Hydrate inhibitor dosage simulator

Abstract

The invention discloses a hydrate inhibitor dosage simulator. The invention belongs to the technical field of hydrate blockage prevention. The method uses a hydinhibitorcal.xlsx simulator, and comprises the following steps: (1) collecting production data; (2) collecting hydrate test data; (3) determining pressure and temperature distribution of production facilities; (4) determining a suppression temperature according to the production system and the safety margin; (5) according to the field data, using an experimental data fitting formula and an empirical formula to calculate a hydrate forming condition; (6) determining a hydrate formation position and an inhibitor dosage according to pressure and temperature distribution of production facilities and hydrate formation conditions; and (7) determining an inhibitor injection process according to the calculated inhibitor dosage. According to the method and the simulator, the hydrate formation condition prediction precision can be obviously improved, and the inhibition cost is reduced under the condition of ensuring production safety.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrate blockage prevention. Background Art

[0002] Under certain pressure and temperature conditions, oil and gas reservoir fluids react with water to form solid crystals, thereby blocking oil and gas production facilities and causing production stoppage accidents. Production stoppage not only delays oil and gas production, but also generates high processing costs. Therefore, prevention and treatment measures for hydrate blockage must be considered during oil and gas reservoir fluid production. At present, the industry adopts the addition of chemical inhibitors [Yousif, OTC8234, 1996], or pressure reduction, or insulation, or heating, or dehydration, or downhole throttling, or a combination of the above methods to prevent hydrate blockage. Methanol or ethylene glycol is a hydrate control method commonly used in the industry. Using experimental equipment to study the conditions for fluid hydrate formation is the basis for preventing hydrate blockage [Chen Weidong et al., JNOC, 1998; Chemical Engineering, Vol. 58, No. 21, 2007]. When there is no measured data, it is necessary to use correlation formulas or models to predict the conditions for hydrate formation.

[0003] On May 28, 2024, the patent application CN118088129A "A system and method for filling and dispensing inhibitors for hydrates" was published. The patent describes the information perception module, the collaborative calculation module, and the dispensing control module. The inhibitor dosage calculation module uses the Ponomarev (abbreviated as bo method) empirical formula to calculate the natural gas hydrate formation conditions and the Hammerschmidt empirical formula to calculate the inhibitor dosage. However, the present invention uses experimental data fitting formulas and empirical formulas to accurately predict hydrate formation conditions and inhibitor dosage, thereby avoiding the incorrect or excessive addition of inhibitors and ensuring safe production while reducing the cost of inhibition. Summary of the invention

[0004] The present invention solves the technical problem of preventing hydrate blockage during oil and gas reservoir production. To solve this problem, the present invention uses the injection of thermodynamic inhibitors to prevent hydrate formation. The principle of the present invention is to continuously add hydrate inhibitors to the production fluid to reduce the hydrate formation temperature, thereby causing the production fluid temperature to be higher than the hydrate formation temperature and preventing the formation of hydrates in the wellbore. Figure 1 shown. Figure 1 The results show that: (1) as the methanol content in water increases, the hydrate curve moves to the left; (2) the left side of the curve is the hydrate formation area, while the right side of the curve is the non-hydrate formation area; (3) the temperature line of the production fluid that changes with the season and production capacity determines whether the fluid forms hydrates and the amount of hydrate inhibitor; (4) when the pressure is 12.89 MPa and the temperature is 283.15 K, the fluid is in the hydrate formation area, so 10% methanol needs to be added to put the fluid in the non-hydrate area.

[0005] The present invention uses the hydinhibitorcal.xlsx simulator to calculate the inhibitor dosage in the following steps: (1) collecting production facility structure data and production data; (2) collecting hydrate test data and determining the experimental data fitting formula; (3) determining the pressure and temperature distribution of the production facility; (4) determining the inhibitor inhibition temperature target as the hydrate formation temperature without inhibitor minus the lowest fluid temperature of the production facility plus a safety margin of 3 to 5 degrees; (5) due to changes in on-site fluid composition and pressure and temperature changes, the experimental data fitting formula and the empirical formula are used to calculate the on-site hydrate formation conditions; (6) determining the hydrate formation location and inhibitor dosage based on the production facility pressure and temperature distribution and the hydrate formation conditions; (7) determining the inhibitor injection process based on the calculated inhibitor dosage; (8) on-site personnel can adjust and optimize the thermodynamic inhibitor dosage and test the kinetic inhibitor effect based on the production situation, but it is necessary to continuously observe the pressure changes in the production system to prevent hydrate blockage as a principle. Simulator step 5 is the innovation of the present invention. The error of the hydrate formation conditions calculated using the present invention is less than 2 degrees, but the error of the hydrate formation conditions calculated using the bo method disclosed in CN118088129A is 3.55 to 7.35 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 .Conditions for formation of fluid hydrates at different methanol contents

[0008] Figure 2 Example 1 Relationship between the amount of inhibitor used and the wellhead temperature during natural gas reservoir production

