High-temperature-resistant water shutoff agent as well as preparation and application thereof

Abstract

The invention provides a high-temperature-resistant water shutoff agent as well as preparation and application thereof. The water shutoff agent is prepared from the following components in parts by weight: 100 to 110 parts of sodium lauryl alcohol phthalate, 45 to 55 parts of polyoxyethylene sorbitan monooleate, 60 to 70 parts of lignin surfactant, 65 to 75 parts of alpha-olefin sulfonate and 330 to 380 parts of oleic acid. The preparation process of the water shutoff agent comprises the following steps: adding the sodium lauryl alcohol ester phthalate and the polyoxyethylene sorbitan monooleate into a reaction kettle, and uniformly stirring to obtain a first reaction solution; adding a lignin surfactant and alpha-olefin sulfonate into the first reaction solution at one time, and uniformly stirring to obtain a third reaction solution; equally dividing oleic acid into two groups, adding one group of oleic acid into the third reaction solution, and uniformly stirring to obtain a fourth reaction solution; and adding another group of oleic acid into the fourth reaction liquid, uniformly stirring, and standing to obtain the water shutoff agent. The problems that a water plugging agent is poor in plugging effect in a high-temperature oil reservoir and low in crude oil recovery rate can be solved.

Description

Technical Field

[0001] This application relates to the technical field of oilfield chemical agents, specifically to a high-temperature resistant water-blocking agent and its preparation and application. Background Technology

[0002] During oilfield development, some oil wells are prone to premature water encounter or water flooding due to water layer channeling, bottom water coning or injection, and edge water inrush. To eliminate or reduce water flooding, control the flow of water in the producing layer, change the direction of water flow during water-driven oil recovery, and improve the water recovery rate, chemical treatment agents used in production wells to seal the water-producing sections are called water-blocking agents.

[0003] Based on their blocking effects on oil and water layers, water-blocking agents are further classified into selective and non-selective water-blocking agents. Non-selective water-blocking agents can block both water and oil layers, and are used to seal high-water-cut layers and single-water layers in oil wells. During application, the water-producing layer must first be located, an appropriate process string selected, and the oil and water layers separated. Then, the water-blocking agent is injected into the high-water-cut layer to achieve the sealing purpose. Selective water-blocking agents, on the other hand, effectively reduce the permeability of the aqueous phase while causing minimal damage to the permeability of the oil phase. Specifically, they significantly reduce the permeability of the aqueous phase while reducing or not reducing the permeability of the oil (gas) phase.

[0004] Currently, when most water shut-off agents are applied to high-temperature oil reservoirs, the emulsion formed by the water shut-off agent and the water in the underground high water-cut channels of the oil well has a low viscosity, which cannot effectively seal the high water-cut channels and has a poor oil displacement effect in the high water-cut channels. Therefore, it cannot effectively improve the oil recovery rate. Summary of the Invention

[0005] To address the problem of poor sealing effect and low oil recovery rate of water-blocking agents in high-temperature reservoirs, this application proposes a high-temperature resistant water-blocking agent, its preparation method, and its application. The technical solution adopted in this application is as follows:

[0006] In a first aspect, this application discloses a high-temperature resistant water-blocking agent comprising the following components in parts by weight: 100-110 parts sodium monolaurate phthalate, 45-55 parts polyoxyethylene sorbitan monooleate, 60-70 parts lignin surfactant, 65-75 parts α-olefin sulfonate, and 330-380 parts oleic acid.

[0007] Optionally, the water-blocking agent comprises the following components in parts by weight: 105 parts sodium monolaurate phthalate, 50 parts polyoxyethylene sorbitan monooleate, 65 parts lignin surfactant, 68 parts α-olefin sulfonate, and 370 parts oleic acid.

[0008] Secondly, this application also discloses a method for preparing a water-blocking agent as described in the first aspect, the method comprising the following steps:

[0009] Sodium monolaurate phthalate and polyoxyethylene sorbitan monooleate were added to the reaction vessel and stirred evenly to obtain the first reaction solution.

