1. The low-density water shutoff agent for high temperature is characterized by comprising the following components:

100 parts by weight of limestone powder;

5-15 parts by weight of cotton fibers;

10-50 parts by weight of an oxide;

5-15 parts by weight of oil-soluble resin;

1-3 parts by weight of a high-temperature crosslinking agent;

the particle size of each component is smaller than 47 micrometers, the content of calcium carbonate in the limestone powder is larger than 95% by weight, the content of fibers in the cotton fibers is larger than 85% by weight, and the content of oxides is larger than 95% by weight.

2. The low-density water shutoff agent for high temperature according to claim 1, wherein the oil-soluble resin is a natural resin and/or a synthetic resin, the softening point is 100-300 ℃, and the dissolution rate in anhydrous kerosene is greater than 90% wt.

3. The low-density water shutoff agent for high temperature use according to claim 1, wherein said oxide is at least one of calcium oxide, magnesium oxide, barium oxide, calcium hydroxide, magnesium hydroxide and barium hydroxide.

4. A preparation method of the low-density water shutoff agent for high temperature according to any one of claims 1 to 3, comprising the following steps:

(1) taking a proper amount of limestone powder, and performing ultrafine grinding to obtain particles with the particle size of less than 47 microns;

(2) mixing oxide with high temperature cross-linking agent, and micronizing to particle size less than 47 μm;

(3) preparing cotton fibers: taking cotton linters, soaking the cotton linters in an acid solution with the concentration of 5-10%, heating to 80-90 ℃, soaking for 6-8 hours, centrifuging and spin-drying the acid-treated cotton linters at a high speed, neutralizing with an alkali solution with the concentration of 15-30% until the pH value reaches 7-9, and drying;

(4) uniformly mixing the dried cotton fiber and the oil-soluble resin according to the design amount, and performing ultrafine grinding to obtain particles with the particle size of less than 47 microns;

(5) uniformly mixing the materials prepared in the steps (1) to (4) according to the designed dosage to obtain the low-density water plugging agent for high temperature;

(6) and finally weighing and bagging.

5. The method for preparing the low-density water shutoff agent for high temperature according to claim 4, wherein after the crosslinking reaction of the high-temperature crosslinking agent and the oil-soluble resin, the liquid volume is increased by more than 5%, and a rapid chemical reaction occurs at more than 120 ℃, and the crosslinked material of the high-temperature crosslinking agent and the oil-soluble resin resists more than 360 ℃.

6. The method for preparing a low-density water shutoff agent for high temperature according to claim 4, wherein the limestone powder: 100 parts by weight, cotton fiber: 13 parts by weight, oxide: 40 parts by weight, oil-soluble resin: 13 parts by weight, high temperature crosslinking agent: 2 parts by weight.

7. The method for preparing a low-density water shutoff agent for high temperature according to claim 4, wherein the acid solution is at least one selected from the group consisting of: hydrochloric acid, phosphoric acid, hydrofluoric acid and acetic acid; the alkali solution is at least one of the following solutions: sodium hydroxide solution, sodium carbonate solution, potassium hydroxide solution and magnesium hydroxide solution.

8. The field use method of the low-density water shutoff agent for high temperature prepared by the method of claim 4 is characterized by comprising the following specific construction processes:

(a) injecting industrial water with a designed amount into a 20-40-square stirring tank;

(b) under the stirring state of 100-500 r/min, adding 20-35 wt% of high-temperature low-density water plugging agent, wherein the feeding speed is 25-50 kg/min;

(c) after the low-density water plugging agent is added at high temperature, stirring is continued for 30 minutes, and the properties such as apparent viscosity, density and the like are measured; the apparent viscosity is required to be 15-80 mpa.s; performance adjustment of density less than 0.95g/cm 3;

(d) if the apparent viscosity is less than 15mpa.s, increasing the addition of the low-density water plugging agent for high temperature until the design requirement is met; if the apparent viscosity is more than 80mpa.s, the industrial water consumption is increased until the design requirement is met; the density is more than 0.95g/cm3, and the stirring speed is increased;

(e) and then constructing according to the plugging adjusting process and the drilling plugging requirements.

9. The in-situ use method of the low-density water shutoff agent for high temperature according to claim 8, wherein the industrial water is replaced by formation sewage or highly mineralized brine.

