阅读说明：本技术 一种自动预警加热抑制井筒水合物生成的装置和方法 (Device and method for inhibiting generation of hydrate in shaft by automatic early warning and heating ) 是由 陈晨 马英瑞 孟奕龙 聂帅帅 刘昆岩 钟秀平 李曦桐 翟梁皓 陈勇 朱颖 潘栋彬 于 2020-12-21 设计创作，主要内容包括：本发明公开了一种自动预警加热抑制井筒水合物生成的装置和方法,属于天然气水合物开采技术领域,本发明中油管的外表面上沿轴向每隔预定距离设有由电阻丝紧密螺旋缠绕形成的电阻丝绕组,电阻丝两头分别焊接在两个导电金属片上,任意相邻两个电阻丝绕组中间位置设有温压传感器；在隔水管的内侧壁上沿隔水管轴向对称开设有两道作为电极移动通道的滑槽,滑槽上设有卡槽,在卡槽处,电极与导电金属片接触连接；第一电缆的输入端与电机连接,输出端分别连接两个电极。本发明能够实现针对特定的时间特定的区域进行局部加热避免天然气水合物的生成,和传统方法相比更节能,且安全环保。发热装置一般处于关闭状态,可保证系统长期有效运行。(The invention discloses a device and a method for inhibiting generation of a shaft hydrate by automatic early warning and heating, belonging to the technical field of natural gas hydrate exploitation, wherein resistance wire windings formed by tightly and spirally winding resistance wires are arranged on the outer surface of an oil pipe at intervals of a preset distance along the axial direction, two ends of each resistance wire are respectively welded on two conductive metal sheets, and a temperature and pressure sensor is arranged in the middle position of any two adjacent resistance wire windings; two chutes which are used as electrode moving channels are symmetrically arranged on the inner side wall of the marine riser along the axial direction of the marine riser, clamping grooves are arranged on the chutes, and the electrodes are in contact connection with the conductive metal sheets at the clamping grooves; the input end of the first cable is connected with the motor, and the output end of the first cable is respectively connected with the two electrodes. The method can realize local heating aiming at a specific area at a specific time to avoid the generation of the natural gas hydrate, and is more energy-saving, safe and environment-friendly compared with the traditional method. The heating device is normally in a closed state, and long-term effective operation of the system can be ensured.)

1. An apparatus for inhibiting formation of hydrate in a wellbore by automatic forewarning heating, comprising: the temperature and pressure measuring device comprises a first cable (1), electrodes (2), a water-resisting pipe (3), an oil pipe (4), a sliding groove (5), a clamping groove (6), conductive metal sheets (7), a temperature and pressure sensor (8), a temperature and pressure indicating instrument (9), a second cable (10), a resistance wire (11) and a motor (12), wherein resistance wire windings are arranged on the outer surface of the oil pipe (4) at intervals of a preset distance along the axial direction, the resistance wire windings are formed by tightly and spirally winding the resistance wire (11), two ends of the resistance wire (11) are respectively welded on the two conductive metal sheets (7), the two conductive metal sheets (7) are distributed on two sides of the oil pipe (4), and the temperature and pressure sensor (8) is arranged in the middle position of any two; the temperature and pressure sensor (8) is embedded on the inner wall of the oil pipe (4), and the temperature and pressure sensor (8) is connected with a temperature and pressure indicating instrument (9) positioned on the ground through a second cable (10); the marine riser (3) is sleeved outside the oil pipe (4), two sliding grooves (5) are symmetrically formed in the inner side wall of the marine riser (3) along the axial direction of the marine riser (3), the sliding grooves (5) are axially communicated, the sliding grooves (5) serve as moving channels of the electrodes (2), clamping grooves (6) are formed in the sliding grooves (5), the positions of the clamping grooves (6) correspond to the positions where the resistance wires (11) are connected with the conductive metal sheets (7), and the electrodes (2) are in contact connection with the conductive metal sheets (7) at the positions of the clamping grooves (6); the first cable (1) adopts a pre-branching cable, the pre-branching cable comprises a main cable, branch connectors and branch cables, the input end of the main cable is connected with the motor (12), the output end of the main cable is connected with the input ends of the branch cables through the branch connectors, the number of the branch cables is two, and the output ends of the two branch cables are respectively connected with the two electrodes (2); the motor (12) is respectively connected with the first cable (1) and the temperature and pressure indicating instrument (9).