[0010] Add lignin surfactant to the first reaction solution and stir until homogeneous to obtain the second reaction solution;

[0011] Add α-olefin sulfonate to the second reaction solution and stir until homogeneous to obtain the third reaction solution;

[0012] Oleic acid was divided into two groups, and one group of oleic acid was added to the third reaction solution. The mixture was stirred until homogeneous to obtain the fourth reaction solution.

[0013] Add another group of oleic acid to the fourth reaction solution, stir evenly, and let stand to obtain a water-blocking agent.

[0014] Optionally, the step of adding sodium monolaurate phthalate and polyoxyethylene sorbitan monooleate to a reaction vessel and stirring until homogeneous includes:

[0015] The stirring temperature is 20-25℃ and the stirring time is 30-35 minutes.

[0016] Optionally, the step of adding a lignin surfactant to the first reaction solution and stirring until homogeneous includes:

[0017] The stirring temperature is 20-25℃ and the stirring time is 20-25 min.

[0018] Optionally, before adding one group of the oleic acids to the third reaction solution, the method further includes:

[0019] The third reaction solution is cooled to 20-25°C.

[0020] Thirdly, this application discloses the application of the water-blocking agent as described in the first aspect in high-temperature oil reservoirs, including: mixing the water-blocking agent with dehydrated crude oil to obtain a heavy oil water-blocking agent;

[0021] The water-blocking agent has a weight content ranging from 2% to 3%, calculated as 100% of the weight of the dehydrated crude oil.

[0022] Optionally, in the heavy oil water-blocking agent, the step of mixing the water-blocking agent with dehydrated crude oil to obtain the heavy oil water-blocking agent includes:

[0023] The heavy oil water-blocking agent is injected into oil wells with a temperature range of 90–110°C.

[0024] Optionally, injecting the heavy oil water-blocking agent into an oil well with a temperature range of 90–110°C includes:

[0025] When the water cut of the oil well is 50-98%, the heavy oil water shut-off agent is injected into the oil well.

[0026] Optionally, the viscosity of the dehydrated crude oil at 45°C is 300–1000 mPa·s.

[0027] In summary, the advantages of this application over the prior art include:

[0028] 1. The water-blocking agent in this application embodiment is a brown viscous liquid. The components are compounded according to a set ratio to obtain a water-blocking agent with the advantage of high emulsifiable viscosity. When this water-blocking agent is added to the oil layer for water blocking, it adsorbs onto the oil-water interface to reduce the oil-water interfacial tension. The lignin surfactant (PS) can reduce the oil-water interfacial tension to 10. -3 This water-blocking agent can form a water-in-oil emulsion with water. The emulsion remains stable above 100°C, extending its effective lifespan by more than 100 days compared to conventional water-blocking agents, resulting in superior sealing performance. Furthermore, it can increase the total oil recovery of the reservoir by more than 150 tons within its effective lifespan, significantly improving oil production efficiency.

[0029] 2. The water-blocking agent in this application embodiment is compounded with dehydrated crude oil to form a heavy oil water-blocking agent. Its viscosity in the temperature range of 90–110°C is more than three times higher than that of conventional water-blocking agents. Viscosity is a crucial factor affecting the sealing effect of water-blocking agents. Therefore, the heavy oil water-blocking agent in this application can form a high-viscosity emulsion with water in the high-water-cut channels of oil wells at high temperatures, resulting in a relatively stable emulsion that effectively seals the high-water-cut channels.

[0030] 3. The water-blocking agent in this embodiment is a selective water-blocking agent. When this agent is back-injected into the formation from the oil well, the emulsified heavy oil enters the high-water-cut layer and forms a high-viscosity emulsion with the water in the underground high-water-cut channels, thus physically blocking the flow. This effectively reduces the permeability of the aqueous phase while causing minimal damage to the permeability of the oil phase.

[0031] 4. The water-blocking agent in this application embodiment, when applied to oil wells with a water cut between 50% and 98%, can increase the oil recovery rate by more than 10%. Therefore, using the water-blocking agent in this application is beneficial for improving the plugging effect on high water-cut reservoirs.

