CN113090241A - Acid fracturing method for carbonate reservoir - Google Patents
Acid fracturing method for carbonate reservoir Download PDFInfo
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- CN113090241A CN113090241A CN202010017020.5A CN202010017020A CN113090241A CN 113090241 A CN113090241 A CN 113090241A CN 202010017020 A CN202010017020 A CN 202010017020A CN 113090241 A CN113090241 A CN 113090241A
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- 239000002253 acid Substances 0.000 title claims abstract description 180
- 238000000034 method Methods 0.000 title claims abstract description 33
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 title claims abstract description 26
- 239000012530 fluid Substances 0.000 claims abstract description 45
- 239000003921 oil Substances 0.000 claims abstract description 37
- 238000004132 cross linking Methods 0.000 claims abstract description 28
- 239000007788 liquid Substances 0.000 claims abstract description 23
- 239000003381 stabilizer Substances 0.000 claims description 42
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 40
- 238000005260 corrosion Methods 0.000 claims description 26
- 230000007797 corrosion Effects 0.000 claims description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 239000003112 inhibitor Substances 0.000 claims description 22
- 230000020477 pH reduction Effects 0.000 claims description 22
- 239000000654 additive Substances 0.000 claims description 21
- 230000000996 additive effect Effects 0.000 claims description 21
- 239000004927 clay Substances 0.000 claims description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 21
- 229910052742 iron Inorganic materials 0.000 claims description 21
- -1 iron ion Chemical class 0.000 claims description 21
- 239000000080 wetting agent Substances 0.000 claims description 21
- 238000000605 extraction Methods 0.000 claims description 13
- 238000011084 recovery Methods 0.000 claims description 8
- 239000003638 chemical reducing agent Substances 0.000 claims description 7
- 239000003349 gelling agent Substances 0.000 claims description 7
- 239000003795 chemical substances by application Substances 0.000 claims description 5
- 239000002562 thickening agent Substances 0.000 claims description 5
- 230000000903 blocking effect Effects 0.000 claims description 4
- 230000009286 beneficial effect Effects 0.000 abstract description 6
- 230000015572 biosynthetic process Effects 0.000 abstract description 4
- 230000035699 permeability Effects 0.000 abstract description 4
- 239000010779 crude oil Substances 0.000 abstract description 3
- 238000011161 development Methods 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 33
- 239000011435 rock Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 238000009933 burial Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000011229 interlayer Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 241000191291 Abies alba Species 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- 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
-
- 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
Abstract
The invention discloses an acid fracturing method for a carbonate reservoir, and belongs to the field of oil and gas development. The method comprises the following steps: injecting acid fracturing fluid into the shaft to a target layer through the oil pipe and/or the oil sleeve annulus; and closing the well for setting time to finish acid fracturing. The acid fracturing fluid comprises: resistance reducing liquid, gelled acid, cross-linked acid, diverting acid and closed acid; injecting an acid fracturing fluid into a wellbore comprises: and injecting the resistance reducing liquid, the cross-linking acid, the gelled acid, the diverting acid, the resistance reducing liquid, the cross-linking acid, the gelled acid, the closed acid and the resistance reducing liquid to the target layer in the same application amount into the shaft in sequence. The method provided by the embodiment of the invention can be used for deep fracturing, is beneficial to forming complex cracks, effectively improves the formation permeability, obviously improves the crack flow conductivity and widens the crude oil flow channel.
Description
Technical Field
The invention relates to the field of oil and gas development, in particular to an acid fracturing method for a carbonate reservoir.
Background
Carbonate reservoirs, especially buried carbonate reservoirs in the mountains, have abundant oil and gas resources, strong reservoir heterogeneity, deep reservoir burial depth (for example, the burial depth is 3900-4500 m), high stress, high reservoir temperature (for example, 150-180 ℃), and short effective acting distance of acid liquor. The buried depth of the buried hill production zone peak group and the Majiagou group is 3900-4500m, and the formation temperature is 150-180 ℃, so in order to improve the productivity, reservoir transformation is needed.
