Simulator for preventing wellbore hydrate blockage in multi-branch drilling and completion design
Through the joint production of oil and gas reservoirs of branch wells, the wellbore fluid temperature is increased to prevent hydrate blockage, which solves the production shutdown caused by hydrate blockage, and achieves cost saving and environmental protection effects.
Patent Information
- Application Number
- CN202410765379.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-14
- Publication Date
- 2025-02-11
AI Technical Summary
The blockage of wellbore hydrate during oil and gas reservoir production leads to production shutdowns, and the prior art relies on chemical inhibitors or other costly methods for prevention and treatment.
The oil and gas reservoirs are collected through branch wells, and the wellbore fluid temperature is increased so that it is higher than the hydrate-generating area, thereby preventing the wellbore hydrate blockage. The effect of branch well parameters on capacity and temperature pressure distribution was analyzed using the mlgproduction.xlsx simulator, and the wellbore design was optimized to avoid hydrate formation.
It effectively reduces the frequency of wellbore hydrate blockage, saves traditional hydrate blockage control costs, reduces the overall cost of oil and gas production, and avoids environmental pollution caused by chemical inhibitors.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of wellbore hydrate blockage prevention. Background Art
[0002] Under certain pressure and temperature conditions, oil and gas reservoir fluids form solid crystals with water, thereby blocking the oil and gas production wellbore and causing a shutdown accident. The shutdown not only delays oil and gas production, but also generates high processing costs. Therefore, the prevention and treatment measures of hydrate blockage need to be considered in the drilling and completion design stage of oil and gas reservoir 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 commonly used in the industry to inhibit hydrate formation. If 10 cubic meters of water are produced per day, 0.2 cubic meters of methanol needs to be added to each cubic meter of water to inhibit hydrate formation. The cost of methanol per ton is 3,000 yuan. Then the methanol required to inhibit hydrate formation in the well costs about 5,000 yuan per day, and the methanol cost per well is about 1.8 million yuan per year. The methanol cost of inhibiting hydrate formation in 11 wells on the offshore platform is 20 million yuan per year.
[0003] Using experimental devices to study the formation conditions of fluid hydrates 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 formation conditions of hydrates [Guo et al., Science, Technology and Engineering, Vol. 18, No. 29, 2018]. Chen Weidong et al. (SPE64751, 2000) proposed the calculation of reservoir branch well productivity in 2000. Summary of the invention
[0004] The present invention solves the technical problem of preventing wellbore hydrate blockage during oil and gas reservoir production. To solve this problem, the present invention adopts a technical solution of increasing the production well capacity by co-producing oil and gas reservoirs with branch wells, thereby increasing the wellbore fluid temperature to outside the hydrate formation area. The present invention is different from the traditional wellbore hydrate control method, and belongs to a brand-new wellbore hydrate blockage prevention solution. The present invention develops the mlgproduction.xlsx simulator to analyze the influence of factors such as branch length, skin factor, permeability and intelligent valve on branch well capacity, wellbore temperature and pressure distribution and hydrate formation, and optimizes the branch well drilling and completion design to prevent wellbore hydrate blockage. The process steps of using mlgproduction.xlsx to simulate and design branch well parameters are as follows: (1) calculation of oil and gas water capacity under different branch well parameters; (2) calculation of wellbore pressure and temperature distribution under different branch well capacity; (3) calculation of oil and gas reservoir fluid hydrate formation temperature under wellbore pressure distribution; (4) comparison of wellbore fluid temperature distribution curve and wellbore fluid hydrate formation curve, thereby determining the branch well characteristic parameters when no hydrate is formed in the wellbore.
[0005] The present invention is superior to the traditional hydrate blockage control method because the present invention utilizes the natural heat energy of the oil and gas reservoir fluid to inhibit the formation of wellbore hydrates, thereby saving the traditional hydrate blockage control cost, thereby reducing the oil and gas production cost.
[0006] The present invention is superior to conventional chemical control methods for solving hydrate blockage because the present invention utilizes natural heat energy of oil and gas reservoirs to inhibit wellbore hydrate formation and eliminates environmental pollution and oil and gas product pollution caused by chemical inhibitors. BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Figure 1 .The location of hydrate formation is determined during single mining of the first branch.
[0008] Figure 2 .The influence of the second branch length on hydrate formation during combined production.
[0009] Figure 3 .The influence of the second branch layer skin factor on hydrate formation during combined mining.
