Throttling type process temperature automatic control method for offshore test

Abstract

The invention discloses a throttling type process temperature automatic control method for offshore testing, which comprises the following steps: step 1, according to a sampling period, collecting an electric control throttling oil nozzle upstream temperature, an electric control throttling oil nozzle downstream temperature, an electric control throttling oil nozzle upstream pressure and an electric control throttling oil nozzle downstream pressure; 2, the size of the oil nozzle is adjusted according to the collected various parameters of the electric control throttling oil nozzle, and the size of the electric control throttling oil nozzle after preliminary adjustment is obtained; and thirdly, under the preliminarily adjusted size of the electric control throttling oil nozzle, the size of the target oil nozzle is obtained according to the downstream temperature of the electric control throttling oil nozzle. The device has the characteristics of high-temperature gas cooling, equipment miniaturization, high efficiency, environmental protection and energy conservation.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas drilling and production, and more particularly to a throttling process temperature automatic control method for offshore testing. Background Art

[0002] When high-temperature natural gas flows from the bottom of the well to the wellhead, it may still remain at a high temperature, posing a significant threat to surface equipment and connecting pipelines (collectively, the "process"). Deepwater / ultra-deepwater oil and gas testing platforms typically utilize floating semi-submersible drilling platforms, which are subject to erratic heaving and swaying due to wind and waves. In these conditions, high-pressure flexible hoses are required to connect the surface test tree and the surface equipment at the test wellhead to mitigate the effects of platform movement. (The surface test tree is connected to the test string and is not affected by platform movement, while the surface equipment is placed on the semi-submersible platform, and there is relative displacement between the two.) Currently, the maximum operating temperature of high-pressure flexible hoses is 130°C (the temperature limit of existing technology). While the service life of high-pressure flexible hoses is unlimited between -20°C and 100°C, their service life is shortened to several dozen hours at temperatures between 0°C and 130°C, and to just one hour at temperatures between 130°C and 160°C, after which they must be scrapped. Furthermore, high-pressure flexible hoses are extremely expensive to purchase, with top-tier brands costing millions of RMB. Therefore, high-temperature fluids can cause significant economic losses to testing operations.

[0003] To ensure the safety of downstream processes and protect high-pressure flexible hoses, the natural gas temperature must typically be lowered to within the applicable process range (typically <100°C). This cooling must be performed in the confined space of a wellhead, making it unsuitable for large cooling devices (which must be installed at the outlet of a ground test tree, located 5 to 10 meters above the ground, limiting both the installation space and weight). As is well known, the Joule-Thomson effect causes high-temperature natural gas to rapidly cool and reduce pressure after passing through a throttling nozzle. Throttling can be achieved by adding a nozzle. A smaller nozzle results in a more pronounced temperature drop, paving the way for smaller and lighter equipment.

[0004] Therefore, it is urgent to develop a method or structure that can automatically control the size of the throttle nozzle, so as to achieve the purpose of process cooling and protect the downstream high-pressure flexible hose. Summary of the Invention

[0005] The purpose of the present invention is to design and develop a throttling process temperature automatic control method for offshore testing, which adjusts the nozzle size according to multiple real-time electronically controlled throttling nozzle parameters to achieve the purpose of process cooling and protect the downstream high-pressure flexible hose.

[0006] The technical solution provided by the present invention is:

[0007] A method for automatically controlling the temperature of a throttling process for offshore testing comprises the following steps:

[0008] Step 1: Collect the temperature upstream of the electronically controlled throttle nozzle, the temperature downstream of the electronically controlled throttle nozzle, the pressure upstream of the electronically controlled throttle nozzle, and the pressure downstream of the electronically controlled throttle nozzle according to the sampling period;

[0009] Step 2: adjusting the nozzle size according to the collected parameters of the various electronically controlled throttle nozzles to obtain the electronically controlled throttle nozzle size after preliminary adjustment;

[0010] The nozzle size satisfies:

[0011]

[0012] Where, d i is the size of the electronically controlled throttle nozzle in the i-th sampling period, i=0,1, Q i is the natural gas production in the i-th sampling period, γ is the gas density, is the upstream temperature of the electronically controlled throttling nozzle in the i-th sampling period, is the upstream pressure of the nozzle in the i-th sampling period, λ i k is the ratio of the pressure downstream of the nozzle to the pressure upstream of the nozzle in the i-th sampling period, s Calculate the adiabatic index for the nozzle;

