Energy-saving group control method for water injection pumps for offshore oil and gas platform

Abstract

The invention discloses an energy-saving group control method of water injection pumps for an offshore oil and gas platform, which comprises the following steps: S1, establishing a group control objective function containing platform production and energy conservation; s2, water injection group control constraint conditions of oil and gas production water injection requirements and power supply stability are calculated; and S3, the control target quantity of each pump is calculated. According to the method, the platform income and energy-saving requirements are comprehensively considered, the operation power of each water injection pump in the water injection pump group is optimally controlled on the premise of ensuring the water injection requirement, the water injection energy consumption of the system is lowest, the method has important significance on promoting energy conservation and carbon reduction of the offshore platform, and the method is suitable for popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy-saving control, and in particular relates to an energy-saving group control method for water injection pumps used in offshore oil and gas platforms. Background Art

[0003] At the present stage, offshore oil and gas platforms use water injection for oil displacement. The power consumption of its water injection system accounts for 30% - 60% of the total power consumption of the entire platform, which is an important starting point for implementing energy conservation and carbon reduction. Energy-saving group control of water injection pumps is an important energy-saving measure. On the premise of ensuring the water injection demand, optimizing the operating power of each water injection pump in the water injection pump group to minimize the water injection energy consumption of the system is of great significance for promoting energy conservation and carbon reduction on offshore platforms. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide an energy-saving group control method for water injection pumps used in offshore oil and gas platforms, which is energy-saving and environmentally friendly and can ensure the production water injection demand.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: an energy-saving group control method for water injection pumps used in offshore oil and gas platforms, including the following steps,

[0006] S1: Establish a group control objective function including platform production and energy conservation;

[0007] S2: Calculate the water injection group control constraint conditions for oil and gas production water injection demand and stable power supply;

[0008] S3: Calculate the control target quantity of each pump.

[0009] Further, in the S1, the objective function formula is as follows,

[0010] max f = f 1 + f 2 + f 3

[0011] where f is the total revenue increment after energy-saving group control of the water injection system; f 1 is the oil revenue increment after energy-saving group control of the water injection system; f 2 is the natural gas revenue increment after energy-saving group control of the water injection system; f 3 is the reduction of energy consumption cost after energy-saving group control of the water injection system.

[0012] Further, the calculation of the oil revenue increment after energy-saving group control of the water injection system is as follows,

[0013]

[0014] where α 1 is the unit price of crude oil, I oilis the oil injection-production ratio, m is the number of injection pumps participating in the energy-saving group control of the offshore water injection system; ΔQ i is the increment of the water injection volume after the energy-saving group control of the i-th injection pump.

[0015] Furthermore, the increment of the natural gas revenue after the energy-saving group control of the water injection system is calculated as follows:

[0016]

[0017] where β 1 is the unit price of natural gas, and G gas is the natural gas injection-production ratio.

[0018] Furthermore, the reduction of the energy consumption cost after the energy-saving group control of the water injection system is calculated as follows:

[0019]

[0020] where: λ is the unit price of energy consumption, and ε i is the flow rate and energy consumption conversion coefficient near the operating point of the i-th injection pump.

[0021] Furthermore, the constraint conditions of the energy-saving group control of the water injection include the constraints related to electric energy and the constraints related to oil and gas production water injection. The constraints related to electric energy include the single-pump power constraint, and the formula of the single-pump power constraint is as follows,

[0022] P i (Q imin ) ≤ P i0 (Q i,0 ) + ΔP i (Q io , ΔQ i ) ≤ P iN

[0023] where: Q i,0 is the flow rate of the i-th pump during regulation; P i0 is the electric power of the i-th pump during regulation; ΔP i (Q io , ΔQ i ) represents the additional electric power required for the i-th pump to increase the flow rate by ΔQ i,0 on the basis of Q i ; P iN is the rated electric power of the i-th pump, and P i (Q imin ) is the power consumption of the i-th pump at its minimum flow rate Q imin .

[0024] Furthermore, the constraints related to electric energy include the total power constraint of the injection pump group, and the formula of the total power constraint of the injection pump group is as follows,

[0025]

[0026] Further, the constraints related to oil and gas production water injection include the water injection flow rate constraint of a single water injection pump. The formula for the water injection flow rate constraint of a single water injection pump is as follows:

[0027] Q imin ≤Q i0 +ΔQ i ≤Q iN

[0028] Where: Q iN and Q imin are the rated flow rate and the minimum required flow rate for production of the i-th pump, respectively.

