CN111963100A - Water plugging method for fractured reservoir - Google Patents
Water plugging method for fractured reservoir Download PDFInfo
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- CN111963100A CN111963100A CN202010839975.9A CN202010839975A CN111963100A CN 111963100 A CN111963100 A CN 111963100A CN 202010839975 A CN202010839975 A CN 202010839975A CN 111963100 A CN111963100 A CN 111963100A
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- Prior art keywords
- water
- agent
- plugging
- injection
- slug
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Classifications
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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
- 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
-
- 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
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
Abstract
The invention provides a water plugging method for a fractured reservoir, which comprises the following steps: firstly, preparing a water plugging agent; secondly, determining the dosage of the water shutoff agent, the injection speed, the injection pressure and the injection slug; thirdly, plugging water in the target oil reservoir; the plugging device can realize plugging of deep parts of cracks to start residual oil in the matrix, and has ideal use effect.
Description
Technical Field
The invention belongs to the technical field of oil and gas field development, and particularly relates to a water plugging method for a fractured reservoir.
Background
For a fractured reservoir, because the permeability distribution difference is large, injected water or bottom water flows along a high-permeability fracture, a fracture system with high water saturation and a matrix system with high oil saturation coexist in an interweaving mode in the later stage of water flooding, a large amount of residual oil in a matrix rock block cannot be extracted, an oil well quickly sees water and quickly reaches high water content, and the reservoir development faces a severe situation that the oil well is subjected to violent flooding and the yield is quickly reduced. Under the situation, how to carry out efficient water control and water plugging becomes a technical problem which needs to be solved in oil field development.
At present, profile control water shutoff/deep profile control technology has a good effect in increasing and controlling water of a conventional sandstone reservoir, but the application success rate in a fractured compact reservoir is still low, and the main problem is that a fracture channel is different from a large-channel channeling channel, while the current profile control technology in a fractured low-permeability reservoir mostly adopts the conventional sandstone reservoir mature technology, so that effective balance of injectivity and plugging property is difficult to form, the problem of 'no injectivity or no plugging' is easy to occur in the construction process, and residual oil in a matrix can not be started due to the fact that deep plugging of fractures is realized. And thus, there is a need for improvement.
Disclosure of Invention
The invention aims to provide a water plugging method for a fractured reservoir, which aims to solve the technical problems of water control and water plugging in oil field development.
In order to achieve the purpose, the specific technical scheme of the fractured reservoir water plugging method is as follows:
a method for plugging water of a fractured reservoir comprises the following steps: firstly, preparing a water plugging agent; secondly, determining the dosage of the water shutoff agent, the injection speed, the injection pressure and the injection slug; and thirdly, plugging water in the target oil reservoir.
In the method for blocking water in a fractured reservoir, the water blocking agent is a mixed solution of a polymer, a cross-linking agent and water; the weight percentage of the polymer is 0.5 to 1.0 percent, the weight percentage of the cross-linking agent is 0.3 to 0.5 percent, and the balance is water; the cross-linking agent is a composition of a reinforcing agent and a curing agent, wherein the weight percentage of the reinforcing agent to the curing agent is 0.5 to 1.0 percent, and the balance is the curing agent;
the polymer is polyacrylamide with the molecular weight of 1600 ten thousand or 1400 ten thousand; the reinforcing agent is a phenolic resin reinforcing agent; the curing agent is sodium thiosulfate; the water is tap water.
