Profile control agent and its application

Abstract

The application relates to a profile control agent and application thereof, raw material components including a first plugging agent, a thickening agent, a crosslinking agent and a heat stabilizer, and further including a cellulose ether and a second plugging agent; wherein the raw material components of the second plugging agent include lignocellulose, starch and resin, and the second plugging agent has a different particle size from the first plugging agent. The application solves the technical problem that existing profile control agents are difficult to carry solid-phase particles to the deep part of an oil layer.

Description

Technical Field

[0001] The present application relates to the field of oil production technology, and in particular to a profile control agent and its application. Background Art

[0002] As steam drive enters the middle and late stages of development, affected by factors such as reservoir heterogeneity, formation dip, sedimentary phase, steam overlap, and the inability to dynamically adjust the injection process, steam breaks through the main layer, forming a dominant channel between the injection and production wells, causing serious steam channeling in the production wells, manifested as high temperature, high liquid, and high water content. The injected steam circulates inefficiently and ineffectively, while the steam production in non-main layers and non-main directions is poor.

[0003] At present, polyacrylamide gel profile control agents have difficulty carrying solid particles to deep oil layers for plugging, and cannot meet the requirements of long-radius deep plugging in steam drive. Steam easily bypasses, resulting in poor profile control and oil production increase effects and a short effective period. Summary of the Invention

[0004] The present application provides a profile control agent and its application to solve the technical problem that existing profile control agents are difficult to carry solid phase particles to deep oil layers.

[0005] In a first aspect, the present application provides a profile control agent, the raw material components of which include a first plugging agent, a thickener, a cross-linking agent, and a thermal stabilizer, characterized in that the raw material components also include cellulose ether and a second plugging agent; wherein,

[0006] The raw material components of the second plugging agent include lignin fiber, starch and resin.

[0007] The second blocking agent has a different particle size from the first blocking agent.

[0008] Optionally, the cellulose ether includes one of the following: hydroxypropyl cellulose ether, hydroxyethyl cellulose ether, and hydroxybutyl cellulose ether.

[0009] Optionally, the resin includes one of the following: modified furfural resin, polyurethane.

[0010] Optionally, the particle size of the second plugging agent is 1.5 mm to 3 mm.

[0011] Optionally, the weight ratio of the lignin fiber, the starch and the resin is (55-65):(15-25):(15-25).

[0012] Optionally, the particle size of the first plugging agent is 0.2 mm to 2 mm.

[0013] Optionally, the content of the cellulose ether is 1.0% to 1.5% by mass.

[0014] Optionally, the content of the second plugging agent is 2% to 3% by mass.

[0015] Optionally, in terms of mass fraction, the content of the first blocking agent is 6% to 8%, the content of the thickener is 0.2% to 0.3%, the content of the cross-linking agent is 0.2% to 0.3%, and the content of the heat stabilizer is 0.1% to 0.15%.

[0016] In a second aspect, the present application provides an application of the profile control agent described in any embodiment of the first aspect in steam flooding production.

[0017] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0018] The profile control agent provided in the embodiment of the present application comprises cellulose ether which undergoes polymerization reaction with a thickener, a cross-linking agent and a thermal stabilizer in the formation to form a gelling system. The gelling system has the advantages of good temperature resistance, adjustable gelling time and high plugging strength.

[0019] Among the raw materials of the second plugging agent, lignin fiber enhances its sealing strength, starch acts as a binder, bonding the lignin fibers together, and resin coating the bonded lignin fibers improves their heat resistance. Through the synergistic effect of lignin fiber, starch, and resin, the second plugging agent possesses both high sealing strength and high heat resistance. The second plugging agent has a different particle size from the first plugging agent, achieving deep, high-strength plugging of large pores and high permeability in steam-driven formations, improving the steam absorption profile of the reservoir. Therefore, by introducing cellulose ether and the second plugging agent into the raw materials of the profile control agent, the technical problem of existing profile control agents' difficulty in carrying solid particles deep into the reservoir is resolved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] Figure 1 This is an apparent diagram of a second plugging agent provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0024] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0025] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0027] In a first aspect, the present application provides a profile control agent, the raw material components of which include a first plugging agent, a thickener, a cross-linking agent, and a thermal stabilizer, characterized in that the raw material components also include cellulose ether and a second plugging agent; wherein,

[0028] The raw material components of the second plugging agent include lignin fiber, starch and resin.