Background

The reserves of the thick oil resources in China are rich, about 250 multiplied by 108t, and account for 28 percent of the total oil and gas resources. The best way to recover heavy and ultra-heavy oil resources is thermal recovery, including steam swallowing and steam flooding. However, due to factors such as the difference of fluidity between steam and heavy oil and the gravity overlap of steam, in actual production, steam is easy to enter and blow in a high permeability layer, so that the steam swept volume is reduced, the steam utilization rate is influenced, the thermal recovery effect is poor, the heavy oil thermal recovery yield is reduced, and the energy consumption is increased. The problems of steam channeling, water channeling, edge water bottom water coning and the like become the most troublesome problems in the development of the thick oil and are the difficulties to be solved urgently in the exploitation of the thick oil. Among the technical measures for solving the problems, the water plugging technology is an effective means for improving the water injection development effect of the oil field and realizing the stable production of the oil reservoir.

The water plugging is to control the water-oil ratio or the water production, and the essence of the water plugging is to change the flow characteristic of water in the stratum, namely, the penetration rule of water in the stratum and prevent the water flow from passing through or change the water flow direction. Water shutoff operation is divided into two types, namely water shutoff of an oil well (production well) and profile control of a water well (injection well), according to different construction objects. The types of the plugging agent mainly used at home at present comprise: inorganic salt plugging agents, polymer gel plugging agents, resin plugging agents, foam profile control plugging agents and the like. In a high-salinity oil reservoir water shutoff profile control agent system, the application range of the cross-linked polymer plugging agent is limited due to salt sensitivity, heat sensitivity, flocculation of multivalent ions and the like; the inorganic solid particle channeling sealing agent has good temperature resistance, but has poor injectability, can not enter the deep part of a stratum, has short plugging distance, and continues to cone after steam flows around; after the blocking effect of the particles, fine gaps still exist, and steam can still flow by means of channeling; the generated plugging is non-selective permanent plugging and has great damage to the oil reservoir. The foam type plugging agent has the defects of low plugging capability; the foam stability is poor, and in order to obtain an ideal plugging effect, the injection dosage is required to be large so as to maintain the foam stability and the treatment period; less foaming agents can be selected at home, and the cost of the foaming agent is higher. The resin type plugging agent is prepared from materials such as phenolic resin, epoxy resin, urea-formaldehyde resin and the like, and is solidified in a preset time period underground through formula adjustment and setting to form a consolidation body with high strength, good temperature resistance, salt resistance and aging resistance. Most in field applications are thermosetting resins. The thermosetting resin is heated to generate chemical change, gradually hardened and formed, and is not softened or dissolved after being heated. Thermosetting resins have the disadvantage of poor mechanical properties. For a microbial polysaccharide polymer profile control water shutoff agent system, the currently adopted formula is a microbial polysaccharide curdlan and hydrogen bonding force promoter compound or a microbial polysaccharide curdlan and coagulant aid compound system.

Disclosure of Invention

In order to solve the problems of water channeling and steam channeling in the thermal recovery production of the thick oil, through research and a large number of experiments, the invention provides the low-density water plugging agent for high temperature, which has the advantages of wide raw material source, simple production process, convenient construction, safety and environmental protection and can meet the construction requirement of water plugging for sealing channeling and plugging in the thermal recovery of the thick oil, and the fluid system of the low-density water plugging agent for high temperature prepared by adopting the water plugging agent has low viscosity and good fluidity and can carry out deep plugging adjustment; salt resistance, temperature resistance, long effective time and strong pressure resistance; the water-plugging agent has a selective water-plugging function, and does not block oil when plugging water; the plugging rate of the water flow permeable layer and the steam channeling permeable layer reaches more than 98 percent; the yield of the thickened oil is improved by more than 50 percent, the water yield is reduced, the recovery ratio is improved, and the development cost is reduced.

The invention relates to a high-temperature oil-gas well and heavy oil thermal recovery well production device, which is used for plugging a high-temperature oil reservoir steam channeling layer, a water channeling layer and a water outlet layer; the high-temperature steam swept volume is used for adjusting the steam injection well; adjusting the water absorption profile of the water injection well, the water plugging of the oil production well and the water plugging technology of the side water, bottom water and water flow channeling of the oil layer.

Provides a low-density water shutoff agent for high temperature and a preparation method thereof, which are used for solving the problem of water channeling and steam channeling in the thermal recovery production of thick oil.