At present, the method for modifying carbonate reservoirs mainly comprises the following steps: the multistage injection acid fracturing technology is characterized in that the pad fluid and the acid fluid are alternately injected, and the filtration rate of the acid fluid is lower than that of the acid injected at the upper stage, and meanwhile, the acid fluid forms fingering in the pad fluid for multiple times, so that more cracks are favorably formed. The closed acid fracturing technology utilizes acid liquor to etch the stratum in the existing natural cracks or partially closed cracks, improves the stratum permeability and communicates the stratum cracks.
In the process of implementing the invention, the inventor finds that at least the following problems exist in the prior art:
the multi-stage injection acid fracturing technology has the problems of high acid rock reaction rate and small treatment range, the closed acid fracturing technology is not beneficial to forming complex cracks, and the improvement on the flow conductivity of cracks in a near well zone is very limited.
Disclosure of Invention
In view of the above, the invention provides an acid fracturing method for a carbonate reservoir, which can perform deep fracturing, is beneficial to forming complex cracks and improves the flow conductivity of the cracks.
An acid fracturing method of a carbonate reservoir, the acid fracturing method comprising: injecting acid fracturing fluid into the shaft to a target layer through the oil pipe and/or the oil sleeve annulus;
closing the well for setting time to finish acid fracturing;
wherein the acid fracturing fluid comprises: resistance reducing liquid, gelled acid, cross-linked acid, diverting acid and closed acid;
the step of injecting the acid fracturing fluid into the well bore comprises the following steps in sequence: injecting the resistance reducing fluid into the shaft to a target layer according to the first dosage;
continuing to inject the crosslinking acid into the wellbore to the target zone according to the second dosage;
according to a third dosage, continuously injecting the gelled acid into the shaft until the target layer is formed;
according to a fourth dosage, continuing to inject the diverting acid into the well bore to the target layer;
according to a fifth dosage, continuing to inject the resistance reducing fluid into the shaft until the target layer is reached;
continuing to inject the crosslinking acid into the wellbore to the target zone according to a sixth dosage;
according to a seventh dosage, continuing to inject the gelled acid into the well bore to the target layer;
continuing to inject the closure acid into the wellbore to the zone of interest at an eighth dosage below fracture closure pressure;
and continuing to inject the resistance reducing fluid into the well bore to the target layer according to a ninth dosage under the condition of lower than the fracture closing pressure.
In one possible implementation manner, the resistance reducing liquid comprises the following components in percentage by mass: 0.5-1% of resistance reducing agent and the balance of water.
In one possible implementation manner, the gelling acid comprises the following components in percentage by mass: 10 to 20 percent of industrial synthetic hydrochloric acid, 10 to 15 percent of gelling agent for acidification, 2 to 5 percent of corrosion inhibitor, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of cleanup additive, 2 to 5 percent of wetting agent for oil recovery, 1 to 3 percent of clay stabilizer and the balance of water.
In one possible implementation manner, the crosslinking acid comprises the following components in percentage by mass: 10 to 20 percent of industrial synthetic hydrochloric acid, 0.2 to 0.5 percent of crosslinking acid liquid conditioner for acidification, 0.5 to 1 percent of crosslinking acid thickener for acidification, 3 to 8 percent of high-temperature corrosion inhibitor, 3 to 8 percent of wetting agent for oil extraction, 2 to 5 percent of cleanup additive for fracturing, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of clay stabilizer and the balance of water.
In one possible implementation manner, the diverting acid comprises the following components in percentage by mass: 10 to 30 percent of industrial synthetic hydrochloric acid, 3 to 8 percent of high-temperature corrosion inhibitor, 3 to 8 percent of self-steering agent for acidification, 3 to 8 percent of wetting agent for oil extraction, 2 to 5 percent of cleanup additive for fracturing, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of clay stabilizer and the balance of water.
In one possible implementation manner, the closed acid comprises the following components in percentage by mass: 10 to 30 percent of industrial synthetic hydrochloric acid, 3 to 8 percent of high-temperature corrosion inhibitor, 3 to 8 percent of wetting agent for oil extraction, 2 to 5 percent of cleanup additive for fracturing, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of clay stabilizer and the balance of water.
