An intelligent pressure control system and pressure control method for unconventional gas wells

Abstract

The present invention discloses an unconventional gas well intelligent pressure control system and pressure control method, and relates to the field of unconventional gas well production. It includes a detection unit group, a data transmission unit, a nozzle control unit, a control judgment unit and a remote real-time monitoring terminal; the data transmission unit sends the detection data of the detection unit group to the remote real-time monitoring terminal and the control judgment unit; the remote real-time monitoring terminal summarizes the monitoring data and calculates the reasonable state data of the gas well; the control judgment unit obtains the detection data and the reasonable state data, and generates control information through the detection data and the reasonable state data to transmit it to the nozzle control unit; the nozzle control unit controls the opening size of the nozzle according to the control information. The liquid carrying capacity and gas production of the gas well are stable, and the probability of crack closure and permeability reduction in the gas well is reduced, thereby effectively extending the production life of the gas well.

Description

Technical Field

[0001] The present invention relates to the field of unconventional gas well production, and in particular to an intelligent pressure control system and a pressure control method for unconventional gas wells. Background Art

[0002] In recent years, with the advancement of exploration and development technology, unconventional gas fields have gradually begun to be developed. However, whether it is the shale gas reservoirs in the Sichuan and Chongqing areas or the tight gas reservoirs in the Sulige area, there are generally geological characteristics such as low permeability, low production, and strong heterogeneity, and the single gas well controlled reserves are low. At this stage, unconventional gas wells usually adopt the "horizontal well + hydraulic fracturing" production method, and the gas well production dynamics show a two-stage production feature. In the early stage of production, a large-diameter blowout prevention production method was adopted, which led to a rapid decline in gas well pressure and production. Most wells had continuous sand production during the production process, which may further lead to fracture closure and permeability decline; in the later period, the pressure drop trend slowed down significantly, but the formation energy was insufficient, production was unstable, and gas well flooding was prone to occur.

[0003] The Christmas tree is a wellhead device used for gas well production. The Christmas tree is the main equipment for controlling and regulating oil and gas production at the top of the gas well. It is composed of valves, reducers, nozzles and pipeline accessories. It is a device used to control production and provide conditions for well repair operations such as steel wire, cable, and continuous oil pipe. The nozzle is a component on the Christmas tree used to control the flow of the oil well. It is installed between the wing valve and the oil flow pipeline. The nozzle is mainly adjustable. The throttle hole of the adjustable nozzle is a number of small holes distributed on the tubular part. The change in the number of small holes covered by the outer sleeve of the tubular part moving axially is the change in the flow area.

[0004] Formation pressure has an impact on gas well productivity, especially on unconventional gas wells. As formation pressure decreases, the open-flow rate of gas wells gradually decreases. Therefore, during the production process of gas wells, formation energy must be used reasonably, otherwise the gas well productivity will decrease rapidly as formation pressure decreases. Therefore, for unconventional gas wells, pressure control should be done well and a reasonable production system should be formulated from the early stage of production to maintain formation energy, maintain gas well productivity, and maximize the final recovery rate of gas wells. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides an intelligent pressure control system and a pressure control method for unconventional gas wells, which are capable of controlling the stable production of unconventional gas wells.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0007] Provided is an intelligent pressure control system for unconventional gas wells, comprising a detection unit group, a data sending unit, a nozzle control unit, a control determination unit and a remote real-time monitoring terminal; the data sending unit sends detection data of the detection unit group to the remote real-time monitoring terminal and the control determination unit; the remote real-time monitoring terminal aggregates the monitoring data and calculates reasonable state data of the gas well; the control determination unit acquires the detection data and reasonable state data, determines the generation of control information based on the detection data and the reasonable state data, and transmits it to the nozzle control unit; the nozzle control unit controls the opening size of the nozzle according to the control information.

[0008] Furthermore, the detection unit group includes a pressure detection unit of the gas well and a production detection unit of the gas well; the pressure detection unit includes a casing pressure detection unit for detecting casing pressure, a tubing pressure detection unit for detecting tubing pressure, a pipeline pressure detection unit for detecting outlet pipe pressure, and a bottom hole pressure detection unit for detecting bottom hole pressure; the production detection unit includes a gas production detection unit and a liquid production detection unit; the casing pressure detection unit, the tubing pressure detection unit, the pipeline pressure detection unit and the bottom hole pressure detection unit are respectively installed on the casing of the gas well, the tubing of the gas well, the outlet pipe of the gas well and the bottom of the well; the gas production detection unit and the liquid production detection unit are both installed on the outlet pipe of the gas well.

