A finite state simulation method and system for complex well control in offshore oil fields

Abstract

The present invention relates to a finite state simulation method and system for complex well control of an offshore oil field, which is characterized by comprising the following contents: 1) establishing the topological structure of the current production unit in the offshore oil field to be tested, and defining that the same level of the topological structure includes single wells and well groups; 2) setting the control state of the current production unit topological structure, and calculating the output and pressure of the production unit topological structure under the current control state; 3) detecting the control state of the current production unit topological structure according to predefined active and passive control rules and state conversion parameters; 4) recalculating the output and pressure of the current production unit topological structure; 5) entering the step 3) to update the control state of the current production unit topological structure until the control state of the current production unit topological structure no longer changes, and then entering the step 1) to calculate the next production unit. The present invention can be widely used in the field of improving oil and gas field development and recovery.

Description

Technical Field

[0001] The present invention relates to a finite state simulation method and system for complex well control in offshore oil fields, belonging to the field of application of reservoir numerical simulation technology and improving recovery rate in oil and gas field development. Background Art

[0002] Unlike onshore oil fields, offshore oil fields rely on offshore platforms for exploitation. From the reservoir to the platform, crude oil is extracted to the ground through sea pipes, risers, etc. This makes the wells, pipes, and networks of offshore oil fields more complex than onshore oil fields. At the same time, the corresponding well control methods have also become very complex. If reservoir numerical simulation is used to simulate such problems, the first thing to do is to solve the numerical simulation of complex well control. This is an important problem that needs to be solved urgently in reservoir numerical simulation, because the rationality and reliability of complex well control simulation determines the accuracy of numerical simulation applied to offshore oil fields. However, there is no simulation method for complex well control in offshore oil fields in the existing technology. Summary of the invention

[0003] In view of the above problems, the object of the present invention is to provide a finite state simulation method and system for complex well control in offshore oil fields with high reliability and simple operation.

[0004] To achieve the above object, the present invention adopts the following technical scheme: a finite state simulation method for complex well control in offshore oil fields, comprising the following contents:

[0005] 1) Establish the topological structure of the current production unit in the offshore oil field to be tested, and define that the same level of the topological structure includes single wells and well groups;

[0006] 2) Setting the control state of the current production unit topology structure and calculating the output and pressure of the production unit topology structure under the current control state;

[0007] 3) According to the predefined active and passive control rules and state transition parameters, the control state of the current production unit topology structure is detected and the control state of the current production unit topology structure is updated;

[0008] 4) Recalculate the output and pressure of the current production unit topology;

[0009] 5) Enter the step 3) to update the control state of the current production unit topology structure until the control state of the current production unit topology structure no longer changes, then enter the step 1) to calculate the next production unit, and complete the finite state simulation of the complex well control of the offshore oil field to be tested.

[0010] Furthermore, in the step 1), for any production unit, there is only one upper-level production unit, but it may include multiple lower-level production units; for any production unit, it may include one or more production units at the same level.

[0011] Furthermore, the specific process of step 3) is as follows:

[0012] 3.1) Define the control state of the current production unit topology structure into two categories: active control state and passive control state;

[0013] 3.2) According to the actual well control situation of the offshore oil field to be tested, define the state transition parameters of the current production unit topology structure, including the transition conditions between the various control states of the current production unit topology structure;

[0014] 3.3) The state machine updates the control state of the current production unit topology according to the predefined active and passive control rules and state transition parameters.

[0015] Furthermore, the rules of the active control state and the passive control state in step 3.1) include:

[0016] ① At any time, any production unit has only one active control state and only one control parameter;

[0017] ② At any time, any production unit includes one or more passive control states, and can poll and calculate the passive control states according to a certain priority;

[0018] ③ In the passive control state, the production unit can transform from the passive control state to the active control state;

[0019] ④ Both active control state and passive control state include control mode and control parameters;

[0020] ⑤Only well groups and single wells have both active control and passive control states, and perforating only has passive control state;

[0021] ⑥ The priority of the current production unit when it is in a passive control state is lower than that when it is in an active control state;

[0022] ⑦ The current production unit is in active control state at the beginning of the simulation.

