CN111927387A - Two-stage temporary plugging combined selective water plugging method - Google Patents
Two-stage temporary plugging combined selective water plugging method Download PDFInfo
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- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical group C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 claims description 8
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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Abstract
The invention discloses a two-stage temporary plugging combined selective water plugging method, which comprises the following steps: injecting a low-viscosity temporary plugging agent A, wherein the temporary plugging agent A enters a high-permeability layer with high water saturation to temporarily plug the high-permeability layer, and the injection pressure of the temporary plugging agent A is less than the starting pressure of the low-permeability layer; injecting a temporary plugging agent B with long gel breaking time to plug the hypotonic layer; after the temporary plugging agent A breaks the gel, injecting the plugging agent into the target stratum, closing the well and waiting for setting to realize the plugging of the high-permeability water producing layer; and after the temporary plugging agent B fails, opening the well and recovering production. The water plugging method provided by the invention realizes effective plugging of the water production channel of the high-permeability layer, and improves the flow rate of the low-permeability layer. The method fully starts the residual oil in the low-permeability layer, improves the sweep coefficient of water injection, enlarges the sweep volume and finally improves the crude oil recovery ratio.
Description
Technical Field
The invention relates to the technical field of oil and gas exploitation, in particular to a two-stage temporary plugging combined selective water plugging method.
Background
Well plugging refers to the control of water production from a well in order to improve the production efficiency of the well. The common water plugging method in oil field includes two kinds of mechanical water plugging and chemical water plugging, the chemical water plugging is the water plugging caused by chemical plugging agent to the water outlet layer, and the mechanical water plugging is the water outlet layer blocked in the shaft by a separator to prevent water from flowing into the well. In terms of application and development at present, chemical water plugging methods are mainly applied in China. According to the blocking effect of the blocking agent on an oil layer and a water layer and the chemical property of the blocking agent, the chemical water blocking is non-selective water blocking and selective water blocking. The non-selective water plugging technology means that a plugging agent is injected into a stratum and then simultaneously plugs an oil layer and a water layer; the selective water-blocking technology is a selective water-controlling oil-stabilizing technology, and can attain the goal of blocking water and not blocking oil by means of self-selectivity of blocking agent, and at the same time can effectively control water discharge in high-permeability layer, and does not produce damage and pollution to oil layer.
The existing oil reservoir is mostly suitable for a selective water plugging method, for example, Tangxiaofen and the like propose a method for realizing selective water plugging of a strong gel plugging agent by matching temporary plugging, the method utilizes the principle that high pressure and high energy of a water producing layer are not beneficial to fluid entering, and low pressure is beneficial to fluid entering, weak gel temporary plugging agent is injected into a stratum to protect a low-permeability layer, high-strength gel is injected to plug the high-permeability layer, and mining is carried out after the weak gel of the low-permeability layer breaks the gel, namely, the selective water plugging of the strong gel is realized under the condition of not damaging the low-permeability layer. However, in the actual exploitation of the oil reservoir, the whole oil reservoir is in the same stratum pressure gradient, the pressure difference between the high water-bearing stratum and the medium-low permeability non-target stratum is not large, and the high water-bearing stratum has higher flow conductivity, so that in the actual injection process, the injected weak gel temporary plugging system still enters the high water-bearing stratum and cannot well protect the low permeability stratum. The method is characterized in that a weak gel temporary plugging agent with higher initial viscosity is injected into a stratum at a higher speed (lower than the fracture pressure of the stratum) before the plugging agent is injected, and the system can form serious surface plugging in a low-permeability layer to form a filter cake, but cannot penetrate into the low-permeability layer, so that the low-permeability layer is protected. However, when the temporary plugging agent is injected by this method, the system viscosity is high, and thus the injectability is poor. And most of the system still flows along the high water-bearing layer, if a filter cake is formed on the surface of the low-permeability layer to protect the low-permeability layer, the dosage of the system is greatly increased. Secondly, in the process that the weak gel forms a filter cake on the surface of the hypotonic layer to protect the hypotonic layer, as the hypotonic layer is continuously blocked, the starting pressure required by the hypotonic layer is higher, so that a subsequently injected weak gel system further flows towards a high water-bearing layer, and the implementation effect is poor and the cost consumption is high.