2. The apparatus for suppressing hydrate formation in a wellbore with automatic forewarning heating of claim 1, wherein: the predetermined distance is 100 m.

3. The apparatus for suppressing hydrate formation in a wellbore with automatic forewarning heating of claim 1, wherein: the diameter of the resistance wire (11) is larger than 5mm and smaller than 10mm, the number of winding turns of the resistance wire (11) is N, and N is larger than or equal to 20.

4. A method for inhibiting the generation of a hydrate in a shaft by automatic early warning and heating is characterized in that: the method adopts the device for inhibiting the generation of the hydrate in the shaft by automatic early warning and heating as claimed in claim 1, 2 or 3 to carry out automatic early warning and heating to inhibit the generation of the hydrate in the shaft, and specifically comprises the following steps:

step 1, measuring the temperature and pressure in a shaft through a temperature and pressure sensor (8), and putting two electrodes (2) in the shaft through a first cable (1) when the temperature and pressure measurement result shows that the temperature and pressure condition of secondary formation of the natural gas hydrate is met;

step 2, the two electrodes (2) drive the first cable (1) to move along the two sliding grooves (5) through self gravity;

step 3, the two electrodes (2) reach a secondary formation area of the natural gas hydrate, the two electrodes (2) are clamped on the corresponding clamping grooves (6), and the two electrodes (2) are respectively in contact connection with the two conductive metal sheets (7);

step 4, starting a motor (12), conducting an electrode (2) and a conductive metal sheet (7), heating a resistance wire (11) in a secondary formation area of the natural gas hydrate, and decomposing the natural gas hydrate along with the temperature rise;

and 5, finishing the decomposition of the natural gas hydrate, separating the electrode (2) from the clamping groove (6), turning off the motor (12), and recovering the electrode (2) to the ground.

Technical Field

The invention relates to the technical field of natural gas hydrate exploitation, in particular to a device and a method for inhibiting generation of wellbore hydrate through automatic early warning and heating.

Background

The natural gas hydrate is an ice-like crystalline compound with a cage-shaped structure formed by natural gas and water under the conditions of low temperature and high pressure, and is mainly found in land frozen soil areas and marine sediments. The natural gas hydrate reserves are huge, and are considered as ideal alternative energy sources in the 21 st century.

26 days 3 and 26 months in 2020, the gas hydrate in the sea area of China is produced by 86.14 million cubic meters in accumulated gas production through the second trial production, and the gas production per day is 2.87 million cubic meters, so that two new world records of 'total gas production amount and daily gas production amount' are created, and a solid foundation is laid for commercial exploitation of the gas hydrate.

During the sea natural gas hydrate exploitation process, natural gas generated by reservoir hydrate decomposition and water flow into the bottom of a well together, and the natural gas and the water move in a wellbore in a gas-water two-phase flow state. The temperature and pressure in the shaft are constantly changed along with the depth of the well under the influence of the temperature of seawater, throttling effect, pressure of the wellhead and the like. Hydrate is easily generated on the inner wall of the device for the second time, the device blocks a pipe column, and pressure building can be formed in serious cases to cause the pipe column to break, thereby causing huge economic loss.

At present, the commonly used methods for preventing the formation of gas hydrate in a gas well shaft mainly comprise a chemical inhibitor injection method and a downhole throttling method. The chemical inhibitor injection method is to inject chemical agents into a shaft from the ground regularly, breaks the continuity of production, and has the defects of high cost, insufficient safety, environmental protection and the like. The downhole throttling technology is to heat gas by means of formation heat energy to prevent hydrate from being generated, but in a low-temperature deep-water marine environment, the heat dissipation speed is high, and a heat source provided by the formation is not enough to inhibit the generation of secondary hydrate in a shaft.

