Keratinoin composite foam plugging agent and preparation method, injection method and application thereof

Abstract

The invention belongs to the technical field of thickened oil recovery, and relates to a keratin composite foam plugging agent as well as a preparation method, an injection method and application thereof. The keratin composite foam plugging agent provided by the invention comprises keratin, a foam stabilizer, a foaming agent and water. The keratin composite foam plugging agent can form plugging structural bodies with different scales to establish a multi-dimensional plugging structure, the keratin composite foam can fully play the advantages of plugging near wellbore zones by a flexible long-chain keratin system and plugging far wells by a flexible short-chain keratin system, and has the advantages of far plugging and near regulation; meanwhile, the raw material cost is low, the usage amount is small, the operation period is short, and good economic benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy oil exploitation and relates to a keratin composite foam plugging agent and a preparation method, an injection method and an application thereof. Background Art

[0002] Heavy oil resources are widely distributed in the world and have huge reserves. At present, thermal production methods mainly based on steam stimulation, steam flooding, oil layer combustion, SAGD, etc. have gradually been formed, among which steam stimulation and steam flooding are the most widely used. In the process of high-temperature steam injection, due to the strong heterogeneity of the stratigraphic structure and reservoir of heavy oil reservoirs, the large difference in the steam and heavy oil vapor mobility ratio and steam overlay, the steam absorption profile of the oil-producing layer is uneven, and the phenomena of steam channeling and fingering between wells are serious, which reduces the sweep coefficient and affects the heavy oil production effect. Therefore, it is necessary to seal the near-well area and the far-well area to improve the recovery rate of heavy oil reservoirs.

[0003] At present, there are many types of plugging agent systems used in heavy oil thermal recovery wells. According to their mechanism of action, they can be roughly divided into: high temperature resistant polymer gel, solid phase particles, foam, emulsified heavy oil and salt precipitation. Foam plugging agent is a hot profile adjustment method. The foam enters the high permeability pores and adheres to the rock surface or deforms at the throat deformation to produce the Jamin effect, thereby adjusting the steam absorption profile. In the plugging technology of heavy oil production, conventional foam systems (such as Figure 2 ) The plugging time is short, the foam is unstable, the plugging distance is short and it is impossible to enter the deep formation for plugging and adjustment. At the same time, the amount of enhanced foam used is large, the requirements for offshore implementation resources are high, the operation time is long, and the operation cost is high. Summary of the invention

[0004] The purpose of the present invention is to provide a keratin composite foam plugging agent and a preparation method, injection method and application thereof in view of the defects of the prior art.

[0005] Specifically, the keratin composite foam regulating and plugging agent provided by the present invention comprises: keratin, a foam stabilizer, a foaming agent, and water.

[0006] The keratin composite foam plugging agent comprises, by weight percentage, 0.30% to 1.5% keratin, 0.2% to 0.4% foam stabilizer, 0.3% to 0.5% foaming agent, and the balance is water.

[0007] The keratin composite foam plugging agent comprises, by weight percentage, 0.50% to 1.0% keratin, 0.2% to 0.4% foam stabilizer, 0.3% to 0.5% foaming agent, and the balance is water.

[0008] The keratin composite foam plugging agent mentioned above, the keratin is natural hair of specific size.

[0009] The keratin composite foam plugging agent mentioned above, the keratin is a short-chain keratin with a length of less than 2 mm and / or a medium-long chain keratin with a length of more than 2 mm.

[0010] The above-mentioned keratin composite foam regulating and plugging agent, the foam stabilizer is trimethylolpropane; the foaming agent is sodium dodecylbenzene sulfonate and / or sodium fatty alcohol polyoxyethylene ether sulfate.

[0011] On the other hand, the present invention provides a method for preparing a keratin composite foam plugging agent, comprising:

[0012] (1) crushing natural hair to obtain keratin;

[0013] (2) adding keratin and a foaming agent into water and stirring;

[0014] (3) Add a foam stabilizer and stir to obtain a keratin protein composite foam plugging agent.