[0023] Furthermore, the specific process of step 3.3) is as follows:

[0024] The state machine detects the control state of the current production unit topology structure according to the pre-defined active and passive control rules and state transition parameters. When the current production unit topology structure reaches the transition condition of any control state, the original passive control state of the current production unit topology structure is converted into an active control state, and the original active control state of the current production unit topology structure is converted into a passive control state, and the control state of the current production unit topology structure is updated.

[0025] Furthermore, the control state of the current production unit topology structure includes a well group control state, a fixed oil production control state, a fixed water production control state, a fixed gas production control state, a fixed liquid production control state, a fixed reservoir volume production control state and a fixed bottom hole pressure control state.

[0026] Furthermore, the control parameters include well group control parameters, oil production control parameters, water production control parameters, gas production control parameters, liquid production control parameters, reservoir volume production control parameters and bottom hole pressure control parameters.

[0027] A finite state simulation system for complex well control in offshore oil fields, comprising:

[0028] A topology building module is used to build the topology of each production unit in the offshore oil field to be tested, and define that the same level of the topology structure includes single wells and well groups;

[0029] A control state setting module is used to set the control state of each production unit topology structure;

[0030] Parameter calculation module, used to calculate the output and pressure of each production unit topology under the current control state;

[0031] The state machine is used to detect the control state of each production unit topology structure according to predefined active and passive control rules and state conversion parameters, and update the control state of each production unit topology structure.

[0032] Furthermore, the state machine is provided with:

[0033] The control rule definition unit is used to define the control state of the current production unit topology structure, which is divided into two categories: active control state and passive control state;

[0034] A state transition parameter definition unit is used to define the state transition parameters of the current production unit topology structure according to the actual well control situation of the offshore oil field to be tested, including the transition conditions between the control states of the current production unit topology structure;

[0035] The control state updating unit is used to update the control state of the current production unit topology structure according to predefined active and passive control rules and state conversion parameters.

[0036] The present invention adopts the above technical solution, which has the following advantages:

[0037] 1. The present invention aims at the characteristics of well groups and well control conditions commonly used in offshore oil field development, converts multi-level well groups and multiple well control conditions into linear finite states, each state corresponds to a processing action, and according to different control states, the corresponding action can be selected to execute the processing process, and then the variables are updated, and the multi-branch logical judgment is converted into a cyclic state polling judgment method. The state changes of all wells can be processed in real time, thereby improving the computing efficiency.

[0038] 2. The present invention realizes simulation of complex well control status by describing the status of wells and well groups in different forms, thus avoiding confusion caused by process control of multiple branch structures.

[0039] 3. The present invention defines and controls the complex control states of wells and well groups in numerical simulation of offshore oil and gas field reservoirs, and provides stable and reliable methodological theoretical support for clearly calculating the dynamic changes of offshore oil and gas field production units including wells, well groups, and perforation layers. It can be widely used in the application of reservoir numerical simulation technology and the field of improving oil and gas field development recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic flow diagram of the method of the present invention;

[0041] Figure 2 It is a schematic diagram of the topological structure of the production unit in the present invention;

[0042] Figure 3 Schematic diagram of control state and conversion mode of complex well control in offshore oil fields according to an embodiment of the present invention;

[0043] Figure 4 It is a schematic diagram of the calculation curve of realizing complex control of a single well according to the finite state simulation method in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention is described in detail below in conjunction with the accompanying drawings. However, it should be understood that the accompanying drawings are provided only for a better understanding of the present invention and should not be construed as limiting the present invention.