[0009] Figure 3 Example 1 Relationship between the amount of inhibitor used and the amount of water produced during natural gas reservoir production

[0010] Figure 4 Example 2 Relationship between the amount of inhibitor used and the wellhead temperature during the production of condensate gas reservoir

[0011] Figure 5 Example 2 Relationship between the amount of inhibitor used and the amount of water produced during the production of condensate gas reservoir

[0012] Figure 6 Example 3 Relationship between inhibitor dosage and wellhead temperature during oil reservoir production

[0013] Figure 7 Example 3 Relationship between the amount of inhibitor used and the amount of water produced during oil reservoir production DETAILED DESCRIPTION

[0014] The present invention uses the hydinhibitorcal.xlsx simulator to calculate the inhibitor dosage, and the specific optimization calculation steps are as follows: (1) Collect production facility structure data and production data; (2) Collect hydrate test data and determine the experimental data fitting formula; (3) Determine the pressure and temperature distribution of the production facility; (4) Determine the inhibitor inhibition temperature target as the hydrate formation temperature without inhibitor minus the lowest fluid temperature of the production facility plus a safety margin of 3 degrees; (5) Calculate the hydrate formation conditions using the experimental data fitting formula and the empirical formula according to the changes in the on-site fluid composition and pressure and temperature changes; (6) Determine the hydrate formation location and inhibitor dosage according to the pressure and temperature distribution of the production facility and the hydrate formation conditions; (7) Determine the inhibitor injection process according to the calculated inhibitor dosage; (8) According to the production situation, the thermodynamic inhibitor dosage can be adjusted and optimized and the kinetic inhibitor effect can be tested, but it is necessary to continuously observe the pressure changes in the production system to prevent hydrate blockage as a principle. To further illustrate the content, characteristics and efficacy of the present invention, the following examples are listed:

[0015] Example 1: The bottom hole pressure of a natural gas reservoir is 18Mpa, the gas reservoir temperature is 90 degrees, the wellhead production pressure is 4.64Mpa, and the natural gas production capacity is 20000m 3 / d. The composition of natural gas is 93.8378%C1+1.3461%C2+0.3203%C3+0.0466%iC4+0.0788%nC4+

[0016] 0.0253%iC5+0.0347%nC5+0.0358%C6+0.0241%C7+0.0118%C8+3.6349%N2+0.6038%CO2, use hydinhibitorcal.xlsx simulator to calculate the relationship between inhibitor dosage and wellhead temperature and between inhibitor dosage and water production. Figures 2 to 3 . Figure 2 The results are analyzed as follows: (1) The measured wellhead hydrate formation temperature is 9 degrees, the hydrate formation temperature calculated by the present invention is 8.61 degrees, and the hydrate formation temperature calculated by the BO method is 12.55 degrees. Therefore, the error of the hydrate formation temperature predicted by the present invention is 0.39 degrees, while the error of the BO method is 3.55 degrees; (2) The figure shows that the water production is 10m 3 / d shows the inhibitor dosage requirement. When the wellhead fluid temperature is less than 12 degrees, inhibitors need to be added, and the inhibitor dosage increases significantly as the wellhead temperature decreases. Figure 3 The results are analyzed as follows: (1) When the water production is 0.5m 3 / d, the required methanol injection amount is 115.54kg / d. The methanol dosage calculated by the bo method is 53.7kg / d higher than the actual requirement, and the methanol dosage calculated by the present invention is 5.12kg / d less than the actual requirement; (2) When the produced water is 50m 3 / d, the required methanol injection amount is 10688.35kg / d. The methanol consumption calculated by BO method is 5361.85kg / d higher than the actual demand. If methanol is calculated at 2500 yuan per ton, the cost of excess methanol per day is 13404 yuan.

[0017] Example 2: The bottom hole pressure of a condensate gas reservoir is 18Mpa, the gas reservoir temperature is 90 degrees, the wellhead production pressure is 4.16Mpa, and the gas production capacity is 20000m 3 / d, the production gas-oil ratio is 1000m3 / m3. The condensate gas composition is 73.53%C1+8.53%C2+2.45%C3+0.45%iC4+