[0009] Furthermore, the nozzle control unit is connected to the nozzle of the pipeline node on the gas tree.

[0010] Furthermore, the control determination unit includes an RTU processing module and a control information transmission module. The built-in determination logic of the RTU processing module determines and generates control information. The control information transmission module transmits the control information to the nozzle control unit, and the control information transmission module generates control log information and transmits it back to the remote real-time monitoring terminal.

[0011] A pressure control method using an unconventional gas well intelligent pressure control system comprises the following steps:

[0012] S1: The pressure detection unit collects the pressure at the pipeline node at each time point during gas well production to obtain a node pressure value collection R, and the data sending unit sends the node pressure value collection R to the remote real-time monitoring terminal;

[0013] S2: The remote real-time monitoring terminal collects the node pressure value set R of all gas wells in the same geological area and calculates the reasonable node pressure drop factor K;

[0014] S3: The pressure detection unit detects and collects the actual pressure P of the nodes of the gas wells to be controlled in the same geological area. t The production detection unit detects and collects the current gas production Q of the gas well to be controlled; the data sending unit sends the actual node pressure P t And the current gas production Q is sent to the remote real-time monitoring terminal;

[0015] S4: Remote real-time monitoring end through the actual node pressure P t Calculate the critical flow rate of continuous liquid carrying at the node Q g ; The remote real-time monitoring terminal calculates the node reasonable pressure drop factor K and the node continuous liquid carrying critical flow rate Q g Sending to the control and determination unit;

[0016] S5: The RTU processing module determines whether the current gas production Q is greater than the critical flow rate for continuous liquid carrying Q g ; If yes, go to S6; otherwise, the RTU processing module generates the nozzle opening increase information and goes to S7;

[0017] S6: The RTU processing module calculates the actual pressure P t With theoretical pressure P r The difference ΔP is determined by comparing the difference ΔP with the maximum difference threshold ΔP. max The minimum difference threshold ΔP min relationship;

[0018] When ΔP>ΔP max , the RTU processing module generates the information of reducing the nozzle opening;

[0019] When ΔP<ΔP min , the RTU processing module generates the nozzle opening increase information;

[0020] When ΔP min <ΔP<ΔP max , the RTU processing module generates the nozzle opening holding information;

[0021] S7: The control information transmission module transmits the control information generated by the RTU processing module to the nozzle control unit; and the control information transmission module generates control log information based on the control information and transmits it back to the remote real-time monitoring terminal;

[0022] S8: The nozzle control unit controls and adjusts the nozzle corresponding to the pipeline node according to the control information.

[0023] Furthermore, the pipeline node includes a casing node, a tubing node, a pipeline node or a bottom hole node.

[0024] Furthermore, the calculation method of the reasonable node voltage drop factor K is:

[0025] ;

[0026] ;

[0027] in,n is the number of gas wells in the same geological area, k i is the actual pressure drop factor of the gas well; Δ t is the time step, Δ p i is the pressure drop value at the pipeline node under the time step.

[0028] Furthermore, the critical flow rate of continuous liquid carrying at the node Q g The calculation method is:

[0029] ;

[0030] in, σ is the surface tension of natural gas water, is the pipe diameter at the node, C is the impact factor.

[0031] Furthermore, the calculation method of the difference ΔP is:

[0032] ;

[0033] ;

[0034] Among them, P r is the theoretical node pressure, P i is the node pressure at the beginning of gas well production, and t is the production time.