In the method for plugging water in a fractured reservoir, the amount of the plugging agent is determined by an empirical formula method and a volume formula method, and the average value of the calculation results according to the empirical formula method and the volume formula method is used as the amount of the plugging agent; wherein the empirical formula is:
Q＝2.64×L×f (1)
in the formula, Q is the dosage of the water plugging agent, m 3; l is the plugging length, m; f-adjustment factor, 1.0 to 2.0;
the volume formula is:
wherein, the dosage of Q-water plugging agent, m3(ii) a L is the plugging length, m; r-plugging radius, m;
-porosity,%;
the injection pressure is determined to reduce the pollution of the water plugging agent to small and medium cracks so as to ensure the smooth construction and the normal production after operation; controlling the pressure acting on the stratum to be within 80% of the starting pressure of the medium and small fractures, and calculating according to a calculation formula (3) of the highest injection pressure of a wellhead;
Pnote that＝0.8POpener-PLiquid for treating urinary tract infection+Pf+Ph (3)
In the formula (I), the compound is shown in the specification,
Pnote that-maximum injection pressure, MPa;
Popener-rupture pressure, MPa;
Pliquid for treating urinary tract infection-liquid column pressure, MPa;
Pf-loss of on-way friction, MPa;
Ph-additional pressure, MPa (between 0.5 and 1 MPa);
the determination of the injection speed of the water shutoff agent aims at the large fracture plugging of the well, and selects a lower injection speed, generally 8-12 m, by combining the field pump condition, the gelling time of the water shutoff agent and the highest injection pressure under the condition of protecting the medium and small fractures3/h；
The injection slug is determined because the seepage section is gradually increased from the bottom to the outside, and the flow passing through each section is equal when seepage is stabilized, so that the larger the section is, the smaller the seepage speed is, and the smaller the pressure difference is; accordingly, the injection of the chemical water shutoff agent is carried out by time division and multi-section plug injection: pre-injection of slug, injection of polymer, slug length 150 to 250m3(ii) a When the section of polymer advances along the crack, the formed protective film can be attached to the crack surface so as to prevent small molecules in the subsequently injected water shutoff agent from diffusing and filtering into the microcracks and the matrix, and the functions of pretreating the stratum and protecting the main body slug are achieved; the main body is injected with a slug, a water plugging agent is injected, and the length of the slug is 900-3(ii) a Sealing the slug, injecting water shutoff agent, the length of slug is 500-600 m3(ii) a Replacing the slug, injecting water, the length of the slug being 40 to 60m3。
The water plugging method for the fractured reservoir has the following advantages: the method is reasonable in design, can realize plugging of deep parts of cracks to start residual oil in the matrix, and is ideal in use effect.
Detailed Description
In order to better understand the purpose, structure and function of the invention, the following describes the water plugging method of fractured reservoir of the invention in further detail.
Example 1:
the E22H well is a horizontal well, the oil reservoir temperature is 90 ℃, and the oil reservoir is a fractured bottom water oil reservoir. 200m of daily oil production at initial production stage3And/d, substantially free of water. After 10 months the water content rises, afterThe water content is too high, so that the stopping of injection of a water injection well, the closing of a well pressure cone of an oil well and the amplification of the production pressure difference are carried out for many times, but the effects are not obvious. From the analysis of the physical property and the production dynamic state of the logging reservoir, the physical property of the reservoir in the middle part of the E22H well close to the heel is good, cracks develop, the injection and production intensity of the heel of the horizontal well is high, and the water-avoiding height is only 40m, so that bottom water is easy to cone, and the water content of the oil well is increased. The method for plugging the fractured reservoir has the advantages that the plugging of the fractured reservoir is carried out, the plugging of the deep part of the fracture is realized, the residual oil in the matrix is started, and the using effect is ideal.
Firstly, preparing a water plugging agent:
weighing 1.0% of polyacrylamide with the molecular weight of 1600 ten thousand and 1.0% of cross-linking agent according to the weight percentage, and sequentially putting the polyacrylamide and the cross-linking agent into the balance of tap water to prepare the water shutoff agent; wherein the cross-linking agent is a composition of a reinforcing agent and a curing agent, the weight percentage of the reinforcing agent is 1.0 percent, and the balance is the curing agent; the reinforcing agent is phenolic resin reinforcing agent, and the curing agent is sodium thiosulfate.