[0032] 5. The water-blocking agent in this application embodiment has a simple preparation process, mild reaction conditions, does not require a high reaction temperature, and is low in cost. Furthermore, the raw materials are environmentally friendly and readily available, and the produced fluid requires no special treatment. Detailed Implementation

[0035] The inventors discovered that most current water-blocking agents, when used in high-temperature oil reservoirs, do not significantly improve crude oil recovery and cannot effectively seal water in underground high-water-cut channels. In laboratory tests, the inventors prepared a water-blocking agent based on Chinese Patent CN102676137A – Crude Oil Emulsifier for Water Blocking in Oil Wells and its Preparation Method and Application. The resulting water-blocking agent, when used with water at temperatures exceeding 100°C, generally formed an emulsion with a viscosity below 1000 mPa·s, which was insufficient to effectively seal high-water-cut channels.

[0036] Therefore, in order to solve the problem of poor sealing effect of water-blocking agents on high-temperature oil reservoirs, the inventors further developed and made this invention.

[0037] In a first aspect, embodiments of this application disclose a high-temperature resistant water-blocking agent, which comprises the following components in parts by weight: 100-110 parts sodium monolaurate phthalate, 45-55 parts polyoxyethylene sorbitan monooleate, 60-70 parts lignin surfactant, 65-75 parts α-olefin sulfonate and 330-380 parts oleic acid.

[0038] In the water-blocking agent of this application embodiment, each component in the above formulation is a water-in-oil surfactant, thereby forming a water-in-oil emulsion, which is beneficial to enhancing the water-blocking effect. When this water-blocking agent is added to the oil layer for water blocking, the water-blocking agent will be adsorbed on the oil-water interface, thereby reducing the oil-water interfacial tension, which can be reduced to 10. -3 The mN / m ratio ensures that the emulsion remains relatively stable above 100℃, maintaining a high viscosity and thus producing a better water-blocking effect.

[0039] In an optional embodiment, the water-blocking agent specifically comprises the following components in parts by weight: 105 parts sodium monolaurate phthalate, 50 parts polyoxyethylene sorbitan monooleate, 65 parts lignin surfactant, 68 parts α-olefin sulfonate, and 370 parts oleic acid.

[0040] Secondly, this application discloses a method for preparing the above-mentioned water-blocking agent, specifically including the following steps:

[0041] S1: Sodium monolaurate phthalate and polyoxyethylene sorbitan monooleate are added to a reaction vessel and stirred until homogeneous to obtain the first reaction solution. In this step, the stirring temperature can be 20–25°C, and the stirring time can be 30–35 minutes. In a specific embodiment, 105 parts of sodium monolaurate phthalate and 50 parts of polyoxyethylene sorbitan monooleate can be mixed.

[0042] S2: Continue adding lignin surfactant to the first reaction solution in the above-mentioned reactor, and then continue stirring at a temperature of 20-25°C for 20-25 minutes to obtain the second reaction solution. In a specific embodiment, 65 parts of lignin surfactant may be added to the reactor.

[0043] S3: Continue adding α-olefin sulfonate to the second reaction solution in the above-mentioned reactor, and then continue stirring at a temperature of 20-25°C for 20-25 minutes to obtain the third reaction solution. In a specific embodiment, 68 parts of α-olefin sulfonate may be added to the reactor.

[0044] S4: Divide the oleic acid into two equal groups, add one group of the oleic acid to the third reaction solution, and stir at 20-25°C for 20 minutes to obtain the fourth reaction solution. Specifically, since heat is generated during the reactions in S1-S3 above, the temperature of the third reaction solution should be lowered to 20-25°C before adding oleic acid to the fourth reaction solution. In a specific embodiment, 370 parts of oleic acid can be divided into two equal parts, and then 185 parts of oleic acid can be added to the third reaction solution.

[0045] S5: Add another group of oleic acid to the fourth reaction solution and stir evenly to obtain the water-blocking agent. Specifically, before adding oleic acid, let the fourth reaction solution stand for 1-2 hours, then add 185 parts of oleic acid to the fourth reaction solution and stir at 20-25℃ for 20 minutes. Finally, let it stand for 2-3 hours to obtain the water-blocking agent.