The invention is realized by the following technical scheme: a low-density water shutoff agent for high temperature comprises the following components: 100 parts by weight of limestone powder; 5-15 parts by weight of cotton fibers; 10-50 parts by weight of an oxide; 5-15 parts by weight of oil-soluble resin; 1-3 parts by weight of a high-temperature crosslinking agent; the particle size of each component is smaller than 47 micrometers, the content of calcium carbonate in the limestone powder is larger than 95% by weight, the content of fibers in the cotton fibers is larger than 85% by weight, and the content of oxides is larger than 95% by weight.

Further, the oil-soluble resin is natural resin and/or synthetic resin, the softening point is 100-300 ℃, and the dissolution rate in the anhydrous kerosene is more than 90 wt%;

further, the oxide is at least one of calcium oxide, magnesium oxide, barium oxide, calcium hydroxide, magnesium hydroxide and barium hydroxide;

the invention also provides a preparation method of the low-density water shutoff agent for high temperature, which comprises the following steps:

(1) taking a proper amount of limestone powder, and performing ultrafine grinding to obtain particles with the particle size of less than 47 microns;

(2) mixing oxide with high temperature cross-linking agent, and micronizing to particle size less than 47 μm;

(3) preparing cotton fibers: taking cotton linters, soaking the cotton linters in an acid solution with the concentration of 5-10%, heating to 80-90 ℃, soaking for 6-8 hours, centrifuging and spin-drying the acid-treated cotton linters at a high speed, neutralizing with an alkali solution with the concentration of 15-30% until the pH value reaches 7-9, and drying;

(4) uniformly mixing the dried cotton fiber and the oil-soluble resin according to the design amount, and performing ultrafine grinding to obtain particles with the particle size of less than 47 microns;

(5) uniformly mixing the materials prepared in the steps (1) to (4) according to the designed dosage to obtain the low-density water plugging agent for high temperature;

(6) and finally weighing and bagging.

Further, after the high-temperature crosslinking agent and the oil-soluble resin are subjected to crosslinking reaction, the liquid volume is increased by more than 5%, rapid chemical reaction is carried out at the temperature of more than 120 ℃, and the crosslinking substance of the high-temperature crosslinking agent and the oil-soluble resin can resist the temperature of more than 360 ℃.

Further, limestone powder: 100 parts by weight, cotton fiber: 13 parts by weight, oxide: 40 parts by weight, oil-soluble resin: 13 parts by weight, high temperature crosslinking agent: 2 parts by weight.

Further, the acid solution is at least one selected from the following: hydrochloric acid, phosphoric acid, hydrofluoric acid and acetic acid; the alkali solution is at least one of the following solutions: sodium hydroxide solution, sodium carbonate solution, potassium hydroxide solution and magnesium hydroxide solution.

The low-density water shutoff agent for high temperature has the following specific advantages:

(1) the low-density water plugging agent for high temperature prepared by the invention has strong high temperature resistance and good water plugging effect, can effectively adjust the steam injection profile, enlarge the high-temperature steam swept volume, improve the yield of thickened oil and the recovery ratio of the thickened oil, and reduce the development cost of the thickened oil.

(2) In an acid environment, most of materials of the low-density water plugging agent for high temperature prepared by the invention are acidified and unplugged to generate soluble inorganic salt, and the good permeability is kept;

(3) the high-temperature low-density water shutoff agent prepared by the invention is coated by crude oil in an underground crude oil reservoir environment, a high-temperature cross-linking agent and the like are coated, foams disappear, and a water-in-oil inverse emulsion is formed, so that the way of chemical cross-linking reaction of the high-temperature low-density water shutoff agent is blocked, phase change is not generated, an oil flow channel is not blocked, and the oil flow channel is discharged out of the place in the oil and gas production process, thereby being beneficial to protecting a reservoir stratum and having the function of selective water shutoff;

(4) the low-density water plugging agent for high temperature prepared by the invention is added with part of oil-soluble resin, and the oil-soluble resin can be dissolved in crude oil without blocking an oil layer;

(5) the low-density water plugging agent for high temperature prepared by the invention is retained in a water channeling channel and undergoes phase change, and liquid is converted into solid, thereby playing a permanent plugging role in the water channel;

(6) the low-density water plugging agent for high temperature prepared by the invention can fully exert the advantage of low density, so that an isolation layer is formed on the interface of an oil layer and a water layer, and the rapid coning of bottom water is effectively blocked.