[0029] Further, the constraints related to oil and gas production water injection include the demand constraint for the total amount of water injection required for production. The formula for the demand constraint for the total amount of water injection required for production is as follows:

[0030]

[0031] Where: Q ∑max and Q ∑min are the maximum and minimum values of the total water injection flow rate required for water injection on the oil and gas platform, respectively.

[0032] Further, the constraints related to oil and gas production water injection include the pressure constraint of the water injection pipeline network. The formula for the pressure constraint of the water injection pipeline network is as follows:

[0033] H i (Q i0 +ΔQ i )≥H imin

[0034] Where: H i (Q i0 +ΔQ i ) represents the head provided when the flow rate of the i-th pump is increased by ΔQ i,0 based on Q i ; H imin is the minimum required value of the head of the i-th pump.

[0035] The advantages and positive effects of the present invention are as follows:

[0036] The present invention comprehensively considers the requirements of platform revenue and energy conservation. On the premise of ensuring water injection needs, it optimizes and controls the operating power of each water injection pump in the water injection pump group, minimizing the water injection energy consumption of the system, which is of great significance for promoting energy conservation and carbon reduction on offshore platforms and is suitable for popularization and application. Description of the Drawings

[0037] Figure 1 is the overall flow schematic diagram of the embodiment of the method of the present invention. Detailed implementation mode

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0039] The following further describes the embodiments of the present invention with reference to the accompanying drawings:

[0040] Offshore oil and gas platforms generally drive oil by injecting water to increase the recovery rate. Appropriate water injection can help increase crude oil production, but excessive water injection may also lead to too high a water-oil ratio, reducing the oil production efficiency while increasing energy consumption.

[0041] As Figure 1 shown, an energy-saving group control method for a water injection pump used in an offshore oil and gas platform includes the following steps

[0042] S1: Establish a group control objective function including platform production and energy saving. Specifically, the objective function formula is as follows

[0043] maxf = f 1 + f 2 + f 3

[0044] where f is the total revenue increment after energy-saving group control of the water injection system; f 1 is the oil revenue increment after energy-saving group control of the water injection system; f 2 is the natural gas revenue increment after energy-saving group control of the water injection system; f 3 is the reduction in energy consumption costs after energy-saving group control of the water injection system.

[0045] Specifically, the calculation of the oil revenue increment after energy-saving group control of the water injection system is as follows

[0046]

[0047] where α 1 is the unit price of crude oil, I oil is the oil injection-production ratio, m is the number of water injection pumps participating in energy-saving group control in the offshore water injection system; ΔQ i is the increment of the water injection volume of the i-th water injection pump after energy-saving group control.

[0048] The calculation of the natural gas revenue increment after energy-saving group control of the water injection system is as follows:

[0049]

[0050] where β 1is the unit price of natural gas, G gas is the injection-production ratio of natural gas.

[0051] The calculation of the reduction in energy consumption cost after the energy-saving group control of the water injection system is as follows:

[0052]

[0053] Where: λ is the unit price of energy consumption, ε i is the flow rate and energy consumption conversion coefficient near the operating point of the i-th water injection pump.

[0054] S2: Calculate the water injection group control constraint conditions for the water injection demand in oil and gas production and the stability of power supply. Specifically, the constraint conditions for the energy-saving group control of water injection include two categories. The first category is the constraints related to electric energy, and the second category is the constraints related to water injection in oil and gas production.

[0055] Among them, the constraints related to electric energy include the single-pump power constraint. The formula for the single-pump power constraint is as follows:

[0056] P i (Q imin ) ≤ P i0 (Q i,0 ) + ΔP i (Q io , ΔQ i ) ≤ P iN

[0057] Where: Q i,0 is the flow rate of the i-th pump during regulation; P i0 is the electric power of the i-th pump during regulation; ΔP i (Q io , ΔQ i ) represents the additional electric power required for the i-th pump to increase the flow rate by ΔQ i,0 on the basis of Q i ; P iN is the rated electric power of the i-th pump, and P i (Q imin ) is the power consumption of the i-th pump at its minimum flow rate Q imin .

