Enhanced heat transfer well completion structure and well completion method for shale oil in-situ modification heating well

Abstract

The invention discloses an enhanced heat transfer well completion structure and a well completion method for a shale oil in-situ modification heating well. The well completion structure comprises a heater sealing tool, an upper end sealing suspension tool, a continuous pipe electric heater, a guide centralizing tool, a one-way filling valve tool, a well completion oil pipe and a casing pipe column. The upper end sealing suspension tool is arranged at the tail part of the casing string; the continuous pipe electric heater is arranged at a designated position of a well completion oil pipe; the guiding and centralizing tool is arranged on the well completion oil pipe connecting section; the one-way filling valve tool is arranged at the bottom of the casing string; and the heater sealing tool is arranged at a preset position of the cold end of the heater.

Description

Technical Field

[0001] This article relates to the technical field of oil and gas well engineering optimization design, and in particular to a heat transfer enhanced completion structure and completion method for a shale oil in-situ reformed heating well. Background Art

[0002] my country's shale oil resources are very rich, but most of the shale oil resources are relatively low in maturity, and it is necessary to carry out in-situ modification of medium and low maturity shale oil. The research on the mechanism of in-situ modification technology mainly draws on the theoretical research in the field of in-situ conversion of oil shale and heavy oil modification and exploitation, and mainly examines the mechanism of conversion of heavy heavy oil, asphalt, kerogen and other solid organic matter in the reservoir into light oil and gas during continuous artificial heating. In the process of in-situ heating and exploitation of shale oil, the heat transfer efficiency of the heating well is a key factor affecting the production efficiency. The heat transfer efficiency can be improved by designing a wellbore enhanced heat transfer method and device, and the recovery rate can be improved. To improve the in-situ heating efficiency of shale oil, efficient enhanced heat transfer structures and heat transfer media are needed to more efficiently transfer heat energy to more distant oil layers in a limited wellbore space. Therefore, it is necessary to optimize the design of the heat transfer structure of the wellbore under in-situ modification conditions, use the downhole electric heater as the heat source, heat the high-efficiency heat-conducting medium to a high temperature state through enhanced heat transfer methods and devices, and inject it into the formation to heat the kerogen to the cracking temperature by convection heat transfer and heat conduction.

[0003] Therefore, how to realize a completion structure and completion method for enhancing the heat transfer of the wellbore of shale oil in-situ reformed heating wells is an urgent problem to be solved. Summary of the invention

[0004] The present application provides an enhanced heat transfer completion structure and completion method for a shale oil in-situ reformed heating well. The enhanced heat transfer completion structure implemented in the present application can improve the heat transfer efficiency of the electric heating device, reduce energy loss, increase the shale oil conversion recovery rate and reduce heating costs.

[0005] In the first aspect, the present application provides a shale oil in-situ reformed heating well enhanced heat transfer completion structure, the completion structure comprising: a heater sealing tool, an upper end sealing suspension tool, an electric heater, a guide straightening tool, a one-way filling valve tool, a completion tubing and a casing string;

[0006] An upper end sealing hanging tool is arranged at the tail end of the casing string;

[0007] An electric heater is arranged at a designated position of the completion tubing;

[0008] A guiding and straightening tool is provided at the connection section of the completion tubing;

[0009] A one-way filling valve tool is arranged at the bottom of the casing string;

[0010] The heater sealing tool is arranged at a predetermined position of the cold end of the heater.

[0011] Optionally,

[0012] The upper end sealing suspension tool is a tool used to prevent the heat-conducting filling medium from returning to the wellbore;

[0013] Guiding and straightening tools are tools used to provide guiding support during the running of the completion tubing;

[0014] One-way filling valve tool, a tool used to prevent the backflow of heat-conducting filling medium;

[0015] Heater sealing tool, a tool used to prevent the heat generated by an electric heater from escaping.

[0016] Optionally,

[0017] The completion structure is based on an open hole completion section.

