CN113214818A - Fracturing preposed self-acid-generating system and breaking reduction method thereof - Google Patents
Fracturing preposed self-acid-generating system and breaking reduction method thereof Download PDFInfo
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- CN113214818A CN113214818A CN202110618353.8A CN202110618353A CN113214818A CN 113214818 A CN113214818 A CN 113214818A CN 202110618353 A CN202110618353 A CN 202110618353A CN 113214818 A CN113214818 A CN 113214818A
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/72—Eroding chemicals, e.g. acids
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/72—Eroding chemicals, e.g. acids
- C09K8/725—Compositions containing polymers
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/72—Eroding chemicals, e.g. acids
- C09K8/74—Eroding chemicals, e.g. acids combined with additives added for specific purposes
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
Abstract
The invention provides a fracturing preposed self-generated acid system and a breaking method thereof, wherein the fracturing preposed self-generated acid system comprises a self-generated acid mother liquor A, a self-generated acid mother liquor B and a self-generated acid mother liquor C; the self-generated acid mother liquor A is a paraformaldehyde aqueous solution, and the polymerization degree n is 10-100; the self-generated acid mother liquor B is an ammonium chloride aqueous solution; the self-generated acid mother liquor C is ammonium fluoride aqueous solution. The fracturing preposed self-acid-generating system can mix the self-acid-generating mother liquor A, the self-acid-generating mother liquor B and the self-acid-generating mother liquor C at the bottom of a well on the basis of efficient transportation and no corrosion to a pipe column, and spontaneously and continuously generate acid liquor so as to achieve the purpose of no corrosion to the pipe column. Meanwhile, the generated acid liquid reacts with rock minerals, so that the pollution of drilling and completion fluid in a zone close to a well bore can be effectively removed, the porosity and the permeability of a reservoir are increased, the liquid absorption capacity of the reservoir is improved, the fracture pressure of the reservoir is reduced, the construction discharge capacity is improved, and the effect of large-scale production increase and transformation is achieved.
Description
Technical Field
The invention belongs to the technical field of hydraulic fracturing production increase, and particularly relates to a fracturing preposed self-generating acid system and a breaking reduction method thereof.
Background
Hydraulic fracturing or acid fracturing is an important yield increasing means for unconventional oil and gas resources such as shale gas, tight sandstone gas, carbonate tight oil and the like, but due to geology, engineering and other reasons, the fracture pressure of a reservoir is often abnormal before yield increasing transformation, so that the hydraulic fracturing or acid fracturing construction fails.
The acid treatment breaking reduction technology is an effective measure for reducing the breaking pressure, and the acid breaking reduction technology is mainly used for performing acid breaking on a sandstone reservoir at present, wherein the related breaking acid liquid comprises acid liquid systems such as hydrochloric acid, hydrofluoric acid and the like; however, the acid liquor can cause strong corrosion to the pipe column, and meanwhile, the conventional breaking acid liquor cannot meet the requirement of yield increase transformation due to the limitation of the current measures such as safety, environmental protection and the like on acid liquor transportation. In addition, if the heterogeneity of the horizontal well section is too strong, the conventional acid liquor cannot reduce and transform the hypotonic section. In conclusion, an acid system and an acid process are needed, which do not corrode a shaft pipe column, can effectively reduce the fracture pressure of a vertical well and a horizontal well, and are beneficial to the development of subsequent large-scale production increase transformation.
Disclosure of Invention
Aiming at the technical problems, the invention aims to provide a pre-acid-generating breaking system and a pre-acid-generating breaking method for yield increasing transformation, which can enable acid liquor to react with rock minerals on the basis of efficient transportation and no corrosion of a pipe column, efficiently remove the pollution of drilling and completion fluid in a zone close to a well barrel, increase the porosity and permeability of a reservoir, improve the liquid absorption capacity of the reservoir, reduce the fracture pressure of the reservoir, contribute to improving the construction displacement of subsequent yield increasing transformation and achieve the effect of large-scale yield increasing transformation. In addition, when a horizontal well section with strong heterogeneity is encountered, a self-foaming solution system can be provided to form a self-foaming acid working solution system containing self-generating acid, so that the aim of uniformly distributing acid and uniformly reducing breakage is fulfilled.
The specific technical scheme is as follows:
the fracturing preposed self-generated acid system comprises a self-generated acid mother liquor A, a self-generated acid mother liquor B and a self-generated acid mother liquor C;
the self-generated acid mother liquor A is a paraformaldehyde aqueous solution, and the polymerization degree n is 10-100; the self-generated acid mother liquor B is an ammonium chloride aqueous solution; the self-generated acid mother liquor C is ammonium fluoride aqueous solution.
The mass concentration of the paraformaldehyde aqueous solution is 10-15%; the mass concentration of the ammonium chloride aqueous solution is 10-30%; the mass concentration of the ammonium fluoride aqueous solution is 1-1.5%.
Also comprises a spacer fluid. The isolation liquid is an aqueous solution, contains a cleanup additive and a clay stabilizer, and respectively comprises 0.2-0.4% of alpha-sodium alkenyl sulfonate and 1-3% of ammonium chloride.
