Temperature and pressure monitoring tubular column for in-situ conversion heating well

Abstract

The invention discloses a temperature and pressure monitoring pipe column for an in-situ conversion heating well, which comprises an oil pipe, a pressure testing tool and a temperature testing tool are arranged on the outer wall of the oil pipe, a heater is arranged in the oil pipe, and a packer is arranged between the oil pipe and a sleeve of an oil well. The method is used for accurately obtaining the temperature and pressure information of the oil well shaft in real time in the in-situ mining process.

Description

Technical Field

[0001] The invention belongs to the technical field of oil field production, and in particular relates to a temperature and pressure monitoring pipe column for an in-situ conversion heating well. Background Art

[0002] In-situ mining refers to the method of converting the solid kerogen in the oil shale into liquid hydrocarbons by heating the oil shale reservoir at high temperature, and then extracting the liquid hydrocarbons from underground through traditional oil and gas drilling and production processes. According to different heating methods, it is mainly divided into electric heating, fluid convection heating, radiation heating and combustion heating.

[0003] Theoretically, using electric heaters to inject heat into underground shale layers mainly undergoes two dynamic evolution processes to achieve the goals of hydrocarbon generation, pressurization, reservoir formation, pressure maintenance and improved recovery: ① Heat storage and hydrocarbon generation and pressurization process. In the early stage of the heating stage, the temperature of the shale section rises slowly, and the formation pressure increases with thermal expansion. When the temperature continues to rise to a certain level (about 280°C), light hydrocarbon gas and oil begin to be produced. As the temperature rises further, the gas-oil ratio increases, the fluid flow capacity in the shale section increases significantly, and the oil and gas flow production capacity is already available. ② Reservoir formation, heat preservation and pressure maintenance to increase fluidity process. In the later stage of heating, the temperature reaches a peak value (about 330℃), the shale section undergoes bedding peeling due to thermal action, and book-shaped interlayer microcracks are formed on a large scale. The shale section has the ability to store and transport oil and gas on a large scale, and the gas-oil ratio is further increased. The generated gas contains a large amount of C3S and C4S (a good solvent), which, combined with the natural gas and light oil produced by high-temperature cracking, reduces the viscosity of liquid hydrocarbons and enhances their fluidity. In this way, the shale section is fully capable of storing oil and gas on a large scale and allowing oil and gas to flow. Due to continuous heating and maintaining a relatively constant temperature, the continuous generation of oil and gas and the increase in the gas-oil ratio enable the formation pressure to be maintained, and the oil and gas production process can continue until the hydrocarbon generation process is terminated.

[0004] In the process of in-situ mining, it is necessary to carry out wellbore temperature and pressure testing, the purpose of which is to understand the changes in formation energy and to formulate an important basis for reasonable working system of oil wells. Therefore, how to accurately obtain wellbore temperature and pressure information has gradually become an important research direction. Summary of the invention

[0005] The purpose of the present invention is to provide a temperature and pressure monitoring column for an in-situ conversion heating well, which is used to timely and accurately obtain the temperature and pressure information of the oil wellbore during the in-situ production process.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a temperature and pressure monitoring string for an in-situ conversion heating well includes an oil pipe, a pressure testing tool and a temperature testing tool are arranged on the outer wall of the oil pipe, a heater is arranged inside the oil pipe, and a packer is arranged between the oil pipe and the casing of the oil well.

[0007] As a preferred technical solution of the present invention, the heater is assembled in the oil pipe through a continuous oil pipe.

[0008] As a preferred technical solution of the present invention, the packer includes an upper packer and a lower packer.

[0009] As a preferred technical solution of the present invention, the temperature testing tool is a thermocouple.

[0010] As a preferred technical solution of the present invention, the thermocouple is an armored thermocouple.

[0011] As a preferred technical solution of the present invention, there are three thermocouples, which are respectively arranged at the toe, middle and heel of the horizontal well section.

[0012] As a preferred technical solution of the present invention, the pressure testing tool is composed of an optical fiber and a pressure sensor.

[0013] The beneficial effects of the present invention are as follows: the temperature and pressure monitoring string for the in-situ conversion heating well of the present invention is used for a well in which an electric heater is lowered for in-situ conversion. By lowering the temperature and pressure testing string of the present invention, on the one hand, the operating temperature of the electric heater and the pressure at the location of the electric heater can be tested so as to more reasonably control the operation of the heater and reach the conversion temperature required for the in-situ conversion in real time; on the other hand, an effective seal can be provided above the wellbore where the electric heater is located, thereby reducing heat loss from the wellhead and promoting heat conduction into the formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention is a schematic diagram of the assembly principle of a temperature and pressure monitoring column for an in-situ conversion heating well.

[0015] In the figure: 1. pressure test tool, 2. oil pipe, 3. heater, 4. upper packer, 5. lower packer, 6. casing, 7. temperature test tool. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings, tables and specific embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] The present invention is further described below by way of examples, but is not limited to the following embodiments.