[0029] The second blocking agent has a different particle size from the first blocking agent.

[0030] In the embodiment of the present application, cellulose ether undergoes polymerization reaction with thickener, cross-linking agent and thermal stabilizer in the formation to form a gelling system, which has the advantages of good temperature resistance, adjustable gelling time and high plugging strength; among the raw material components of the second plugging agent, lignin fiber improves the plugging strength of the second plugging agent, starch has a bonding effect, bonding the lignin fibers together, and resin is coated on the surface of the bonded lignin fibers to improve the temperature resistance of the second plugging agent. Through the synergistic effect of lignin fiber, starch and resin, the second plugging agent has both high plugging strength and high temperature resistance; the second plugging agent has a different particle size from the first plugging agent, achieving deep and high-strength plugging of large pores and high permeability in steam-driven formations, and improving the steam absorption profile of the oil layer. Among them, the second plugging agent prevents particles from entering the deep formation, improving the plugging strength of the near-wellbore area. For the appearance diagram of the second plugging agent, please refer to Figure 1 , which are white particles; the first plugging agent realizes deep plugging of the formation.

[0031] In addition, the first plugging agent is used to improve the strength of the gelling system and the heat resistance of the profile control agent, achieving deep stratum plugging. Specifically, the first plugging agent can be plant fiber or rubber powder; the raw materials of the plant fiber can include bark powder, rubber powder, and rice husk powder. The thickener is used to increase the initial viscosity of the gelling system to prevent the solid phase particles in the profile control system from settling in the wellbore or near-wellbore area. Specifically, the thickener can be polyacrylamide, polyvinyl alcohol, or polyethylene oxide. Furthermore, polyacrylamide with a molecular weight of 18 million to 23 million and a degree of hydrolysis of 20% to 25% is preferred. The crosslinker is used to react with other raw material components to form a steam-driven deep profile control agent. Specifically, the crosslinker can be a phenolic resin or an organic chromium crosslinker. The phenolic resin can be an oil-soluble phenolic resin or a water-soluble phenolic resin, preferably a water-soluble phenolic resin. The heat stabilizer is used to improve the temperature resistance of the gelling system. Specifically, the heat stabilizer can be a silane coupling agent, thiourea, or sodium sulfite.

[0032] The raw material component of the profile control agent further includes water, which includes at least one of the following: clean water, shallow water, and oilfield produced wastewater. Preferably, the water can be oilfield produced wastewater.

[0033] In some embodiments, the cellulose ether includes one of the following: hydroxypropyl cellulose ether, hydroxyethyl cellulose ether, and hydroxybutyl cellulose ether.

[0034] In the examples of this application, hydroxypropyl cellulose ether, hydroxyethyl cellulose ether, and hydroxybutyl cellulose ether are selected as cellulose ethers to effectively improve the temperature resistance of the gel-forming system. Preferably, the cellulose ether can be hydroxypropyl cellulose ether, with a molecular weight of 80,000 to 120,000, while ensuring the initial viscosity of the profile control agent and the strength of the gel.

[0035] In some embodiments, the resin includes one of the following: modified furfural resin, polyurethane.

[0036] In the examples of the present application, modified furfural resin and polyurethane are selected as the resin to improve the temperature resistance of the second plugging agent to above 260° C. Considering the cost, polyurethane is preferred.

[0037] In some embodiments, the particle size of the second plugging agent is 1.5 mm to 3 mm.