[0010] Figure 4 .The influence of the permeability of the second branch layer on hydrate formation during combined production. DETAILED DESCRIPTION
[0011] The present invention uses mlgproduction.xlsx to simulate the design of branch well parameters as follows: (1) Calculation of oil, gas and water production capacity under different branch well parameters; (2) Calculation of wellbore pressure and temperature distribution under different branch well production capacities; (3) Calculation of oil and gas reservoir fluid hydrate formation conditions under wellbore pressure distribution; (4) Comparison of wellbore fluid temperature distribution curve with wellbore fluid hydrate formation curve, so as to determine the wellbore hydrate formation location and branch well characteristic parameters when no wellbore hydrate is formed. To further illustrate the content, features and efficacy of the present invention, the following two-branch gas reservoir production example is listed to illustrate the branch well parameter simulation design: Example: A gas reservoir has two gas layers, gas layer 1 is located between 1713 and 1718.2 meters, gas layer 1 has a permeability of 3md, and gas layer 1 has a drainage area of 600m 2 The gas reservoir pressure and temperature are 17.56Mpa and 359.82K respectively; gas layer 2 is located between 1628 and 1633.5 meters, the permeability of gas layer 2 is 4md, and the gas layer drainage area is 600m 2, and its gas reservoir pressure and temperature are 16.74Mpa and 358.71K respectively. Two gas layers are exploited by drilling branch wells 1 and 2 in a vertical wellbore. The length of the branch well is 300 meters. The vertical distance of the branch well 1 inclination section is 71.63m, and the inclination angle is 45 degrees. The vertical distance between the node of branch well 1 and the node of branch well 2 is 84.12m, and the vertical distance of the branch well 2 inclination section is 90.83m, and the inclination angle is 45 degrees. The ambient temperature is 277.15K, the diameters of the vertical wellbore and the branch wellbore are both 0.06m, and the absolute roughness of the wellbore is 0.00036m. The bottom hole flow pressure is 15.5Mpa, and the specific gravity of natural gas is 0.588. The example analysis of using mlgproduction.xlsx to simulate the design of branch well parameters is as follows:
[0012] 1. Impact of single mining in the first branch on hydrate formation
[0013] Figure 1 The results show that: (1) the temperature of the wellbore fluid increases with the depth of the well, and the temperature of the wellbore fluid is lowest at the wellhead; (2) the hydrate formation temperature at the wellhead is 3.6 K higher than the wellhead fluid temperature, so hydrates are generated at the wellhead during single production of the first branch; (3) the hydrate formation area is the area between the wellhead and 80 meters below the wellbore.
[0014] 2. Effect of the length of the second branch well on hydrate formation during commingled production
[0015] Figure 2 The results show that: (1) when only the first branch is producing, the wellhead temperature is lower than the hydrate formation temperature; (2) when the length of the second branch increases from 50m to 600m, the wellhead temperature of the combined production is always higher than the hydrate formation temperature, so hydrates will not form in the wellbore during combined production; (2) when the length of the second branch well reaches 600m, the wellhead temperature is 3.64K higher than the hydrate formation temperature. III. Effect of the second branch skin factor on hydrate formation during combined production
[0016] Figure 3 The results show that: (1) when the skin factor is greater than 4.8, the wellhead temperature is lower than the hydrate formation temperature, and hydrates will be generated in the combined production wellbore; (2) when the skin factor is equal to -1, the wellhead temperature is 4.36 K higher than the hydrate formation temperature, so hydrates will not be formed in the combined production wellbore.
[0017] 4. Effect of the permeability of the second branch layer on hydrate formation during commingled production
[0018] Figure 4 The results show that: (1) when the permeability of the second branch layer is less than 1.8, the wellhead temperature is lower than the hydrate formation temperature and hydrates are formed near the wellhead; (2) when the permeability of the second branch layer is less than 10, the wellhead temperature is 7.64 K higher than the hydrate temperature, so hydrate blockage will not form in the wellbore.
Claims
1. A simulation method for preventing wellbore hydrate blockage in multi-branch drilling and completion design, characterized by: The mlgproduction.xlsx simulator is used to analyze the effects of factors such as branch length, skin factor, permeability, and smart valve on branch well productivity, wellbore pressure and temperature distribution, and hydrate formation, and to optimize branch well drilling and completion design to prevent wellbore hydrate blockage, including the following process steps: (1) Calculation of oil, gas and water productivity under different branch well parameters; (2) Calculation of wellbore pressure and temperature distribution under different branch well productivity; (3) Calculation of hydrate formation temperature of oil and gas reservoir fluid under wellbore pressure distribution; (4) Comparison of wellbore fluid temperature distribution curve with wellbore fluid hydrate formation curve, so as to determine the characteristic parameters of branch wells when there is no hydrate formation in the wellbore.
2. The simulation method for preventing wellbore hydrate blockage in multi-branch drilling and completion design according to claim 1 is characterized by: Multi-branch drainage of oil and gas reservoirs and commingled production avoids wellbore hydrate formation.
3. The simulation method for preventing wellbore hydrate blockage in multi-branch drilling and completion design according to claim 1 is characterized by: The surface gas-oil ratio of oil and gas reservoir fluid is greater than 100m 3 / m 3 .