[0035] The beneficial effects of the present invention are:

[0036] The present invention detects the pressure on the pipeline node of the unconventional gas well through the detection unit group, collects and sends the pressure information to the control judgment unit and the remote real-time monitoring terminal, and generates control information for the nozzle after judging the collected information through the judgment logic built into the control judgment unit. The nozzle control unit controls the nozzle on the pipeline node according to the control information, thereby completing the intelligent pressure control production of the unconventional gas well, so that the pressure of the unconventional gas well drops smoothly during the production process, and reduces the occurrence of continuous sand production in the gas well during the production process. The gas well carries stable liquid and gas production, and at the same time reduces the probability of crack closure and permeability reduction in the gas well, thereby effectively extending the production life of the gas well. The staff can remotely monitor the timely production status of the gas well and the nozzle adjustment information based on the gas production data and control log information of the gas well, without having to be dispatched to the gas well, saving manpower. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A flow chart of a pressure control method using an intelligent pressure control system for unconventional gas wells;

[0038] Figure 2 This is a schematic diagram of gas well production in Sichuan and Chongqing;

[0039] Figure 3 This is a schematic diagram of gas well production simulated using the pressure control method of the present invention. DETAILED DESCRIPTION

[0040] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0041] An intelligent pressure control system for unconventional gas wells comprises a detection unit group, a data transmission unit, a nozzle control unit, a control determination unit and a remote real-time monitoring terminal; the data transmission unit transmits the detection data of the detection unit group to the remote real-time monitoring terminal and the control determination unit; the remote real-time monitoring terminal summarizes the monitoring data and calculates reasonable state data of the gas well; the control determination unit obtains the detection data and reasonable state data, generates control information through the detection data and reasonable state data, and transmits it to the nozzle control unit; the nozzle control unit controls the opening size of the nozzle according to the control information.

[0042] The detection unit group includes a pressure detection unit of the gas well and a production detection unit of the gas well; the pressure detection unit includes a casing pressure detection unit for detecting casing pressure, a tubing pressure detection unit for detecting tubing pressure, a pipeline pressure detection unit for detecting outlet pipe pressure, and a bottom hole pressure detection unit for detecting bottom hole pressure; the production detection unit includes a gas production detection unit and a liquid production detection unit; the casing pressure detection unit, the tubing pressure detection unit, the pipeline pressure detection unit and the bottom hole pressure detection unit are respectively installed on the casing of the gas well, the tubing of the gas well, the outlet pipe of the gas well and the bottom of the well; the gas production detection unit and the liquid production detection unit are both installed on the outlet pipe of the gas well.

[0043] The nozzle control unit is connected to the nozzle of the pipeline node on the gas tree.

[0044] The control determination unit includes an RTU processing module and a control information transmission module. The built-in determination logic of the RTU processing module determines and generates control information. The control information transmission module transmits the control information to the nozzle control unit, and the control information transmission module generates control log information and transmits it back to the remote real-time monitoring terminal.

[0045] like Figure 1 As shown, a pressure control method using an unconventional gas well intelligent pressure control system comprises the following steps:

[0046] S1: The pressure detection unit collects the pressure at the pipeline node at each time point during gas well production to obtain a node pressure value collection R, and the data sending unit sends the node pressure value collection R to the remote real-time monitoring terminal;

[0047] The casing pressure detection unit collects the pressure at the casing node during gas well production to obtain a casing node pressure value collection R1; the tubing pressure detection unit collects the pressure at the tubing node during gas well production to obtain a tubing node pressure value collection R2; the pipeline pressure detection unit collects the pressure at the gas outlet pipe node during gas well production to obtain a pipeline node pressure value collection R3; the bottom hole pressure detection unit collects the pressure at the bottom hole node during gas well production to obtain a bottom hole node pressure value collection R4.

[0048] S2: Remote real-time monitoring terminal summarizes the same geological area n The node pressure value set R{R1, R2, R3, R4} of each gas well is used to calculate the reasonable pressure drop factor K1 of the casing node; the reasonable pressure drop factor K2 of the tubing node; the reasonable pressure drop factor K3 of the pipeline node and the reasonable pressure drop factor K4 of the bottom hole node;

[0049] The calculation method of the reasonable node pressure drop factor K is:

[0050] ;

[0051] ;

[0052] in, n is the number of gas wells in the same geological area, k i is the actual pressure drop factor of the node of the gas well; Δ t is the time step, Δ p i is the pressure drop value at the pipeline node under the time step.

[0053] S3: The pressure detection unit detects and collects the actual node pressure P of the gas well to be controlled in the same geological area. t The production detection unit detects and collects the current gas production Q of the gas well to be controlled; the data sending unit sends the actual node pressure P t And the current gas production Q is sent to the remote real-time monitoring terminal;

[0054] When it is necessary to control the pressure of the gas well to be controlled, the same geological area is selected to collect and calculate the reasonable pressure drop factor of each pipeline node, and the pressure at each pipeline node of the gas well to be controlled is detected and collected using a pressure detection unit, and steps S4-S8 are used to control the pressure of each pipeline node to achieve pressure controlled production of the entire gas well.