[0038] In the embodiments of the present application, the particle size of the second plugging agent is controlled to improve the plugging strength in the near-wellbore zone. If the particle size of the second plugging agent is too high, it may cause the perforation holes to become blocked to a certain extent; if the particle size of the second plugging agent is too low, it may affect the plugging strength in the near-wellbore zone to a certain extent. Specifically, the particle size of the second plugging agent can be 1.5 mm, 1.7 mm, 1.9 mm, 2.1 mm, 2.3 mm, 2.5 mm, 2.7 mm, 2.9 mm, 3.0 mm, etc.

[0039] In some embodiments, the weight ratio of the lignin fiber, the starch, and the resin is (55-65):(15-25):(15-25).

[0040] In the embodiments of the present application, the ratio of lignin fiber, starch, and resin is controlled to ensure the wrapping effect of the lignin fiber and the strength of the second plugging agent. If the lignin fiber content is too high, the integrity of the particles will be reduced to a certain extent. If the lignin fiber content is too low, the strength of the second plugging agent will be reduced to a certain extent. If the starch content is too high, the particle strength will be reduced to a certain extent. If the starch content is too low, the adhesion to the lignin fiber will be deteriorated to a certain extent. If the resin content is too high, the cost will be increased to a certain extent. If the resin content is too low, the wrapping of the lignin fiber will be reduced to a certain extent, which is not conducive to forming an effective plugging wall. Specifically, the weight ratio of lignin fiber, starch, and resin can be 55:25:20, 60:20:20, 65:15:20, 60:25:15, etc.

[0041] In some embodiments, the particle size of the first plugging agent is 0.2 mm to 2 mm.

[0042] In the embodiments of the present application, the particle size of the first plugging agent is controlled to achieve deep-seated plugging. If the particle size of the first plugging agent is too large, it may not penetrate deep into the formation to a certain extent. If the particle size of the first plugging agent is too small, it may not achieve a plugging effect to a certain extent. Specifically, the particle size of the first plugging agent can be 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, etc.

[0043] In some embodiments, the content of the cellulose ether is 1.0% to 1.5% by mass.

[0044] In the embodiments of the present application, an appropriate amount of cellulose ether is used to achieve the desired gel strength. If the cellulose ether content is too high, the gelation time will be shortened and the cost will increase. If the cellulose ether content is too low, the gel strength will be reduced. Specifically, the cellulose ether content can be 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, etc.

[0045] In some embodiments, the content of the second plugging agent is 2% to 3% by mass.

[0046] In the embodiments of this application, an appropriate amount of the second plugging agent ensures long-term, effective plugging of the near-wellbore zone. If the second plugging agent content is too high, it may cause formation blockage to a certain extent, making injection difficult. If the second plugging agent content is too low, the plugging strength of the near-wellbore zone may be affected to a certain extent. Specifically, the second plugging agent content can be 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, etc.

[0047] In some embodiments, by mass fraction, the content of the first blocking agent is 6% to 8%, the content of the thickener is 0.2% to 0.3%, the content of the cross-linking agent is 0.2% to 0.3%, and the content of the thermal stabilizer is 0.1% to 0.15%.

[0048] In the embodiment of the present application, an appropriate amount of the first plugging agent is used to ensure effective plugging deep in the stratum; an appropriate amount of the thickener is used to control the initial viscosity of the gel; an appropriate amount of the cross-linking agent is used to control the gelling strength of the gel; and an appropriate amount of the thermal stabilizer is used to improve the temperature resistance of the gel system. Specifically, the content of the first plugging agent can be 6%, 6.2%, 6.4%, 6.6%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, 8%, etc., the content of the thickener can be 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, etc., the content of the cross-linking agent can be 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, etc., and the content of the thermal stabilizer can be 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, etc.

[0049] The preparation method of the above-mentioned profile control agent comprises: adding weighed thickener, crosslinking agent, thermal stabilizer and cellulose ether to sewage, stirring for 20 minutes to obtain a mixture; adding a first plugging agent and a second plugging agent to the above-mentioned mixture, stirring for 25 minutes to obtain the profile control agent.

[0050] In a second aspect, the present application provides an application of the profile control agent described in any embodiment of the first aspect in steam flooding production.