[0018] In a second aspect, the present application provides a completion method for enhancing heat transfer of a shale oil in-situ reformed heating well, wherein the completion method is performed according to the completion structure described in any one of the above embodiments, and the method includes:

[0019] Lowering an upper end sealing hanging tool to the tail of the casing string, lowering the completion tubing and hanging it on the upper end sealing hanging tool;

[0020] Lowering the electric heater to a predetermined position in the completion tubing;

[0021] After injecting the heat-conducting filling medium, the heater sealing tool is set at a predetermined position of the cold end of the heater;

[0022] Open the valve of the one-way filling valve tool, inject the heat-conducting filling medium into the annulus, return to the upper end sealing hanging tool, and close the valve of the one-way filling valve tool.

[0023] Optionally,

[0024] The process of determining the setting position of the heater sealing tool is as follows:

[0025] The relationship between the heater temperature and the distance between the heater sealing tool and the heater is established according to the heat transfer equation of the heater and the thermal diffusion coefficient of the material;

[0026] According to the operating conditions and performance standards of the heater sealing tool, combined with the relationship between the heater temperature and the distance between the heater sealing tool and the heater, determine the distance between the heater sealing tool and the hot end of the heater at the maximum temperature at which the heater sealing tool can operate safely;

[0027] The predetermined position of the heater sealing tool is determined according to the distance of the heater sealing tool from the hot end of the heater and the end point of the electric heater.

[0028] Optionally,

[0029] The heat transfer equation is:

[0030]

[0031] In the formula, ΔH is the heat released by the heater, is the differential of heating efficiency with respect to time, E is the heating efficiency, T is the heating temperature of the heater, L is the distance between the heater sealing tool and the hot end of the heater, and λ is the thermal diffusion coefficient of the material.

[0032] Optionally,

[0033] The relationship between the heater temperature and the distance between the heater sealing tool and the heater is:

[0034]

[0035] In the above formula, T2 is the temperature of the location of the heater sealing tool, R is the cold end boundary, and T1 is the heater temperature.

[0036] Optionally,

[0037] The heat-conducting filling medium comprises: a rigid proppant, a soluble heat-conducting metal and expansion agent particles.

[0038] Optionally,

[0039] Turning on the electric heater to convert the soluble heat-conducting metal and the expansion agent particles in the heat-conducting filling medium into a fluid by using the heat of the electric heater;

[0040] After the heat-conducting filling medium becomes fluid, the fractured formation expands along the cracks to transfer heat.

[0041] Optionally, the method further comprises:

[0042] After turning on the heater, the heat transfer results are determined based on the comprehensive thermal conductivity;

[0043] Wherein, the comprehensive thermal conductivity is:

[0044]

[0045] In the formula, K is the comprehensive thermal conductivity, γ is the thermal conductivity of the fluid medium, C is the specific heat capacity, R e is the Reynolds number of the fluid medium flow, Pr is the Prandtl number, and l is the distance from the heater

[0046] Compared with the related art, the present application provides a heat transfer enhanced completion structure and completion method for shale oil in-situ reforming heating wells, wherein the completion structure includes: a heater sealing tool, an upper end sealing hanging tool, an electric heater, a guide straightening tool, a one-way filling valve tool, a completion tubing and a casing string; the upper end sealing hanging tool is arranged at the tail of the casing string; the electric heater is arranged at a designated position of the completion tubing; the guide straightening tool is arranged at the connection section of the completion tubing; the one-way filling valve tool is arranged at the bottom of the casing string; the heater sealing tool is arranged at a predetermined position of the cold end of the heater. The completion structure realized by the present application improves the heat transfer efficiency of the electric heating device, reduces energy loss, improves the shale oil conversion recovery rate and reduces the heating cost.

[0047] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by implementing the present application. Other advantages of the present application can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0049] Figure 1 A schematic diagram of a well completion structure for enhancing heat transfer of a shale oil in-situ reformed heating well according to an embodiment of the present application;

[0050] Figure 2 This is a flow chart of a completion method for enhancing heat transfer of a shale oil in-situ reformed heating well according to an embodiment of the present application;

[0051] Figure 3 is a diagram of plane stress of the wellbore after heating in an exemplary embodiment;

[0052] Figure 4 A schematic diagram showing a comparative analysis of the wellbore enhanced heat transfer effect in an exemplary embodiment. DETAILED DESCRIPTION