(7) The low-density water plugging agent for high temperature prepared by the invention has simple preparation process and low cost.

The on-site construction process of the low-density water shutoff agent for high temperature comprises the following steps:

(a) injecting industrial water with a designed amount into a 20-40-square stirring tank;

(b) under the stirring state of 100-500 r/min, adding 20-35 wt% of high-temperature low-density water plugging agent, wherein the feeding speed is 25-50 kg/min;

(c) after the low-density water plugging agent is added at high temperature, stirring is continued for 30 minutes, and the properties such as apparent viscosity, density and the like are measured; the apparent viscosity is required to be 15-80 mpa.s; density less than 0.95g/cm³Adjusting the performance;

(d) if the apparent viscosity is less than 15mpa.s, increasing the addition of the low-density water plugging agent for high temperature until the design requirement is met; if the apparent viscosity is more than 80mpa.s, the industrial water consumption is increased until the design requirement is met; the density is more than 0.95g/cm3, and the stirring speed is increased;

(e) and then constructing according to the plugging adjusting process and the drilling plugging requirements.

In conclusion, the low-density plugging agent for high temperature is uniformly stirred in water to form a low-density plugging agent fluid system for high temperature, the system has better suspension stability and low density, can stand for more than two weeks at room temperature for a long time without obvious layering, and can meet the long-term stability requirement of a plugging agent injection link in site construction and a long-term long-acting plugging link in a later period on the plugging agent injection fluid.

The fluid system prepared by the low-density water plugging agent for high temperature starts to thicken at the temperature of more than 120 ℃, shortens thickening time along with the rise of temperature, and finally achieves the effect of converting liquid into solid to play a good role in plugging water. Under the high temperature condition, the phase change time can be adjusted between 10 hours and 72 hours, and the construction requirement of long-time plugging operation of deep wells and ultra-deep wells can be met. The construction method has the advantages of safe field construction, wide application, and remarkable economic and social benefits.

The low-density plugging agent for high temperature provided by the invention can change performance indexes such as thickening temperature, thickening time, thickening strength and the like of the plugging agent by adjusting the effective content of the components of the low-density plugging agent for high temperature according to the specific plugging construction operation requirement.

The low-density water plugging agent fluid system for the heavy oil thermal recovery at high temperature can be injected into a heavy oil steam drive thermal recovery well for water plugging profile control after the preparation is finished.

The low-density water shutoff agent fluid system for the heavy oil thermal recovery at the high temperature has good fluidity at normal temperature, the viscosity is 15-80 mPa.s, the density is 0.85-0.95 g/cm3, and the low-density water shutoff agent fluid system is easy to prepare, pump and inject, construct and regulate and block in deep parts.

The low-density water plugging agent fluid system for the heavy oil thermal recovery high temperature has low viscosity and low density, can be quickly injected into a heavy oil steam-drive thermal recovery well, and can selectively enter a water channeling channel in the oil well due to large viscosity difference between the heavy oil and formation water, and under the pushing of the post-injection fluid, the water plugging agent fluid enters the deep part of the water channeling channel, and the performance of the water plugging agent fluid is kept stable for a long time in the environment that the formation temperature is less than 100 ℃. After steam is injected, the temperature of the stratum rises, and along with the continuous production process of the oil well for a plurality of periods, bottom water on the edge begins to taper towards the periphery of the production well, so that the plugging agent fluid is pushed to flow towards the environment with higher temperature. The plugging agent is excited at high temperature to generate a crosslinking reaction, the viscosity is rapidly increased to form a solidification body, and water channeling is blocked, so that the effect of plugging for a long time is achieved.