[0051] The profile control agent provided in the embodiments of the present application has at least the following beneficial effects:

[0052] (1) The profile control agent has good temperature resistance, which can reach above 300°C, meeting the long-term high-temperature plugging requirements of steam flooding;

[0053] (2) The profile control agent has a gelling temperature of 70°C to 120°C and a gelling time of 12 to 48 hours. The gelling time is long and adjustable, and the shear resistance is strong, which meets the requirements of long-term injection and long-distance migration of steam flooding profile control agents and can achieve deep formation plugging.

[0054] (3) The profile control agent has a high plugging rate and strong plugging strength, meeting the long-term high-temperature scouring requirements of steam flooding;

[0055] (4) The profile control agent has a significant oil production increase effect when used in steam injection well profile control construction. During the construction operation, the deep profile control agent has a high plugging strength and can effectively plug large pores and high permeability layers in the near-well area for a long time, with a significant production increase effect.

[0056] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0057] Table 1 Raw material components of profile control agent, the balance is oilfield produced wastewater

[0058]

[0059] The preparation method of the profile control agent provided in Examples 1 to 3 is as follows: adding weighed thickener, crosslinker, thermal stabilizer and cellulose ether to sewage, stirring for 20 minutes to obtain a mixture; adding the first plugging agent and the second plugging agent to the above mixture, stirring for 25 minutes to obtain the profile control agent.

[0060] Example 1

[0061] The profile control agent provided in Example 1 was tested in terms of initial viscosity, thermal stability and high-temperature plugging performance.

[0062] 1. Initial viscosity of profile control agent

[0063] The viscosity of the profile control agent was measured using a Brookfield viscometer. The results showed that the viscosity of the newly prepared profile control agent was 168.2 mPa.s at room temperature (22°C) and 142.3 mPa.s at 50°C.

[0064] The above test results show that the profile control agent has a low initial viscosity, good pumpability, and is easy to enter deep formations. The viscosity will further decrease under high temperature conditions of the formation. Therefore, the profile control agent prepared in Example 1 has good injectability and is suitable for deep profile control operations in steam flooding.

[0065] 2. Thermal stability of profile control agent

[0066] The prepared profile control agent was placed in a 280°C oven for a long period of time, and the gel strength was measured regularly. The viscosity of the profile control agent was above 37.6 Pa.s after 15 days of aging, above 33.2 Pa.s after 30 days, and above 31.8 Pa.s after 60 days.

[0067] The above test results show that the viscosity of the profile control agent tends to decrease gradually with time, but the reduction rate gradually decreases and tends to be stable. It has strong plugging ability and can meet the requirement of steam flooding for a profile control agent viscosity higher than 20 Pa.s.

[0068] 3. Plugging performance test of profile control agent

[0069] The equipment used in the experiment includes: quartz sand (median particle size 0.15-0.30 mm), sand filling tube (Φ25 mm × 500 mm), horizontal flow pump, pressure gauge, electronic balance, and profile control agent.

[0070] The experimental method involved evacuating the sandfill tube, saturating it with water, measuring porosity and pore volume, and then measuring water permeability after water flooding until the pressure stabilized. A profile control agent was injected at a rate of 20 mL / h, and injection was stopped once the agent filled the core. After setting at 300°C for 72 hours, clean water was injected at the same rate of 20 mL / h until the core broke through, and the breakthrough pressure was measured. The test results are shown in Table 1.

[0071] Table 1 Plugging performance test results of profile control agent

[0072] Core number Original permeability (mD) Permeability after plugging (mD) Blockage rate (%) <![CDATA[突破压力(Mpa.m -1 )]]> 1 1986 158 91.5 11.2 2 1597 114 92.8 12.3 3 1164 79 93.2 13.6

[0073] As can be seen from Table 1, the profile control agent prepared in Example 1 can achieve a plugging rate of more than 90% under high temperature conditions of 300°C, and a plugging strength of more than 11.2 MPa / m, indicating that the profile control agent has the characteristics of high temperature resistance and high plugging strength, and has a good plugging effect on high permeability layers.