[0045] like Figure 1 As shown, the finite state simulation method for complex well control in offshore oil fields provided by the present invention comprises the following steps:

[0046] 1) Before each iteration of reservoir numerical simulation, the topological structure of the current production units (i.e., single wells and well groups) in the offshore oil field to be tested is established, and the same level of the topological structure is defined to include single wells and well groups, such as Figure 2As shown, a well group is a production unit, which can be a production unit including multiple single wells or a production unit including a single well and other well groups, specifically:

[0047] 1.1) For any production unit (perforation, well or well group), there is only one upper-level production unit, but it can include multiple lower-level production units. For example, a well group can belong to the upper-level well group, or it can include the lower-level well group or multiple single wells. A single well usually also contains multiple perforations.

[0048] 1.2) Any production unit may include one or more production units of the same level. For example, multiple wells may belong to the same upper level well group at the same time, and the levels of these wells are the same.

[0049] 2) Set the control state of the current production unit topology and calculate the output and pressure of the production unit topology under the current control state, where the control state includes the well group control state, fixed oil production control state, fixed water production control state, fixed gas production control state, fixed liquid production control state, fixed reservoir volume production control state and fixed bottom hole pressure control state.

[0050] 3) The state machine detects the control state of the current production unit topology structure according to the predefined active and passive control rules and state transition parameters, and updates the control state of the current production unit topology structure, specifically:

[0051] 3.1) Define the control state of the current production unit topology structure into two categories: active control state and passive control state to describe the control state of a single well and a well group. The rules of active control state and passive control state include:

[0052] ① At any time, any production unit has only one active control state and only one control parameter, which includes well group control parameters, oil production control parameters, water production control parameters, gas production control parameters, liquid production control parameters, reservoir volume production control parameters and bottom hole pressure control parameters.

[0053] ② At any time, any production unit can have one or more passive control states, and can poll and calculate the passive control states according to a certain priority.

[0054] ③ In the passive control state, the production unit can transform from the passive control state to the active control state.

[0055] ④ Both the active control state and the passive control state are described by two important parameters: control mode and control parameters.

[0056] ⑤Only well groups and single wells have both active control and passive control states, and perforating only has passive control state.

[0057] ⑥ The priority of the current production unit when it is in the passive control state is lower than that when it is in the active control state. The passive control state is a delayed calculation after the active control state is updated. It limits the control parameters calculated in the active control state and can change the calculation method of the active control state. The passive control state can also be called a restricted state.

[0058] ⑦ The current production unit is in the active control state at the beginning of the simulation. The control parameters corresponding to the current production unit control state play a major role. The remaining parameters are calculated or updated according to the control parameters. The active control state can also be called the control definition state. The parameters calculated under the active control state are the control definition parameters. The control definition is a separate concept, which represents the control mode of the current production unit and the defined parameters and the set of all variables of the state. The control definition state is the state variable, and the control definition parameter is the parameter variable corresponding to a certain state. A control definition state is determined by these two parameters:

[0059] Since the control states set in the present invention include well group control state, fixed oil production control state, fixed water production control state, fixed gas production control state, fixed liquid production control state, fixed reservoir volume production control state and fixed bottom hole pressure control state, the parameters corresponding to these control states are control parameters, including well group control parameters, oil production control parameters, water production control parameters, gas production control parameters, liquid production control parameters, reservoir volume production control parameters and bottom hole pressure control parameters. At the same time, any production unit has only one control state and the control parameters corresponding to the control state, and the remaining control states are temporarily restricted states, and the control parameters corresponding to these control states are called remaining parameters.

[0060] 3.2) According to the actual well control situation of the offshore oil field to be tested, the state transition parameters of the current production unit topology structure are defined, including the transition conditions between the various control states of the current production unit topology structure, as shown in the following table:

[0061]

[0062] The state transition parameters are used to solve the changes of complex well control. For example, if the current control state of the current production unit is the fixed oil production control state S1, and its corresponding oil production C1 is the control parameter, the remaining parameters are C0, C2, C3, C4, C5, and C6, which can include any combination of the above control parameters (C0, C2, C3, C4, C5, and C6). When the current production unit produces with the control parameter C1, the actual remaining parameters will be calculated. If the calculated water production is greater than the control parameter C2, the current production unit will be converted to the fixed water production control state S2. At this time, the water production C2 becomes the control parameter, and the previous oil production C1 becomes the remaining parameters.