[0053] The present application describes multiple embodiments, but the description is exemplary rather than restrictive, and it is obvious to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described in the present application. Although many possible feature combinations are shown in the drawings and discussed in the specific embodiments, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0054] The present application includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features and elements disclosed in the present application may also be combined with any conventional features or elements to form a unique invention scheme defined by the claims. Any features or elements of any embodiment may also be combined with features or elements from other invention schemes to form another unique invention scheme defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in the present application may be implemented individually or in any appropriate combination. Therefore, except for the limitations made according to the attached claims and their equivalents, the embodiments are not subject to other restrictions. In addition, various modifications and changes may be made within the scope of protection of the attached claims.

[0055] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps of the specific order described. As will be understood by those of ordinary skill in the art, other sequences of steps are also possible. Therefore, the specific sequence of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to the steps of performing them in the order written, and those skilled in the art can easily understand that these sequences can be changed and still remain within the spirit and scope of the embodiments of the present application.

[0056] The embodiment of the present invention provides a completion structure for in-situ reforming and heating wells of shale oil to enhance heat transfer, such as Figure 1 As shown, the completion structure includes: a heater sealing tool 100, an upper end sealing hanging tool 101, an electric heater 102, a guide straightening tool 103, a one-way filling valve tool 104, a completion tubing 105 and a casing string 106;

[0057] An upper end sealing hanging tool is arranged at the tail end of the casing string;

[0058] An electric heater is arranged at a designated position of the completion tubing;

[0059] A guiding and straightening tool is provided at the connection section of the completion tubing;

[0060] A one-way filling valve tool is arranged at the bottom of the casing string;

[0061] The heater sealing tool is arranged at a predetermined position of the cold end of the heater.

[0062] In an exemplary embodiment, the completion structure for enhancing heat transfer of shale oil in-situ reformed heating wells is based on open hole completion. Open hole completion means that the reservoir (heating layer) at the bottom of the well is exposed during completion, and the heat transfer medium can directly contact the reservoir, rather than through small holes perforated in the casing.

[0063] In an exemplary embodiment, the upper end sealing suspension tool is used to prevent the heat-conducting filling medium from returning to the wellbore; the guide straightening tool is used to provide guide support for the completion tubing lowering process; the one-way filling valve tool is used to prevent the filling medium from flowing back; and the heater sealing tool is used to prevent heat loss. In this embodiment, specifically:

[0064] The main functions of the heater sealing tool include: injecting heat-conducting filling medium to the predetermined position before the tool is set, and isolating the wellbore annulus and heating section after the heater sealing tool is lowered to prevent heat loss.

[0065] The upper sealing hanging tool has the following main functions: after the heat conductive filling medium is injected, the upper sealing hanging tool is lowered into the tail of the casing string to prevent the heat conductive filling medium from returning to the wellbore, and at the same time, it provides hanging support for the completion tubing to block the cross-flow of the heat conductive filling medium.

[0066] The main functions of the coiled tubing electric heater include: after the completion tubing is lowered into the designated position, the heating section is ensured to be located at the heating target oil layer section; when the power is turned on for heating, the heating section exchanges heat with the heat-conducting filling medium to heat the entire target oil layer.

[0067] The main functions of the guiding and straightening tool include: providing guiding support for the completion tubing, ensuring the centering of the tubing string, allowing the heat from the heater to be evenly transferred to the formation, and improving the heat transfer efficiency.

[0068] The one-way filling valve tool has the following main functions: the one-way valve is lowered with the oil pipe and located at the bottom of the pipe string. When the heat conductive filling medium is injected into the formation, the injection is controlled to prevent the heat conductive filling medium from flowing back.

[0069] In an exemplary embodiment, the heat-conducting filling medium includes: a rigid proppant, a soluble heat-conducting metal, an expansion agent particle (fluid), etc., and is mixed in a certain proportion. Among them, the heat-conducting filling medium is a solid particle when injected, which is easy to inject and convenient. During the heating process, the soluble heat-conducting metal in the heat-conducting filling medium partially melts and flows outward along the cracks, thereby improving the heat transfer efficiency; the rigid proppant is a metal or non-metal filling ball, which has the characteristics of high strength and light density, and provides mechanical support for the shale oil well wall to provide the wellbore pipe string with the ability to resist external loads; the expansion agent particle injection process is a solid phase material, which can release a large amount of gas after being heated at high temperature in the injection well, assisting the thermal effect, so that the microcracks around the wellbore are further expanded, thereby increasing the pressure, increasing the crack gap, and improving the heat exchange efficiency.