Secondly, design of dosage of water shutoff agent
1. Empirical formula method:
calculating according to an empirical formula (1), wherein the plugging length of the horizontal section of the E22H well is 344m, the adjustment coefficient is 1.8, and the dosage of the water plugging agent is 1587m3。
Q＝2.64×L×f (1)
Wherein the content of the first and second substances,
q-amount of plugging agent, m3
L-length of occlusion, m
f-adjustment factor, 1.0 to 2.0
2. Volume method:
calculated according to the volume method formula (2), the plugging length of the horizontal section of the E22H well is 344m, the plugging radius is 5m, and the calculated usage amount of the plugging agent is 1573m3。
Wherein, Q-amount of the plugging agent, m3(ii) a L is the plugging length, m;r-plugging radius, m;
in conclusion, the dosage of the plugging agent is designed to be 1600m3。
Third, the injection speed and injection pressure design
1. Injection speed:
aiming at the actual situation that the well blocks large cracks and small and medium cracks are protected as far as possible, the injection displacement as low as possible is selected by combining the field pump condition and the gelling time of the blocking agent. The working fluid injection speed of the operation is designed to be 8-12 m3And h, determining the final injection speed according to the field injection test condition.
2. Injection pressure
In order to reduce the pollution of the plugging agent to small and medium cracks and ensure the smooth construction and the normal production after operation, the pressure acting on the stratum needs to be controlled within 80 percent of the starting pressure of the small and medium cracks, the highest injection pressure is designed to be not more than 10MPa in principle according to the calculation formula (3) of the highest injection pressure of a wellhead.
PNote that＝0.8POpener-PLiquid for treating urinary tract infection+Pf+Ph (3)
In the formula (I), the compound is shown in the specification,
Pnote that-maximum injection pressure, MPa; pOpener-rupture pressure, MPa; pLiquid for treating urinary tract infection-liquid column pressure, MPa;
Pf-loss of on-way friction, MPa; phAdditional pressure, MPa (from 0.5 to 1 MPa).
3. Injection slug design
Because the seepage section is gradually increased from the bottom to the outside, and the flow passing through each section is equal when seepage is stabilized, the larger the section is, the smaller the seepage speed is, and the smaller the pressure difference is. Accordingly, the plugging agent should be designed to be injected from weak to strong in multiple stages.
In addition, a polymer slug is injected before the water plugging agent enters the crack, and the formed protective film is attached to the crack surface while the polymer advances along the crack so as to prevent small molecules in the subsequently injected plugging agent from diffusing and losing into the microcracks and the matrix, thereby playing the roles of pretreating the stratum and protecting the main slug.
Thus, the E22H well plug is designed as a "front + body + seal + displacement" quad-plug. Wherein, the main body and the sealing slug adjust the concentration of the water plugging agent in due time according to the injection condition of the front slug, as shown in table 1.
TABLE 1E 22H well plug design
And fourthly, plugging the E22 well.
1. Preparing a front-mounted slug solution with 0.5% concentration polyacrylamide with the molecular weight of 1600 ten thousand, and preparing the solution with the particle size of 8-12 m3The injection speed of the injection is 200m3And the injection time is 25h, and the formation is pretreated.
2. At 8 to 12m3The injection speed of/h is 1050m for injecting the configured water shutoff agent into the main body slug in the well3And the injection time is 132h, and the water outlet channel is blocked.
3. At 8 to 12m3The injection speed of/h is 550m for injecting the configured water plugging agent into the seal section plug in the well3And the injection time is 69h, and the water outlet channel is blocked.
4. At 8 to 12m3The injection speed of the water/h is 50m3And the injection time is 6 hours, and the plugging agent is replaced to the stratum.
Fifth, plugging effect
This is illustrated by production data. 225.5 parts of daily produced liquid and 3.4 parts of daily produced oil before the operation of the E22 well, and the water content is 98.5 percent. After water plugging construction, the daily produced fluid of the E22H well is reduced to 43 square, but the daily oil yield is increased to 20 square, the water content is about 45 percent, 2 months after the water plugging construction, the daily produced fluid is 45 square, the daily oil yield is 23.2 square, the water content is 48.2 percent, the average daily oil increase is 19.8 square, the water content is reduced by 50.3 percent, and the oil increase is accumulated by 1261 square, so that an obvious oil increase and water reduction effect is obtained.
The content that is not described in this embodiment is the prior art, and therefore, the description thereof is omitted.
The design principle of the invention is as follows: the water shutoff agent is naturally selected to enter large cracks, the injection pressure is controlled, and the damage to small and medium cracks is reduced by adopting a weak-to-strong multi-section plug injection mode, so that the effects of pretreating the stratum and protecting the main body section plug are achieved.