[0063] 3.3) The state machine detects the control state of the current production unit topology structure according to the pre-defined active and passive control rules and state transition parameters. When the current production unit topology structure reaches the transition condition of any control state, the original passive control state of the current production unit topology structure is converted into an active control state, and the original active control state of the current production unit topology structure is converted into a passive control state, and the control state of the current production unit topology structure is updated.

[0064] 4) Recalculate the output and pressure of the current production unit topology.

[0065] 5) Go to step 3) to update the control state of the current production unit topology structure until the control state of the current production unit topology structure no longer changes, then go to step 1) to calculate the next production unit, and complete the finite state simulation of the complex well control of the offshore oil field to be tested.

[0066] The finite state simulation method for complex well control in offshore oil fields of the present invention is described in detail below through specific embodiments:

[0067] A numerical simulation model of offshore oil and gas fields is established. A five-point well grid is used for well layout, four injections and one production. The simulation time is 10 years. The grid size is 100*100*40 meters, the grid step size is 50*50*1, and each production well produces a fixed amount of oil. At the same time, the complex well control method of the platform is simulated. The liquid volume, water volume, and bottom hole pressure of the well are controlled separately. Different control conditions are applied. The states and conversion relationships corresponding to each control condition are shown in the following figure. Figure 3 As shown in the figure, the production result curve of a single well (production unit) after calculation is consistent with the actual change situation, such as Figure 4 As shown, it can be seen that the correct state control change is achieved after the complex control conditions are met.

[0068] Based on the above finite state simulation method for complex well control in offshore oil fields, the present invention also provides a finite state simulation system for complex well control in offshore oil fields, comprising:

[0069] The topology building module is used to build the topology of each production unit in the offshore oil field to be tested, and defines that the same level of the topology structure includes single wells and well groups.

[0070] The control state setting module is used to set the control state of each production unit topology structure.

[0071] The parameter calculation module is used to calculate the output and pressure of each production unit topology under the current control state.

[0072] The state machine is used to detect the control state of each production unit topology structure according to predefined active and passive control rules and state conversion parameters, and update the control state of each production unit topology structure.

[0073] In a preferred embodiment, the state machine is provided with:

[0074] The control rule definition unit is used to define the control state of the current production unit topology structure, which is divided into two categories: active control state and passive control state.

[0075] The state transition parameter definition unit is used to define the state transition parameters of the current production unit topology structure according to the actual well control situation of the offshore oil field to be tested, including the transition conditions between the various control states of the current production unit topology structure.

[0076] The control state updating unit is used to update the control state of the current production unit topology structure according to predefined active and passive control rules and state conversion parameters.