[0013] Step 3: After the initial adjustment of the electronically controlled throttle nozzle size, obtain the target nozzle size according to the downstream temperature of the electronically controlled throttle nozzle:

[0014] If |s|>3 and s<0, it means that the downstream temperature of the electronically controlled throttle nozzle is greater than the target downstream temperature, and the nozzle size needs to be reduced to d=d1-2;

[0015] If |s|>3 and s≥0, it means that the downstream temperature of the electronically controlled throttle nozzle is lower than the target downstream temperature, and the nozzle size needs to be increased to d=d1+2;

[0016] Where d is the target nozzle size, s is the temperature difference downstream of the electronically controlled throttle nozzle;

[0017] Step 4: Continuously adjust the nozzle size based on the various electronically controlled throttle nozzle parameters collected during the sampling period.

[0018] Preferably, the temperature upstream of the electronically controlled throttle nozzle and the temperature downstream of the electronically controlled throttle nozzle are both collected by a temperature monitoring device;

[0019] The pressure upstream of the electronically controlled throttle nozzle and the pressure downstream of the electronically controlled throttle nozzle are both collected through a pressure monitoring device.

[0020] Preferably, the step 2 specifically includes:

[0021] Step 1: determining target parameters of the electronically controlled throttle nozzle;

[0022] Step 2: Calculate the initial value of the pressure downstream of the nozzle;

[0023] Step 3: Calculate the ratio of the pressure downstream of the nozzle to the pressure upstream of the nozzle in the i-th sampling period:

[0024] Step 4: Calculate the initial value of the nozzle size;

[0025] Step 5: Adjust the initial value of the nozzle size according to the collected parameters of the various electronically controlled throttle nozzles to obtain the electronically controlled throttle nozzle size after preliminary adjustment.

[0026] Preferably, the target parameters include: expected natural gas production, expected wellhead temperature, expected wellhead pressure, gas density and target downstream temperature.

[0027] Preferably, the initial value of the pressure downstream of the nozzle satisfies:

[0028]

[0029] Where Q0 is the expected natural gas production, is the expected wellhead temperature, is the estimated wellhead pressure, and λ0 is the initial value of the ratio of the pressure downstream of the nozzle to the pressure upstream of the nozzle.

[0030] Preferably, the ratio of the pressure downstream of the nozzle to the pressure upstream of the nozzle in the i-th sampling period satisfies:

[0031]

[0032] Where, is the downstream pressure of the nozzle in the i-th sampling period.

[0033] Preferably, the initial value of the pressure downstream of the nozzle satisfies:

[0034]

[0035] Where, is the initial value of the temperature downstream of the nozzle, is the expected wellhead temperature, is the expected wellhead pressure, k is the insulation coefficient, is the initial value of the pressure downstream of the nozzle.

[0036] Preferably, the temperature difference downstream of the electronically controlled throttle nozzle satisfies:

[0037]

[0038] Among them, T1 2′It is the downstream temperature under the electronically controlled throttle nozzle size after preliminary adjustment.

[0039] Preferably, the sampling period is 10 seconds.

[0040] Preferably, it also includes:

[0041] If the downstream temperature of the electronically controlled throttle nozzle after preliminary adjustment is greater than the set target downstream temperature for more than 1 minute, an alarm will be issued to prompt human intervention.

[0042] The beneficial effects of the present invention are:

[0043] (1) The present invention designs and develops a throttling process temperature automatic control method for offshore testing, which achieves the purpose of cooling high-temperature gas through gas throttling control based on the Joule-Thomson effect, thereby ensuring the safety of downstream high-pressure flexible hoses and reducing or avoiding operational risks and economic losses in offshore high-temperature natural gas exploration and testing.