[0018] 0.5%nC4+0.13%iC5+0.59%nC5+0.88%C6+9.33%C7+3.14%N2+0.47%CO2, use hydinhibitorcal.xlsx simulator to calculate the relationship between inhibitor dosage and wellhead temperature and the relationship between inhibitor dosage and water production. Figures 4 to 5 . Figure 4 The results are analyzed as follows: (1) The measured wellhead hydrate formation temperature is 14 degrees, the hydrate formation temperature calculated by the present invention is 12.69 degrees, and the hydrate formation temperature calculated by the BO method is 18.85 degrees. Therefore, the error of the hydrate formation temperature predicted by the present invention is 1.31 degrees, while the error of the BO method is 4.85 degrees; (2) The figure shows that the water production is 10m 3 / d shows the inhibitor dosage requirement. When the wellhead fluid temperature is less than 17 degrees, inhibitors need to be added, and the inhibitor dosage increases significantly as the wellhead temperature decreases. Figure 5 The results are analyzed as follows: (1) When the water production is 0.5m 3 / d, the required methanol injection amount is 198.2kg / d. The methanol dosage calculated by the bo method is 80.3kg / d higher than the actual requirement, and the dosage calculated by the present invention is 20.81kg / d less than the actual requirement; (2) When the water production is 50m 3 / d, the required methanol injection amount is 18321.15kg / d. The methanol consumption calculated by BO method is 8029.87kg / d higher than the actual demand. If methanol is calculated at 2500 yuan per ton, the cost of excess methanol per day is 20074 yuan.

[0019] Example 3: The bottom hole pressure of a certain oil reservoir is 18Mpa, the reservoir temperature is 90 degrees, the wellhead production pressure is 4.49Mpa, and the gas production capacity is 20000m 3 / d, the production gas-oil ratio is 500m3 / m3. The condensate gas composition is 66.43%C1+7.71%C2+2.21%C3+0.41%iC4+

[0020] 0.45%nC4+0.12%iC5+1%nC5+1.56%C6+16.85%C7+2.83%N2+0.43%CO2, use hydinhibitorcal.xlsx simulator to calculate the relationship between inhibitor dosage and wellhead temperature and the relationship between inhibitor dosage and water production. Figures 6 to 7 . Figure 6 The results are analyzed as follows: (1) The measured wellhead hydrate formation temperature is 14 degrees, the hydrate formation temperature calculated by the present invention is 12.1 degrees, and the hydrate formation temperature calculated by the BO method is 21.35 degrees. Therefore, the error of the hydrate formation temperature predicted by the present invention is 1.9 degrees, while the error of the BO method is 7.35 degrees; (2) The graph shows that the water production is 10m 3 / d shows the inhibitor dosage requirement. When the wellhead fluid temperature is less than 17 degrees, inhibitors need to be added, and the inhibitor dosage increases significantly as the wellhead temperature decreases. Figure 7 The results are analyzed as follows: (1) When the water production is 0.5m 3 / d, the required methanol injection amount is 204.6kg / d. The methanol dosage calculated by the bo method is 124.69kg / d higher than the actual requirement, and the methanol dosage calculated by the present invention is 31.17kg / d less than the actual requirement; (2) When the water production is 50m 3 / d, the required methanol injection amount is 18327.55kg / d. The methanol consumption calculated by BO method is 12469.23kg / d higher than the actual demand. If methanol is calculated at 2500 yuan per ton, the cost of excess methanol per day is 31173 yuan.

[0021] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may be applicable to various changes. All modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included within the scope of the claims of the present application.

Claims

1. Hydrate inhibitor dosage simulator, characterized by Using hydinhibitorcal.xlsx to analyze the effects of each phase's production capacity, temperature and pressure distribution, fluid composition and calculation method on inhibitor dosage includes the following calculation steps: (1) Collecting production facility structure data and production data; (2) Collecting hydrate test data and determining the experimental data fitting formula; (3) Determining the pressure and temperature distribution of production facilities; (4) Determining the inhibitor inhibition temperature; (5) Using the experimental data fitting formula and empirical formula to calculate the hydrate formation conditions according to the changes in the on-site fluid composition and pressure and temperature changes; (6) Determine the hydrate formation location and inhibitor dosage based on the pressure and temperature distribution of the production facilities and the hydrate formation conditions; (7) Determine the inhibitor injection process based on the calculated inhibitor dosage; (8) The thermodynamic inhibitor dosage can be adjusted and the kinetic inhibitor effect can be tested based on the production situation, but the principle is to continuously observe the pressure changes in the production system to prevent hydrate blockage.

2. The hydrate inhibitor dosage simulator according to claim 1, characterized in that: Use field production facility data, measured fluid composition, and measured hydrate formation data.

3. The hydrate inhibitor dosage simulator according to claim 1, characterized in that: The surface gas-oil ratio of oil and gas reservoir fluid is greater than 50m 3 / m 3 That is, it is suitable for exploitation of oil reservoirs, condensate gas reservoirs and natural gas reservoirs.

4. The hydrate inhibitor dosage simulator according to claim 1, characterized in that: The effects of various inhibitors such as methanol, ethylene glycol, ethanol, and triethylene glycol on the hydrate formation of oil and gas reservoir fluids were analyzed.

5. The hydrate inhibitor dosage simulator according to claim 1, characterized in that: The error of using experimental data fitting formula and empirical formula to predict hydrate formation conditions is less than 2 degrees, which exceeds the existing empirical method.

6. The hydrate inhibitor dosage simulator according to claim 1, characterized in that: Use a computer and EXCEL office software to run the hydinhibitorcal.xlsx simulator to calculate the inhibitor dosage.

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