[0070] The well completion structure for enhancing heat transfer of a shale oil in-situ reformed heating well implemented in this embodiment has the following technical effects:

[0071] Based on the completion structure involved, the heat transfer efficiency of the electric heating device can be improved and energy loss can be reduced. The heat-conducting medium has the advantages of easy insertion, good thermal fluidity, good support, and the ability to transform formation conditions and transfer heat over a longer distance.

[0072] In a second aspect, an embodiment of the present invention provides a completion method for in-situ reforming and heating wells for shale oil to enhance heat transfer. The completion method is performed according to the completion structure for in-situ reforming and heating wells for shale oil to enhance heat transfer. The specific completion process is as follows: Figure 2 As shown, steps S200-230 are included:

[0073] S200: lowering an upper end sealing hanging tool to the tail of the casing string, lowering a completion tubing and hanging it on the upper end sealing hanging tool;

[0074] S210: lowering an electric heater to a predetermined position in the completion tubing;

[0075] S220: After injecting the heat-conducting filling medium, the heater sealing tool is set at a predetermined position of the cold end of the heater;

[0076] S230: Open the valve of the one-way filling valve tool, inject the heat-conducting filling medium into the annulus, return to the upper end sealing hanging tool, and close the valve of the one-way filling valve tool.

[0077] In an exemplary embodiment, the process of determining the setting position of the heater sealing tool is as follows:

[0078] Step 1, according to the heat transfer equation of the heater and the thermal diffusion coefficient of the material, the relationship between the heater temperature and the distance between the heater sealing tool and the heater is established;

[0079] In this step, the one-dimensional heat transfer equation of the heater can be expressed as:

[0080]

[0081] In the formula, ΔH is the heat released by the heater, is the differential of heating efficiency with respect to time, E is the heating efficiency, T is the heating temperature of the heater, L is the distance between the heater sealing tool and the hot end of the heater, and λ is the thermal diffusion coefficient of the material.

[0082] Integrate L on both sides and bring in the boundary conditions L=0, then:

[0083]

[0084] Continue integrating L:

[0085]

[0086] Assuming the cold end boundary R and the heater temperature T1, the relationship between the heater temperature and the distance between the heater sealing tool and the heater is:

[0087]

[0088] In the above formula, T2 is the temperature of the location of the heater sealing tool, R is the cold end boundary, and T1 is the heater temperature. Among them, the cold end boundary is a value set according to the performance of the heater.

[0089] Step 2, according to the operating conditions and performance standards of the heater sealing tool, combined with the relationship between the heater temperature and the distance between the heater sealing tool and the heater, determine the distance between the heater sealing tool and the hot end of the heater at the maximum safe working temperature of the heater sealing tool;

[0090] In this step, according to the operating conditions and performance standards of the heater sealing tool, the heater sealing tool is lowered to a position at a distance L from the hot end of the heater so that the maximum temperature at the heater sealing tool is lower than the maximum temperature for safe operation of the heater sealing tool.

[0091] Step 3: Determine the predetermined position of the heater sealing tool based on the determined distance between the heater sealing tool and the hot end of the heater and the end point of the heater.

[0092] In an exemplary embodiment, after executing step S230, turning on the heater;

[0093] The heat emitted by the heater converts the soluble metal and expansion agent in the heat-conducting filling medium into fluid, and the fractured formation expands along the cracks to enhance heat transfer.

[0094] In this embodiment, the heat-conducting filling medium includes: a rigid proppant, a soluble heat-conducting metal, and expansion agent particles (fluid).