[0044] (2) The present invention designs and develops a throttling process temperature automatic control method for offshore testing. The throttling cooling method creates conditions for miniaturization of equipment and cooling of wellheads in small spaces. At the same time, the method has the advantages of high efficiency, environmental protection, and energy saving. It simplifies the equipment lifting and installation procedures, improves operating efficiency, and does not require the provision of coolant and the consumption of fuel and electricity, thereby greatly reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The figure is a flow chart of the automatic temperature control method of the throttling process for offshore testing according to the present invention.

[0046] Figure 2 This is a schematic diagram of the system structure of the throttling process temperature automatic control method for offshore testing according to the present invention. DETAILED DESCRIPTION

[0047] The present invention will be further described below in detail with reference to the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0048] like Figure 1 As shown, the present invention provides a throttling process temperature automatic control method for offshore testing, comprising the following steps:

[0049] Step 1: Collect the temperature upstream of the electronically controlled throttle nozzle, the temperature downstream of the electronically controlled throttle nozzle, the pressure upstream of the electronically controlled throttle nozzle, and the pressure downstream of the electronically controlled throttle nozzle according to the sampling period;

[0050] Among them, such as Figure 2As shown, the electronically controlled throttle nozzle is arranged between a ground test tree 1 and a high-pressure flexible hose 7, which is connected to a ground pipeline 8. A temperature monitoring device 2 and a pressure monitoring device 3 are provided between the electronically controlled throttle nozzle 4 and the ground test tree 1 for collecting the upstream temperature and upstream pressure of the electronically controlled throttle nozzle. A temperature monitoring device 5 and a pressure monitoring device 6 are also provided between the electronically controlled throttle nozzle 4 and the high-pressure flexible hose 7 for collecting the downstream temperature and downstream pressure of the electronically controlled throttle nozzle. The two temperature monitoring devices and the two pressure monitoring devices are connected to a control center 9 for data transmission and processing. The control center 9 is also used to control the size of the electronically controlled throttle nozzle 4.

[0051] Step 2: Adjust the nozzle size according to the collected parameters of the various electronically controlled throttle nozzles to obtain the size of the electronically controlled throttle nozzle after preliminary adjustment. Specifically:

[0052] Step 1: determining target parameters of the electronically controlled throttle nozzle;

[0053] The target parameters include: expected natural gas production Q0, expected wellhead temperature Estimated wellhead pressure Gas specific gravity γ and target downstream temperature T 目标 ;

[0054] Step 2: Calculate the initial value of the pressure downstream of the nozzle;

[0055] Among them, since the speed of gas passing through the electronically controlled throttle nozzle is very fast and the heat exchange with the outside world is approximately zero, it is considered that the process of gas passing through the fixed electronically controlled throttle nozzle is an isentropic expansion process. According to the state equation of ideal gas:

[0056] PV = nRT;

[0057] Where P refers to pressure, unit is pa, V refers to volume, unit is m 3 , n refers to the number of moles of gas (the mass of the gas divided by the molar mass of the gas); R is the molar gas constant, generally R = 8.31 in SI units; T is the gas temperature, generally in Kelvin (K);

[0058] Since the isentropic process satisfies:

[0059] Pv k =con;

[0060] Where con is a constant.

[0061] Combining the above two equations, we can get:

[0062]

[0063] Where, is the upstream temperature of the electronically controlled throttle nozzle (i.e., the temperature before throttling) in the i-th sampling period, in K; is the nozzle downstream temperature of the i-th sampling period (i.e., the set temperature after throttling), unit K; is the upstream pressure of the nozzle in the i-th sampling period (i.e., the wellhead pressure before throttling), unit: MPa; is the downstream pressure of the nozzle (i.e., the pressure after throttling) in the i-th sampling period, in MPa; k is the insulation coefficient;

[0064] The upstream and downstream temperatures of the electronically controlled throttle nozzle both meet the following requirements:

[0065] (T (K) =273.15+T (℃) )

[0066] Where, T (K) is the Kelvin temperature, T (℃) is degrees Celsius;

[0067] Let i = 0, 目标 , substitute into the above formula to obtain the initial value of the pressure downstream of the nozzle

[0068] Step 3: Calculate the ratio of the pressure downstream of the nozzle to the pressure upstream of the nozzle in the i-th sampling period:

[0069]

[0070] Step 4, calculate the initial value d0 of the nozzle size;

[0071] The nozzle size satisfies:

