A profile control method for heavy oil wells

Abstract

The invention provides a profile control method for a heavy oil well, and relates to the technical field of oilfield profile control and water plugging. The A liquid of the profile control agent is a mixture of sodium bentonite, fly ash, a gel promoter and water, and the B liquid is a polyacrylamide aqueous solution. First, inject B liquid into the heavy oil well, and then inject A liquid and B liquid alternately in sequence to form a plurality of B liquid segment plugs and A liquid segment plugs arranged alternately; the amount of A liquid in each A liquid segment plug is 1 / 15 to 1 / 3 of the total amount of the profile control agent; the amount of B liquid in each B liquid segment plug is 1 / 10 to 2 / 3 of the amount of A liquid in each A liquid segment plug; after B liquid enters the formation, an organic film is formed, and the inorganic particles in the A liquid injected later are captured by the organic film to form an inorganic flocculent, and the B liquid that enters later forms another layer of organic film on the upper plugging layer, and the A liquid and the B liquid are injected alternately to finally form a cumulative membrane structure of inorganic membrane superimposed on organic membrane, and the membrane is resistant to pressure shock and high temperature for a long time, which prolongs the effective period of the measure and improves the oil recovery efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield profile control and water plugging, and in particular relates to a profile control method for a heavy oil well. Background Art

[0002] In the process of oil field development, efficient exploitation of heavy oil wells has always been a technical challenge. Heavy oil has the characteristics of high viscosity and low fluidity, and traditional exploitation technology is difficult to effectively improve the recovery rate of heavy oil. In order to overcome these challenges, profile control technology is widely used in the exploitation of heavy oil wells. Profile control technology injects profile control agents to block high permeability layers, change the fluid flow path, and allow more displacement fluid to enter the low permeability layer, thereby improving the recovery rate. However, existing profile control technologies and profile control agents have many limitations in practical applications and are difficult to meet the needs of efficient exploitation of heavy oil wells.

[0003] At present, the commonly used profile control methods in domestic oil fields mainly include physical profile control, chemical profile control and microbial profile control. Physical profile control materials are prone to blockage during the injection process, affecting the injection effect. Some physical profile control materials have poor stability in underground environments and short service life. In highly heterogeneous formations, physical profile control methods are not effective and have limited scope of application. Chemical profile control methods mostly use high-temperature resistant organic profile control agents and inorganic profile control agents for profile control. Organic profile control agents mainly include profile control systems such as phenolic resin, urea-formaldehyde resin, phenolic resin plus rubber particles or chrome gel polymer gel. The gelling conditions of organic profile control agents are harsh and are easily affected by the process flow, reservoir temperature and mineralization, resulting in poor gelling effect or even difficulty in gelling. In addition, the cost is high and the measures are complicated, resulting in a large-scale application of high-temperature resistant organic profile control systems. Inorganic profile control agents are represented by the double liquid method, namely the calcium chloride-water glass method. Due to the instability of the gel properties, they are easy to cause damage to reservoirs, screens and wellbores or even blockage. The effect of microbial profile control is easily affected by the formation environment, such as temperature, pH value, salinity, etc., resulting in unstable effects.

[0004] Therefore, it is particularly important to develop a profile control method with low damage, simple measures and processes, excellent and stable profile control effect. Summary of the invention

[0005] In view of the technical problems existing in the prior art, the present invention aims to provide a profile control method for a heavy oil well, the profile control method comprising:

[0006] S1 Reservoir analysis to obtain the total demand for profile control agents;

[0007] S2 injects water into the heavy oil well to clean the wellbore;

[0008] S3 injects profile control agent into the heavy oil well;

[0009] The profile control agent includes liquid A and liquid B, wherein the liquid A is a suspension formed by mixing sodium bentonite, fly ash, a gel promoter and water, and the liquid B is an aqueous solution of polyacrylamide;

[0010] First, inject liquid B into the heavy oil well, and then inject liquid A and liquid B alternately in sequence to form multiple liquid B slugs and liquid A slugs arranged alternately;

[0011] The injection amount of A liquid in each A liquid slug is 1 / 15~1 / 3 of the total required amount of profile control agent; the injection amount of B liquid in each B liquid slug is 1 / 10~2 / 3 of the injection amount of A liquid in each A liquid slug;

[0012] During the injection process, the injection pressure P is monitored in real time, and the injection of profile control agent is stopped when the pressure increase value △p is 1MPa~2MPa;

[0013] S4 finally injects water again to clean the wellbore and complete the profile adjustment.