The invention has the overall advantages that: aiming at the defects of the prior art, the design method of the water plugging scheme of the fractured reservoir is provided, the water plugging agent has good reservoir adaptability and high strength, can protect medium and small fractures and low permeability layers, effectively plugs a high channeling channel formed by large fractures, inhibits bottom water, reduces water content, obtains good oil increasing effect, and can well solve the problem of low application success rate of water plugging of a fractured reservoir oil well.
It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (3)
1. A method for plugging water of a fractured reservoir is characterized by comprising the following steps:
firstly, preparing a water plugging agent;
secondly, determining the dosage of the water shutoff agent, the injection speed, the injection pressure and the injection slug;
and thirdly, plugging water in the target oil reservoir.
2. The method for plugging water from a fractured reservoir of claim 1, wherein the water plugging agent is a mixed solution of a polymer, a cross-linking agent and water; the weight percentage of the polymer is 0.5 to 1.0 percent, the weight percentage of the cross-linking agent is 0.3 to 0.5 percent, and the balance is water; the cross-linking agent is a composition of a reinforcing agent and a curing agent, wherein the weight percentage of the reinforcing agent to the curing agent is 0.5 to 1.0 percent, and the balance is the curing agent;
the polymer is polyacrylamide with the molecular weight of 1600 ten thousand or 1400 ten thousand; the reinforcing agent is a phenolic resin reinforcing agent; the curing agent is sodium thiosulfate; the water is tap water.
3. The method for plugging the fractured reservoir according to claim 1, wherein the amount of the plugging agent is determined by adopting an empirical formula method and a volume formula method, and the average value of the calculation results of the empirical formula method and the volume formula method is used as the amount of the plugging agent; wherein the empirical formula is:
Q＝2.64×L×f (1)
in the formula, Q is the dosage of the water plugging agent, m 3; l is the plugging length, m; f-adjustment factor, 1.0 to 2.0;
the volume formula is:
wherein, the dosage of Q-water plugging agent, m3(ii) a L is the plugging length, m; r-plugging radius, m;
-porosity,%;
the injection pressure is determined to reduce the pollution of the water plugging agent to small and medium cracks so as to ensure the smooth construction and the normal production after operation; controlling the pressure acting on the stratum to be within 80% of the starting pressure of the medium and small fractures, and calculating according to a calculation formula (3) of the highest injection pressure of a wellhead;
Pnote that＝0.8POpener-PLiquid for treating urinary tract infection+Pf+Ph (3)
In the formula (I), the compound is shown in the specification,
Pnote that-maximum injection pressure, MPa;
Popener-rupture pressure, MPa;
Pliquid for treating urinary tract infection-liquid column pressure, MPa;
Pf-loss of on-way friction, MPa;
Ph-additional pressure, MPa (between 0.5 and 1 MPa);
the determination of the injection speed of the water shutoff agent aims at the large fracture plugging of the well, and selects a lower injection speed, generally 8-12 m, by combining the field pump condition, the gelling time of the water shutoff agent and the highest injection pressure under the condition of protecting the medium and small fractures3/h；
The injection slug is determined because the seepage section is gradually increased from the bottom to the outside, and the flow passing through each section is equal when seepage is stabilized, so that the larger the section is, the smaller the seepage speed is, and the smaller the pressure difference is; accordingly, the injection of the chemical water shutoff agent is carried out by time division and multi-section plug injection: pre-injection of slug, injection of polymer, slug length 150 to 250m3(ii) a The main body is injected with a slug, a water plugging agent is injected, and the length of the slug is 900-3(ii) a Sealing the slug, injecting water shutoff agent, the length of slug is 500-600 m3(ii) a Replacing the slug, injecting water, the length of the slug being 40 to 60m3。
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| CN202010839975.9A CN111963100A (en) | 2020-08-20 | 2020-08-20 | Water plugging method for fractured reservoir |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114151048A (en) * | 2021-12-07 | 2022-03-08 | 西南石油大学 | Gas channeling prevention and oil displacement method for compact reservoir horizontal well |
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| CN114151048A (en) * | 2021-12-07 | 2022-03-08 | 西南石油大学 | Gas channeling prevention and oil displacement method for compact reservoir horizontal well |
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