[0015] In the preparation method of the keratin composite foam plugging agent, the stirring speed in step (2) and step (3) is 1000-3000 r / min, and the stirring time is 30-60 min.

[0016] In another aspect, the present invention further provides a method for injecting a keratin composite foam plugging agent, comprising:

[0017] (1) injecting a first keratin composite foam plugging agent to form a stable composite foam; wherein the length of keratin in the first keratin composite foam plugging agent is less than 2 mm;

[0018] (2) injecting a second keratin composite foam plugging agent to form a stable composite foam; wherein the length of keratin in the second keratin composite foam plugging agent is ≥ 2 mm;

[0019] (3) Inject the displacement fluid and repeat steps (1) and (2) according to the on-site injection situation.

[0020] In the above-mentioned method for injecting keratin composite foam plugging agent, the injection amount of the first keratin composite foam plugging agent is 0.01PV; the injection amount of the second keratin composite foam plugging agent is 0.01PV.

[0021] In another aspect, the present invention also provides a use of a keratin composite foam plugging agent in heavy oil thermal recovery.

[0022] In another aspect, the present invention further provides a method for evaluating the plugging performance of a keratin composite foam plugging agent, characterized in that it comprises:

[0023] (1) Dry the core to saturate the formation water, inject simulated water at 2-4 ml / min, and record the pressure difference P1 after the pressure stabilizes;

[0024] (2) Inject keratin composite foam plugging agent and record the pressure P2 after the pressure stabilizes;

[0025] (3) Subsequent water injection: after the pressure stabilizes, record the pressure P3 and calculate the resistance coefficient FR and the residual resistance coefficient FRR; wherein, the resistance coefficient FR = P2 / P1, and the residual resistance coefficient FRR = P3 / P1.

[0026] The technical solution of the present invention has the following beneficial effects:

[0027] (1) The keratin composite foam plugging agent of the present invention has a main agent of a pure natural structure, does not cause reservoir damage, is degradable, and is suitable for well group displacement;

[0028] (2) The keratin composite foam plugging agent of the present invention has good plugging performance, is resistant to high temperatures, and has a simple system formation and low cost. By utilizing the characteristics of keratin of different lengths, it can well achieve plugging between wells.

[0029] (3) The keratin composite foam plugging agent of the present invention can form a plugging structure of different sizes to establish a multi-dimensional plugging structure. The keratin composite foam can give full play to the advantages of the flexible long-chain keratin system to plug the near-well area and the flexible short-chain long-chain keratin system to plug the far-well area, and has the advantages of far plugging and near adjustment. At the same time, the raw material cost is low, the usage amount is small, the operation cycle is short, and it has excellent economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiment.The drawings are only for the purpose of illustrating the preferred embodiments and are not to be construed as limiting the invention.

[0031] Figure 1 It is a schematic diagram of the structure of the keratin composite foam plugging agent of the present invention;

[0032] Figure 2 This is a schematic diagram of the structure of a conventional foam plugging agent;

[0033] Figure 3 It is a schematic diagram of the structure of the long-chain and short-chain keratin composite foam injected by the present invention for plugging near and far wells. DETAILED DESCRIPTION

[0034] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific embodiments. Except for the following contents, the process method of the present invention adopts conventional methods or devices in the art. Unless otherwise specified, the following terms have the meanings commonly understood by those skilled in the art.

[0035] The terms "first", "second", etc. used in the present invention do not indicate any order or importance, but are used to distinguish one element from another. The terms "said", "one", and "an" do not indicate a limitation on quantity, but indicate the presence of at least one of the objects mentioned. The terms "preferred", "more preferred", etc. refer to embodiments of the present invention that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. In addition, the description of one or more embodiments does not imply that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present invention.

[0036] When a numerical range is disclosed in the present invention, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed in the present invention should be understood to include any and all subranges included therein.