[0014] Preferably, the injection amount of liquid A in each liquid A segment plug is 1 / 10 to 1 / 3 of the total required amount of profile control agent.

[0015] Preferably, the injection amount of B liquid in each B liquid segment plug is 1 / 3 to 2 / 3 of the injection amount of A liquid in each A liquid segment plug.

[0016] Preferably, step S4 of cleaning the wellbore includes forward washing and backwashing respectively; the sum of the forward washing water injection volume and the backwashing water injection volume is the same as the A liquid injection volume of each A liquid segment plug, and the water injection volume in step S2 is the same as the B liquid injection volume of each B liquid segment plug.

[0017] Preferably, the water injection speed in steps S2 and S4 is 5-15 m / s. 3 / h.

[0018] Preferably, the injection speed of liquid A and liquid B in step S3 is the same, both of which are 5-12 m / s. 3 / h.

[0019] Preferably, the liquid A comprises the following raw materials in parts by weight based on a total amount of 100 parts: 10-12 parts of sodium bentonite, 30-36 parts of fly ash, 0.10-0.40 parts of a gel promoter, and the balance is water.

[0020] Preferably, based on 100 parts of total volume of liquid B, the weight portion of polyacrylamide in liquid B is 0.25 to 0.35 parts, and the remainder is water;

[0021] The molecular weight of the polyacrylamide is ≥10 million, and the degree of hydrolysis is ≥20%. The polyacrylamide includes one or more of cationic polyacrylamide, anionic polyacrylamide or zwitterionic polyacrylamide.

[0022] Preferably, the water comprises tap water, industrial water or surface water;

[0023] Preferably, the preparation method of the liquid A and the liquid B comprises:

[0024] Add sodium bentonite and water, stir for 15-30 minutes, then add fly ash and gel promoter in sequence, continue stirring for 15-30 minutes, the stirring speed for both times is 550-660 rpm, to obtain liquid A;

[0025] Add polyacrylamide and water and dissolve to obtain solution B.

[0026] Beneficial effects of the present invention:

[0027] The present invention provides a profile control method for a heavy oil well, which uses a method of alternately injecting liquid A and liquid B to eventually form an alternatingly superimposed cumulative membrane structure of a layer of organic elastic membrane superimposed on a layer of inorganic rigid membrane and a layer of organic elastic membrane, that is, multiple layers of alternately arranged organic elastic membranes and inorganic rigid membranes are formed in sequence, thereby completing the accumulation, retention and even bridging of microcracks and loose macropores.

[0028] Liquid A is used as the plugging body, and the injection amount of each liquid A segment is 1 / 10~1 / 3 of the total required amount of profile control agent, so as to achieve multiple superposition of membrane layers and ensure the pressure shock tolerance and long-term high temperature resistance of the composite membrane. Liquid B is used as the spacer liquid, and the injection amount of each liquid B segment is 1 / 10~2 / 3 of the injection amount of each liquid A segment. While ensuring the integrity of the plugging layer, the condensation speed is controlled by adjusting the injection amount of liquid B, thereby controlling the stable pressure rise speed.

[0029] During the injection process, liquid B enters the formation first. The organic film formed by liquid B has strong hydrophilicity and can easily enter the hydrophilic microcracks or loose large pore inner walls that have been purged by steam. Due to adsorption, flocculants are retained on the inner wall of the oil layer. The inorganic particles in the subsequently injected liquid A are easily captured by the newly formed organic film with certain viscoelasticity, and inorganic flocs are formed through adsorption, bridging and coagulation, and retained on the inner wall of the pore. The liquid B that enters later forms another layer of organic elastic film on the inner surface of the inorganic film formed by the previous plug. With the alternating injection of liquid A and liquid B, the film layers accumulate, and finally a membrane structure with alternating superposition of rigid inorganic membranes and organic elastic membranes is formed, thereby realizing the functions of profile adjustment and channel blocking.