The water for preparing the liquid for the field construction can be industrial water, stratum sewage, high salinity brine and the like. The formation sewage is oil-containing sewage from the oil well development process. The total mineralization of the high-mineralization saline water is less than 20 ten thousand mg/L, wherein the mineralization of calcium and magnesium is less than 1 ten thousand mg/L. The thick oil prepared by the liquid is not affected by the low-density high-temperature plugging slurry adjusting performance, and the plugging performance adjusting index can meet the construction operation requirement. Therefore, the low-density water shutoff agent fluid system for heavy oil thermal recovery at high temperature has lower requirements on fluid preparation, and can be widely applied to profile control and water shutoff construction operation and well drilling and plugging of oil wells in oceans, deserts and other areas. The low-density water shutoff agent fluid system for heavy oil thermal recovery high temperature has low density, and can be widely applied to water shutoff construction of low-pressure oil-gas layers, bottom water reservoirs and the like. The low-density water shutoff agent fluid system for heavy oil thermal recovery at high temperature has no toxic or side effect on human bodies, thereby ensuring the health and safety requirements of construction operators.

Detailed Description

The invention is further illustrated by the following non-limiting examples:

the following is test data of the low-density water plugging agent for high temperature of the invention when the components have different contents.

Example 1

1) Preparing the low-density water plugging agent for high temperature according to the following different component contents: 100 parts by weight of limestone powder; cotton fibers and oil-soluble resins (both 1: 1): 20 parts by weight; calcium oxide and high temperature crosslinker (both 40: 2): 42 parts by weight; and mixing and stirring the substances uniformly to obtain the low-density water plugging agent for high temperature.

2) Preparing a low-density water plugging agent water plugging system for high temperature: 10%, 13%, 15%, 18%, 20%, 25%, 30%, 35%, 40% of a low-density water shutoff agent for high temperature use was added to the measured amount of water.

3) Adding a low-density water plugging agent for high temperature into water, continuously stirring for 2 hours at the rotating speed of 100-.

4) The apparent viscosity and density of the obtained low-density water plugging system for high temperature are measured at room temperature and are shown in table 1;

TABLE 1 viscosity/Density values at different addition levels at room temperature

And standing the high-temperature low-density water plugging system obtained in the step (A) under the closed condition of 80 ℃ and keeping the temperature for 48 hours. It was cooled to room temperature, stirred for 2 hours respectively, and the apparent viscosity/density was measured, as shown in table 2;

TABLE 280 ℃ various additive viscosity/Density values

As can be seen from the data in tables 1 and 2, the addition of the low-density water shutoff agent for high temperature is controlled to be below 30%, so that the high-density water shutoff agent keeps good fluidity and achieves the aim of deep water shutoff adjustment.

5) Standing the obtained low-density water plugging system for high temperature under a sealed condition at 150 ℃, keeping the temperature for 24 hours, cooling the system to room temperature, and respectively observing and measuring the curing condition of the low-density water plugging system for high temperature, wherein the curing condition is shown in table 3;

TABLE 3150 ℃ various additive viscosity/density values

As can be seen from the data in Table 3, the addition of the low-density plugging agent for high temperature and the formation temperature should be controlled below 25% at 150 ℃ so as to keep better fluidity and achieve the purpose of deep plugging adjustment.

6) Standing the obtained low-density water plugging system for high temperature under a 250 ℃ closed condition, keeping the temperature constant for 24 hours, cooling the system to room temperature, and respectively observing and measuring the curing condition of the low-density water plugging system for high temperature, wherein the curing condition is shown in table 4;

TABLE 4250 ℃ different additive viscosity/Density values

As can be seen from the data in Table 4, the addition of the low-density plugging agent for high temperature is controlled to be below 20% under the condition that the formation temperature is 250 ℃, so that the good fluidity of the plugging agent is maintained, and the purpose of deep plugging adjustment is achieved.

7) Standing the obtained low-density water plugging system for high temperature under a 360-degree closed condition, keeping the temperature constant for 24 hours, cooling the system to room temperature, and respectively observing and measuring the curing condition of the low-density water plugging system for high temperature, wherein the curing condition is shown in table 5;

TABLE 5360 ℃ various values of additive viscosity/density

As can be seen from the data in Table 5, the addition of the low-density plugging agent for high temperature is controlled to be below 15% under the condition that the formation temperature is 360 ℃, so that the good fluidity of the plugging agent is maintained, and the purpose of deep plugging adjustment is achieved.

8) Standing the obtained low-density water plugging system for high temperature under the closed condition of 400 ℃, keeping the temperature for 24 hours, cooling the system to room temperature, and respectively observing and measuring the curing condition of the low-density water plugging system for high temperature, wherein the curing condition is shown in table 6;

TABLE 6400 ℃ different values of additive viscosity/density

As can be seen from the data in Table 6, the addition of the low-density plugging agent for high temperature is controlled to be less than 13% under the condition that the formation temperature is 400 ℃, so that the good fluidity of the plugging agent is maintained, and the purpose of deep plugging adjustment is achieved.

