure is 2.4MPa / 100m. All the other are with embodiment 1. After gelling, inject 2.0% SUN-Y100 bio-enzyme breaker solution into the casing, the total amount of SUN-Y100 bio-enzyme breaker is 1% of the total weight of the gel cross-linking system, at 40°C , After 1.5 hours, the gel is broken, and the apparent viscosity of the broken gel is 10mPa.s.

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Abstract

The invention discloses a blocking method adopting fluid gel for producing a blocking valve by a formation temperature to block a gas reservoir. The blocking method comprises the following steps that a), a gel crosslinked system and a gel initiator are uniformly mixed until the mixed solution has no fish eye-shaped structure so that a fluid solution is obtained; b), the fluid solution is fed into a shaft by a pump and forms gel after gelation waiting; c), after ground operation, a gel breaker aqueous solution is added into the gel in the shaft, wherein the gel breaker aqueous solution comprises 2-5wt% of a gel breaker and the total weight of the gel breaker is 0.1-2% of that of the gel crosslinked system; and d), after the fed gel breaker aqueous solution contacts with the gel, the gel breaker makes the gel lose blocking performances and the broken gel is fed back to the ground. The blocking method has simple processes. The fluid gel for blocking has a low cost and very high pressure resistance.

Description

[0001] technical field [0002] The invention relates to a method for preparing a fluid used to form a gel isolation valve to seal an oil and gas layer by using formation temperature. The prepared fluid gel is especially suitable for an oil and gas reservoir as a casing valve to form an isolation area between the reservoir and the ground , It is convenient for low-pressure operations such as wellhead disassembly and assembly. Background technique [0003] In the process of wellhead construction in medium and low pressure reservoirs, in order to prevent formation fluids (oil, gas, water) from gushing out of the wellhead and cause danger, mechanical packers are often lowered and installed in the wellbore at a certain depth, between the wellbore and the surface. Form a blockage between them, which is convenient for wellhead construction operations. [0004] At present, the price of mechanical casing valves used is relatively high, and the equipment is mainly imported. The d...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K8/44E21B33/13C08F220/56C08F222/38C08F220/34C08F220/58C08F228/02C08F4/40
Inventor 李华坤罗陶涛吴正良
Owner BC P INC CHINA NAT PETROLEUM CORP
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