[0030] The presence of the organic elastic film improves the composite membrane's ability to withstand pressure shocks at the plugging site, while the presence of the inorganic rigid film improves the composite membrane's ability to withstand high temperature and high pressure for a long time. Therefore, the composite membrane structure achieves the comprehensive ability to withstand pressure shocks and long-term high temperatures, prolongs the effectiveness of the measures, and improves oil recovery efficiency. DETAILED DESCRIPTION

[0031] The present invention provides a profile control method for a heavy oil well, the profile control method comprising:

[0032] S1 Reservoir analysis to obtain the total demand for profile control agents;

[0033] S2 injects water into the heavy oil well to clean the wellbore;

[0034] S3 injects profile control agent into the heavy oil well;

[0035] The profile control agent includes liquid A and liquid B, wherein the liquid A is a suspension formed by mixing sodium bentonite, fly ash, a gel promoter and water, and the liquid B is an aqueous solution of polyacrylamide;

[0036] First, inject liquid B into the heavy oil well, and then inject liquid A and liquid B alternately in sequence to form multiple liquid B slugs and liquid A slugs arranged alternately;

[0037] The injection amount of A liquid in each A liquid slug is 1 / 15~1 / 3 of the total required amount of profile control agent; the injection amount of B liquid in each B liquid slug is 1 / 10~2 / 3 of the injection amount of A liquid in each A liquid slug;

[0038] During the injection process, the injection pressure P is monitored in real time, and the injection of profile control agent is stopped when the pressure increase value △p is 1MPa~2MPa;

[0039] S4 finally injects water again to clean the wellbore and complete the profile adjustment.

[0040] The present invention uses a method of alternately injecting liquid A and liquid B, so that a cumulative membrane structure of an organic elastic membrane superimposed on an inorganic rigid membrane and then an organic elastic membrane is finally formed, thereby completing the accumulation, retention and even bridging of microcracks and loose macropores.

[0041] During the injection process, liquid B enters the formation first, and forms an organic film with strong hydrophilicity. It is easy to enter the hydrophilic microcracks or the inner wall of the loose large pores that have been purged by steam. Due to the adsorption effect, flocculants are retained on the inner wall of the oil layer. The inorganic particles in the subsequently injected liquid A are easily captured by the newly formed organic film with a certain viscoelasticity, and inorganic floccules are formed through the adsorption, bridging and coagulation between hydrogen bonds and polar groups, and are retained on the inner wall of the pore. The liquid B that enters later forms another layer of organic elastic film on the inner surface of the inorganic film formed by the previous plug. What is finally formed is an alternating superimposed cumulative membrane structure with rigid inorganic membranes superimposed on organic elastic membranes, thereby realizing the functions of profile adjustment and channel blocking.

[0042] The presence of the organic elastic film improves the composite film's ability to withstand pressure shocks at the plugging site, while the presence of the inorganic rigid film improves the composite film's ability to withstand high temperature and high pressure for a long time. Therefore, the composite film structure achieves the comprehensive ability to withstand pressure shocks and long-term high temperatures, extending the effectiveness of the measure.

[0043] In the present invention, liquid A is used as the plugging body, and the injection amount of liquid A in each liquid A segment plug is 1 / 10 to 1 / 3 of the total required amount of the profile control agent, ensuring that the particle size of the independent particles of the formed inorganic floccules is small enough, the flocculation particles of the horizontally spread single-layer membrane are sufficient, and there are sufficient buffer zones between the small particle sizes. Multiple rounds of measures will form a continuous cumulative film layer with a buffer zone in the longitudinal direction, ensuring the pressure shock tolerance and long-term high temperature resistance of the composite membrane body. If the injection amount of liquid A in each liquid A segment plug is less than 1 / 15 of the total required amount of the profile control agent, although more cumulative film layers can be formed, too many cycles increase the difficulty of on-site implementation, making the operation difficult and difficult to achieve; if the injection amount of liquid A in each liquid A segment plug is greater than 1 / 3 of the total required amount of the profile control agent, the number of alternating injections of liquid A and liquid B is too small, the number of cumulative film layers formed is small, the pressure shock tolerance and long-term high temperature resistance of the composite membrane body are insufficient, and it is difficult to meet the profile control requirements. The injection amount of liquid A in each liquid A slug is, for example, 1 / 15, 1 / 14, 1 / 13, 1 / 12, 1 / 11, 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4 or 1 / 3 of the total required amount of the profile control agent.