In a possible implementation manner, for the resistance reducing liquid, the first dosage is 200m3-1000m3The fifth dosage is 200m3-500m3The ninth dosage is 20m3-80m3。
In one possible implementation, for the crosslinking acid, the second amount is 100m3-300m3The sixth dosage is 100m3-300m3。
In one possible implementation, for the gelling acid, the third amount is 300m3-500m3The seventh dosage is 100m3-300m3。
In one possible implementation, for the diverting acid, the fourth amount is 200m3-300m3；
For the blocking acid, the eighth amount is 20m3-80m3。
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
according to the acid fracturing method provided by the embodiment of the invention, specific types of acid fracturing fluids are sequentially injected into a shaft to perform deep fracturing by aiming at the characteristics of carbonate reservoirs, particularly high-temperature carbonate reservoirs in a buried hill, and complex fractures are formed at the same time. Specifically, a resistance reducing fluid is injected into the shaft to a target layer for resistance reduction, the temperature of the shaft is reduced, and the reaction rate of acid rock is slowed down, so that the acid corrosion crack length is increased, and the acid corrosion range is enlarged. And then continuously injecting the crosslinking acid into the well bore to the target layer to perform seam making. And then continuously injecting gelled acid into the shaft to the target layer so as to deeply etch the crack. And then, continuously injecting steering acid into the shaft to a target layer so as to perform temporary blocking in the formed artificial cracks, improving the net pressure in the cracks, forcing the artificial cracks to form a plurality of branch cracks to realize interlayer steering, and improving the complexity of the cracks. And then, continuously injecting resistance reducing fluid, cross-linking acid and gelling acid into the shaft to a target layer so as to further deepen the branch cracks, communicate and prolong the stratum cracks, realize deep fracturing and form complex cracks. And finally, injecting a resistance reducing fluid into the shaft under the pressure lower than the fracture closure pressure so as to push the acid fracturing fluid in the shaft into the deep part of the stratum, dredging the existing fracture and further optimizing the acid fracturing effect. Therefore, the method provided by the embodiment of the invention can be used for deep fracturing, is beneficial to forming complex cracks, effectively improves the formation permeability, obviously improves the crack flow conductivity and widens the crude oil flow channel.
Detailed Description
In order to make the technical solutions and advantages of the present invention more clear, embodiments of the present invention will be described in further detail below.
The embodiment of the invention provides an acid fracturing method of a carbonate reservoir, which comprises the following steps: injecting acid fracturing fluid into the shaft to a target layer through the oil pipe and/or the oil sleeve annulus;
and closing the well for setting time to finish acid fracturing.
Wherein, the acid fracturing fluid comprises: resistance reducing liquid, gelled acid, cross-linking acid, diverting acid and closed acid.
Injecting the acid fracturing fluid into the wellbore comprises the following steps in sequence: injecting resistance reducing liquid into the shaft to a target layer according to the first dosage;
according to the second dosage, continuously injecting the cross-linking acid into the shaft to the target layer;
according to the third dosage, continuously injecting gelled acid into the shaft until the target layer is reached;
according to the fourth dosage, continuously injecting diverting acid into the shaft to the target layer;
according to the fifth dosage, continuously injecting resistance reducing liquid into the shaft to a target layer;
according to the sixth dosage, continuously injecting the crosslinking acid into the shaft to the target layer;
according to the seventh dosage, continuously injecting gelled acid into the shaft to a target layer;
under the condition that the pressure is lower than the fracture closure pressure, according to the eighth dosage, continuing to inject closure acid into the shaft to a target layer;
and under the condition of being lower than the fracture closing pressure, continuously injecting the resistance reducing liquid into the shaft to the target layer according to the ninth dosage.