[0046] As can be seen from steps S1 to S5 above, the preparation process of the water-blocking agent provided in this application embodiment is carried out at room temperature under mild reaction conditions. Therefore, no special conditions such as temperature control are required, and it can be carried out in an ordinary reaction vessel, which can greatly save resources and reduce production costs. At the same time, the water-blocking agent obtained through steps S1 to S5 is a brown viscous liquid with high emulsion viscosity, which can meet the requirements for high-strength water blocking. Furthermore, this water-blocking agent also has the advantages of low raw material cost, wide availability, and environmental friendliness, meaning that the oil extracted from the oil well does not require special treatment.

[0047] Thirdly, this application also discloses the application of the above-mentioned water-blocking agent in high-temperature reservoirs. Specifically, it includes: mixing the above-mentioned water-blocking agent with dehydrated crude oil to obtain a heavy oil water-blocking agent, and then further injecting the heavy oil water-blocking agent into a reservoir with an injection temperature range of 90-110°C.

[0048] In an optional embodiment, based on 100% by weight of dehydrated crude oil, the above-mentioned water-blocking agent can be added to the dehydrated crude oil at a weight percentage of 1% to 3%, and stirred thoroughly for 1 hour to finally obtain a heavy oil water-blocking agent. The viscosity of the dehydrated crude oil at 45°C is in the range of 300–1000 mPa·s. This heavy oil water-blocking agent is injected into the oil well using an annulus pump to achieve selective water plugging of the oil well.

[0049] In this embodiment, the substance injected into the oil well is a heavy oil water-blocking agent containing a water-blocking agent and high-viscosity heavy oil. After the heavy oil water-blocking agent is pumped into the formation of the oil well under high pressure, the heavy oil water-blocking agent entering the oil flow channels will dissolve in the formation crude oil and be extracted from the oil well. The heavy oil water-blocking agent entering the water flow channels mixes and emulsifies with the seeping formation water or injected water to form a water-in-oil emulsion, whose viscosity increases significantly. It can produce a water-blocking effect in the following ways: First, the emulsified heavy oil water-blocking agent is cut into spherical shapes by the water flow, causing physical blockage at the throat of the water flow channel; second, the heavy oil water-blocking agent is adsorbed on the wall of the water flow channel, changing the wall rock from hydrophilic to oleophilic, and narrowing the channel, thus hindering the flow of water. Finally, the surfactant component in the heavy oil water-blocking agent emulsifies the heavy oil in water into oil droplets, thereby producing the Jamin effect in the pores, reducing the water permeability.

[0050] Furthermore, in an optional embodiment, since the above-mentioned heavy oil water-blocking agent needs to be mixed with water to produce an effect, the injection timing of the heavy oil water-blocking agent can be: during water-drive oil production, when the water cut is 50% to 98%, the heavy oil water-blocking agent is injected into the oil well.

[0051] The present application will be described in detail below through specific embodiments:

[0052] (1) Preparation of water-blocking agent

[0053] Example 1

[0054] The water-blocking agent in this embodiment comprises the following components in parts by weight: 105 parts sodium monolaurate phthalate, 50 parts polyoxyethylene sorbitan monooleate (Tween 80), 65 parts lignin surfactant (PS), 68 parts α-olefin sulfonate (AOS), and 370 parts oleic acid.

[0055] The water-blocking agent in this embodiment is prepared using the following process:

[0056] S1: Weigh 105 parts of sodium monolaurate phthalate and 50 parts of polyoxyethylene sorbitan monooleate (Tween 80), add them to the reaction vessel, and stir for 30 minutes at 20-25°C to obtain the first reaction solution.

[0057] S2: Weigh 65 parts of lignin surfactant (PS) and add it to the first reaction solution while stirring. Then continue stirring for 20 minutes at 20-25°C to obtain the second reaction solution.

[0058] S3: Weigh 68 parts of α-olefin sulfonate (AOS) and add it to the second reaction solution while stirring. Then continue stirring for 20 minutes at 20-25°C to carry out the reaction and obtain the third reaction solution.