9) Standing the obtained low-density water plugging system for high temperature under a sealed condition of 360 ℃, keeping the temperature for 24 hours, cooling the system to room temperature, and respectively observing and measuring the curing condition of the low-density water plugging system for high temperature, wherein the curing condition is shown in table 7;

TABLE 7360 ℃ Cure

As can be seen from the data in Table 7, the addition of the low-density water shutoff agent for high temperature reaches 20%, and the low-density water shutoff agent has strong curing strength under the condition that the formation temperature is 360 ℃, and completely meets the requirements of high-temperature water shutoff and channeling sealing.

(II) example 2

1) The low-density water plugging agent for high temperature is produced according to the following different component contents: 100 parts by weight of limestone powder; 10 parts by weight of cotton fiber and oil-soluble resin (1: 1 of the two); 21 parts by weight of calcium oxide and a high-temperature crosslinking agent (40: 2); and mixing and stirring the substances uniformly to obtain the low-density water plugging agent for high temperature.

2) Preparing a low-density water shutoff agent system for high temperature: 10%, 13%, 15%, 18%, 20%, 25%, 30%, 35%, 40% of a low-density water shutoff agent for high temperature use was added to the measured amount of water.

3) Adding a low-density water plugging agent for high temperature into water, continuously stirring for 2 hours at the rotating speed of 100-.

4) The resulting low density water shutoff system for high temperature was measured for apparent viscosity/density at room temperature, see table 8;

TABLE 8 viscosity/Density values at different addition levels at room temperature

4) Standing the obtained high-temperature low-density water plugging system under the airtight condition of 80 ℃, keeping the temperature for 48 hours, respectively stirring for 2 hours, cooling the water plugging system to room temperature, and respectively observing and measuring the solidification condition of the high-temperature low-density water plugging system, wherein the solidification condition is shown in table 9;

TABLE 980 ℃ values for various additive viscosities/density values

As can be seen from the data in tables 8 and 9, the addition of the low-density plugging agent for high temperature should be controlled below 35%, so that the good fluidity is maintained, and the purpose of deep plugging adjustment is achieved.

5) Standing the obtained low-density water plugging system for high temperature under a sealed condition of 150 ℃, keeping the temperature for 24 hours, cooling the system to room temperature, and respectively observing and measuring the curing condition of the low-density water plugging system for high temperature, wherein the curing condition is shown in table 10;

TABLE 10150 ℃ values of different additive viscosities/densities

As can be seen from the data in Table 10, the addition of the low-density plugging agent for high temperature and the formation temperature should be controlled below 35% at 150 ℃ so as to maintain good fluidity and achieve the purpose of deep plugging adjustment.

6) Standing the obtained low-density water plugging system for high temperature under a 250 ℃ closed condition, keeping the temperature constant for 24 hours, cooling the system to room temperature, and respectively observing and measuring the curing condition of the low-density water plugging system for high temperature, wherein the curing condition is shown in table 11;

TABLE 11250 ℃ values for different additive viscosity/Density values

As can be seen from the data in Table 11, the addition of the low-density plugging agent for high temperature is controlled to be below 25% under the condition that the formation temperature is 250 ℃, so that the good fluidity of the plugging agent is maintained, and the purpose of deep plugging adjustment is achieved.

7) Standing the obtained low-density water plugging system for high temperature under a 360-degree closed condition, keeping the temperature constant for 24 hours, cooling the system to room temperature, and respectively observing and measuring the curing condition of the low-density water plugging system for high temperature, wherein the curing condition is shown in table 12;

TABLE 12360 ℃ values for various additive viscosities/densities

From the data in table 12, it can be seen that the addition of the low-density plugging agent for high temperature should be controlled to be less than 20% at a formation temperature of 360 ℃ so as to maintain good fluidity and achieve the purpose of deep plugging adjustment.