[0044] In the present invention, liquid B is used as a spacer fluid, and the injection amount of liquid B in each liquid B segment plug is 1 / 10 to 2 / 3 of the injection amount of liquid A in each liquid A segment plug. When the injection amount of liquid B in each liquid B segment plug is less than 1 / 10, the plugging layer solidifies faster, causing the pressure to rise faster, exceeding the bearing capacity of the wellbore, causing the wellbore to rupture, triggering formation cracks, causing the profile control fluid and the oil-water mixture to leak to non-target areas, and also causing the profile control fluid to be not evenly distributed in the target area, affecting the profile control effect. When the injection amount of liquid B in each liquid B segment plug is higher than 2 / 3, the plugging layer solidifies slower, resulting in low injection efficiency, uneven dispersion of the profile control agent during the injection process, and difficulty in forming a complete and stable plugging layer. The lower pressure is not enough to push the profile control agent deep into the reservoir, especially in high permeability channels and large pores, making it difficult to achieve deep plugging. The injection amount of B liquid in each B liquid slug is, for example, 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2 or 2 / 3 of the injection amount of A liquid in each A liquid slug.

[0045] In the present invention, the pressure increase value Δp is, for example, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, or 2.0 MPa.

[0046] In a preferred embodiment of the present invention, the injection amount of liquid A in each liquid A slug is 1 / 10 to 1 / 3 of the total required amount of the profile control agent.

[0047] In the present invention, the total demand is designed as 1.0 times of the mined volume, the mined volume is represented by PV, and the total demand is 1.0PV.

[0048] In a preferred embodiment of the present invention, the injection amount of B liquid in each B liquid slug is 1 / 3 to 2 / 3 of the injection amount of A liquid in each A liquid slug.

[0049] In a preferred embodiment of the present invention, the water washing in step S4 includes forward washing and backwashing respectively, and the sum of the forward washing water injection amount and the backwashing water injection amount is the same as the A liquid injection amount of each A liquid slug;

[0050] The water injection amount in step S2 is the same as the amount of liquid B injected into each liquid B segment plug.

[0051] In the present invention, the water injection amount in step S2 is, for example, 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2 or 2 / 3 of the A liquid injection amount of each A liquid segment plug; the sum of the forward wash water injection amount and the backwash water injection amount in step S4 is, for example, 1 / 15, 1 / 14, 1 / 13, 1 / 12, 1 / 11, 1 / 10, 1 / 9, 1 / 8, 1 / 7, 1 / 6, 1 / 5, 1 / 4 or 1 / 3 of the total required amount of the profile control agent.

[0052] In a preferred embodiment of the present invention, the injection speed of water in steps S2 and S4 is 5-15 m / s. 3 / h.

[0053] In the present invention, the water injection speed is, for example, 5 m 3 / h、6m 3 / h、7m 3 / h、8m 3 / h、9m 3 / h、10m 3 / h、11m 3 / h、12m 3 / h、13m 3 / h、14m 3 / h or 15m 3 / h.

[0054] In a preferred embodiment of the present invention, the injection speed of liquid A and liquid B in step S3 is the same, both of which are 5-12 m / s. 3 / h.

[0055] In the present invention, if the injection speed of liquid A and liquid B is higher than 12m 3 / h, the pressure rises too fast and is difficult to control, and it is easy to cause well-to-well connection or surface leakage after the pressure rises too fast. 3 / h, the required pressure cannot be reached, affecting the injection depth and coverage of the profile control agent. At the same time, the profile control agent stays in the wellbore for too long, which is prone to blockage. The injection speed of liquid A and liquid B during the profile control process is, for example, 5m 3 / h、6m 3 / h、7m 3 / h、8m 3 / h、9m 3 / h、10m 3 / h、11m 3 / h or 12m 3 / h.