According to the acid fracturing method provided by the embodiment of the invention, specific types of acid fracturing fluids are sequentially injected into a shaft to perform deep fracturing by aiming at the characteristics of carbonate reservoirs, particularly high-temperature carbonate reservoirs in a buried hill, and complex fractures are formed at the same time. Specifically, a resistance reducing fluid is injected into the shaft to a target layer for resistance reduction, the temperature of the shaft is reduced, and the reaction rate of acid rock is slowed down, so that the acid corrosion crack length is increased, and the acid corrosion range is enlarged. And then continuously injecting the crosslinking acid into the well bore to the target layer to perform seam making. And then continuously injecting gelled acid into the shaft to the target layer so as to deeply etch the crack. And then, continuously injecting steering acid into the shaft to a target layer so as to perform temporary blocking in the formed artificial cracks, improving the net pressure in the cracks, forcing the artificial cracks to form a plurality of branch cracks to realize interlayer steering, and improving the complexity of the cracks. And then, continuously injecting resistance reducing fluid, cross-linking acid and gelling acid into the shaft to a target layer so as to further deepen the branch cracks, communicate and prolong the stratum cracks, realize deep fracturing and form complex cracks. And finally, injecting a resistance reducing fluid into the shaft under the pressure lower than the fracture closure pressure so as to push the acid fracturing fluid in the shaft into the deep part of the stratum, dredging the existing fracture and further optimizing the acid fracturing effect. Therefore, the method provided by the embodiment of the invention can be used for deep fracturing, is beneficial to forming complex cracks, effectively improves the formation permeability, obviously improves the crack flow conductivity and widens the crude oil flow channel.
Aiming at the characteristic that the reservoir temperature of the acid salt rock reservoir, particularly the buried hill carbonate reservoir is high (for example, 150-180 ℃), various acid fracturing fluids with high temperature resistance are selected in the embodiment of the invention, the temperature resistance can reach more than 180 ℃, and the various acid fracturing fluids are exemplified as follows:
as an example, the resistance-reducing liquid comprises the following components in percentage by mass: 0.5-1% of resistance reducing agent and the balance of water. For example, the mass percent of the friction reducer may be 0.8%.
The resistance reducer can adopt the resistance reducer modified polymer GC-212L for fracture acidizing, which is commonly used in the field.
As an example, the gelled acid comprises the following components in percentage by mass: 10 to 20 percent of industrial synthetic hydrochloric acid, 10 to 15 percent of gelling agent for acidification, 2 to 5 percent of corrosion inhibitor, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of cleanup additive, 2 to 5 percent of wetting agent for oil recovery, 1 to 3 percent of clay stabilizer and the balance of water.
Preferably, the gelling acid comprises the following components in percentage by mass: 15% of industrial synthetic hydrochloric acid, 10% of gelling agent for acidification, 3% of corrosion inhibitor, 3% of iron ion stabilizer, 3% of cleanup additive, 3% of wetting agent for oil recovery, 2% of clay stabilizer and the balance of water.
As an example, the cross-linking acid comprises the following components in percentage by mass: 10 to 20 percent of industrial synthetic hydrochloric acid, 0.2 to 0.5 percent of crosslinking acid liquid conditioner for acidification, 0.5 to 1 percent of crosslinking acid thickener for acidification, 3 to 8 percent of high-temperature corrosion inhibitor, 3 to 8 percent of wetting agent for oil extraction, 2 to 5 percent of cleanup additive for fracturing, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of clay stabilizer and the balance of water.
Preferably, the crosslinking acid comprises the following components in percentage by mass: 20 percent of industrial synthetic hydrochloric acid, 0.4 percent of cross-linked acid liquid conditioner for acidification, 0.8 percent of cross-linked acid thickener for acidification, 5 percent of high-temperature corrosion inhibitor, 3 percent of wetting agent for oil extraction, 3 percent of cleanup additive for fracturing, 3 percent of iron ion stabilizer, 2 percent of clay stabilizer and the balance of water.
As an example, the diverting acid comprises the following components in percentage by mass: 10 to 30 percent of industrial synthetic hydrochloric acid, 3 to 8 percent of high-temperature corrosion inhibitor, 3 to 8 percent of self-steering agent for acidification, 3 to 8 percent of wetting agent for oil extraction, 2 to 5 percent of cleanup additive for fracturing, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of clay stabilizer and the balance of water.