8) Standing the obtained high-temperature low-density water plugging system under a closed condition at 400 ℃, keeping the temperature for 24 hours, cooling the water plugging system to room temperature, and respectively observing and measuring the curing condition of the high-temperature low-density water plugging system, wherein the curing condition is shown in Table 13;

TABLE 13400 ℃ viscosity/density values at different addition levels

As can be seen from the data in Table 13, the addition of the low-density plugging agent for high temperature is controlled to be below 15% under the condition that the formation temperature is 400 ℃, so that the good fluidity is maintained, and the purpose of deep plugging adjustment is achieved.

9) Standing the obtained high-temperature low-density water plugging system under the sealed condition of 360 ℃, keeping the temperature for 24 hours, cooling the water plugging system to room temperature, and respectively observing and measuring the curing condition of the high-temperature low-density water plugging system, wherein the curing condition is shown in table 14;

TABLE 14360 ℃ Cure

As can be seen from the data in Table 14, the addition of the low-density water shutoff agent for high temperature reaches 30%, and the low-density water shutoff agent has strong curing strength under the condition that the formation temperature is 360 ℃, and completely meets the requirements of high-temperature water shutoff and channeling sealing.

Compared with the data analysis of the embodiment 1 and the embodiment 2, the embodiment 1 has small addition amount and good water plugging effect; example 2, the addition amount is large and the cost is high.

(III) the field test conditions are as follows:

(1) water plugging test of side water flooding production stopping well

C, flat 17 well: and developing a horizon museum I, wherein the perforation length of a horizontal well section is 150m, and the horizontal well is positioned at the edge of the edge water.

The well is injected with steam 7 months in 2005, and after 153 days of well production, the water content is increased from 56% to 100%, and the well is forced to stop production. The daily liquid before the production is stopped is 83.1t/d, the daily oil is 0t/d, and the water content is 100 percent. The well is analyzed to be influenced by the water coning at the south of the block, and the horizontal section has multi-section water outlet.

And (3) performing water plugging construction on the level 17 well C in 12 months and 1 day in 2015, co-injecting a water plugging agent system of 280m3, discharging capacity of 10-20m3/h, and increasing injection pressure from 4MPa to 6.5 MPa.

12 and 20 days in 2015, after steam injection, 10.2 tons of oil are produced in the initial stage, about 5.0 tons of oil are produced in the current day, the water content is below 70%, and the water layer is effectively blocked after continuous production for nearly two years.

(2) Oil layer bottom water flooding oil well water plugging test

The clear river M-X16 well is put into operation in 2009, and 1700 tons of oil are produced by 12 months in 2010, because the bottom water of the oil layer is coning, the water content is rapidly increased to 100 percent from 22 percent of the initial production, and the production is forced to be stopped for a long time. And (3) performing bottom water plugging construction by using a high-temperature low-density water plugging system in 2016, co-injecting the high-temperature low-density water plugging system into the well at a rate of 150m3, wherein after the well is put into operation, the daily yield peak period is 36.2t/d, the daily oil content is 18.4t/d, and the water content is 49.2%. By 6 months in 2017, the well produces oil at 7.6t/d daily and contains 78% of water.

(III) plugging test of oil well steam channeling channel

The distance between the B509-X100 well and the B509-X51 well target point is 41 meters, steam channeling occurs in the steam injection thermal recovery process, the B509-X100 steam channeling affects the B509-X9 months in 2016, the B509-X51 well stops producing for 200 days, and the crude oil yield is affected by 450 tons. In 2017, in 1 month, the construction of bottom water plugging is implemented by using a low-density water plugging system for high temperature, and the well is co-injected with a low-density water plugging system for high temperature of 80m³The steam injection pressure of the B509-X100 well is stably increased from 15MPa to 16.3 MPa in the steam injection process, the steam channeling well B509-X51 well normally produces the steam, the yield is not influenced, the normal production is realized by 8 months in 2017, and a steam channeling channel is effectively blocked.

Therefore, the low-density water shutoff agent system for high temperature can be widely applied to water shutoff construction under the following complex conditions: (1) water plugging of the water outlet layer section is carried out by water explosion; (2) plugging water in the water layer section of the bottom water burst flooding; (3) water plugging of a large-pore water layer section; (4) plugging water in a water outlet layer section of the thickened oil thermal recovery multi-round huff and puff well; (5) plugging a steam channeling layer of the steam flooding section; (6) water layer water plugging is carried out by high and medium permeation; (7) plugging a damaged and missed layer of the sleeve; (7) and plugging a sleeve gas channeling channel and the like.

The above description is only an embodiment of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in 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.