[0074] Example 2

[0075] The profile control agent provided in Example 2 was tested in terms of initial viscosity, thermal stability and high-temperature plugging performance.

[0076] 1. Initial viscosity of profile control agent

[0077] The viscosity of the profile control agent was measured using a Brookfield viscometer. The results showed that the viscosity of the newly prepared profile control agent was 243.6 mPa.s at room temperature (22°C) and 224.3 mPa.s at 50°C.

[0078] The above test results show that the profile control agent has a low initial viscosity, good pumpability, and is easy to enter deep formations. The viscosity will further decrease under high temperature conditions of the formation. Therefore, the profile control agent prepared in Example 2 has good injectability and is suitable for deep steam flooding profile control operations.

[0079] 2. Thermal stability of profile control agent

[0080] The prepared profile control agent was placed in a 280°C oven for a long period of time, and the gel strength was measured regularly. The viscosity of the profile control agent was above 45.2 Pa.s after 15 days of aging, above 41.3 Pa.s after 30 days, and above 38.6 Pa.s after 60 days.

[0081] The above test results show that the viscosity of the profile control agent tends to decrease gradually with time, but the reduction rate gradually decreases and tends to be stable. It has a strong plugging ability and can meet the requirement of steam flooding for a profile control agent viscosity higher than 20 Pa.s.

[0082] 3. Plugging performance test of profile control agent

[0083] The equipment used in the experiment includes: quartz sand (median particle size 0.15-0.30 mm), sand filling tube (Φ25 mm × 500 mm), horizontal flow pump, pressure gauge, electronic balance, and profile control agent.

[0084] The experimental method involved evacuating the sandfill tube, saturating it with water, measuring porosity and pore volume, and then measuring water permeability after water flooding until the pressure stabilized. A profile control agent was injected at a rate of 20 mL / h, and injection was stopped once the agent filled the core. After setting at 300°C for 72 hours, clean water was injected at the same rate of 20 mL / h until the core broke through, and the breakthrough pressure was measured. The test results are shown in Table 2.

[0085] Table 2 Plugging performance test results of profile control agent

[0086] Core number <![CDATA[原始渗透率(μm 2 )]]> <![CDATA[堵后渗透率(μm 2 )]]> Blockage rate (%) <![CDATA[突破压力(Mpa.m -1 )]]> 1 5218 461 91.2 13.1 2 4973 391 92.1 14.2 3 3129 263 91.6 13.8

[0087] As can be seen from Table 2, the profile control agent prepared in Example 2 can achieve a plugging rate of more than 90% under high temperature conditions of 300°C, and a plugging strength of more than 13.1 MPa / m, indicating that the profile control agent has the characteristics of high temperature resistance and high plugging strength, and has a good plugging effect on high permeability layers.

[0088] Example 3

[0089] The profile control agent provided in Example 3 was tested in terms of initial viscosity, thermal stability and high-temperature plugging performance.

[0090] 1. Initial viscosity of profile control agent

[0091] The viscosity of the profile control agent was measured using a Brookfield viscometer. The results showed that the viscosity of the newly prepared profile control agent was 183.2 mPa.s at room temperature (22°C) and 210.6 mPa.s at 50°C.

[0092] The above test results show that the profile control agent has a low initial viscosity, good pumpability, and is easy to enter deep formations. The viscosity will further decrease under high temperature conditions of the formation. Therefore, the profile control agent prepared in Example 3 has good injectability and is suitable for deep profile control operations in steam flooding.

[0093] 2. Thermal stability of profile control agent

[0094] The prepared profile control agent was placed in a 280°C oven for a long period of time, and the gel strength was measured regularly. The viscosity of the profile control agent was above 43.1 Pa.s after 15 days of aging, above 40.5 Pa.s after 30 days, and above 39.8 Pa.s after 60 days.

[0095] The above test results show that the viscosity of the profile control agent tends to decrease gradually with time, but the reduction rate gradually decreases and tends to be stable. It has a strong plugging ability and can meet the requirement of steam flooding for a profile control agent viscosity higher than 20 Pa.s.