[0072]

[0073] Where, d i is the size of the electronically controlled throttle nozzle in the i-th sampling period, i = 0, 1, unit: mm; Q i is the natural gas production in the i-th sampling period, in Nm 3 / d (cubic meters per day); γ is the gas density; k s Calculate the adiabatic index for the nozzle;

[0074] When i=0, the initial value of the nozzle size d0 can be calculated;

[0075] Step 5: Adjust the initial value of the nozzle size according to the collected parameters of the various electronically controlled throttle nozzles to obtain the electronically controlled throttle nozzle size d1 after preliminary adjustment;

[0076] The plurality of electronically controlled throttle nozzle parameters include: electronically controlled throttle nozzle upstream temperature, electronically controlled throttle nozzle downstream temperature, electronically controlled throttle nozzle upstream pressure, electronically controlled throttle nozzle downstream pressure, natural gas production and gas specific gravity;

[0077] Step 3: After the initial adjustment of the electronically controlled throttle nozzle size, obtain the target nozzle size according to the downstream temperature of the electronically controlled throttle nozzle:

[0078] If |s|>3 and s<0, it means that the downstream temperature of the electronically controlled throttle nozzle is greater than the target downstream temperature, and the nozzle size needs to be reduced to d=d1-2mm;

[0079] If |s|>3 and s≥0, it means that the downstream temperature of the electronically controlled throttle nozzle is lower than the target downstream temperature, and the nozzle size needs to be increased to d=d1+2mm;

[0080] Where d is the target nozzle size, s is the temperature difference downstream of the electronically controlled throttle nozzle, and they satisfy:

[0081] s=T 目标 -T1 2′ ;

[0082] Among them, T1 2′ is the downstream temperature under the electronically controlled throttle nozzle size after preliminary adjustment;

[0083] Step 4: Continuously adjust the nozzle size according to the various electronically controlled throttle nozzle parameters collected during the sampling period, that is, repeat steps 1 to 3.

[0084] In this embodiment, the sampling period is 10 seconds.

[0085] In this embodiment, the thermal insulation coefficient is 1.11, and the calculated thermal insulation index of the nozzle is 1.3.

[0086] In this embodiment, the maximum size of the electronically controlled throttle nozzle is generally 2 inches, and if the system instruction exceeds 2 inches, the maximum size remains unchanged at 2 inches.

[0087] In this embodiment, λ i Usually greater than 0.54, if λ i If it is less than 0.54, the system will issue a warning (λ i A throttling flow less than 0.54 becomes critical flow. To ensure the accuracy of data acquisition during oil and gas testing, the last level of throttling is usually set to critical flow, rather than at the wellhead).

[0088] At the same time, when the downstream temperature T1 under the electronically controlled throttle nozzle size after preliminary adjustment 2′ The temperature is higher than the set target temperature T for more than 1 minute continuously. 目标 A warning will also be issued, prompting human intervention to eliminate the fault and avoid the risk of overheating.

[0089] The present invention designs and develops a throttling process temperature automatic control method for offshore testing. Based on the Joule-Thomson effect, it achieves the purpose of cooling high-temperature gas through gas throttling control, thereby ensuring the safety of downstream high-pressure flexible hoses and reducing or avoiding operational risks and economic losses in offshore high-temperature natural gas exploration and testing. The throttling cooling method creates conditions for miniaturization of equipment and cooling of wellheads in small spaces. At the same time, this method has the advantages of high efficiency, environmental protection, and energy saving. It simplifies equipment lifting and installation procedures, improves operational efficiency, and does not require the provision of coolant and consumption of fuel and electricity, greatly reducing operating costs.