[0055] S4: Remote real-time monitoring end through the actual node pressure P t Calculate the critical flow rate of continuous liquid carrying at the node Q g ; The remote real-time monitoring terminal calculates the node reasonable pressure drop factor K and the node continuous liquid carrying critical flow rate Q g Sending to the control and determination unit;

[0056] Critical flow rate of continuous liquid carrying at the node Q g The calculation method is:

[0057] ;

[0058] in, σ is the surface tension of natural gas water, is the pipe diameter at the node, C is the impact factor.

[0059] S5: The RTU processing module determines whether the current gas production Q is greater than the critical flow rate for continuous liquid carrying Q g ; If not, the RTU processing module generates the nozzle opening increase information and enters S7; otherwise, it enters S6;

[0060] S6: The RTU processing module calculates the actual pressure P t With theoretical pressure P r The difference ΔP,

[0061] The calculation method of the difference ΔP is:

[0062] ;

[0063] ;

[0064] Among them, P r is the theoretical node pressure, P i is the node pressure at the beginning of gas well production, and t is the production time. According to the different pipeline nodes controlled, K1, K2, K3 or K4 are selected as K to be brought into the operation logic formula of the difference ΔP.

[0065] Determine the difference ΔP and the maximum difference threshold ΔP max The minimum difference threshold ΔP min relationship;

[0066] When ΔP>ΔP max , the RTU processing module generates the information of reducing the nozzle opening;

[0067] When ΔP<ΔP min , the RTU processing module generates the nozzle opening increase information;

[0068] When ΔP min <ΔP<ΔP max , the RTU processing module generates the nozzle opening holding information;

[0069] S7: The control information transmission module transmits the control information generated by the RTU processing module to the nozzle control unit; and the control information transmission module generates control log information based on the control information and transmits it back to the remote real-time monitoring terminal;

[0070] S8: The nozzle control unit controls and adjusts the nozzle corresponding to the pipeline node according to the control information.

[0071] like Figure 2 As shown in FIG. 1 , a production data curve of a gas well in Sichuan and Chongqing without using the pressure control method of the present invention is selected. The pressure control method of the present invention is used to control the pressure of the gas well in the simulation software, and the production data is shown in FIG. Figure 3 As shown. Figure 2 and Figure 3 It can be clearly seen from the comparison that after using the pressure-controlled production of the present invention, the pressure and daily gas and liquid production of the gas well are more stable, thereby reducing the occurrence of continuous sand production in the gas well during the production process. At the same time, the probability of crack closure and permeability reduction in the gas well is reduced, thereby effectively extending the production life of the gas well.

[0072] The present invention detects the pressure on the pipeline node of the unconventional gas well through the detection unit group, collects and sends the pressure information to the control judgment unit and the remote real-time monitoring terminal, and generates control information for the nozzle after judging the collected information through the judgment logic built into the control judgment unit. The nozzle control unit controls the nozzle on the pipeline node according to the control information, thereby completing the intelligent pressure control production of the unconventional gas well, so that the pressure of the unconventional gas well drops smoothly during the production process, and reduces the occurrence of continuous sand production in the gas well during the production process. The gas well carries stable liquid and gas production, and at the same time reduces the probability of crack closure and permeability reduction in the gas well, thereby effectively extending the production life of the gas well. The staff can remotely monitor the timely production status of the gas well and the nozzle adjustment information based on the gas production data and control log information of the gas well, without having to be dispatched to the gas well, saving manpower.