[0059] S4: Cool the third reaction solution to 20-25℃, add 185 parts of oleic acid evenly to the third reaction solution while stirring, stir for 20 minutes at 20-25℃ and let stand for 1 hour to obtain the fourth reaction solution.

[0060] S5: Continue to add 185 parts of oleic acid evenly to the fourth reaction solution while stirring. Stir for 20 minutes at 20-25°C, let stand for 3 hours, and then encapsulate to obtain the water-blocking agent.

[0061] Example 2

[0062] The preparation process of the water-blocking agent in this embodiment is the same as that in Example 1. The difference is that the water-blocking agent in this embodiment includes the following components in parts by weight: 100 parts sodium monolaurate phthalate, 45 parts polyoxyethylene sorbitan monooleate (Tween 80), 60 parts lignin surfactant (PS), 65 parts α-olefin sulfonate (AOS) and 330 parts oleic acid.

[0063] Example 3

[0064] The preparation process of the water-blocking agent in this embodiment is the same as that in Example 1. The difference is that the water-blocking agent in this embodiment includes the following components in parts by weight: 110 parts sodium monolaurate phthalate, 55 parts polyoxyethylene sorbitan monooleate (Tween 80), 70 parts lignin surfactant (PS), 75 parts α-olefin sulfonate (AOS) and 380 parts oleic acid.

[0065] Comparative Example 1

[0066] The preparation process of the water-blocking agent in this embodiment is the same as that in Example 1. The difference is that the water-blocking agent in this embodiment includes the following components in parts by weight: 95 parts sodium monolaurate phthalate, 40 parts polyoxyethylene sorbitan monooleate (Tween 80), 32 parts lignin surfactant (PS), 60 parts α-olefin sulfonate (AOS) and 300 parts oleic acid.

[0067] Comparative Example 2

[0068] The preparation process of the water-blocking agent in this embodiment is the same as that in Example 1. The difference is that the water-blocking agent in this embodiment includes the following components in parts by weight: 130 parts sodium monolaurate phthalate, 60 parts polyoxyethylene sorbitan monooleate (Tween 80), 75 parts lignin surfactant (PS), 80 parts α-olefin sulfonate (AOS) and 400 parts oleic acid.

[0069] The formulations of the water-blocking agents in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1:

[0070] Table 1. Formulations of water-blocking agents in Examples 1-3 and Comparative Examples 1-2.

[0071]

[0072] (2) Experiment on the effect of moisture content on the performance of water-blocking agents

[0073] The water-blocking agents prepared in (1) are mixed with dehydrated crude oil at a ratio of 4% to obtain a heavy oil water-blocking agent. The viscosity of the dehydrated crude oil at 45°C is 500 mPa·s.

[0074] Five heavy oil water-blocking agents were obtained following the above steps, with four groups of each agent prepared. Water was added to all four groups of heavy oil water-blocking agents to achieve water contents of 30%, 40%, 50%, and 60%, respectively. The viscosity of each group of heavy oil water-blocking agents was then measured at 90°C. The viscosities of each group of heavy oil water-blocking agents at 90°C in Examples 1-3 and Comparative Examples 1-2 are shown in Tables 2-6.

[0075] Table 2 shows the viscosity of the four groups of heavy oil water-blocking agents in Example 1 at 90°C.

[0076]

[0077] Table 3 shows the viscosity of the four groups of heavy oil water-blocking agents in Example 2 at 90°C.

[0078]

[0079] Table 4 shows the viscosity of the four groups of heavy oil water-blocking agents in Example 3 at 90°C.

[0080]

[0081] Table 5 shows the viscosity of the four groups of heavy oil water-blocking agents in Comparative Example 1 at 90℃.

[0082]

[0083] Table 6 shows the viscosity of the four groups of heavy oil water-blocking agents in Comparative Example 2 at 90℃.

[0084]

[0085] As shown in Tables 2 to 6, within the water content range of 30% to 60%, the viscosity of the heavy oil water-blocking agent tends to increase with increasing water content. The viscosity increase is particularly pronounced when the water content of the heavy oil water-blocking agent is between 40% and 50%.