[0056] In a preferred embodiment of the present invention, the liquid A comprises the following raw materials in parts by weight based on a total amount of 100 parts: 10-12 parts of sodium bentonite, 30-36 parts of fly ash, 0.10-0.40 parts of a gel promoter, and the balance is water.

[0057] In the present invention, sodium bentonite will significantly swell after absorbing water to form a gel-like structure, and its good suspension performance enables the particles in the profile control agent to be evenly distributed and not easy to settle, thereby ensuring the uniformity of the profile control effect.

[0058] The weight of sodium bentonite is, for example, 10.0 parts, 10.2 parts, 10.4 parts, 10.6 parts, 10.8 parts, 11.0 parts, 11.2 parts, 11.4 parts, 11.6 parts, 11.8 parts or 12.0 parts.

[0059] Fly ash has a fine particle structure, which can fill the pores in the formation, enhance the plugging effect of the profile control agent, improve the mechanical strength of the profile control agent, keep it stable under high pressure environment, and prevent it from being washed away by fluid. The weight of fly ash is, for example, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts or 36 parts.

[0060] The gel promoter promotes colloid formation, improves rheological properties and increases temperature and salt resistance. The weight of the gel promoter is, for example, 0.10 parts, 0.15 parts, 0.20 parts, 0.25 parts, 0.30 parts, 0.35 parts or 0.40 parts.

[0061] In the present invention, the sodium bentonite is industrial grade sodium bentonite, preferably sodium bentonite for drilling, with a particle size of 5um≥98%.

[0062] In the present invention, the fly ash is industrial fly ash and is not lower than the secondary standard of industrial fly ash, with a particle size of 45um≥70%, and first-grade fly ash is preferred.

[0063] In the present invention, the gelling agent is, for example, NaOH, Na2SO4, Na2CO3, NaOH and Na2SO4, Na2SO4 and Na2CO3, NaOH and Na2CO3, or a combination of NaOH, Na2SO4 and Na2CO3.

[0064] Preferably, the gel promoter comprises NaOH.

[0065] In a preferred embodiment of the present invention, based on 100 parts of the total amount of liquid B, the weight portion of polyacrylamide in liquid B is 0.25-0.35 parts, and the balance is water;

[0066] The molecular weight of the polyacrylamide is ≥10 million, and the degree of hydrolysis is ≥20%. The polyacrylamide includes one or more of cationic polyacrylamide, anionic polyacrylamide or zwitterionic polyacrylamide.

[0067] In the present invention, the weight of polyacrylamide is, for example, 0.25 parts, 0.26 parts, 0.27 parts, 0.28 parts, 0.29 parts, 0.30 parts, 0.31 parts, 0.32 parts, 0.33 parts, 0.34 parts or 0.35 parts.

[0068] The polyacrylamide is, for example, cationic polyacrylamide, anionic polyacrylamide, zwitterionic polyacrylamide, cationic polyacrylamide and anionic polyacrylamide, anionic polyacrylamide and zwitterionic polyacrylamide, or a combination of cationic polyacrylamide, anionic polyacrylamide and zwitterionic polyacrylamide.

[0069] Preferably, the polyacrylamide comprises cationic polyacrylamide.

[0070] In a preferred embodiment of the present invention, the water includes tap water, industrial water or surface water.

[0071] In the present invention, the water is, for example, tap water, industrial water, surface water, tap water and industrial water, industrial water and surface water, or a combination of tap water, industrial water and surface water.

[0072] Preferably, the water comprises tap water.

[0073] In a preferred embodiment of the present invention, the preparation method of liquid A and liquid B comprises:

[0074] Add sodium bentonite and water, stir for 15-30 minutes, then add fly ash and gel promoter in sequence, continue stirring for 15-30 minutes, the stirring speed for both times is 550-660 rpm, to obtain liquid A;

[0075] Add polyacrylamide and water and dissolve to obtain solution B.