Also included are self-foaming solutions. The self-foaming solution is an aqueous solution and comprises a gas initiator and a foaming agent. The gas initiator is one of sodium nitrite or ammonium persulfate, and the foam generating agent is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polyoxyethylene lauryl ether sodium sulfate and diethanolamine lauric acid. In the self-foaming solution, the mass concentration of the gas initiator is 10-21%, and the mass concentration of the foaming agent is 0.2-0.6%.
The breaking reduction method of the fracturing preposed self-generated acid system adopts the fracturing preposed self-generated acid system and comprises the following steps:
(1) adding the self-generated acid mother liquor A into a shaft;
(2) then adding isolation liquid;
(3) then adding the self-generated acid mother liquor B and the self-generated acid mother liquor C.
If the horizontal well is broken, the steps (1), (2) and (3) can be operated repeatedly, so that the acid liquor can further flow to the far end of the horizontal well, and the deep breaking reduction effect is improved. If strong heterogeneity exists in the horizontal well section, namely uniform acid distribution is needed, the method also comprises the following steps:
(4) adding a spacer fluid on the basis of the steps (1), (2) and (3);
(5) finally, the self-foaming solution is added.
The fracturing preposed self-acid-generating system provided by the invention can mix the self-acid-generating mother liquor A, the self-acid-generating mother liquor B and the self-acid-generating mother liquor C at the bottom of a well on the basis of efficient transportation and no corrosion to a pipe column, and spontaneously and continuously generate acid liquor so as to achieve the purpose of no corrosion to the pipe column. Meanwhile, the generated acid liquid reacts with rock minerals, so that the pollution of drilling and completion fluid in a zone close to a well bore can be effectively removed, the porosity and the permeability of a reservoir are increased, the liquid absorption capacity of the reservoir is improved, the fracture pressure of the reservoir is reduced, the construction discharge capacity is improved, and the effect of large-scale production increase and transformation is achieved.
In addition, a gas initiator and a foam generating agent can be added in a horizontal well section with strong heterogeneity to form a self-generating foam acid working solution system containing self-generating acid, so that the aim of uniformly distributing acid and uniformly reducing breakage is fulfilled.
The specific principle is as follows: after the gas initiator is contacted with the self-acid-generating mother liquor B, oxidation-reduction reaction can be carried out, a large amount of nitrogen is generated, and a large amount of foams are generated in the presence of the foam generating agent. The redox reaction releases a large amount of heat, which is helpful to improve the acid generation rate of the self-generated acid mother liquor A, the mother liquor B and the mother liquor C at the bottom of the well, thereby achieving the triple self-generation functions of self-generated acid, self-generated hot gas and self-generated foam.
The invention has the technical effects that:
the benefits brought are:
(1) the self-generated acid mother liquor A, the mother liquor B, the mother liquor C, the gas initiator and the foam generating agent can be solid before use, are convenient to transport and easy to store, and can be blended into a solution for use on site.
(2) The acid liquor is mixed at the bottom of the well, and the corrosion to the shaft is small.
(3) After the gas initiator and the foam generating agent are added, an acid liquid system with triple self-generating functions of self-generating acid, self-generating hot gas and self-generating foam can be formed, and uniform acid distribution can be realized at a horizontal well section with strong heterogeneity, so that the fracture pressure is uniformly reduced.
(4) After the fracture pressure is reduced, a higher-displacement hydraulic fracturing or acid fracturing technology can be adopted subsequently, and the large-scale reservoir transformation technology of unconventional oil and gas resources is facilitated to be realized.
Drawings
FIG. 1 is a graph of acid concentration of the self-generated acid mother liquor A, B, C after mixing in different ratios of example 1;
figure 2 is a triple self-generating acid system of self-generating acid, self-generating gas, self-generating foam of example 2.
Detailed Description
The specific technical scheme of the invention is described by combining the embodiment.
Example 1
30g of paraformaldehyde (degree of polymerization n is 10 to 100) is added into 70ml of water to form an authigenic acid mother liquor A; 30g of ammonium chloride was added to 70ml of water to form a mother liquor B of the self-generated acid. 30g of ammonium fluoride was added to 70ml of water to form a mother liquor C of the self-generated acid. Mixing the three materials at different volume ratios, rapidly placing in a water bath at 50 deg.C, and measuring the acid data of the mixture, as shown in the figure. As can be seen from FIG. 1, the acid-generating effect was the best when the three were mixed at a volume ratio of 1:1:0.1, and the hydrogen ion concentration was 3.70 mol/L.
Example 2
(1) 30g of paraformaldehyde (degree of polymerization n is 10 to 100) is added into 70ml of water to form an authigenic acid mother liquor A; 30g of ammonium chloride was added to 70ml of water to form a mother liquor B of the self-generated acid. 30g of ammonium fluoride was added to 70ml of water to form a mother liquor C of the self-generated acid. The mixed solution of the three components of the authigenic acid A, B, C was prepared in a volume ratio of 1:1:0.1 to form a mixed solution 1 having a volume of 50 ml.