Preferably, the diverting acid comprises the following components in percentage by mass: 20% of industrial synthetic hydrochloric acid, 5% of high-temperature corrosion inhibitor, 5% of self-diverting agent for acidification, 5% of wetting agent for oil recovery, 3% of cleanup additive for fracturing, 3% of iron ion stabilizer, 2% of clay stabilizer and the balance of water.
As an example, the closed acid comprises the following components in percentage by mass: 10 to 30 percent of industrial synthetic hydrochloric acid, 3 to 8 percent of high-temperature corrosion inhibitor, 3 to 8 percent of wetting agent for oil extraction, 2 to 5 percent of cleanup additive for fracturing, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of clay stabilizer and the balance of water.
Preferably, the closed acid comprises the following components in percentage by mass: 20% of industrial synthetic hydrochloric acid, 5% of high-temperature corrosion inhibitor, 5% of wetting agent for oil extraction, 3% of cleanup additive for fracturing, 3% of iron ion stabilizer, 2% of clay stabilizer and the balance of water.
For the above-mentioned various acid fracturing fluids, each of the components contained therein may be common in the art and may be commercially available. For example, the water may be clean water, the wetting agent for oil recovery may be ether, the cleanup additive for fracturing may be a fluorocarbon surfactant, the iron ion stabilizer may be an organic sodium salt, the clay stabilizer may be an organic salt, the corrosion inhibitor for acidification may be a quaternary ammonium salt corrosion inhibitor, and the gelling agent for acidification may be a sulfopolymer gelling agent, which is not illustrated herein.
In the acid fracturing process, in order to obtain good acid fracturing effect and make the acid fracturing process more controllable, the discharge capacity of the various acid fracturing fluids can be controlled at 6.5m3/min-7.5m3Min, e.g. 6.5m3/min、6.7m3/min、6.8m3/min、6.9m3/min、7.0m3/min、7.1m3/min、7.2m3/min、7.3m3/min、7.4m3Min, etc.
When the various acid fracturing fluids are injected into the well bore, the injection is carried out at a design pressure, and the design pressure can be obtained by the following formula for each acid fracturing fluid:
Pw＝Pk-Ph+Pf
wherein, PwTo design the pressure, PkTo a breaking pressure, PhIs hydrostatic column pressure, PfThe pipelines are friction resistance and the units of the pipelines are the same.
The usage amount of the various acid fracturing fluids can be calculated according to oil layer data and Meyer software simulation, in general, for the high-temperature carbonate rock reservoir in the buried hill, in order to obtain a good acid fracturing effect and avoid excessive usage amount, the usage amount of the various acid fracturing fluids can be in the following range, and the specific usage amount of the various acid fracturing fluids is adjusted in a targeted manner according to the specific situation of a target well:
for the resistance reducing liquid, the first dosage referred to above is 200m3-1000m3For example, 200m3、300m3、400m3、500m3、600m3、700m3、800m3、900m3、1000m3Etc.;the fifth dosage is 200m3-500m3For example, 200m3、300m3、400m3、500m3Etc.; the ninth dosage is 20m3-80m3E.g. 20m3、30m3、40m3、50m3、60m3、70m3、80m3And the like.
For the crosslinking acid, the second amount referred to above is 100m3-300m3E.g. 100m3、150m3、200m3、250m3、300m3Etc.; the sixth dosage is 100m3-300m3E.g. 100m3、150m3、200m3、250m3、300m3And the like.
For the gelled acid, the third quantity referred to above is 300m3-500m3E.g. 300m3、350m3、400m3、450m3、500m3Etc.; the seventh dosage is 100m3-300m3E.g. 100m3、150m3、200m3、250m3、300m3And the like.
For diverting acids, the fourth quantity referred to above is 200m3-300m3E.g. 200m3、250m3、300m3And the like.