[0076] In the present invention, the rotating speed is, for example, 550 rpm, 560 rpm, 570 rpm, 580 rpm, 590 rpm, 600 rpm, 610 rpm, 620 rpm, 630 rpm, 640 rpm, 650 rpm or 660 rpm. The stirring time is, for example, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes or 30 minutes.

[0077] Example 1

[0078] A single core was used for plugging test and scour resistance evaluation. The core diameter was 1.98 cm and the length was 49 cm. The core was saturated with water to simulate formation water, and the core pore volume was measured to be 1PV.

[0079] Experimental steps: 1. Inject tap water into the core, measure the initial fluid flow rate of 1PV / h=17.34ml / h, the pressure of 1.10MPa, and record the core permeability K before plugging W1 =2185.25mD.

[0080] 2. Prepare profile control agent A and B

[0081] Liquid A is a suspension formed by mixing 11 parts of sodium bentonite, 33 parts of fly ash and 0.3 parts of a gel promoter with 55.7 parts of water, and liquid B is an aqueous solution formed by mixing 0.3 parts of polyacrylamide with 99.7 parts of water.

[0082] 3. Injection of profile control agent

[0083] First, inject liquid B, then inject liquid A and liquid B alternately into the core, and the total injection volume of liquid A and liquid B is 1PV. The injection volume of liquid A in each liquid A segment is 1 / 15PV; the injection volume of liquid B in each liquid B segment is 1 / 2 of the injection volume of liquid A in each liquid A segment, that is, 1 / 30PV;

[0084] 4. Place the core injected with liquid A and liquid B in a constant temperature oven at 80°C for 27 hours of solidification and then age for 72 hours;

[0085] 5. Inject tap water from the inlet of the core tube at a constant rate of 0.5 mL / min until breakthrough. Record the breakthrough pressure, calculate the breakthrough pressure gradient (ratio of breakthrough pressure to core length); measure the core permeability K after plugging W2 ; Calculate the core plugging rate. The core plugging rate is shown in the formula:

[0086] Blockage rate =

[0087] Where: KW1 —Core permeability before plugging, mD;

[0088] K W2 —Core permeability after plugging, mD;

[0089] Breakthrough pressure gradient = breakthrough pressure / core length.

[0090] Among them, the breakthrough pressure can characterize the plugging effect and the strength of the plugging agent: the higher the breakthrough pressure, the better the plugging effect formed by the profile control agent in the core. A higher breakthrough pressure means that a greater force is required to break through the plugging layer, which shows that the profile control agent effectively blocks the passage of fluid in the core. A high breakthrough pressure also means that the plugging agent is strong and can form a solid plugging layer in the core.

[0091] The breakthrough pressure gradient can characterize the plugging uniformity and scour resistance: if the gradient is high, it means that the plugging agent has formed a relatively uniform plugging layer in the core. A higher breakthrough pressure gradient indicates that the profile control agent has a stronger scour resistance because a high pressure difference is maintained in a certain length of the core. This means that the profile control agent can effectively maintain its plugging performance during the scour process.

[0092] Example 2

[0093] The injection volume of liquid A in each liquid A slug is 1 / 10PV; the injection volume of liquid B in each liquid B slug is 1 / 2 of the injection volume of liquid A in each liquid A slug, i.e., 1 / 20PV;

[0094] The remaining steps and parameters are the same as those in implementation 1.

[0095] Example 3

[0096] The injection volume of liquid A in each liquid A slug is 1 / 6PV, and the injection volume of liquid B in each liquid B slug is 1 / 2 of the injection volume of liquid A in each liquid A slug, i.e., 1 / 12PV;

[0097] The remaining steps and parameters are the same as those in implementation 1.

[0098] Example 4

[0099] The injection volume of liquid A in each liquid A slug is 1 / 3PV, and the injection volume of liquid B in each liquid B slug is 1 / 2 of the injection volume of liquid A in each liquid A slug, i.e., 1 / 6PV;

[0100] The remaining steps and parameters are the same as those in implementation 1.