Although the method for selectively blocking water by using the temporary plugging agent plays a certain water blocking effect in an oil reservoir and can also achieve yield increase in the initial stage after water blocking, the effective period is short, the oil yield is reduced to the level before water blocking generally about half a year, and water blocking operation needs to be carried out again; some matching processes are not suitable and even can not block water, so that the later water yield is increased, and the water outlet of a high-permeability layer is serious. In addition, because the temporary plugging effect is not ideal, when the plugging agent is injected into a high-permeability layer, a part of the plugging agent can be shunted to enter a low-permeability layer to damage the low-permeability layer, and the productivity of an oil well is reduced.
Disclosure of Invention
The invention aims to provide a two-stage temporary plugging combined selective water plugging method which can effectively plug a high-permeability water producing layer, fully start residual oil of a low-permeability layer and improve the crude oil recovery rate.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a two-stage temporary plugging combined selective water plugging method comprises the following steps:
(1) injecting a low-viscosity temporary plugging agent A with gel breaking time not more than 3 days, wherein the temporary plugging agent A enters a high-permeability layer with high water saturation to temporarily plug the high-permeability layer, and the injection pressure of the temporary plugging agent A is less than the starting pressure of the low-permeability layer;
(2) injecting a temporary plugging agent B with gel breaking time not less than 5 days to form plugging on the hypotonic layer;
(3) after the temporary plugging agent A breaks the gel, injecting the plugging agent into the target stratum, closing the well and waiting for setting to realize the plugging of the high-permeability water producing layer;
(4) and after the temporary plugging agent B breaks the gel, opening the well and recovering production.
In one embodiment of the present invention, the temporary plugging agent a has an initial viscosity of 20 to 40mPa · s.
One embodiment of the present invention is that the temporary plugging agent a is automatically broken in 1 to 3 days.
The invention also provides a formula and a preparation method of the temporary plugging agent A capable of meeting the requirements, and a person skilled in the art knows that the temporary plugging agent A provided by the invention is not to be considered as a limitation to the method of the invention, and the temporary plugging agent A is within the protection scope of the invention as long as the requirements of the temporary plugging agent A in the invention can be met. The temporary plugging agent A comprises the following components in percentage by weight:
the molecular weight of the polyacrylamide is 500-600 ten thousand, and the degree of hydrolysis is 5% -13%; the first cross-linking agent is hexamethylenetetramine; the second cross-linking agent is m-diphenol; the first gel breaker is hydrogen peroxide; the second breaker was potassium persulfate.
The preparation method of the temporary plugging agent A adopting the formula comprises the following steps: dissolving polyacrylamide in water, sequentially adding a first cross-linking agent, a second cross-linking agent, a first gel breaker and a second gel breaker, stirring to dissolve, adjusting the pH to 3-5 with hydrochloric acid, and keeping the temperature at 60 ℃ for 12 hours to obtain the polyacrylamide gel breaker.
In one embodiment of the present invention, the temporary plugging agent B has an automatic gel breaking time of 5 to 10 days.
In one embodiment of the present invention, the temporary plugging agent B is an oil-based temporary plugging agent.
The invention also provides a formula and a preparation method of the temporary plugging agent B capable of meeting the requirements, and a person skilled in the art knows that the temporary plugging agent B provided by the invention is not to be considered as a limitation to the method of the invention, and the temporary plugging agent B provided by the invention is within the protection scope of the invention as long as the requirements of the temporary plugging agent B in the invention can be met. The temporary plugging agent B comprises the following components in percentage by mass:
2 to 4 percent of polyethylene resin;
2.8 to 3 percent of dicumyl peroxide;
0.4 to 0.6 percent of cumene hydroperoxide;
the balance being diesel oil.
The preparation method of the temporary plugging agent B adopting the formula comprises the following steps: adding diesel oil into a reaction vessel at room temperature, introducing N2Under the conditions of deoxidization and stirring, dissolving polyethylene resin in diesel oil, adding dicumyl peroxide and cumyl peroxide, and stirring for 15min under the condition of 400r/min to obtain the catalyst.
The invention has the following beneficial effects:
the invention provides a fixed-point two-stage temporary plugging combined selective water plugging method in the water plugging process, which comprises the steps of injecting a first temporary plugging agent A through different gel breaking time of two temporary plugging agents, ensuring low viscosity and low speed injection, and preferentially plugging a high permeability layer due to different permeability grades. And at the moment, the low-permeability oil layer is basically not damaged, and then a second temporary plugging agent B is injected into the low-permeability layer for plugging, so that after temporary plugging protection of the oil layer to be protected is realized, the temporary plugging agent A is broken to lose effectiveness, and the permeability of the high-permeability water production layer is recovered. And injecting a long-acting plugging agent into the high-permeability water producing layer for water plugging, closing a well and waiting for coagulation, realizing effective plugging of a water producing channel of the high-permeability layer, and improving the flow rate of the low-permeability layer. The method fully starts the residual oil in the low-permeability layer, improves the sweep coefficient of water injection, enlarges the sweep volume and finally improves the crude oil recovery ratio.