Still other measures, see patent document, CN201910128714.3, disclose an electromagnetic heating device and method for exploiting seabed combustible ice, wherein a certain length of electromagnetic heating device is installed at the inlet end of an electric submersible pump to heat the bottom of the well, which is not suitable for a well bore above a deep cement line. The document number CN201810345979.4 discloses a method for exploiting natural gas hydrate by using a sleeve type heater, the sleeve type heater is placed in an exploitation interval, and for a low-temperature marine environment, the heat dissipation speed of a shaft is high, and the problem of secondary hydrate blockage of the shaft above a deepwater cement line cannot be solved. The publication No. CN201510183801.0 discloses a method for removing hydrate blockage of a gas recovery well shaft, which removes ice blockage by using reaction of an acidic solution and calcium oxide to release heat, but the method cannot be used for preventing secondary hydrate from generating. Document No. CN201110313048.4 discloses a spontaneous heating natural gas hydrate control device, which works by means of formation gas and is not suitable for gas-water co-production wells.

Therefore, an effective prevention method is needed for solving the problem of secondary hydrate formation in the shaft in the low-temperature environment in the sea natural gas hydrate exploitation process.

Disclosure of Invention

The invention aims to provide a device and a method for inhibiting generation of a wellbore hydrate by automatic early warning and heating, aiming at the problem of secondary formation of a natural gas hydrate in a wellbore in a low-temperature environment in the process of exploiting the sea natural gas hydrate, and the device and the method can effectively prevent the secondary formation of the natural gas hydrate.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a device for inhibiting generation of a hydrate in a shaft by automatic early warning and heating, which is characterized by comprising the following components: the temperature and pressure measuring device comprises a first cable, an electrode, a water-resisting pipe, an oil pipe, a sliding chute, a clamping groove, conductive metal sheets, a temperature and pressure sensor, a temperature and pressure indicating instrument, a second cable, a resistance wire and a motor, wherein resistance wire windings are arranged on the outer surface of the oil pipe at intervals of a preset distance along the axial direction, the resistance wire windings are formed by tightly and spirally winding the resistance wire, two ends of the resistance wire are respectively welded on the two conductive metal sheets, the two conductive metal sheets are distributed on two sides of the oil pipe 4, and the temperature and pressure sensor is arranged in the middle position of; the temperature and pressure sensor is embedded in the inner wall of the oil pipe and is connected with a temperature and pressure indicating instrument on the ground through a second cable; the riser is sleeved outside the oil pipe, two sliding grooves are symmetrically formed in the inner side wall of the riser along the axial direction of the riser, the sliding grooves are axially communicated and serve as moving channels of the electrodes, clamping grooves are formed in the sliding grooves and correspond to the positions where the resistance wires are connected with the conductive metal sheets, and the electrodes are in contact connection with the conductive metal sheets at the clamping grooves; the first cable adopts a pre-branching cable, the pre-branching cable comprises a main cable, branch connectors and branch cables, the input end of the main cable is connected with the motor, the output end of the main cable is connected with the input ends of the branch cables through the branch connectors, the number of the branch cables is two, and the output ends of the two branch cables are respectively connected with two electrodes; the motor is connected with the first cable and the temperature and pressure indicating instrument respectively.

As a preferable aspect of the present invention, the predetermined distance is 100 m.

Furthermore, the diameter of the resistance wire is larger than 5mm and smaller than 10mm, the winding number of the resistance wire is N, and N is larger than or equal to 20.

The invention also provides a method for inhibiting the generation of the wellbore hydrate by automatic early warning and heating, which is characterized by comprising the following steps: the method adopts the device for inhibiting the generation of the hydrate of the shaft by automatic early warning and heating to automatically early warn, heat and inhibit the generation of the hydrate of the shaft, and specifically comprises the following steps:

step 1, measuring temperature and pressure in a shaft through a temperature and pressure sensor, and putting two electrodes into the shaft through a first cable when temperature and pressure measurement results show that temperature and pressure conditions of secondary formation of natural gas hydrate are met;

step 2, the two electrodes drive the first cable to move along the two sliding grooves through self gravity;

step 3, enabling the two electrodes to reach a secondary formation area of the natural gas hydrate, clamping the two electrodes on the corresponding clamping grooves, and respectively connecting the two electrodes with the two conductive metal sheets in a contact manner;

step 4, starting a motor, conducting an electrode with a conductive metal sheet, heating a resistance wire in a secondary formation area of the natural gas hydrate, and decomposing the natural gas hydrate along with the temperature rise;

and 5, finishing the decomposition of the natural gas hydrate, separating the electrode from the clamping groove, closing the motor, and recovering the electrode to the ground.