[0101] Example 5

[0102] The injection volume of liquid A in each liquid A slug is 1 / 6PV, and the injection volume of liquid B in each liquid B slug is 2 / 3 of the injection volume of liquid A in each liquid A slug, i.e., 1 / 9PV;

[0103] Example 6

[0104] The injection volume of liquid A in each liquid A slug is 1 / 6PV, and the injection volume of liquid B in each liquid B slug is 1 / 3 of the injection volume of liquid A in each liquid A slug, i.e., 1 / 18PV;

[0105] The remaining steps and parameters are the same as those in implementation 1.

[0106] Example 7

[0107] The injection volume of liquid A in each liquid A slug is 1 / 6PV, and the injection volume of liquid B in each liquid B slug is 1 / 10 of the injection volume of liquid A in each liquid A slug, i.e., 1 / 60PV;

[0108] The remaining steps and parameters are the same as those in implementation 1.

[0109] Example 8

[0110] The experimental well in Xinjiang Oilfield was used as the injection well. The average daily liquid production of the experimental well 1 was 5.5m³, the water content was 92.15%, and the average daily oil production was 0.43t.

[0111] S1 Reservoir analysis, the total demand for profile control agent 1PV is obtained;

[0112] S2 injects 1 / 12PV of water into the heavy oil well to clean the wellbore, and the water flow rate is 5m 3 / h;

[0113] S3 injection profile control agent

[0114] The profile control agent is divided into liquid A and liquid B. Liquid A is a suspension formed by mixing 11 parts of sodium bentonite, 33 parts of fly ash, 0.3 parts of a gel promoter and 55.7 parts of water. Liquid B is an aqueous solution formed by mixing 0.30 parts of polyacrylamide and 99.7 parts of water.

[0115] First, inject liquid B into the heavy oil well, and then inject liquid A and liquid B alternately in sequence to form multiple alternating liquid B slugs and liquid A slugs; the injection speed of liquid A and liquid B is 8m / s. 3 / h.

[0116] The injection amount of A liquid in each A liquid slug is 1 / 6 of the total required amount of profile control agent, that is, 1 / 6PV; the injection amount of B liquid in each B liquid slug is 1 / 2 of the injection amount of A liquid in each A liquid slug, that is, 1 / 12PV;

[0117] During the injection process, the injection pressure P is monitored in real time, and the injection is stopped when the pressure increase value △p reaches 2MPa;

[0118] S4 finally injects 1 / 12PV water to wash the wellbore forward, and then injects 1 / 12PV water to backwash the wellbore. The forward and backwash water flow rate is 15m 3 / h complete profile adjustment.

[0119] By using the profile control method provided in this embodiment, after the profile control is completed, the average daily liquid production of the oil well is 7.6m³, the water content is 72.55%, and the average daily oil production is 2.09t.

[0120] Comparative Example 1

[0121] Prepare a solution A which is a mixture of 11 parts of sodium bentonite, 33 parts of fly ash, 0.3 parts of a gel promoter and 55.7 parts of water, and inject 1 PV of the solution A into the core.

[0122] The remaining steps and parameters are the same as those in implementation 1.

[0123] Comparative Example 2

[0124] Prepare liquid A, which is a mixture of 11 parts of sodium bentonite, 33 parts of fly ash, 0.3 parts of a gel promoter and 55.7 parts of water, and liquid B, which is a mixture of 0.3 parts of polyacrylamide and 99.7 parts of water. Mix them evenly in a mass ratio of 1:1 between liquid A and liquid B, and take 1PV to inject into the core.

[0125] The remaining steps and parameters are the same as those in implementation 1.

[0126] Comparative Example 3

[0127] The injection volume of each A-liquid plug injected into the core is 1 / 2PV, and the injection volume of each B-liquid plug is 1 / 2 of the injection volume of each A-liquid plug, that is, 1 / 4PV;

[0128] The remaining steps and parameters are the same as those in implementation 1.

[0129] Comparative Example 4

[0130] The injection volume of each A-liquid plug injected into the core is 1 / 20PV, and the injection volume of each B-liquid plug is 1 / 2 of the injection volume of each A-liquid plug, that is, 1 / 40PV;

[0131] The remaining steps and parameters are the same as those in implementation 1.