Drawings
FIG. 1 is a graph showing the relationship between the high and low permeability flow rates of example 1 and the injection amount of the temporary plugging agent and the long-acting plugging agent;
FIG. 2 is a graph showing the relationship between the high and low permeability split rates and the injection amounts of the temporary plugging agent and the long-acting plugging agent in example 2;
FIG. 3 is a graph showing injection pressure of the temporary plugging agent A versus gel breaking time in example 1;
FIG. 4 is a graph showing injection pressure of the temporary plugging agent B with respect to gel breaking time in example 1;
FIG. 5 is a graph showing oil-water relative permeability.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Unless otherwise specified, all experimental methods and procedures used in the following examples are conventional methods or procedures.
Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.
In order to judge whether the plugging agent completely enters the hypertonic layer, the determination can be carried out by the ratio of the liquid absorption amount between two layers of sections, and the calculation formula is as follows:
in the formula q1，q2-instantaneous liquid absorption in the interval 1 and in the interval 2, respectively;
λ1，λ2instantaneous total flow of fluid in stages 1 and 2, respectively;
K1，K2-permeability of the hypertonic and hypotonic layers, respectively;
Krw1，Kro1-instantaneous water and oil relative permeability in interval 1;
Krw2，Kro2-instantaneous water and oil relative permeability in interval 2, respectively;
μw，μowater, oil viscosity, constant, respectively.
And (4) calculating the liquid absorption ratio of the two intervals under different water saturation degrees according to the relative permeability curve of the water flooding and the oil-water viscosity. The oil-water relative permeability curve is shown in fig. 5.
Example 1:
the preparation method of the temporary plugging agent A comprises the following steps (the following contents are all in percentage by mass):
preparing polyacrylamide into a solution with a certain concentration of 8000mg/L, adding hexamethylenetetramine to make the concentration of 1200mg/L, adding resorcinol to make the concentration of 500mg/L, adding hydrogen peroxide of a gel breaker to make the concentration of 3500mg/L, adding potassium persulfate to make the concentration of 4000mg/L, adjusting the pH value of the solution to be 4 by hydrochloric acid, keeping the temperature at 60 ℃ for 12 hours to obtain the gel temporary plugging agent A in the embodiment, and measuring the viscosity of the gel temporary plugging agent A by a viscometer to be 20 mPas.
In this example, the polyacrylamide used had a molecular weight of 500 ten thousand and a degree of hydrolysis of 8%.
The preparation method of the temporary plugging agent B comprises the following steps:
at room temperature, 100g of diesel oil is added into a reactor, 2.5g of polyethylene resin serving as a main agent is taken and dissolved in the oil solvent diesel oil under the conditions of introducing nitrogen to remove oxygen and stirring, 2.8g of dicumyl peroxide serving as a crosslinking agent and 0.4g of cumene hydroperoxide serving as a gel breaker are added into the reactor until the main agent is completely dissolved, and the mixture is stirred for 15min at the speed of 400r/min, so that the temporary plugging agent B can be obtained.
Testing the gel breaking time of the temporary plugging agent A:
a single sand-filled pipe model is adopted indoors to simulate a stratum test, and the method comprises the following specific steps:
(1) under the experimental condition that the temperature is 60 ℃, the sand filling pipe is saturated with water until the pressure is stable;
(2) injecting 0.5PV temporary plugging agent A, standing for gelation waiting, and gelling for 6 hours;
(3) and measuring the water drive pressure change values at 6h, 12h, 24h, 48h and 72h respectively, and judging the gel breaking condition and the complete gel breaking time within 3 days.
The result is shown in fig. 3, the pressure is stable during primary water flooding, and after the temporary plugging agent A is injected to wait for 6 hours for gelling, the water flooding pressure reaches a higher peak value, which indicates that the temporary plugging agent A has better plugging capability. And (3) starting from 12h, gradually reducing the pressure value in each test, particularly starting at 24h, and greatly reducing the pressure until 72h later, and recovering the water-driving pressure to the pressure value before the plugging agent injection, which indicates that the temporary plugging agent A starts to crack after 24h and can completely crack until 72 h.