[0058] The constraints related to electric energy include the total power constraint of the water injection pump group. The formula for the total power constraint of the water injection pump group is as follows:

[0059]

[0060] The constraints related to water injection in oil and gas production include the water injection flow rate constraint of a single water injection pump. The formula for the water injection flow rate constraint of a single water injection pump is as follows:

[0061] Q imin ≤ Q i0 + ΔQ i ≤ QiN

[0062] Where: Q iN and Q imin are the rated flow rate and the minimum required flow rate for production of the i-th pump, respectively.

[0063] Constraints related to oil and gas production water injection include the demand constraint for the total amount of water injection required for production. The formula for the demand constraint for the total amount of water injection required for production is as follows.

[0064]

[0065] Where: Q ∑max and Q ∑min are the maximum and minimum values of the total water injection flow rate required for water injection on the oil and gas platform, respectively.

[0066] Constraints related to oil and gas production water injection include the injection pipeline network pressure constraint. The formula for the injection pipeline network pressure constraint is as follows.

[0067] H i (Q i0 +ΔQ i )≥H imin

[0068] Where: H i (Q i0 +ΔQ i ) represents the head provided when the flow rate of the i-th pump is increased by ΔQ i,0 on the basis of Q i ; H imin is the minimum required value of the head of the i-th pump.

[0069] S3: Calculate the control target quantity of each pump.

[0070] Construct an energy-saving group control algorithm model for water injection pumps used in offshore oil and gas platforms in the following form through the above objective function and constraint conditions:

[0071] min F(ΔQ 1 ,ΔQ 2 ,…ΔQ m )

[0072] s.t.G(ΔQ 1 ,ΔQ 2 ,…ΔQ m )≤0

[0073] This model is an extreme value problem under constraint conditions, and the constraint conditions are non-linear. Corresponding commands in the Optimization Toolbox in Matlab, such as, can be selected to solve the flow rate increment ΔQ i of each pump, and then substitute it into P i0 (Qi,0 ) + ΔP i (Q io , ΔQ i ) to solve the electric power of each pump and send it to each pump for execution, thereby realizing energy-saving group control.

[0074] The following takes a specific embodiment as an example to specifically elaborate on the present invention:

[0075] There are 15 injection pumps in a certain offshore platform injection water system, among which 3 are adjustable pumps. This method is used for energy-saving group control of these 3 pumps. Among them, the basic parameters of the three injection pumps are as follows. The rated power of injection pump 1 is 1.8 MW, and the rated flow rate is 300 m 3 / h, and the rated pressure is 14.4 Mpa; the rated power of injection pump 2 is 1.12 MW, and the rated flow rate is 150 m 3 / h, and the rated pressure is 14.4 Mpa; the rated power of injection pump 3 is 0.9 MW, and the rated flow rate is 196 m 3 / h, and the rated pressure is 10.2 Mpa.

[0076] The oil price is selected as $78.16 per barrel, the oil injection-production ratio is taken as 0.75, the natural gas is priced at 4754 yuan / t according to the liquefied natural gas price, the US dollar-renminbi exchange rate is selected as 7, and the natural gas injection-production ratio is taken as 0.25.

[0077] According to the above formula, after optimization calculation, the flow rate increment of injection pump 1 is 43.65 m 3 / h, the flow rate increment of injection pump 2 is -21.63 m 3 / h; the flow rate increment of injection pump 3 is -20.20 m 3 / h; after conversion, the active power increment of injection pump 1 is 0.072 MW; after conversion, the active power increment of injection pump 2 is -0.053 MW; after conversion, the active power increment of injection pump 3 is -0.034 MW; while maintaining the total injection water volume slightly increasing by 1.82 m 3 / h, the power consumption is reduced by 0.015 MW. Through the group control of injection pumps, the goal of energy conservation is achieved under the premise of meeting production in this operating condition.

[0078] The advantages and positive effects of the present invention are:

[0079] The present invention comprehensively considers the requirements of platform revenue and energy conservation. On the premise of ensuring the need for water injection, it optimizes and controls the operating power of each injection pump in the injection pump group, minimizing the water injection energy consumption of the system, which has important significance for promoting energy conservation and carbon reduction of offshore platforms and is suitable for popularization and application.

[0080] The above has described in detail an embodiment of the present invention, but the above content is only a preferred embodiment of the present invention and cannot be considered as defining the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention shall still fall within the scope covered by the patent of the present invention.