[0132] Comparative Example 5

[0133] The injection volume of each A-liquid plug injected into the core is 1 / 6PV, and the injection volume of each B-liquid plug is 1 / 15 of the injection volume of each A-liquid plug, that is, 1 / 90PV;

[0134] The remaining steps and parameters are the same as those in implementation 1.

[0135] Comparative Example 6

[0136] The injection volume of each A-liquid plug injected into the core is 1 / 6PV, and the injection volume of each B-liquid plug is 4 / 5 of the injection volume of each A-liquid plug, that is, 2 / 15PV;

[0137] The remaining steps and parameters are the same as those in implementation 1.

[0138] The performance tests of Examples 1 to 7 and Comparative Examples 1 to 6 are shown in Table 1:

[0139] Table 1 Performance tests of Examples 1 to 7 and Comparative Examples 1 to 6

[0140]

Claims

1. A profile control method for a heavy oil well, characterized in that: The profile adjustment method comprises: S1 Reservoir analysis to obtain the total demand for profile control agents; S2 injects water into the heavy oil well to clean the wellbore; S3 injects profile control agent into the heavy oil well; The profile control agent includes liquid A and liquid B, wherein the liquid A is a suspension formed by mixing sodium bentonite, fly ash, a gel promoter and water, and the liquid B is an aqueous solution of polyacrylamide; First, inject liquid B into the heavy oil well, and then inject liquid A and liquid B alternately in sequence to form multiple liquid B slugs and liquid A slugs arranged alternately; The injection amount of A liquid in each A liquid slug is 1 / 15~1 / 3 of the total required amount of profile control agent; the injection amount of B liquid in each B liquid slug is 1 / 10~2 / 3 of the injection amount of A liquid in each A liquid slug; During the injection process, the injection pressure P is monitored in real time, and the injection of profile control agent is stopped when the pressure increase value △p is 1MPa~2MPa; S4 finally injects water again to clean the wellbore and complete the profile adjustment; Among them, the water injection amount in step S2 is the same as the B liquid injection amount of each B liquid segment plug; the wellbore cleaning described in step S4 includes forward washing and backwashing, and the sum of the water injection amount of forward washing and the water injection amount of backwashing is the same as the A liquid injection amount of each A liquid segment plug.

2. The profile control method according to claim 1, characterized in that: The injection amount of A liquid in each A liquid segment plug is 1 / 10~1 / 3 of the total required amount of profile control agent.

3. The profile control method according to claim 1, characterized in that: The amount of liquid B injected into each liquid B segment plug is 1 / 3 to 2 / 3 of the amount of liquid A injected into the liquid A segment plug.

4. The profile control method according to claim 1, characterized in that: The water injection speed in steps S2 and S4 is 5-15 m 3 / h.

5. The profile control method according to claim 1, characterized in that: In step S3, the injection speed of liquid A and liquid B is the same, both of which are 5~12m 3 / h.

6. The profile control method according to claim 1, characterized in that: The liquid A is calculated based on a total amount of 100 parts, and the liquid A includes the following raw materials in parts by weight: 10-12 parts of sodium bentonite, 30-36 parts of fly ash, 0.10-0.40 parts of a gel promoter, and the balance is water.

7. The profile control method according to claim 1, characterized in that: Based on 100 parts of total volume of liquid B, the weight portion of polyacrylamide in liquid B is 0.25-0.35 parts, and the balance is water; The molecular weight of the polyacrylamide is ≥10 million, and the degree of hydrolysis is ≥20%. The polyacrylamide includes one or more of cationic polyacrylamide, anionic polyacrylamide or zwitterionic polyacrylamide.

8. The profile control method according to claim 1, characterized in that: The water includes tap water, industrial water or surface water.

9. The profile control method according to claim 1, characterized in that: The preparation method of the liquid A and the liquid B comprises: Add sodium bentonite and water, stir for 15-30 minutes, then add fly ash and gel promoter in sequence, continue stirring for 15-30 minutes, the stirring speed for both times is 550-660 rpm, to obtain liquid A; Add polyacrylamide and water and dissolve to obtain solution B.

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