[0037] A keratin composite foam regulating and plugging agent comprises keratin, a foam stabilizer, a foaming agent and water.

[0038] The mechanism of action of the keratin composite foam plugging agent of the present invention is: keratin is used as the main agent, a foaming agent and a foam stabilizer are used as diverting agents, and the protein long chain extension and winding ability is utilized. The longer the chain, the easier it is to bend and wind (such as Figure 1 ), which is easier to form a firm mixed system with the foam system, thereby increasing the resistance coefficient. Experiments show that the liquid separation half-life of the plugging agent is greatly increased by 1.25 times, compared with conventional foam plugging agents (such as Figure 2 ), the plugging agent of the present invention is more likely to form an effective plugging in the crossflow channel.

[0039] The functions and contents of the various components in the keratin composite foam plugging agent of the present invention are introduced in detail below.

[0040] Keratin

[0041] Keratin is used to improve the stability of foam blocking agents, playing a role similar to that of nanomaterials. Compared with conventional foam systems, due to the toughness and flexibility of keratin itself, the aggregation of foam is further increased during the foam generation and collapse process, improving the strength of the foam. In addition, due to the aggregation of keratin, it is interconnected under the action of foam to form a more stable network structure, improving the stability of the foam.

[0042] Preferably, the keratin protein used in the present invention is prepared from natural hair as a raw material, and has excellent water dispersibility, viscosity increasing and temperature resistance. The natural hair is, for example, human hair or animal hair.

[0043] More preferably, the keratin protein of the present invention may also be a polypeptide chain obtained by hydrolysis of keratin protein.

[0044] The present invention uses a shearing device to process natural hair into a desired size. Combined with the injectability of the reservoir, the keratin can be divided into short-chain keratin (length <2 mm) and medium-long chain keratin (length ≥2 mm). According to the requirements of the profile control process, long-chain keratin can be used in the near-well zone, and short-chain keratin can be used in the far-well zone. In the present invention, long-chain keratin is used as the object.

[0045] In the keratin composite foam plugging technology, a multi-dimensional plugging structure is established through plugging structures of different scales. The special structure of keratin, combined with its extension and winding ability, makes the length of the keratin chain an influencing factor for measuring the characteristics of the long-chain keratin system. Specifically, the longer the keratin chain, the easier it is to bend and entangle, and it is easier for it to form a firm mixed system with the foam system, thereby increasing the resistance coefficient; the shorter the chain, the less likely it is to bend and entangle, and its permeability is better, and it is easier to be transported to the far end in the porous medium.

[0046] The length of the keratin in the plugging agent of the present invention is optimized according to the pore size of the porous medium of the reservoir.

[0047] Preferably, the content of keratin in the keratin composite foam plugging agent of the present invention is 0.3% to 1.5% by weight.

[0048] Among them, when the content of keratin is lower than 0.3%, it cannot play a better role in enhancing the stability of foam; when the content of keratin is higher than 1.5%, it is easy to clog the pores.

[0049] More preferably, the content of keratin in the keratin composite foam plugging agent of the present invention is 0.5% to 1.0%.

[0050] Foaming agent

[0051] The foaming agent is a surfactant that mainly reduces the interfacial tension at the air-water interface, prompting the air to form small bubbles in the slurry, expanding the separation interface, and ensuring that the bubbles rise to form a foam layer.

[0052] The foaming agent used in the present invention is an anionic surfactant or an anionic nonionic surfactant, which is a kind of high-temperature foaming agent.

[0053] Preferably, the anionic surfactant includes: sodium dodecylbenzene sulfonate.

[0054] Preferably, the anionic nonionic surfactant includes: sodium fatty alcohol polyoxyethylene ether sulfate.

[0055] Preferably, the content of the foaming agent in the keratin composite foam plugging agent of the present invention is 0.3% to 0.5% by weight.

[0056] When the content of the foaming agent is lower than 0.3%, the foaming effect is not obvious; when the content of the foaming agent is higher than 0.5%, the foaming effect does not change much.