Claims

1. An energy-saving group control method for water injection pumps for offshore oil and gas platforms, characterized in that: The following steps are included: S1: Establish a group control objective function that includes platform production and energy saving; S2: Calculate the water injection demand for oil and gas production and the water injection group control constraints for stable power supply; S3: Calculate the control target quantity of each pump.

2. The energy-saving group control method for water injection pumps for offshore oil and gas platforms according to claim 1 is characterized in that: In S1, the objective function formula is as follows: maxf=f1+f2+f3 Among them, f is the total revenue increment after the energy-saving group control of the water injection system; f1 is the oil revenue increment after the energy-saving group control of the water injection system; f2 is the natural gas revenue increment after the energy-saving group control of the water injection system; f3 is the energy consumption cost reduction after the energy-saving group control of the water injection system.

3. The energy-saving group control method for water injection pumps for offshore oil and gas platforms according to claim 2 is characterized in that: The incremental oil revenue after the energy-saving group control of the water injection system is calculated as follows: Among them, α1 is the unit price of crude oil, I oil is the oil injection-production ratio, m is the number of water injection pumps participating in the energy-saving group control of the offshore water injection system; ΔQ i It is the increment of water injection volume after energy-saving group control of the i-th water injection pump.

4. The energy-saving group control method for water injection pumps for offshore oil and gas platforms according to claim 2 or 3 is characterized in that: The incremental natural gas revenue after the energy-saving group control of the water injection system is calculated as follows: Among them, β1 is the unit price of natural gas, G gas is the natural gas injection-production ratio.

5. The energy-saving group control method for water injection pumps for offshore oil and gas platforms according to claim 2 or 3, characterized in that: The energy consumption reduction after the energy-saving group control of the water injection system is calculated as follows: Among them: λ is the unit price of energy consumption, ε i is the flow rate and energy consumption conversion coefficient near the operating point of the i-th water injection pump.

6. The energy-saving group control method for water injection pumps for offshore oil and gas platforms according to any one of claims 1 to 3, characterized in that: The constraints of the water injection energy-saving group control include power-related constraints and oil and gas production water injection-related constraints. The power-related constraints include single pump power constraints. The single pump power constraint formula is as follows: P i (Q imin )≤P i0 (Q i,0 )+ΔP i (Q io ,ΔQ i )≤P iN Where: Q i,0 is the flow rate of the ith pump during regulation; P i0 The electric power of the i-th pump during regulation; ΔP i (Q io ,ΔQ i ) indicates that the i-th pump is in Q i,0 Basic adjustment to increase ΔQ i The additional electrical power required for flow rate; P iN is the rated electrical power of the i-th pump, P i (Q imin ) is the minimum flow rate Q of the i-th pump imin When power consumption.

7. The energy-saving group control method for water injection pumps for offshore oil and gas platforms according to claim 6 is characterized in that: The power-related constraints include the total power constraint of the water injection pump group. The total power constraint formula of the water injection pump group is as follows:

8. The energy-saving group control method for water injection pumps for offshore oil and gas platforms according to claim 6 is characterized in that: The oil and gas production water injection related constraints include a single water injection pump water injection flow constraint, and the single water injection pump water injection flow constraint formula is as follows: Q imin ≤Q i0 +ΔQ i ≤Q iN Where: Q iN and Q imin are the rated flow rate of the i-th pump and the minimum flow rate required for production respectively.

9. The energy-saving group control method for water injection pumps for offshore oil and gas platforms according to claim 6 is characterized in that: The oil and gas production water injection related constraints include the demand constraint of the total water injection volume required for production. The demand constraint formula of the total water injection volume required for production is as follows: Where: Q ∑max and Q ∑min They are the maximum and minimum values ​​of the total water injection flow rate required for water injection on the oil and gas platform.

10. The energy-saving group control method for water injection pumps for offshore oil and gas platforms according to claim 6, characterized in that: The oil and gas production water injection related constraints include water injection network pressure constraints. The water injection network pressure constraint formula is as follows: H i (Q i0 +ΔQ i )≥H imin Where: H i (Q i0 +ΔQ i ) indicates that the i-th pump is in Q i,0 Basic adjustment to increase ΔQ i Flow is the head provided; H imin is the minimum required value of the head of the i-th pump.

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