Through the design scheme, the invention can bring the following beneficial effects: the invention provides a device and a method for inhibiting generation of a wellbore hydrate by automatic early warning and heating, which are used for locally heating a specific area at a specific time to avoid generation of a natural gas hydrate. The heating device is normally in a closed state, and long-term effective operation of the system can be ensured.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limitation and are not intended to limit the invention in any way, and in which:

FIG. 1 is a schematic structural diagram of an apparatus for inhibiting formation of hydrate in a wellbore by automatic early warning heating;

FIG. 2 is an enlarged view of a portion of FIG. 1;

FIG. 3 is a prior art natural gas hydrate phase equilibrium diagram.

The respective symbols in the figure are as follows: 1-a first cable; 2-an electrode; 3-a riser; 4-oil pipe; 5-a chute; 6-a clamping groove; 7-a conductive metal sheet; 8-a temperature and pressure sensor; 9-temperature pressure indicating instrument; 10-a second cable; 11-resistance wire; 12-motor.

Detailed Description

In order to clearly understand the technical scheme, the purpose and the effect of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described with reference to the accompanying drawings, and obviously, the described embodiment is a part of the embodiment of the present invention, but not the whole embodiment. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.

As shown in fig. 1 and 2, the device for inhibiting generation of hydrate in a shaft by automatic early warning and heating comprises a first cable 1, an electrode 2, a marine riser 3, an oil pipe 4, a chute 5, a clamping groove 6, a conductive metal sheet 7, a temperature and pressure sensor 8, a temperature and pressure indicator 9, a second cable 10, a resistance wire 11 and a motor 12.

In the figure, a represents sea water and b represents a seabed formation.

Resistance wire windings are arranged on the outer surface of the oil pipe 4 at intervals of a preset distance along the axial direction, the preset distance is 100m, more resistance wires 11 and temperature and pressure sensors 8 are needed due to the fact that the distance is too dense, materials are wasted, heat cannot be radiated to a controlled area due to the fact that the distance is too large, the proper distance is 100m, the resistance wire windings are formed by tight spiral winding of the resistance wires 11, the diameter of the resistance wires 11 is larger than 5mm and smaller than 10mm, the diameter of the resistance wires 11 is larger than 5mm, the resistance wires 11 are prevented from being broken due to too small diameter, the diameter of the resistance wires 11 is smaller than 10mm, the resistance wires 11 are prevented from sagging due; two ends of the resistance wire 11 are respectively welded on the two conductive metal sheets 7, the two conductive metal sheets 7 are distributed on two sides of the oil pipe 4, and the temperature and pressure sensors 8 are arranged in the middle positions of any two adjacent resistance wire windings, namely the distance between two adjacent temperature and pressure sensors 8 is 100m in the embodiment.

Temperature and pressure sensor 8 inlays and establishes on oil pipe 4's inner wall, temperature and pressure sensor 8 is connected with the temperature pressure indicating instrument 9 that is located ground through second cable 10 simultaneously, temperature and pressure sensor 8 are used for measuring temperature and pressure in the pit shaft, and transmit the temperature and the pressure signal who will measure to temperature pressure indicating instrument 9 through second cable 10 and show, wherein temperature and pressure sensor 8 includes temperature sensor, pressure sensor and be used for holding temperature sensor and pressure sensor's protective housing, temperature pressure indicating instrument 9 adopts present commonly used display control appearance, if: the 1100 series display controller, temperature and pressure indicating instrument 9 is used to indicate and record the temperature and pressure measurement results from the temperature and pressure sensor 8.