[0057] Foam stabilizer

[0058] Foam stabilizers are chemical agents that have the ability to prolong and stabilize foam for a long time.

[0059] The foam stabilizer used in the present invention is trimethylolpropane, which is a kind of high-temperature foam stabilizer.

[0060] Preferably, the content of the foam stabilizer in the keratin composite foam regulating and blocking agent of the present invention is 0.2% to 0.4% by weight.

[0061] When the content of the foam stabilizer is lower than 0.2%, the foam stabilizing effect is poor; when the content of the foam stabilizer is higher than 0.4%, the foam stabilizing effect is no longer significantly enhanced.

[0062] On the other hand, the present invention provides a method for preparing a keratin composite foam plugging agent, comprising:

[0063] (1) crushing natural hair to obtain keratin of appropriate length;

[0064] (2) Weighing each component according to the weight ratio;

[0065] (3) adding keratin and foaming agent into water and stirring;

[0066] (3) Add a foam stabilizer and stir to obtain a keratin protein composite foam plugging agent.

[0067] Preferably, the stirring speed in step (2) and step (3) is 1000-3000 r / min, and the stirring time is 30-60 min.

[0068] Further preferably, the keratin composite foam plugging agent of the present invention is prepared on-site before being injected into the well group.

[0069] The preparation method of the keratin composite foam plugging agent of the present invention has the advantages of simple operation and low production cost.

[0070] On the other hand, Figure 3 As shown, the present invention provides a method for injecting a keratin composite foam plugging agent, comprising:

[0071] (1) injecting a first keratin composite foam plugging agent to form a stable composite foam at the distal end; wherein the length of keratin in the first keratin composite foam plugging agent is less than 2 mm;

[0072] (2) injecting a second keratin composite foam plugging agent to form a stable composite foam at the middle or proximal end; wherein the length of keratin in the second keratin composite foam plugging agent is ≥ 2 mm;

[0073] (3) Inject the displacement fluid and repeat steps (1) and (2) according to the on-site injection situation.

[0074] Preferably, the injection amount of the first keratin composite foam plugging agent is 0.01 PV, and the injection amount of the second keratin composite foam plugging agent is 0.01 PV.

[0075] The displacement fluid is a substance commonly used in the art, and the present invention does not make any specific limitation thereto.

[0076] Research has found that the longer the keratin chain is, the easier it is to bend and entangle, and it is easier to form a firm mixed system with the foam system, thereby increasing the resistance coefficient; the shorter the chain is, the less likely it is to bend and entangle, the better the permeability, and the easier it is to be transported to the far end in the porous medium. The present invention uses the characteristics of long-chain and short-chain keratin proteins, and uses plugging structures of different sizes to establish a multi-dimensional plugging structure, thereby achieving plugging in the near and far well zones.

[0077] In another aspect, the present invention provides use of the keratin composite foam plugging agent in heavy oil thermal recovery.

[0078] Through practice, the keratin composite foam plugging agent of the present invention can effectively improve the plugging and sweep coefficient in heavy oil thermal recovery.

[0079] In another aspect, the present invention provides a method for evaluating the plugging performance of a keratin composite foam plugging agent, comprising:

[0080] (1) Dry the core to saturate the formation water, simulate water at 2-4 ml / min, wait for the pressure to stabilize, and record the water displacement pressure difference P1;

[0081] (2) Inject keratin composite foam plugging agent and record the pressure P2 after the pressure stabilizes;

[0082] (3) Subsequent water injection: after the pressure stabilizes, record the pressure P3 and calculate the resistance coefficient FR and the residual resistance coefficient FRR; wherein, the resistance coefficient FR = P2 / P1, and the residual resistance coefficient FRR = P3 / P1.

[0083] The larger the resistance coefficient and residual resistance coefficient, the better the plugging effect.

[0084] Example

[0085] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions. The raw materials used in the following examples are all conventionally purchased.