For the closed acid, the eighth dosage is 20m3-80m3E.g. 20m3、30m3、40m3、50m3、60m3、70m3、80m3And the like.
In actual operation, the resistance reducing liquid, the gelled acid, the cross-linking acid, the steering acid and the closed acid can be respectively added into different liquid storage tanks, each liquid storage tank is connected with a ground pipeline, valves are arranged on the ground pipelines, the five ground pipelines are converged and then connected with a high-pressure pipeline, and the injection pump is connected with the Christmas tree through the high-pressure pipeline.
The invention is further illustrated by the following specific examples:
in the following examples, the compositions of the various acid fracturing fluids used are as follows:
the resistance reducing liquid comprises the following components in percentage by mass: 0.8% of resistance reducing agent and the balance of water.
The gelled acid comprises the following components in percentage by mass: 15% of industrial synthetic hydrochloric acid, 10% of gelling agent for acidification, 3% of corrosion inhibitor, 3% of iron ion stabilizer, 3% of cleanup additive, 3% of wetting agent for oil recovery, 2% of clay stabilizer and the balance of water.
The crosslinking acid comprises the following components in percentage by mass: 20 percent of industrial synthetic hydrochloric acid, 0.4 percent of cross-linked acid liquid conditioner for acidification, 0.8 percent of cross-linked acid thickener for acidification, 5 percent of high-temperature corrosion inhibitor, 3 percent of wetting agent for oil extraction, 3 percent of cleanup additive for fracturing, 3 percent of iron ion stabilizer, 2 percent of clay stabilizer and the balance of water.
The diverting acid comprises the following components in percentage by mass: 20% of industrial synthetic hydrochloric acid, 5% of high-temperature corrosion inhibitor, 5% of self-diverting agent for acidification, 5% of wetting agent for oil recovery, 3% of cleanup additive for fracturing, 3% of iron ion stabilizer, 2% of clay stabilizer and the balance of water.
The closed acid comprises the following components in percentage by mass: 20% of industrial synthetic hydrochloric acid, 5% of high-temperature corrosion inhibitor, 5% of wetting agent for oil extraction, 3% of cleanup additive for fracturing, 3% of iron ion stabilizer, 2% of clay stabilizer and the balance of water.
Example 1
Using the object: the well comprises a Qx1 well, well sections 3991.9 m-4040 m, 29.5m/6 layers and a total span of 48.1m, wherein the layer is an Odoku Shanjia ditch group, and a reservoir is buried deeply and belongs to a high-temperature deep well.
The method provided by the embodiment of the invention is used for carrying out acid fracturing on the Qx1 well, and the related operation parameters are shown in the following table 1:
TABLE 1
After the acid fracturing method is implemented, the well is closed for 3 hoursThe acid reacts and then the well is opened. Tests show that Qx1 well produces no oil before acid fracturing, 22.3 tons of oil produced in the day after acid fracturing and 5.7X 10 tons of gas produced in the day4m3。
Example 2
Using the object: bx1 well, well section 4630.9-4653.4m, 18m/5 layers, total span 22.5m, the layer is Ordovician; the reservoir is buried deeply and belongs to a high-temperature deep well Bx1 well, the well section is 4630.9-4653.4m, the total span is 22.5m, and the layer is an Ordovician; the reservoir is buried deeply and belongs to a high-temperature deep well.