[0095] In an exemplary embodiment,

[0096] After turning on the heater, the heat transfer results are determined based on the comprehensive thermal conductivity;

[0097] Wherein, the comprehensive thermal conductivity is:

[0098]

[0099] In the formula, K is the comprehensive thermal conductivity, γ is the thermal conductivity of the fluid medium, C is the specific heat capacity, R e is the Reynolds number of the fluid medium flow, Pr is the Prandtl number, and l is the distance from the heater

[0100] Among them, Re is the Reynolds number of the fluid medium flow - is a known quantity, specific heat c, J / (kg·℃); Prandtl number Pr, thermal conductivity of the fluid medium γ, w / m 2 .

[0101] In an exemplary embodiment, in order to ensure safe operation, it is necessary to calculate the effect of heating on the wellbore pressure based on the implemented heating method; mainly including the casing thermal stress caused by heating and the external squeezing force caused by thermal expansion of the formation.

[0102] The thermal stress of the casing is caused by the high temperature and the surrounding displacement conditions. The factors that affect the thermal stress are mainly the temperature, the properties of the material itself and the properties of the formation. According to the basic relationship between stress and strain of elastic body, when the elastic body is subjected to stress at a certain section, the axial direction of the section of the elastic body will produce corresponding strain. According to Hooke's law, stress and strain are proportional to each other, and the ratio of the two is the elastic modulus, that is:

[0103] or x =Eε x

[0104] ε x is the strain in the x direction; σ x is the stress in the x direction; E is the elastic modulus.

[0105] In the stress and strain of elastic bodies, the generalized Hooke's law applies a certain amount of stress σ in the three directions x, y, and z of the elastic body. x , σ y , σ z , adding together the strain components caused by stress on each section can give the strain in all directions ε x , ε y , ε z According to the theory of elastic mechanics, the expression of stress and strain can be obtained:

[0106]

[0107] Among them, ε x , ε y , ε z is the strain in the three directions x, y, and z, γ xy is the shear strain in the xy direction, γ yz is the shear strain in the yz direction, γ zx is the shear strain in the zx direction; τ xy is the shear stress in the xy direction, τ xx is the shear stress in the xx direction, τ yz is the shear stress in the yz direction;

[0108]

[0109] G is the shear modulus, E is the elastic modulus, and μ is the Poisson's ratio.

[0110] When there is a temperature difference in the elastic body, adding the temperature component to the above expression can obtain the relationship between the stress and strain of the elastic body under the temperature difference T:

[0111]

[0112] Since the main heating section of the casing is in the horizontal direction, it can be considered that the axial strain is 0. Generally, this situation is considered as a plane strain problem. yz =γ xz =ε z =0, can be simplified to:

[0113]

[0114] Assuming that the axial strain is 0 and extended to the other two directions, the stress in each direction can be obtained by the following formula:

[0115]

[0116] in, e=ε x +ε y +ε z

[0117] For plane strain problems, the formula can be simplified to:

[0118]

[0119] Thermal stress will cause a certain displacement of the object locally, and the displacement is decomposed into u, v, and w in three directions; at the same time, the normal strains of u, v, and w are: ε x , ε y , ε z , the shear strain is γ xy , γ yz , γ xz ;

[0120] but:

[0121]

[0122] The displacement components u, v, and w can all be determined individually, but the strain components cannot be determined individually. The strain compatibility equation can be obtained by eliminating u, v, and w from the strain expression:

[0123]

[0124] When the expressions of the thermal stress of the casing in radial, circumferential and axial directions are obtained, it is considered that the casing has not reached its yield strength. The components of thermal stress are as follows:

[0125]

[0126] Among them, C cl is the coefficient, and its calculation formula is as follows:

[0127]

[0128] The external squeeze force of the thermal expansion of the stratum can be Figure 3 It means that the wellbore is not subjected to external squeeze pressure in the axial direction, therefore, the external squeeze of ground stress can be regarded as a plane stress problem.

[0129] Assume that the maximum horizontal ground stress is σ1, MPa; the minimum horizontal ground stress is σ2, MPa; the internal pressure is P i , MPa. The radius of the casing cement ring formation is as follows: r ci 、r co are the inner and outer radius of the casing, mm; r h is the outer radius of the cement ring, mm; r e is the radius of the circle taken.