[0096] 3. Plugging performance test of profile control agent

[0097] The equipment used in the experiment includes: quartz sand (median particle size 0.15-0.30 mm), sand filling tube (Φ25 mm × 500 mm), horizontal flow pump, pressure gauge, electronic balance, and profile control agent.

[0098] The experimental method involved evacuating the sandfill tube, saturating it with water, measuring porosity and pore volume, and then measuring water permeability after water flooding until the pressure stabilized. A profile control agent was injected at a rate of 20 mL / h, and injection was stopped once the agent filled the core. After setting at 300°C for 72 hours, clean water was injected at the same rate of 20 mL / h until the core broke through, and the breakthrough pressure was measured. The test results are shown in Table 3.

[0099] Table 3 Plugging performance test results of profile control agent

[0100] Core number Original permeability (μm 2 ) <![CDATA[堵后渗透率(μm 2 )]]> Blockage rate (%) <![CDATA[突破压力(Mpa.m -1 )]]> 1 4538 354 92.2 12.9 2 4762 372 92.2 13.5 3 3312 281 91.5 14.1

[0101] As can be seen from Table 3, the profile control agent prepared in Example 3 can achieve a plugging rate of more than 90% under high temperature conditions of 300°C, and a plugging strength of more than 12.9 MPa / m, indicating that the profile control agent has the characteristics of high temperature resistance and high plugging strength, and has a good plugging effect on high permeability layers.

[0102] Comparative Example 1

[0103] Table 4 Raw material components of existing profile control agents, the remainder is oilfield produced wastewater

[0104]

[0105] The profile control agent provided in Comparative Example 1 was tested in terms of initial viscosity, thermal stability and high-temperature plugging performance.

[0106] 1. Initial viscosity of profile control agent

[0107] The viscosity of the profile control agent was measured using a Brookfield viscometer. The results showed that the viscosity of the newly prepared profile control agent was 262.3 mPa.s at room temperature (22°C) and 231.2 mPa.s at 50°C.

[0108] The above test results show that the profile control agent has low initial viscosity, good pumpability, easy to enter the deep formation, and the viscosity will further decrease under the high temperature environment of the formation, so the profile control agent prepared by Comparative Example 1 has good injectability.

[0109] 2. Thermal stability of the profile control agent

[0110] The prepared profile control agent was placed in a 200℃ oven for a long time, and the gel strength was measured regularly. After aging for 5 days, the viscosity of the profile control agent was 3.1 Pa.s or more, after 10 days, the viscosity of the profile control agent was 4.5 mPa.s or more, and after 20 days, the viscosity of the profile control agent was 3.8 mPa.s or more.

[0111] The above test results show that the viscosity of the profile control agent decreases significantly with time, and does not have long-term high-temperature resistance, which cannot meet the requirements of steam flooding on the viscosity of the profile control agent.

[0112] 3. Test of the plugging performance of the profile control agent

[0113] The experimental apparatus used in the experiment includes: quartz sand (particle size medium 0.15-0.30 mm), sand filling pipe (Φ25 mm x 500 mm), horizontal flow pump, pressure gauge, electronic balance, and profile control agent.

[0114] The experimental method is as follows: the sand filling pipe is vacuumed, saturated with water, and the porosity and pore volume are measured, and then the water phase permeability is measured after water flooding to a stable pressure; the profile control agent is injected at an injection rate of 20 mL / h, and the injection is stopped after the profile control agent fills the core; the profile control agent is allowed to set for 72 h at 200℃, and then clean water is injected at an injection rate of 20 mL / h until the core is broken through, and the breakthrough pressure is measured. The test results are shown in Table 4.