(2) 0.6% sodium polyoxyethylene lauryl ether sulfate was added to the mixed solution in (1) to give a mixed solution 2 having a volume of 50 ml.
(3) A mixed solution of the free acid mother liquor B with the mass concentration of 16% and the gas initiator sodium nitrite with the mass concentration of 21% is prepared to form a mixed solution 3, and the volume of the mixed solution is 50 ml.
(4) The mixed solution 2 and the mixed solution 3 were mixed together again to form a mixed solution system 4 having a volume of 100ml using a 2-L beaker.
The mixed system was placed in a 60 ℃ water bath and it was observed that the system rapidly foamed in the beaker, with a foam volume approaching 2L in 20 minutes, as shown in FIG. 2. The foam system can be used as a steering plugging agent, and can effectively solve the problems that a horizontal well is strong in heterogeneity and cannot be uniformly distributed with acid and broken.
Example 3
(1) 30g of paraformaldehyde (degree of polymerization n is 10 to 100) is added into 70ml of water to form an authigenic acid mother liquor A; 30g of ammonium chloride was added to 70ml of water to form a mother liquor B of the self-generated acid. 30g of ammonium fluoride was added to 70ml of water to form a mother liquor C of the self-generated acid. The mixed solution of the three components of the authigenic acid A, B, C was prepared in a volume ratio of 1:1:0.1 to form a mixed solution 1 having a volume of 50 ml.
(2) 0.6% sodium polyoxyethylene lauryl ether sulfate was added to the mixed solution in (1) to give a mixed solution 2 having a volume of 50 ml.
(3) A mixed solution of the free acid mother liquor B with the mass concentration of 16% and the gas initiator ammonium persulfate with the mass concentration of 21% is prepared to form a mixed solution 3, and the volume of the mixed solution is 50 ml.
(4) The mixed solution 2 and the mixed solution 3 were mixed together again to form a mixed solution system 4 having a volume of 100ml using a 2-L beaker.
The mixed system was placed in a 60 ℃ water bath and it was observed that the system rapidly foamed in the beaker, with a foam volume approaching 1.5L in 20 minutes. The foam system can be used as a steering plugging agent, and can effectively solve the problems that a horizontal well is strong in heterogeneity and cannot be uniformly distributed with acid and broken.
Claims (10)
1. The fracturing preposed self-generated acid system is characterized by comprising a self-generated acid mother liquor A, a self-generated acid mother liquor B and a self-generated acid mother liquor C;
the self-generated acid mother liquor A is a paraformaldehyde aqueous solution, and the polymerization degree n is 10-100; the self-generated acid mother liquor B is an ammonium chloride aqueous solution; the self-generated acid mother liquor C is ammonium fluoride aqueous solution.
2. The fracturing pre-autogenous acid system of claim 1, wherein the mass concentration of the aqueous paraformaldehyde solution is 10-15%; the mass concentration of the ammonium chloride aqueous solution is 10-30%; the mass concentration of the ammonium fluoride aqueous solution is 1-2%.
3. The frac pad acid generation system of claim 1, further comprising a spacer fluid.
4. The fracturing pre-autogenous acid system of claim 3, wherein the spacer fluid is an aqueous solution containing a cleanup additive and a clay stabilizer, and the mass concentration of the spacer fluid is 0.2-0.4% of sodium alpha-alkenyl sulfonate and 1-3% of ammonium chloride respectively.
5. The fracturing pre-autogenous acid system of claim 1, further comprising an autogenous foam solution.
6. The fracturing pre-autogenous acid system of claim 5, wherein said autogenous foaming solution is an aqueous solution comprising a gaseous initiator and a foaming agent.
7. The fracturing pre-autogenous acid system of claim 6, wherein the gas initiator is one of sodium nitrite or ammonium persulfate, and the foam generating agent is one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, sodium polyoxyethylene lauryl ether sulfate, and diethanolamine lauric acid.
8. The fracturing pre-autogenous acid system of claim 6, wherein the autogenous foam solution has a gas initiator concentration of 10-21% by mass and a foam generating agent concentration of 0.2-0.6% by mass.
9. A method for reducing the fracture of a fracturing pre-autogenous acid system, which is characterized in that the fracturing pre-autogenous acid system of any one of claims 1 to 8 is adopted, and comprises the following steps:
(1) adding the self-generated acid mother liquor A into a shaft;
(2) then adding isolation liquid;
(3) then adding the self-generated acid mother liquor B and the self-generated acid mother liquor C.
10. The breaking method of the fracturing preposed autogenous acid generating system according to claim 9, wherein if the horizontal well is broken, the steps (1), (2) and (3) can be operated repeatedly, so that the acid liquid flows further to the far end of the horizontal well, and the deep breaking effect is improved; if strong heterogeneity exists in the horizontal well section, namely uniform acid distribution is needed, the method also comprises the following steps:
(4) adding a spacer fluid;
(5) add the self-foaming solution.
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| CN114350343A (en) * | 2022-03-21 | 2022-04-15 | 中海油天津化工研究设计院有限公司 | Composite biological self-generated acid system for reservoir transformation |
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