[0130] The mean stress and deviation stress are introduced here:

[0131]

[0132] The stress state at any point on the circumference r4

[0133]

[0134] The stress state of any point on the circumference can be expressed in polar coordinates and expressed in terms of mean stress and deviation stress as follows:

[0135]

[0136] The stress state is regarded as the superposition of uniform force and non-uniform force. The solution of casing stress under non-uniform ground stress can be transformed into the solution of uniform stress σ 平 Casing force, solve the non-uniform force

[0137] σ 偏 cos2θ and σ 偏 The stress of the casing under the action of sin2θ. After superposition, the stress of the casing under the action of non-uniform ground stress can be obtained, and finally the external extrusion stress of the casing under the action of non-uniform ground stress can be expressed as:

[0138]

[0139] Let σ 偏1 is the external extrusion pressure of the casing, σ 偏2 is the force on the outer wall of the cement ring, all of which are algebraic values; let σ 偏3 , σ 偏4 is the force on the inner wall of the cement ring, which is also an algebraic value. The algebraic values ​​of the above quantities are all related to σ 平 and σ 偏 There is an algebraic relationship, which can be calculated according to different parameters. After the two casing external squeeze forces are obtained, they are superimposed to obtain the casing external squeeze force under the original non-uniform original field stress.

[0140] Based on the thermal stress of the pipe string caused by heating and the external extrusion force of the casing caused by the expansion of the surrounding rock and the squeezing of the casing due to heating, a comprehensive judgment is made to ensure that the maximum heating temperature of the heater is within the safe operating range of the casing, that is, the safe operating temperature.

[0141] In an exemplary embodiment, the enhanced heat transfer completion structure of the shale oil in-situ reforming heating well designed above is used to calculate the comprehensive thermal conductivity to quantitatively evaluate the wellbore enhanced heat transfer effect:

[0142]

[0143] In the formula, R e is the Reynolds number of the fluid medium, l is the distance from the heater. Flow viscosity μ, mPa·s; specific heat c, J / (mol·K); Prandtl number Pr, thermal conductivity of the fluid medium γ, w / m 2 .

[0144] According to the above calculated comprehensive thermal conductivity, the heat transfer enhancement effect of the tube is determined. Figure 4 As shown, the schematic diagram of comparative analysis of wellbore enhanced heat transfer effect shows that compared with the traditional heating structure, the heat-conducting medium in this method can expand reservoir cracks and conduct heat deeply into the reservoir. The heat transfer range is larger, the heating efficiency is higher, and it is safer and more efficient.

[0145] Example 1

[0146] This example shows a completion method for a shale oil in-situ conversion heating well with enhanced heat transfer, including the following steps:

[0147] 1. Complete the drilling and completion work according to the wellbore structure diagram. The horizontal section is an open hole completion. Lower the upper sealing hanging tool, then lower the completion tubing and hang it on the sealing tool, and then lower the electric heater.

[0148] 2. After the heater is lowered, a heat-conducting filling medium is injected. After the heat-conducting filling medium is injected, the heater sealing tool is sealed at the predetermined cold end position of the heater, and the gap between the heater and the completion tubing is greater than 20 mm.

[0149] 3. Open the one-way filling valve tool, inject the heat-conducting filling medium into the annulus, return to the sealing hanging tool, and close the valve.

[0150] 4. Turn on the heater, the soluble metal and expansion agent in the heat transfer medium become fluid, the fracturing formation expands along the cracks to enhance heat transfer, and the final heat transfer effect is as follows: Figure 4 shown.

[0151] The heat transfer-enhanced shale oil in-situ conversion heating well completion method implemented in this example has a heat transfer effect that is better than that of the traditional method. Figure 4 It can be shown that in this example, heat transfer is enhanced by fracturing the formation along the expansion of the cracks, resulting in a better heat transfer effect.

[0152] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

Claims

1. An enhanced heat transfer completion structure for shale oil in-situ reforming and heating wells. It is characterized in that The completion structure includes: a heater sealing tool, an upper end sealing suspension tool, an electric heater, a guide straightening tool, a one-way filling valve tool, a completion tubing and a casing string; The upper end sealing hanging tool is arranged at the tail of the casing string; The electric heater is arranged at a designated position of the completion tubing; The guiding and straightening tool is arranged at the connection section of the completion oil pipe; The one-way filling valve tool is arranged at the bottom of the casing string; The heater sealing tool is arranged at a predetermined position of the cold end of the electric heater.