[0086] As further shown in Tables 2-6, the water-blocking agents prepared according to the formulations in Examples 1-3 exhibit relatively stable viscosity at 90°C. However, in Comparative Example 1, the addition amounts of each component were relatively small, resulting in a lower viscosity of the compounded heavy oil water-blocking agent at the same water content and temperature. In Comparative Example 3, by further increasing the addition amounts of each component based on the original formulation, the viscosity of the compounded heavy oil water-blocking agent also decreased at the same temperature and water content.

[0087] (3) Experiment on the effect of temperature and concentration on the performance of water-blocking agent

[0088] Example 4

[0089] The water-blocking agent prepared in Example 1 was mixed with dehydrated crude oil at a ratio of 1% to obtain a heavy oil water-blocking agent. The viscosity of the dehydrated crude oil at 45°C was 500 mPa·s. Water was added to the heavy oil water-blocking agent to achieve a water content of 50%, and the viscosity of the heavy oil water-blocking agent was measured under controlled emulsification temperatures of 90°C, 95°C, 100°C, 105°C, and 110°C.

[0090] Example 5

[0091] The difference between this embodiment and embodiment 4 is that the water-blocking agent prepared in embodiment 1 is mixed with dehydrated crude oil at a ratio of 2%.

[0092] Example 6

[0093] The difference between this embodiment and embodiment 4 is that the water-blocking agent prepared in embodiment 1 is mixed with dehydrated crude oil at a ratio of 3%.

[0094] Example 7

[0095] The difference between this embodiment and embodiment 4 is that the water-blocking agent prepared in embodiment 1 is mixed with dehydrated crude oil at a ratio of 4%.

[0096] The viscosities of the heavy oil water-blocking agents in Examples 4-7 at 90℃, 95℃, 100℃, 105℃, and 110℃ are shown in Table 7.

[0097] Table 7 shows the viscosity of the heavy oil water-blocking agents in Examples 4-7 at different temperatures.

[0098]

[0099]

[0100] As shown in Table 7, although the viscosity of the heavy oil water-blocking agents in Examples 4-7 tends to decrease with increasing temperature, it still maintains a viscosity above 1000 mPa·s when the temperature rises to 100°C. This indicates that the above-mentioned heavy oil water-blocking agents have more stable performance and still have a relatively ideal sealing effect under conditions above 100°C.

[0101] Table 7 further shows that within the concentration range of 1% to 3%, the initial viscosity of the heavy oil water-blocking agent increases with increasing concentration, indicating a corresponding improvement in emulsification efficiency. When the water-blocking agent concentration is 4%, the initial viscosity of the heavy oil water-blocking agent at the corresponding temperature shows a decreasing trend. The optimal addition concentration of the water-blocking agent in heavy oil is 2% to 3%.

[0102] Comparative Example 3

[0103] A water-blocking agent was prepared according to Chinese Patent Publication No. CN102676137A. The water-blocking agent was mixed with dehydrated crude oil at a ratio of 3% to obtain a heavy oil water-blocking agent. The viscosity of the dehydrated crude oil at 45°C was 500 mPa·s. Water was added to the heavy oil water-blocking agent to achieve a water content of 50%. The viscosity of the heavy oil water-blocking agent was measured under controlled emulsification temperatures of 90°C, 95°C, 100°C, 105°C, and 110°C.

[0104] The viscosities of the heavy oil water-blocking agents in Example 6 and Comparative Example 3 at different temperatures are shown in Table 8:

[0105] Table 8. Viscosities of the heavy oil water-blocking agents in Example 6 and Comparative Example 3 at different temperatures.

[0106]

[0107] As shown in Table 8, under the same conditions, as the temperature rises, the viscosity of the heavy oil water-blocking agent in Example 6 increases significantly compared to Comparative Example 3, by an average of more than 3 times.

[0108] (4) Experiment on the sealing effect of water plugging agent at different water drive moisture contents

[0109] Example 8

[0110] (i) Three types of core samples with low, medium, and high permeability were selected, with permeabilities of 0.02587 μm and 0.02587 μm, respectively. 2 0.10258μm 2 and 0.48946μm 2All three types of core samples were dried in a 110℃ constant temperature oven until constant weight. After cooling, they were weighed separately to obtain the initial weight of each type of core sample.