Gel breaking time test of temporary plugging agent B
The method comprises the following specific steps:
(1) under the experimental condition that the temperature is 60 ℃, saturating the sand filling pipe with water at the speed of 1ml/min by a constant flow pump, after the outlet end stably discharges water, saturating oil to the outlet end at the injection speed of 0.5ml/min to stably discharge oil, stopping the pump and recording the pressure;
(2) injecting 0.5PV temporary plugging agent B, standing for gelation, and gelling for 8 hours;
(3) and measuring the water drive pressure change values at 8h, 12h, 24h, 2D, 4D, 5D, 7D and 10D respectively, and judging the gel breaking condition and the complete gel breaking time within 10 days.
The result is shown in fig. 4, the primary water-driving pressure is stable, after the temporary plugging agent B is injected to wait for gelling for 8 hours, the water-driving pressure reaches a higher peak value, which indicates that the temporary plugging agent B has better plugging capability. And in the time from 8h to 4 days, the water flooding pressure value is not obviously reduced, which shows that the temporary plugging agent B still has better plugging capability. And (3) the pressure starts to be greatly reduced on the 5 th day, and the water-drive pressure value returns to the pressure value equivalent to that before the plugging agent is injected after 10 days, so that the temporary plugging agent B starts to break gel after the 5 th day and completely breaks gel until the 10 th day.
To further illustrate the advantages of the present invention, the methods of the present invention are illustrated by specific experiments.
Parallel sand-packed pipe displacement experiment:
according to the actual condition of the target high water-cut oil reservoir, a double-pipe parallel model is adopted indoors to simulate the heterogeneity of the stratum. The specific embodiment comprises the following steps:
(1) under the experimental condition of 60 ℃, two sand filling pipes are saturated with water and then saturated with crude oil, primary water displacement (at the rate of 1ml/min) is carried out to the limit water content, and parameters such as high-low permeability pore volume, permeability, oil saturation and the like are calculated;
(2) injecting temporary plugging agent A. The injection amount of the blocking agent A is 0.5PV, the injection speed is 0.5ml/min, the viscosity is 20mPa & s, and the gelling time of the blocking agent A is 6-7 hours. When the plugging agent is injected, the ratio of the water absorption capacity of the high-permeability layer to the water absorption capacity of the low-permeability layer is calculated according to the formula (1) and the liquid absorption capacity of the high-permeability layer is up to 98.4 percent, which indicates that most of the plugging agent A can enter the high-permeability pipe for plugging and has little influence on the low-permeability layer;
(3) and injecting a temporary plugging agent B. After the high permeability layer is temporarily blocked by the temporary blocking agent A, injecting 0.5PV temporary blocking agent B into the low permeability layer, and gelling for 8 hours;
(4) after temporary plugging protection of a low-permeability layer, namely a target oil layer, is realized, the time for complete gel breaking is 3 days after the temporary plugging agent A breaks gel, and the permeability of a high-permeability layer is recovered.
(5) Injecting the long-acting plugging agent into the high-permeability layer, wherein the temporary plugging agent B of the low-permeability layer does not break the gel, and the long-acting plugging agent can selectively enter the high-permeability layer, so that the selective plugging of the high-permeability layer is realized;
(6) the time for the temporary plugging agent B to completely break gel is 10 days, after the temporary plugging agent B breaks gel, subsequent water drive is carried out, the liquid yield of a high permeability layer is recorded, the recovery ratio is calculated, and the final result and the experimental conditions are shown in a figure 1 and a table 2.
Table 1 example 1 basic experimental parameters and experimental results
The change curve of the flow rate of the high-low permeability layer is shown in figure 1. The split flow rate is the ratio of the liquid production to the total liquid production and is used for reflecting the profile improvement. Along with the blocking agent blocking the high-permeability pipe, the subsequent injected water continues to increase, the injection pressure is forced to rise, the flow diversion of the high-low permeability pipe is realized, the water injection profile is improved, the liquid yield of a low-permeability layer is increased, and the water flooding effect is greatly improved.
When water is driven once, the high permeability layer is a dominant channel, water is driven to flow along the high permeability layer, and the flow rate of the high permeability layer is far higher than that of the low permeability layer. After the water is driven to the limit water content, the temporary plugging agent A is injected, and the shunt rate of the hypertonic layer is still kept at a higher level at the moment.