2. The enhanced heat transfer completion structure for the shale oil in-situ reforming heating well according to claim 1, It is characterized in that The upper end sealing suspension tool is a tool used to prevent the heat-conducting filling medium from returning to the wellbore; The guiding and straightening tool is a tool used to provide guiding support during the running of the completion tubing; The one-way filling valve tool is a tool used to prevent the backflow of the heat-conducting filling medium; The heater sealing tool is a tool used to prevent the heat generated by the electric heater from dissipating.

3. The enhanced heat transfer completion structure for the shale oil in-situ reforming heating well according to claim 1, It is characterized in that The completion structure is arranged in the open hole completion section.

4. A heat transfer enhanced completion method for shale oil in-situ reforming and heating wells, It is characterized in that A well completion method is performed according to the well completion structure according to any one of claims 1 to 3, the method comprising: Lowering an upper end sealing hanging tool to the tail of the casing string, lowering the completion tubing and hanging it on the upper end sealing hanging tool; Lowering the electric heater to a predetermined position in the completion tubing; After injecting the heat-conducting filling medium, the heater sealing tool is set at a predetermined position of the cold end of the electric heater; Open the valve of the one-way filling valve tool, inject the heat-conducting filling medium into the annulus, return to the upper end sealing hanging tool, and close the valve of the one-way filling valve tool.

5. The enhanced heat transfer completion of the shale oil in-situ reforming heating well according to claim 4, It is characterized in that The process of determining the setting position of the heater sealing tool is as follows: The relationship between the heater temperature and the distance between the heater sealing tool and the heater is established according to the heat transfer equation of the heater and the thermal diffusion coefficient of the material; According to the operating conditions and performance standards of the heater sealing tool, combined with the relationship between the heater temperature and the distance between the heater sealing tool and the heater, determine the distance between the heater sealing tool and the hot end of the heater at the maximum temperature of safe operation of the heater sealing tool; The setting position of the heater sealing tool is determined according to the distance between the heater sealing tool and the hot end of the heater and the end point of the heater.

6. The enhanced heat transfer completion of the shale oil in-situ reforming heating well according to claim 5, It is characterized in that The heat transfer equation is: In the formula, ΔH is the heat released by the heater, is the differential of heating efficiency with respect to time, E is the heating efficiency, T is the heating temperature of the heater, L is the distance between the heater sealing tool and the hot end of the heater, and λ is the thermal diffusion coefficient of the material.

7. The enhanced heat transfer completion of the shale oil in-situ reforming heating well according to claim 6, It is characterized in that The relationship between the heater temperature and the distance between the heater sealing tool and the heater is: In the above formula, T 2 is the temperature of the heater sealing tool, R is the cold end boundary, T 1 is the heater temperature.

8. The enhanced heat transfer completion of the shale oil in-situ reforming heating well according to claim 4, It is characterized in that The method also includes: The heat-conducting filling medium comprises: a rigid proppant, a soluble heat-conducting metal and expansion agent particles.

9. The enhanced heat transfer completion of the shale oil in-situ reforming heating well according to claim 8, It is characterized in that The method also includes: Turning on the electric heater to convert the soluble heat-conducting metal and expansion agent particles in the heat-conducting filling medium into a fluid using the heat of the electric heater; After the heat-conducting filling medium becomes fluid, the fractured formation expands along the cracks to transfer heat.

10. The enhanced heat transfer completion of the shale oil in-situ reforming heating well according to claim 9, It is characterized in that The method also includes: After turning on the heater, the heat transfer results are determined based on the comprehensive thermal conductivity; Wherein, the comprehensive thermal conductivity is: In the formula, K is the comprehensive thermal conductivity, γ is the thermal conductivity of the fluid medium, C is the specific heat capacity, R e is the Reynolds number of the fluid medium flow, Pr is the Prandtl number, and l is the distance from the heater.

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