[0111] (ii) Place the three types of dried cores into a vacuum pump and saturate them with formation water. Stop pumping when no bubbles are generated on the surface of each core. Take out the cores, wipe off the water on the surface of the cores, and weigh them to obtain the mass of each core after saturation with water.

[0112] (iii) After saturating the formation water, the three types of cores were placed in the core holders and the confining pressure was applied to ensure that it was always greater than the saturated water injection pressure by 2 MPa. Then, crude oil was saturated into each type of core at a rate of 0.3 mL / min. After driving the core into the bound water state, the pump was stopped, the cumulative water output was recorded, and each type of core was left to stand for 4 hours for later use.

[0113] (iv) Connect the core holders of the three types of cores saturated with crude oil in (iii) in parallel and conduct a water flooding experiment at a rate of 0.3 mL / min. Stop the experiment when the water cut reaches 98%. Record the oil output at the outlet of each core holder before the addition of water shut-off agent, and the cumulative oil output of the three core holders before the addition of water shut-off agent. Calculate the recovery rate of each type of core before the addition of water shut-off agent and the cumulative recovery rate of the three types of cores before the addition of water shut-off agent.

[0114] (v) Connect the core holders containing the three types of cores saturated with crude oil in (iii) in parallel, and inject the heavy oil water-blocking agent in Example 4 in reverse from the common end of the three core holders. Stop the pump and let it stand for 4 hours before use.

[0115] (vi) A forward waterflooding experiment was conducted at a rate of 0.3 mL / min. The experiment was stopped when the water content reached 98%. The oil yield after adding heavy oil water plugging agent to the outlet of each core holder was recorded, as well as the cumulative oil yield after adding heavy oil water plugging agent to the three core holders. The recovery rate after adding heavy oil water plugging agent to each type of core was calculated, as well as the cumulative recovery rate after adding heavy oil water plugging agent to the three types of cores.

[0116] In (iv) and (vi), the recovery rate of each core is the ratio of the oil yield of that core to the total oil content of the core, and the cumulative recovery rate of the three cores is the ratio of the total oil yield of the three cores to the sum of the total oil content of the three cores.

[0117] Example 9

[0118] The difference between this embodiment and Embodiment 8 is that, in step (i), the permeability of the three types of core samples is 0.02847 μm. 2 0.11008μm 2 and 0.50246μm 2In step (vi), a forward water drive experiment is conducted, and the experiment is stopped when the water drive water content reaches 90%.

[0119] Example 10

[0120] The difference between this embodiment and Embodiment 8 is that, in step (i), the permeability of the three types of core samples is 0.02438 μm. 2 0.09855μm 2 and 0.48276μm 2 In step (vi), a forward water drive experiment is conducted, and the experiment is stopped when the water drive water content reaches 80%.

[0121] Example 11

[0122] The difference between this embodiment and Embodiment 8 is that, in step (i), the permeability of the three types of core samples is 0.03031 μm. 2 0.9439μm 2 and 0.51027μm 2 In step (vi), a forward water drive experiment is conducted, and the experiment is stopped when the water drive water content reaches 70%.

[0123] Example 12

[0124] The difference between this embodiment and Embodiment 8 is that, in step (i), the permeability of the three types of core samples is 0.02107 μm. 2 0.11068μm 2 and 0.52436μm 2 In step (vi), a forward water drive experiment is conducted, and the experiment is stopped when the water drive water content reaches 60%.

[0125] Example 13

[0126] The difference between this embodiment and Embodiment 8 is that, in step (i), the permeability of the three types of core samples is 0.02888 μm. 2 0.10047μm 2 and 0.47534μm 2 In step (vi), a forward water drive experiment is conducted, and the experiment is stopped when the water drive water content reaches 50%.

[0127] The recovery rates of each type of core sample in Examples 8–13 and the cumulative recovery rates of the three types of core samples are shown in Table 9.

[0128] Table 9 shows the recovery rate of each type of core sample in Examples 8-13 and the cumulative recovery rate of the three types of core samples.