The riser 3 is sleeved outside the oil pipe 4, two sliding grooves 5 are formed in the inner side wall of the riser 3 along the axial symmetry of the riser 3, the sliding grooves 5 are axially communicated, the sliding grooves 5 serve as moving channels of the electrodes 2, clamping grooves 6 are formed in the positions, corresponding to the resistance wires 11, of the sliding grooves 5, and the conductive metal sheets 7 are connected, the clamping grooves 6 are used for accurately positioning the electrodes 2 to the positions corresponding to the conductive metal sheets 7, and the electrodes 2 are in contact connection with the conductive metal sheets 7.

The first cable 1 adopts a pre-branch cable, the pre-branch cable comprises a main cable, branch connectors and branch cables, the input end of the main cable is connected with the motor 12, the output end of the main cable is connected with the input ends of the branch cables through the branch connectors, the number of the branch cables is two, the output ends of the two branch cables are respectively connected with the two electrodes 2, and the first cable 1 drives the electrodes 2 to be thrown underground along the sliding grooves 5.

The motor 12 is respectively connected with the first cable 1 and the temperature and pressure indicating instrument 9, the motor 12 is used as a power supply source for the temperature and pressure indicating instrument 9 and the first cable 1, and the motor 12 supplies power to the electrode 2 through the first cable 1; under the condition that the electrodes 2 are communicated with the conductive metal sheets 7, the electrodes 2 and the resistance wires 11 form a closed loop to play a role in electric heating.

With reference to the natural gas hydrate phase equilibrium curve shown in fig. 3, the device for automatically early warning and heating to inhibit the generation of the wellbore hydrate starts a heating device in the region to heat under the condition that the wellbore local temperature and pressure conditions can generate the natural gas hydrate, so as to prevent the secondary generation of the natural gas hydrate, wherein the heating device is a resistance wire winding.

A method of inhibiting wellbore hydrate formation with automatic forewarning heating, the method comprising the steps of:

s1, the temperature and pressure indicating instrument 9 continuously receives temperature and pressure signals sent back by the temperature and pressure sensor 8 located underground through the second cable 10, and displays real-time values of the temperature and pressure of the well bore measured by the temperature and pressure sensor 8;

s2, when the temperature and the pressure measured by two adjacent temperature and pressure sensors 8 indicate that natural gas hydrate can be generated secondarily, starting to heat a resistance wire 11 between the two temperature and pressure sensors 8, putting an electrode 2 into the shaft through a first cable 1, putting the electrode 2 to the position, corresponding to a conductive metal sheet 7, of the bottom of the well through a chute 5 under the action of gravity, after the electrode 2 enters a clamping groove 6, connecting the electrode 2 with the conductive metal sheet 7 in a matched manner, closing a power generation circuit of the resistance wire winding, the conductive metal sheet 7, the electrode 2, the first cable 1 and a motor 12, heating the resistance wire 11, and decomposing the secondary natural gas hydrate at the corresponding well section when the temperature rises;

s3, stopping heating when the temperature and pressure values of the shaft return to normal values measured by the temperature and pressure sensor 8;

and S4, recovering the electrode 2 to the ground.

More specifically:

(a) when the temperature and pressure values measured by the temperature and pressure sensor 8 meet the temperature and pressure conditions of secondary formation of the natural gas hydrate;

(b) the two electrodes 2 drive the first cable 1 to respectively enter two sides of the shaft through self gravity;

(c) the electrodes 2 are positioned and connected to two sides of the resistance wire 11 of the required heating layer and clamped at corresponding positions through clamping grooves 6;

(d) the electrode 2 is connected with the conductive metal sheet 7, the motor 12 generates electricity, and the corresponding section of resistance wire 11 is heated;

(e) as the temperature rises, the equilibrium condition of the natural gas hydrate is broken and decomposed again;

(f) after the decomposition of the natural gas hydrate is finished, separating the electrode 2 from the clamping groove 6, cutting off the power, and recovering the electrode 2;

(g) as production is completed, the device can be removed and applied to production from other wells;

further, in order to ensure that the temperature of the shaft is always higher than the generation temperature of the natural gas hydrate and the heat transfer has loss, the starting temperature of the heating device can be properly increased, and the temperature is recommended to be more than 30 ℃.