[0086] Example 1

[0087] The composition of the keratin composite foam plugging agent is: 0.3% of human hair with a length of ≥2mm; 0.4% of trimethylolpropane, a foam stabilizer; 0.5% of sodium dodecylbenzene sulfonate, a foaming agent; the balance is water; and the sum of the mass percentages of the raw materials is 100%.

[0088] The preparation method of keratin composite foam plugging agent is as follows:

[0089] 3g of human hair with a length of ≥2mm (customized shearing equipment is used for large amounts) is added to 988.2g of water, and then 5g of sodium dodecylbenzene sulfonate, a foaming agent, is added and stirred at room temperature at a high speed of 3000r / min for 10min to obtain a uniformly dispersed foam system. 4g of trimethylolpropane, a foam stabilizer, is added to the foam system at a speed of 1000r / min, and after stirring and dispersing at room temperature for 10min, a keratin composite foam system is obtained.

[0090] Comparative Example 1

[0091] The conventional foam system comprises the following raw materials in percentage by weight: 0.5% by weight of sodium dodecylbenzene sulfonate as a foaming agent; 0.4% by weight of trimethylolpropane as a foam stabilizer; and the balance is water. The sum of the percentages by weight of each raw material is 100%.

[0092] The conventional foam system preparation method is as follows: 5g of the same foaming agent sodium dodecylbenzene sulfonate is stirred at a high speed of 3000r / min at room temperature for 10min to obtain a uniformly dispersed foam system. 4g of the foam stabilizer trimethylolpropane is added to the foam system at a speed of 1000r / min, and the foam system is obtained after being stirred and dispersed at room temperature for 10min.

[0093] Performance Testing

[0094] Research objects: the foam system prepared in Example 1 and Comparative Example 1 and the conventional foam system.

[0095] Table 1 Foam properties in Example 1 and Comparative Example 1

[0096]

[0097]

[0098] By comparing the foam parameters in Example 1 and Comparative Example 1, it is found that compared with the foam system in Comparative Example 1 without adding keratin, the half-life of the liquid separation of the foam system in Example 1 is greatly increased by 1.4 times after adding keratin, indicating that keratin can cause foam molecules to aggregate and form a complex network structure, thereby increasing the mechanical strength of the foam liquid film, thereby significantly improving the stability of high-temperature foam. Therefore, the keratin composite foam plugging agent provided by the present invention can improve the high-temperature stability and high-temperature flooding and plugging ability of the foam system, and has a good application prospect for improving the high-temperature foam flooding effect.

[0099] On-site construction

[0100] The keratin composite foam plugging agent of the present invention is used for flooding construction, and the segment plug is designed as follows: in the first stage, a foaming agent sodium dodecylbenzene sulfonate with a concentration of 0.8% (taking adsorption loss into consideration), a foam stabilizer trimethylolpropane and 0.5% short-chain keratin (less than 2 mm in length) are injected; in the second stage, a foaming agent (sodium dodecylbenzene sulfonate) with a concentration of 0.5% and 0.5% long-chain keratin (greater than or equal to 2 mm in length) are injected.

[0101]

[0102] (1) Normal steam injection, steam injection rate 11.7t / h, according to normal records, record the steam injection pressure every 1h;

[0103] (2) The nitrogen injection port is switched from the casing wing valve to the steam injection manifold, and the nitrogen equipment is started with an injection speed of 380-400 m / s. 3 / h, when the nitrogen purity reaches 99.9%, open the valve connected to the steam main manifold to mix with the steam and inject it into the well from the oil pipe. Inject nitrogen for 2 hours first, record the nitrogen injection pressure every hour, and observe the effect of nitrogen injection on steam injection pressure, oil pressure and casing pressure;

[0104] (3) Add high-temperature foaming agent concentrate and keratin to the reagent tank, set the reagent pump displacement to a concentration of 0.8-1% after mixing with steam. Open the reagent steam injection manifold valve to achieve the mixing of reagent and steam, and inject it into the well together with steam and nitrogen from the oil pipe. Record the reagent injection speed, injection pump pressure and other parameters every hour, and observe the effect of foam injection on steam injection pressure, oil pressure and casing pressure.