[0090] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A throttling process temperature automatic control method for offshore testing, characterized in that: The steps include: Step 1: Collect the temperature upstream of the electronically controlled throttle nozzle, the temperature downstream of the electronically controlled throttle nozzle, the pressure upstream of the electronically controlled throttle nozzle, and the pressure downstream of the electronically controlled throttle nozzle according to the sampling period; Step 2: adjusting the nozzle size according to the collected parameters of the various electronically controlled throttle nozzles to obtain the electronically controlled throttle nozzle size after preliminary adjustment; The nozzle size satisfies: Where, d i is the size of the electronically controlled throttle nozzle in the i-th sampling period, i=0,1, Q i is the natural gas production in the i-th sampling period, γ is the gas density, is the upstream temperature of the electronically controlled throttling nozzle in the i-th sampling period, is the upstream pressure of the nozzle in the i-th sampling period, λ i k is the ratio of the pressure downstream of the nozzle to the pressure upstream of the nozzle in the i-th sampling period, s Calculate the adiabatic index for the nozzle; Step 3: After the initial adjustment of the electronically controlled throttle nozzle size, obtain the target nozzle size according to the downstream temperature of the electronically controlled throttle nozzle: If |s|>3 and s<0, it means that the downstream temperature of the electronically controlled throttle nozzle is greater than the target downstream temperature, and the nozzle size needs to be reduced to d=d1-2; If |s|>3 and s≥0, it means that the downstream temperature of the electronically controlled throttle nozzle is lower than the target downstream temperature, and the nozzle size needs to be increased to d=d1+2; Where d is the target nozzle size, s is the temperature difference downstream of the electronically controlled throttle nozzle; Step 4: Continuously adjust the nozzle size based on the various electronically controlled throttle nozzle parameters collected during the sampling period.

2. The throttling process temperature automatic control method for offshore testing according to claim 1, characterized in that: The temperature upstream of the electronically controlled throttle nozzle and the temperature downstream of the electronically controlled throttle nozzle are both collected by a temperature monitoring device; The pressure upstream of the electronically controlled throttle nozzle and the pressure downstream of the electronically controlled throttle nozzle are both collected through a pressure monitoring device.

3. The automatic temperature control method for throttling process flow for offshore testing according to claim 2, characterized in that: The second step specifically includes: Step 1: determining target parameters of the electronically controlled throttle nozzle; Step 2: Calculate the initial value of the pressure downstream of the nozzle; Step 3: Calculate the ratio of the pressure downstream of the nozzle to the pressure upstream of the nozzle in the i-th sampling period: Step 4: Calculate the initial value of the nozzle size; Step 5: Adjust the initial value of the nozzle size according to the collected parameters of the various electronically controlled throttle nozzles to obtain the electronically controlled throttle nozzle size after preliminary adjustment.

4. The automatic temperature control method for throttling process flow for offshore testing according to claim 3, characterized in that: The target parameters include: expected natural gas production, expected wellhead temperature, expected wellhead pressure, gas density and target downstream temperature.

5. The automatic temperature control method for throttling process for offshore testing according to claim 4, characterized in that: The initial value of the pressure downstream of the nozzle satisfies: Where Q0 is the expected natural gas production, is the expected wellhead temperature, is the estimated wellhead pressure, and λ0 is the initial value of the ratio of the pressure downstream of the nozzle to the pressure upstream of the nozzle.

6. The automatic temperature control method for throttling process for offshore testing according to claim 5, characterized in that: The ratio of the pressure downstream of the nozzle to the pressure upstream of the nozzle in the i-th sampling period satisfies: Where, is the downstream pressure of the nozzle in the i-th sampling period.

7. The automatic temperature control method for throttling process flow for offshore testing according to claim 6, characterized in that: The initial value of the pressure downstream of the nozzle satisfies: Where, is the initial value of the temperature downstream of the nozzle, is the expected wellhead temperature, is the expected wellhead pressure, k is the insulation coefficient, is the initial value of the pressure downstream of the nozzle.

8. The automatic temperature control method for a throttling process for offshore testing according to claim 7, characterized in that: The temperature difference downstream of the electronically controlled throttle nozzle satisfies: s=T 目标 -T1 2 ′; Among them, T1 2 ′ is the downstream temperature under the electronically controlled throttle nozzle size after preliminary adjustment.

9. The automatic temperature control method for a throttling process for offshore testing according to claim 8, characterized in that: The sampling period is 10 seconds.

10. The automatic temperature control method for throttling process for offshore testing according to claim 9, characterized in that: Also includes: If the downstream temperature of the electronically controlled throttle nozzle after preliminary adjustment is greater than the set target downstream temperature for more than 1 minute, an alarm will be issued to prompt human intervention.

Images