Claims

1. A pressure control method using an intelligent pressure control system for unconventional gas wells, the intelligent pressure control system for unconventional gas wells comprising a detection unit group, a data sending unit, a nozzle control unit, a control determination unit and a remote real-time monitoring terminal; the data sending unit sends the detection data of the detection unit group to the remote real-time monitoring terminal and the control determination unit; the remote real-time monitoring terminal summarizes the monitoring data and calculates reasonable state data of the gas well; the control determination unit obtains the detection data and reasonable state data, generates control information through the detection data and reasonable state data, and transmits it to the nozzle control unit; the nozzle control unit controls the opening size of the nozzle according to the control information; the detection unit group comprises a pressure detection unit of the gas well and a production detection unit of the gas well; the pressure detection unit comprises a casing pressure detection unit for detecting casing pressure, a tubing pressure detection unit for detecting tubing pressure, A pipeline pressure detection unit for detecting the pressure of the gas outlet pipe and a bottom hole pressure detection unit for detecting the bottom hole pressure; the production detection unit includes a gas production detection unit and a liquid production detection unit; the casing pressure detection unit, the oil pipe pressure detection unit, the pipeline pressure detection unit and the bottom hole pressure detection unit are respectively installed on the casing of the gas well, the oil pipe of the gas well, the gas outlet pipe and the bottom of the well; the gas production detection unit and the liquid production detection unit are both installed on the gas outlet pipe of the gas well; the nozzle control unit is connected to the nozzle of the pipeline node on the gas production tree; the control judgment unit includes an RTU processing module and a control information transmission module, the built-in judgment logic of the RTU processing module judges and generates control information, the control information transmission module transmits the control information to the nozzle control unit, and the control information transmission module generates control log information and transmits it back to the remote real-time monitoring terminal, characterized in that, The steps include: S1: The pressure detection unit collects the pressure at the pipeline node at each time point during gas well production to obtain a node pressure value collection R, and the data sending unit sends the node pressure value collection R to the remote real-time monitoring terminal; S2: The remote real-time monitoring terminal collects the node pressure value set R of all gas wells in the same geological area and calculates the reasonable node pressure drop factor K; S3: The pressure detection unit detects and collects the actual pressure P of the nodes of the gas wells to be controlled in the same geological area. t The production detection unit detects and collects the current gas production Q of the gas well to be controlled; the data sending unit sends the actual node pressure P t And the current gas production Q is sent to the remote real-time monitoring terminal; S4: Remote real-time monitoring end through the actual node pressure P t Calculate the critical flow rate of continuous liquid carrying at the node Q g ; The remote real-time monitoring terminal calculates the node reasonable pressure drop factor K and the node continuous liquid carrying critical flow rate Q g Sending to the control and determination unit; S5: The RTU processing module determines whether the current gas production Q is greater than the critical flow rate for continuous liquid carrying Q g ; If yes, go to S6; Otherwise, the RTU processing module generates information about increasing the nozzle opening and enters S7; S6: The RTU processing module calculates the actual node pressure P t and theoretical node pressure P r The difference ΔP is determined by comparing the difference ΔP with the maximum difference threshold ΔP. max The minimum difference threshold ΔP min relationship; When ΔP>ΔP max , the RTU processing module generates the information of reducing the nozzle opening; When ΔP<ΔP min , the RTU processing module generates the nozzle opening increase information; When ΔP min <ΔP<ΔP max , the RTU processing module generates the nozzle opening holding information; S7: The control information transmission module transmits the control information generated by the RTU processing module to the nozzle control unit; and the control information transmission module generates control log information based on the control information and transmits it back to the remote real-time monitoring terminal; S8: The nozzle control unit controls and adjusts the nozzle corresponding to the pipeline node according to the control information.

2. The pressure control method of the unconventional gas well intelligent pressure control system according to claim 1, characterized in that: The pipeline node includes a casing node, a tubing node, a pipeline node or a bottom hole node.

3. The pressure control method of the unconventional gas well intelligent pressure control system according to claim 1, characterized in that: The calculation method of the reasonable node pressure drop factor K is: ； ； in, n is the number of gas wells in the same geological area, k i is the actual pressure drop factor of the gas well; Δ t is the time step, Δ p i is the pressure drop value at the pipeline node under the time step.

4. The pressure control method of the unconventional gas well intelligent pressure control system according to claim 1, characterized in that: The critical flow rate of continuous liquid carrying at the node Q g The calculation method is: ； in, σ is the surface tension of natural gas water, is the pipe diameter at the node, C is the impact factor.

5. The pressure control method of the unconventional gas well intelligent pressure control system according to claim 1, characterized in that: The calculation method of the difference ΔP is: ； ； Among them, P r is the theoretical node pressure, P i is the node pressure at the beginning of gas well production, and t is the production time.

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