[0105] Economic Analysis

[0106]

[0107] Through analysis and comparison, under the same benefits, the method of the present invention can save 56.9% of the cost input compared with the conventional method, and has good economy.

[0108] The present invention has been disclosed above with preferred embodiments, but those skilled in the art should understand that these embodiments are only used to describe the present invention and should not be understood as limiting the scope of the present invention. It should be noted that all changes and substitutions equivalent to these embodiments should be deemed to be included in the scope of the claims of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined in the claims.

Claims

1. A keratin composite foam plugging agent, characterized in that: include: Keratin, foam stabilizer, foaming agent, water.

2. The keratin composite foam plugging agent according to claim 1, characterized in that: Calculated by weight percentage, the composition comprises: 0.30% to 1.5% keratin, 0.2% to 0.4% foam stabilizer, 0.3% to 0.5% foaming agent, and the balance is water.

3. The keratin composite foam plugging agent according to claim 2, characterized in that: Calculated by weight percentage, the composition comprises: 0.50% to 1.0% keratin, 0.2% to 0.4% foam stabilizer, 0.3% to 0.5% foaming agent, and the balance is water.

4. The keratin composite foam plugging agent according to claim 1, characterized in that: The keratin is natural hair of a specific size.

5. The keratin composite foam plugging agent according to claim 4, characterized in that: The keratin protein is a short-chain keratin protein with a length of less than 2 mm and / or a medium-chain keratin protein with a length of more than 2 mm.

6. The keratin composite foam plugging agent according to claim 1, characterized in that: The foam stabilizer is trimethylolpropane; the foaming agent is sodium dodecylbenzene sulfonate and / or sodium fatty alcohol polyoxyethylene ether sulfate.

7. The method for preparing the keratin composite foam plugging agent according to any one of claims 1 to 6, characterized in that: include: (1) crushing natural hair to obtain keratin; (2) adding keratin and a foaming agent into water and stirring; (3) Add a foam stabilizer and stir to obtain a keratin protein composite foam plugging agent.

8. The method for preparing the keratin composite foam plugging agent according to claim 7, characterized in that: The stirring speed in step (2) and step (3) is 1000-3000 r / min, and the stirring time is 30-60 min.

9. The method for injecting the keratin composite foam plugging agent according to any one of claims 1 to 6, characterized in that: include: (1) injecting a first keratin composite foam plugging agent to form a stable composite foam; wherein the length of keratin in the first keratin composite foam plugging agent is less than 2 mm; (2) injecting a second keratin composite foam plugging agent to form a stable composite foam; wherein the length of keratin in the second keratin composite foam plugging agent is ≥ 2 mm; (3) Inject the displacement fluid and repeat steps (1) and (2) according to the on-site injection situation.

10. The method for injecting the keratin composite foam plugging agent according to claim 9, characterized in that: The injection amount of the first keratin composite foam plugging agent is 0.01 PV; the injection amount of the second keratin composite foam plugging agent is 0.01 PV.

11. Use of the keratin composite foam plugging agent according to any one of claims 1 to 6 in thermal recovery of heavy oil.

12. The method for evaluating the blocking performance of the keratin composite foam blocking agent according to any one of claims 1 to 6, characterized in that: include: (1) Dry the core to saturate the formation water, inject simulated water at 2-4 ml / min, and record the pressure difference P1 after the pressure stabilizes; (2) Inject keratin composite foam plugging agent and record the pressure P2 after the pressure stabilizes; (3) Subsequent water injection: after the pressure stabilizes, record the pressure P3 and calculate the resistance coefficient FR and the residual resistance coefficient FRR; wherein, the resistance coefficient FR = P2 / P1, and the residual resistance coefficient FRR = P3 / P1.

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