[0115] Table 4. Test results of the plugging performance of the profile control agent

[0116] Core number Original permeability (μm 2 ) <![CDATA[堵后渗透率(μm 2 )]]> Blockage rate (%) <![CDATA[突破压力(Mpa.m -1 )]]> 1 4220 368 91.2 10.5 2 4160 391 90.6 10.1 3 3855 347 90.1 11.3

[0117] As can be seen from Table 4, the profile control agent prepared by Comparative Example 1 has a plugging rate of more than 90% and a plugging strength of more than 10.1 MPa / m under the high temperature condition of 200℃, which shows that the profile control agent has good plugging effect on high permeability layers in the short term, but the gel body cannot resist high temperature of more than 280℃ for a long time, and can only be temporarily plugged, which cannot meet the long-term plugging requirements of steam injection wells.

[0118] Application of the profile control agent provided by the embodiments of the present application in steam flooding

[0119] The above-mentioned profile control agent was used in the profile control of the Qi-40 steam injection well. The A25 well group transitioned to steam flooding in December 2007, with steam injection in two layers, each 23.5 m thick and comprising 16 sub-layers. After long-term steam injection, vertical steam absorption became severely uneven, leading to a gradual decline in production performance for the corresponding oil wells. Oil production in the well group dropped from a peak of 67.5 tons to 21.8 tons. The combined water content of the well group reached 88.4%, and the average temperature of the output fluid from the production wells was 75.6°C. Two production wells required water addition to maintain normal production. To adjust the steam absorption profile of the steam injection wells and suppress high-temperature steam channeling in the production wells, the profile control agent prepared in Example 2 was used.

[0120] The specific construction process is as follows: Use the ground mixing tank to prepare the profile control agent, use the cement truck to mix the 600m 3 Profile control agent is injected into the formation at a low rate through the steam injection string, displacing 60m 3 The oil field produced wastewater and the well was blocked for 48 hours.

[0121] After the measures were taken, the steam injection pressure increased from 4.5MPa to 6.2MPa, an increase of 1.7MPa. 30 days later, the temperature monitoring of the observation wells showed that the temperature of the main layer dropped by 36°C, the temperature of the non-main layer increased by 22°C, and the wellhead temperature of the production well dropped by 9.3°C. The steam channeling layer was effectively blocked, and the vertical production degree was significantly improved. The average daily oil production of the well group increased from 21.8t to 36.6t, the daily liquid production decreased by 20.8t, and the comprehensive water cut decreased by 10.3 percentage points. The measures were effective for 261d, and the cumulative oil production was 1,698t.

[0122] It can be seen from the above performance evaluation and field examples that the profile control agent provided in the examples of the present application has good injectability, good temperature resistance, high plugging strength, high plugging rate under high temperature conditions, and obvious oil-increasing effect in the profile control construction of steam injection wells in steam drive, and can be used in the profile control of steam injection wells in steam drive oil reservoirs.

[0123] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A profile control agent, the raw material components of which include a first plugging agent, a thickener, a cross-linking agent and a thermal stabilizer, characterized in that: The raw material components also include cellulose ether and a second plugging agent; wherein, The raw material components of the second plugging agent include lignin fiber, starch and resin. The second plugging agent and the first plugging agent have different particle sizes; The cellulose ether includes one of the following: hydroxypropyl cellulose ether, hydroxyethyl cellulose ether, hydroxybutyl cellulose ether; The resin is a modified furfural resin; The particle size of the second plugging agent is 1.5 mm to 3 mm; The weight ratio of the lignin fiber, the starch and the resin is (55-65):(15-25):(15-25).

2. The profile control agent according to claim 1, characterized in that The particle size of the first plugging agent is 0.2 mm to 2 mm.

3. The profile control agent according to claim 1, characterized in that Calculated by mass fraction, the content of the cellulose ether is 1.0% to 1.5%.

4. The profile control agent according to claim 1, characterized in that Calculated by mass fraction, the content of the second plugging agent is 2% to 3%.

5. The profile control agent according to claim 1, 3 or 4, characterized in that: In terms of mass fraction, the content of the first blocking agent is 6% to 8%, the content of the thickener is 0.2% to 0.3%, the content of the cross-linking agent is 0.2% to 0.3%, and the content of the heat stabilizer is 0.1% to 0.15%.

6. Use of the profile control agent according to any one of claims 1 to 4 in steam flooding production.

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