[0018] Example 1

[0019] like Figure 1As shown, a temperature and pressure monitoring string for an in-situ conversion heating well of the present invention comprises an oil pipe 2, a pressure testing tool 1 and a temperature testing tool 7 are arranged on the outer wall of the oil pipe 2, a heater 3 is arranged inside the oil pipe 2, and a packer is arranged between the oil pipe 2 and the casing 6 of the oil well.

[0020] The temperature and pressure monitoring string for an in-situ conversion heating well of the present invention is lowered into a wellbore and implemented in sequence according to the following steps:

[0021] Step 1, tie the clips on the temperature test tool 7 and the pressure test tool 1 to the outer wall of the oil pipe 2;

[0022] Step 2, using a conventional workover machine, the oil pipe 2 together with the temperature test tool 7 and the pressure test tool 1 are lowered into the well, and a packer is lowered at the designed position;

[0023] Step 3, hang the oil pipe 2 on the lower flange of the wellhead, lead the cables of the temperature test tool 7 and the pressure test tool 1 out from the casing valve of the wellhead, and then install the lower flange at the wellhead;

[0024] Step 4: Use a coiled tubing vehicle to lower the heater 3 into the tubing 2, then install a flange at the wellhead and hang the heater 3;

[0025] As the coiled tubing is lowered into the horizontal wellbore, the bending will increase with the increase of the lowering depth, the force acting on the pipe wall will increase, and the friction coefficient will continue to change, but the overall friction force will not change much. According to the analysis of relevant literature, the coiled tubing can be sent into the 3000m horizontal wellbore with the existing equipment.

[0026] The coiled tubing operation equipment mainly includes the coiled tubing injection head, roller, control console and hydraulic power system, among which the coiled tubing injection head is one of the most critical components of the coiled tubing operation equipment, providing the power required for the lifting and lowering of the coiled tubing and bearing the entire weight of the suspended part of the coiled tubing. When the coiled tubing passes through the injection head, it will be subjected to axial tension or pressure, the internal pressure of the fluid in the pipe, and the clamping force of the clamping block.

[0027] The axial force when running into the coiled tubing can be expressed as:

[0028]

[0029] The axial force when pulling out the coiled tubing can be expressed as:

[0030]

[0031] Where: F x —Axial force on the coiled tubing during running, N

[0032] Fs —Axial force on the coiled tubing when it is pulled out, N

[0033] D—Outer diameter of coiled tubing, m

[0034] d—Inner diameter of coiled tubing, m

[0035] P o —Oil wellhead pressure, MPa

[0036] ρ y —The density of the liquid in the wellbore, kg / m 3

[0037] ρ g —Density of coiled tubing body material, kg / m 3

[0038] g—acceleration due to gravity, take 9.8N / kg

[0039] L—attempt to run the coiled tubing, m

[0040] The simulation of lifting and lowering was carried out according to the total length of the heater of 1800m (vertical depth of 1400m, horizontal section of 400m), outer diameter of 44.5mm, deadweight of 9kg / m, and wellhead normally open (Po=0).

[0041] Table 2 Calculation table of axial force of coiled tubing lifting and lowering injection head when wellhead is normally open (Po=0)

[0042]

[0043] For directional wells, due to the certain bending radius of the wellbore trajectory and the limitation of the inner diameter of the casing, if the radial or axial dimensions of the downhole tool are not properly selected, the drill may get stuck and encounter resistance in the middle. To ensure the smooth tripping of downhole tools, for a single tool or a combination of pipes with the same diameter, the outer diameter d of the tool and the maximum allowable length L must meet the following relationship:

[0044]

[0045] Where, R is the curvature radius of the wellbore, m;

[0046] D——Inner diameter of casing at the curvature radius R, m;

[0047] d——maximum rigid outer diameter of downhole tool string, m;

[0048] L——The maximum allowable length of the downhole tool string, m.

[0049] It should be noted that in the process of analyzing the passing capacity of the downhole tool string, the deformation of the tool string is not considered, that is, the tool string is considered to be absolutely rigid. The maximum allowable total length of the downhole tool string when the deformation is considered is greater than the maximum allowable total length of the downhole tool string obtained by this method. Therefore, for the downhole tool string, since its deformation is absolutely limited, the maximum total length of the tool string allowed to pass is relatively safe.

[0050] Tool string outer diameter, length passability calculation results table

[0051]

[0052] The temperature and pressure monitoring string for the in-situ conversion heating well of the present invention is used for a well in which an electric heater is lowered for in-situ conversion. By lowering the temperature and pressure testing string of the present invention, on the one hand, the operating temperature of the electric heater and the pressure at the location of the electric heater can be tested, so as to more reasonably control the operation of the heater and achieve the conversion temperature required for in-situ conversion in real time; on the other hand, an effective seal can be provided above the wellbore where the electric heater is located, so as to reduce the heat loss from the wellhead and promote the conduction of heat to the formation.