[0129]

[0130]

[0131] As shown in Table 9, when the forward water drive experiment was carried out and the water cut was driven to 60%, the cumulative recovery rate of the three types of core samples increased by 16.22% after the addition of heavy oil water shut-off agent. At this point, the water shut-off agent had the best sealing effect.

[0132] (5) Evaluation experiment on the sealing performance of water-blocking agent

[0133] Two oil wells were selected, numbered Jin 16-25-211 and Gao 13-08-15, respectively. Water-blocking agents from Example 1 and Comparative Example 3 were used to plug water in the oil layer at a temperature of 100°C, and crude oil was recovered through these two wells. The crude oil recovery rates of the two wells are shown in Table 10.

[0134] Table 10 Crude oil recovery from two oil wells

[0135]

[0136] As shown in Table 10, in the two oil wells mentioned above, compared with Comparative Example 3, the water shut-off agent in Example 1 of this application has a shelf life extended by more than 100 days and an increase in oil production of more than 150 tons, greatly improving oil production efficiency.

[0137] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," just as "comprising" is interpreted as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

Claims

1. A high-temperature resistant water-blocking agent, characterized in that, It comprises the following components in parts by weight: 100-110 parts sodium monolaurate phthalate, 45-55 parts polyoxyethylene sorbitan monooleate, 60-70 parts lignin surfactant, 65-75 parts α-olefin sulfonate and 330-380 parts oleic acid.

2. The water-blocking agent according to claim 1, characterized in that, The product comprises the following components in parts by weight: 105 parts sodium monolaurate phthalate, 50 parts polyoxyethylene sorbitan monooleate, 65 parts lignin surfactant, 68 parts α-olefin sulfonate and 370 parts oleic acid.

3. The method for preparing the water-blocking agent according to any one of claims 1 to 2, characterized in that, Includes the following steps: Sodium monolaurate phthalate and polyoxyethylene sorbitan monooleate were added to the reaction vessel and stirred evenly to obtain the first reaction solution. Add lignin surfactant to the first reaction solution and stir until homogeneous to obtain the second reaction solution; Add α-olefin sulfonate to the second reaction solution and stir until homogeneous to obtain the third reaction solution; Oleic acid was divided into two groups, and one group of oleic acid was added to the third reaction solution. The mixture was stirred until homogeneous to obtain the fourth reaction solution. Add another group of oleic acid to the fourth reaction solution, stir evenly, and let stand to obtain a water-blocking agent.

4. The preparation method according to claim 3, characterized in that, The step of adding sodium lauryl phthalate and polyoxyethylene sorbitan monooleate to a reaction vessel and stirring until homogeneous includes: The stirring temperature is 20-25℃ and the stirring time is 30-35 minutes.

5. The preparation method according to claim 3, characterized in that, The step of adding lignin surfactant to the first reaction solution and stirring until homogeneous includes: The stirring temperature is 20-25℃ and the stirring time is 20-25 min.

6. The preparation method according to claim 3, characterized in that, Before adding one group of the oleic acids to the third reaction solution, the method further includes: The third reaction solution is cooled to 20-25°C.

7. The application of the water-blocking agent according to any one of claims 1 to 2 in high-temperature oil reservoirs, characterized in that, include: The water-blocking agent is mixed with dehydrated crude oil to obtain a heavy oil water-blocking agent; The water-blocking agent has a weight content ranging from 2% to 3%, calculated as 100% of the weight of the dehydrated crude oil.

8. The application according to claim 7, characterized in that, The heavy oil water-blocking agent, wherein mixing the water-blocking agent with dehydrated crude oil to obtain the heavy oil water-blocking agent includes: The heavy oil water-blocking agent is injected into oil wells with a temperature range of 90–110°C.

9. The application according to claim 7, characterized in that, The process of injecting the heavy oil water-blocking agent into an oil well with a temperature range of 90–110°C includes: When the water cut of the oil well is 50-98%, the heavy oil water shut-off agent is injected into the oil well.

10. The application according to claim 7, characterized in that, The viscosity of the dehydrated crude oil at 45°C is 300–1000 mPa·s.

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