After the temporary plugging agent A is gelatinized, the temporary plugging agent B is continuously injected at a low speed, and as the high-permeability layer is plugged by the temporary plugging agent A, the liquid flow is diverted, and the temporary plugging agent B can completely enter the low-permeability layer, the flow splitting rate of the low-permeability layer begins to increase, and as the high-permeability layer is plugged, the flow splitting rate is greatly reduced.
Standing for 3 days, and transferring the long-acting temporary plugging agent after the temporary plugging agent A is completely broken. Because the temporary plugging agent B does not break the gel at this time, and the hypotonic layer is still plugged, the long-acting temporary plugging agent completely enters the hypertonic layer and does not damage the hypotonic layer, so that the flow rate of the hypertonic layer is further increased, and the flow rate of the hypotonic layer is rapidly reduced.
Standing for 7 days, and starting subsequent water drive after the temporary plugging agent B is completely broken. At the moment, the high permeability layer is blocked by the long-acting temporary blocking agent, and the low permeability layer is well started, so that the flow rate of the low permeability layer is gradually increased and the flow rate of the high permeability layer begins to be greatly reduced in the subsequent water flooding process. The method can well realize selective water shutoff without damaging the low permeability layer, and has remarkable effect.
Example 2
The preparation method of the temporary plugging agent A comprises the following steps:
preparing polyacrylamide into a solution with a certain concentration of 10000mg/L, adding hexamethylenetetramine to make the concentration of 1300mg/L, resorcinol to make the concentration of 600mg/L, a gel breaker hydrogen peroxide to make the concentration of 4000mg/L, potassium persulfate to make the concentration of 5000mg/L, adjusting the pH of the solution to 3.5 with hydrochloric acid, keeping the temperature at 60 ℃ for 12 hours to obtain the gel temporary plugging agent A, and measuring the viscosity of the gel temporary plugging agent A by using a viscometer to be 30 mPas.
In this example, the polyacrylamide used had a molecular weight of 600 ten thousand and a degree of hydrolysis of 13%.
The preparation method of the temporary plugging agent B comprises the following steps:
at room temperature, 100g of diesel oil is added into a reactor, under the conditions of introducing nitrogen to remove oxygen and stirring, a proper amount of polyethylene resin as a main agent 4g is taken and dissolved in the oil solvent diesel oil until the polyethylene resin is completely dissolved, 3g of dicumyl peroxide as a crosslinking agent and 0.6g of cumene hydroperoxide as a gel breaker are added into the reactor, and the mixture is stirred for 15min at the speed of 400r/min, so that the temporary plugging agent B can be obtained.
According to the actual condition of the target high water-cut oil reservoir, a double-pipe parallel model is adopted indoors to simulate the heterogeneity of the stratum. The specific embodiment comprises the following steps:
(1) under the experimental condition of 60 ℃, two sand filling pipes are saturated with water and then saturated with crude oil, primary water displacement (at the rate of 1ml/min) is carried out to the limit water content, and parameters such as high-low permeability pore volume, permeability, oil saturation and the like are calculated;
(2) injecting temporary plugging agent A. The injection amount of the blocking agent A is 0.5PV, the injection speed is 0.5ml/min, the viscosity is 30mPa & s, and the gelling time of the blocking agent A is 6-7 hours. In the injection process, the ratio of the water absorption capacity of the high-permeability layer to the water absorption capacity of the low-permeability layer is calculated according to the formula (1), the liquid absorption capacity of the high-permeability layer is up to 98.46 percent, and the plugging agent A can basically enter the high-permeability layer for plugging;
(3) and injecting a temporary plugging agent B. After the high permeability layer is temporarily blocked by the temporary blocking agent A, injecting 0.5PV temporary blocking agent B into the low permeability layer, and gelling for 8 hours;
(4) after temporary plugging protection of a low-permeability layer, namely a target oil layer, is realized, the time for complete gel breaking is 3 days after the temporary plugging agent A breaks gel, and the permeability of a high-permeability layer is recovered.
(5) Injecting a long-acting plugging agent into the high-permeability layer, wherein the low-permeability layer B does not break the gel, and the high-permeability layer is effectively plugged;
(6) the time for the temporary plugging agent B to completely break gel is 10 days, after the temporary plugging agent B breaks gel, subsequent water drive is carried out, the liquid yield of a high permeability layer is recorded, the recovery ratio is calculated, and the final result and the experimental conditions are shown in a figure 2 and a table 2.