The Bx1 wells were subjected to acid fracturing using the method provided by the embodiment of the present invention, and the related operating parameters are shown in table 2 below:
TABLE 2
After the acid fracturing method is implemented, the well is closed for 2 hours, and then the well is opened after the acid reaction. Tests show that the oil can not be produced before the Bx1 well is subjected to acid fracturing, the daily oil production is 21.65 tons after the acid fracturing, and the daily gas production is 5.43 multiplied by 104m3。
The above description is only for facilitating the understanding of the technical solutions of the present invention by those skilled in the art, and is not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method of acid fracturing a carbonate reservoir, the method comprising: injecting acid fracturing fluid into the shaft to a target layer through the oil pipe and/or the oil sleeve annulus;
closing the well for setting time to finish acid fracturing;
wherein the acid fracturing fluid comprises: resistance reducing liquid, gelled acid, cross-linked acid, diverting acid and closed acid;
the step of injecting the acid fracturing fluid into the well bore comprises the following steps in sequence: injecting the resistance reducing fluid into the shaft to a target layer according to the first dosage;
continuing to inject the crosslinking acid into the wellbore to the target zone according to the second dosage;
according to a third dosage, continuously injecting the gelled acid into the shaft until the target layer is formed;
according to a fourth dosage, continuing to inject the diverting acid into the well bore to the target layer;
according to a fifth dosage, continuing to inject the resistance reducing fluid into the shaft until the target layer is reached;
continuing to inject the crosslinking acid into the wellbore to the target zone according to a sixth dosage;
according to a seventh dosage, continuing to inject the gelled acid into the well bore to the target layer;
continuing to inject the closure acid into the wellbore to the zone of interest at an eighth dosage below fracture closure pressure;
and continuing to inject the resistance reducing fluid into the well bore to the target layer according to a ninth dosage under the condition of lower than the fracture closing pressure.
2. The acid fracturing method of a carbonate reservoir according to claim 1, wherein the resistance reducing fluid comprises the following components in percentage by mass: 0.5-1% of resistance reducing agent and the balance of water.
3. The acid fracturing method of a carbonate reservoir according to claim 1, wherein the gelled acid comprises the following components in percentage by mass: 10 to 20 percent of industrial synthetic hydrochloric acid, 10 to 15 percent of gelling agent for acidification, 2 to 5 percent of corrosion inhibitor, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of cleanup additive, 2 to 5 percent of wetting agent for oil recovery, 1 to 3 percent of clay stabilizer and the balance of water.
4. The acid fracturing method of a carbonate reservoir according to claim 1, wherein the cross-linking acid comprises the following components in percentage by mass: 10 to 20 percent of industrial synthetic hydrochloric acid, 0.2 to 0.5 percent of crosslinking acid liquid conditioner for acidification, 0.5 to 1 percent of crosslinking acid thickener for acidification, 3 to 8 percent of high-temperature corrosion inhibitor, 3 to 8 percent of wetting agent for oil extraction, 2 to 5 percent of cleanup additive for fracturing, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of clay stabilizer and the balance of water.
5. The acid fracturing method of a carbonate reservoir according to claim 1, wherein the diverting acid comprises the following components in percentage by mass: 10 to 30 percent of industrial synthetic hydrochloric acid, 3 to 8 percent of high-temperature corrosion inhibitor, 3 to 8 percent of self-steering agent for acidification, 3 to 8 percent of wetting agent for oil extraction, 2 to 5 percent of cleanup additive for fracturing, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of clay stabilizer and the balance of water.
6. The acid fracturing method of a carbonate reservoir according to claim 1, wherein the closed acid comprises the following components in percentage by mass: 10 to 30 percent of industrial synthetic hydrochloric acid, 3 to 8 percent of high-temperature corrosion inhibitor, 3 to 8 percent of wetting agent for oil extraction, 2 to 5 percent of cleanup additive for fracturing, 2 to 5 percent of iron ion stabilizer, 2 to 5 percent of clay stabilizer and the balance of water.
7. The acid fracturing method of a carbonate reservoir according to claim 1, wherein the first amount is 200m for the drag reducing fluid3-1000m3The fifth dosage is 200m3-500m3The ninth dosage is 20m3-80m3。
8. The acid fracturing method of a carbonate reservoir according to claim 1, wherein the second amount is 100m for the cross-linking acid3-300m3The sixth dosage is 100m3-300m3。
9. The acid fracturing method of a carbonate reservoir according to claim 1, characterized in that for the gelled acid, the third purpose isThe amount is 300m3-500m3The seventh dosage is 100m3-300m3。
10. The acid fracturing method of a carbonate reservoir according to claim 1, wherein for the diverting acid, the fourth amount is 200m3-300m3；
For the blocking acid, the eighth amount is 20m3-80m3。
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