[0077] The above embodiments are only used to illustrate the present invention, wherein the structure, connection mode and manufacturing process of each component may be changed. Any equivalent transformations and improvements based on the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. A finite state simulation method for complex well control in offshore oil fields, characterized in that: The following steps are involved: 1) Establish the topological structure of the current production unit in the offshore oil field to be tested, and define that the same level of the topological structure includes single wells and well groups; 2) Setting the control state of the current production unit topology structure and calculating the output and pressure of the production unit topology structure under the current control state; 3) According to the predefined active and passive control rules and state transition parameters, the control state of the current production unit topology structure is detected and the control state of the current production unit topology structure is updated; 4) Recalculate the output and pressure of the current production unit topology; 5) Entering the step 3) to update the control state of the current production unit topology structure until the control state of the current production unit topology structure no longer changes, and then entering the step 1) to calculate the next production unit to complete the finite state simulation of the complex well control of the offshore oil field to be tested; The specific steps of step 3) are: 3.1) Define the control state of the current production unit topology structure into two categories: active control state and passive control state; the rules of active control state and passive control state include: ① At any time, any production unit has only one active control state and only one control parameter; ② At any time, any production unit includes one or more passive control states, and can poll and calculate the passive control states according to a certain priority; ③ In the passive control state, the production unit can transform from the passive control state to the active control state; ④ Both active control state and passive control state include control mode and control parameters; ⑤Only well groups and single wells have both active control and passive control states, and perforating only has passive control state; ⑥ The priority of the current production unit when it is in a passive control state is lower than that when it is in an active control state; ⑦ The current production unit is in active control state at the beginning of the simulation; 3.2) According to the actual well control situation of the offshore oil field to be tested, define the state transition parameters of the current production unit topology structure, including the transition conditions between the various control states of the current production unit topology structure; 3.3) The state machine updates the control state of the current production unit topology according to the predefined active and passive control rules and state transition parameters: The state machine detects the control state of the current production unit topology structure according to the pre-defined active and passive control rules and state transition parameters. When the current production unit topology structure reaches the transition condition of any control state, the original passive control state of the current production unit topology structure is converted into an active control state, and the original active control state of the current production unit topology structure is converted into a passive control state, and the control state of the current production unit topology structure is updated.

2. A finite state simulation method for complex well control in an offshore oil field as claimed in claim 1, characterized in that: In the step 1), for any production unit, there is only one upper-level production unit, but it can include multiple lower-level production units; for any production unit, it can include one or more production units at the same level.

3. The finite state simulation method for complex well control in an offshore oil field according to claim 1, characterized in that: The control status of the current production unit topology structure includes a well group control status, a fixed oil production control status, a fixed water production control status, a fixed gas production control status, a fixed liquid production control status, a fixed reservoir volume production control status and a fixed bottom hole pressure control status.

4. The finite state simulation method for complex well control in an offshore oil field according to claim 1, characterized in that: The control parameters include well group control parameters, oil production control parameters, water production control parameters, gas production control parameters, liquid production control parameters, reservoir volume production control parameters and bottom hole flow pressure control parameters.

5. A finite state simulation system for complex well control in offshore oil fields, characterized in that: include: A topology building module is used to build the topology of each production unit in the offshore oil field to be tested, and define that the same level of the topology structure includes single wells and well groups; A control state setting module is used to set the control state of each production unit topology structure; Parameter calculation module, used to calculate the output and pressure of each production unit topology under the current control state; A state machine is used to detect the control state of each production unit topology structure according to predefined active and passive control rules and state transition parameters, and update the control state of each production unit topology structure; The state machine is provided with: The control rule definition unit is used to define the control state of the current production unit topology structure, which is divided into two categories: active control state and passive control state; The rules for active control state and passive control state include: ① At any time, any production unit has only one active control state and only one control parameter; ② At any time, any production unit includes one or more passive control states, and can poll and calculate the passive control states according to a certain priority; ③ In the passive control state, the production unit can transform from the passive control state to the active control state; ④ Both active control state and passive control state include control mode and control parameters; ⑤Only well groups and single wells have both active control and passive control states, and perforating only has passive control state; ⑥ The priority of the current production unit when it is in a passive control state is lower than that when it is in an active control state; ⑦ The current production unit is in the active control state at the beginning of the simulation; the state transition parameter definition unit is used to define the state transition parameters of the current production unit topology structure according to the actual well control situation of the offshore oil field to be tested, including the transition conditions between the various control states of the current production unit topology structure; The control state updating unit is used to update the control state of the current production unit topology according to the predefined active and passive control rules and state transition parameters: The state machine detects the control state of the current production unit topology structure according to the pre-defined active and passive control rules and state transition parameters. When the current production unit topology structure reaches the transition condition of any control state, the original passive control state of the current production unit topology structure is converted into an active control state, and the original active control state of the current production unit topology structure is converted into a passive control state, and the control state of the current production unit topology structure is updated.

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