[0053] Example 2

[0054] like Figure 1 As shown, different from Example 1, in the temperature and pressure monitoring string for the in-situ conversion heating well of the present invention, the packer includes an upper packer 4 and a lower packer 5.

[0055] The use of double packers for isolation can meet the requirements of heat insulation and heat resistance of the heating wellbore to prevent the heat from being lost upward. Among them: the lower packer 5 is a heat-resistant and corrosion-resistant packer, which is the main component to prevent the heat of the heater from being lost upward along the wellbore. Since it may come into contact with the formation fluid, it needs to withstand both the temperature test and the corrosion of the fluid that may enter the wellbore; the upper packer 4 is a heat-insulating packer, which mainly supplements the sealing of the lower packer to prevent the heat of the heater from being lost upward along the wellbore.

[0056] Example 3

[0057] like Figure 1 As shown, different from Example 1, in the temperature and pressure monitoring string for the in-situ conversion heating well of the present invention, the temperature testing tool 1 is three armored thermocouples, which are respectively arranged at the toe, middle and heel of the horizontal well section.

[0058] Wellbore environment: During the test of temperature and pressure, there may be one or more of about 15% hydrogen sulfide, about 8% carbon dioxide, about 10% hydrogen, and about 4% water (liquid or gas phase) in the wellbore at a certain period. The operating temperature of the heater is about 700℃. After the wellbore is connected to the formation, the pressure in the wellbore may reach 400 standard atmospheres. Therefore, the material of the test tool body or shell needs to have the functions of high temperature resistance, no melting, corrosion resistance, and pressure resistance.

[0059] Therefore, according to the test temperature range and application environment, an S-type armored thermocouple is selected as one of the tools for testing temperature. An armored thermocouple is deployed at the toe, middle and heel of the horizontal well section to test the temperature heated by the heater in the horizontal well section.

[0060] In addition, in order to understand the temperature distribution in the wellbore and whether the heater is uniformly heated in the horizontal well section, distributed optical fiber sensing technology can also be used, which can measure the temperature and strain along the length of the optical fiber. Similarly, in the application environment of thermocouples, distributed optical fibers also need armor protection. The armor sheath material is based on material properties, and the selection of 625 alloy can meet the application requirements.

[0061] Example 4

[0062] like Figure 1 As shown, different from Example 1, in the temperature and pressure monitoring string for the in-situ conversion heating well of the present invention, the pressure testing tool 1 is composed of an optical fiber and a pressure sensor.

[0063] The well section that needs to be heated is located 1,400 meters underground, where the fluid pressure is about 100 standard atmospheres. After the wellbore is connected to the formation, the pressure in the wellbore may reach 400 standard atmospheres.

[0064] The test ranges of conventional electronic downhole pressure gauges and mechanical downhole pressure gauges can meet the pressure that the wellbore may reach, but their maximum operating temperature does not exceed 250°C.

[0065] Therefore, the same temperature test tool 1 needs to select a pressure test tool made of special pipes, and the fiber optic technology has been used in combination with the temperature test. In order to give full play to the role of optical fiber, the combination of optical fiber + pressure sensor is used to test the pressure in the wellbore.

[0066] The above description shows and describes several preferred embodiments of the invention, but as mentioned above, it should be understood that the invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. Changes and modifications made by those skilled in the art should be within the scope of protection of the claims attached to the invention without departing from the spirit and scope of the invention.

Claims

1. A temperature and pressure monitoring column for an in-situ conversion heating well, characterized in that: The invention comprises an oil pipe (2), the outer wall of which is provided with a pressure testing tool (1) and a temperature testing tool (7), a heater (3) is provided inside the oil pipe (2), and a packer is provided between the oil pipe (2) and the casing (6) of the oil well.

2. The temperature and pressure monitoring column for in-situ conversion heating well according to claim 1, characterized in that: The heater (3) is assembled in the oil pipe (2) via a continuous oil pipe.

3. The temperature and pressure monitoring column for the in-situ conversion heating well according to claim 2, characterized in that: The packer comprises an upper packer (4) and a lower packer (5).

4. The temperature and pressure monitoring column for in-situ conversion heating well according to claim 3 is characterized in that: The temperature testing tool (1) is a thermocouple.

5. The temperature and pressure monitoring column for in-situ conversion heating well according to claim 4 is characterized in that: The thermocouple is an armored thermocouple.

6. The temperature and pressure monitoring column for in-situ conversion heating well according to claim 5, characterized in that: There are three thermocouples, which are arranged at the toe, middle and heel of the horizontal well section respectively.

7. The temperature and pressure monitoring column for in-situ conversion heating well according to claim 6 is characterized in that: The pressure testing tool (1) is composed of an optical fiber and a pressure sensor.

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