Table 2 example 2 basic experimental parameters and experimental results
The change curve of the flow rate of the high-low permeability layer is shown in figure 2. When water is driven once, the high permeability layer is a dominant channel, water is driven to flow along the high permeability layer, and the flow rate of the high permeability layer is far higher than that of the low permeability layer.
After the water is driven to the limit water content, the temporary plugging agent A is injected, and the shunt rate of the hypertonic layer has no obvious change, which indicates that the temporary plugging agent A basically enters the hypertonic layer.
After the temporary plugging agent A is gelatinized, the temporary plugging agent B is continuously injected at a low speed, and the temporary plugging agent B can completely enter the low-permeability layer because the high-permeability layer is plugged by the temporary plugging agent A, so that the flow rate of the low-permeability layer begins to increase, and the flow rate of the high-permeability layer is greatly reduced.
Standing for 3 days, and transferring the long-acting temporary plugging agent after the temporary plugging agent A is completely broken. Because the temporary plugging agent B does not break the gel at this time, and the hypotonic layer is still plugged, the long-acting temporary plugging agent completely enters the hypertonic layer and does not damage the hypotonic layer, so that the flow rate of the hypertonic layer is further increased, and the flow rate of the hypotonic layer is rapidly reduced.
Standing for 7 days, and starting subsequent water drive after the temporary plugging agent B is completely broken. At the moment, the high permeability layer is blocked by the long-acting temporary blocking agent, and the low permeability layer is well started, so that the flow rate of the low permeability layer is gradually increased and the flow rate of the high permeability layer begins to be greatly reduced in the subsequent water flooding process. The method can well realize selective water shutoff without damaging the low permeability layer, and has remarkable effect.
In conclusion, the two-stage temporary plugging combined selective water plugging method is adopted, and the high-permeability water producing layer can be effectively plugged, so that the low-permeability layer is developed and utilized, and the recovery ratio can be effectively increased.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A two-stage temporary plugging combined selective water plugging method is characterized by comprising the following steps:
(1) after primary water flooding is finished, injecting a low-viscosity temporary plugging agent A with gel breaking time not more than 3 days, wherein the temporary plugging agent A enters a high-permeability layer with high water saturation to temporarily plug the high-permeability layer, and the injection pressure of the temporary plugging agent A is less than the starting pressure of the low-permeability layer;
(2) injecting a temporary plugging agent B with gel breaking time not less than 5 days to form plugging on the hypotonic layer;
(3) after the temporary plugging agent A breaks the gel, injecting the plugging agent into the target stratum, closing the well and waiting for setting to realize the plugging of the high-permeability water producing layer;
(4) and after the temporary plugging agent B breaks the gel, opening the well and recovering production.
2. The method according to claim 1, wherein the temporary plugging agent a has an initial viscosity of 20 to 40 mPa-s.
3. The method according to claim 2, wherein the temporary plugging agent A has a gel breaking time of 1 to 3 days.
4. The method according to claim 2, wherein the temporary plugging agent a comprises the following components in weight ratio:
the balance of water;
the molecular weight of the polyacrylamide is 500-600 ten thousand, and the degree of hydrolysis is 5% -13%; the first cross-linking agent is hexamethylenetetramine; the second cross-linking agent is m-diphenol; the first gel breaker is hydrogen peroxide; the second breaker was potassium persulfate.
5. The method of claim 3, wherein the temporary plugging agent A is prepared by the following method: dissolving polyacrylamide in water, sequentially adding a first cross-linking agent, a second cross-linking agent, a first additive and a second additive, stirring to dissolve, adjusting the pH value to 3-5 by hydrochloric acid, and keeping the temperature at 60 ℃ for 12 hours to obtain the polyacrylamide gel.
6. The method according to claim 1, wherein the temporary plugging agent B has an automatic gel breaking time of 5-10 days.
7. The method of claim 5, wherein said temporary plugging agent B is an oil-based temporary plugging agent.
8. The method according to claim 6, wherein the temporary plugging agent B has the following composition in mass percent:
2 to 4 percent of polyethylene resin;
2.8 to 3 percent of dicumyl peroxide;
0.4 to 0.6 percent of cumene hydroperoxide;
the balance being diesel oil.
9. The method of claim 7, wherein the temporary plugging agent B is prepared by the following method: adding diesel oil into a reaction vessel at room temperature, introducing N2Removing oxygenAnd dissolving polyethylene resin in diesel oil under stirring, adding dicumyl peroxide and cumyl peroxide, and stirring at 400r/min for 15 min.
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Application publication date: 20201113 |