Rock core temperature calculation method and system in drilling coring lifting process

Abstract

The invention relates to a rock core temperature calculation method and system in the drilling coring lifting process, and the method comprises the following steps: dividing a coring cylinder into multiple layers of cylinder wall structures, and obtaining basic parameters of each cylinder wall structure, related parameters of a shaft and a stratum, and motion parameters in the rock core lifting process; establishing a radial heat transfer model between the cylinder wall structures from inside to outside based on the cylinder wall structures and the corresponding basic parameters; model boundary conditions are set based on the model, and model parameters are initialized according to relevant parameters of the shaft and the stratum; and based on the motion parameters, determining the temperature distribution of the rock core along the whole shaft according to a radial heat transfer model, and obtaining the change rule of the rock core temperature along with the uplift time. By calculating the dynamic change of the rock core temperature in the coring process, the influence of rock core movement, annular fluid and stratum contact is overcome, and the dynamic change rule of the rock core temperature in the whole well section and the lifting process is obtained, so that a basis is provided for coring optimization design, and the working efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of heat and mass transfer in wellbores, and in particular to a method and system for calculating core temperature during the process of coring and lifting in drilling. Background Art

[0002] With the continuous expansion of geothermal and oil and gas resource exploration and development areas, the effective acquisition of formation information has become one of the key core issues faced by the efficient development of geothermal and oil and gas resources. Drilling coring is an effective way to obtain formation information by sending the coring barrel to the bottom of the well to obtain formation core samples, and then moving the coring barrel and the obtained core from the bottom of the well to the wellhead to obtain formation core samples. It can obtain key parameters such as the true porosity, permeability and oil and gas saturation of the target formation.

[0003] However, as the depth of the wellbore continues to increase, the influence of formation pressure and temperature on the core becomes more and more significant. Under different temperature and pressure conditions, the porosity, permeability and oil and gas saturation of the core will change significantly, which in turn affects the accuracy of obtaining formation information by obtaining core samples. Therefore, heat preservation and pressure coring has become a widely used coring method in deep wellbores. Among them, pressure maintenance can use a pressure compensation device to keep the core under formation pressure at all times, and there are many ways to achieve heat preservation, including active heating compensation and passive insulation. In order to select the best heat preservation method and optimize the coring process parameters, it is necessary to analyze and simulate the temperature changes of the core during the drilling and coring process.

[0004] However, the core is always in dynamic motion during the lifting process, with a time scale much smaller than the oil and gas production process, and heat is exchanged with the wellbore fluid and formation, making it difficult to calculate the core temperature during the lifting process using semi-steady-state and other wellbore temperature calculation methods. The current numerical simulation method has the problems of large workload and inability to calculate the temperature change during the entire lifting process, low work efficiency and low accuracy. Summary of the invention

[0005] The present application provides a method and system for calculating the core temperature during the coring and lifting process of drilling. By calculating the dynamic changes in the core temperature during the coring process, the influence of core movement, annular fluid and formation contact is overcome, the temperature distribution of the core along the entire wellbore is obtained, the dynamic change law of the core temperature in the entire well section and the lifting process is determined, the coring accuracy is improved, thereby providing a basis for the coring optimization design and improving work efficiency.

[0006] In a first aspect, the present application provides a method for calculating the core temperature during the process of coring and lifting in a well, comprising the following steps: dividing the coring barrel into a multi-layer barrel wall structure, and obtaining the basic parameters of each barrel wall structure, the parameters related to the wellbore and the formation, and the motion parameters during the process of lifting the core, wherein the barrel wall structure includes a core, an inner core steel barrel, an insulation layer, water between the inner and outer core steel barrels, and an outer core steel barrel; based on the barrel wall structures and the corresponding basic parameters, a radial heat transfer model is established between the barrel wall structures from the inside to the outside; based on the radial heat transfer model, a model boundary condition is set and the model parameters are initialized according to the parameters related to the wellbore and the formation; based on the motion parameters, the temperature distribution of the core along the entire wellbore is determined according to the radial heat transfer model, and the change law of the core temperature with the lifting time is obtained;

[0007] Optionally, the coring barrel is divided into a multi-layer barrel wall structure, and the basic parameters of each barrel wall structure, the parameters related to the wellbore and the formation, and the movement parameters during the core lifting process are obtained, and the parameters include: the basic parameters include the density ρ, specific heat capacity C, height L, radius r, and thermal conductivity λ of each barrel wall structure; the parameters related to the wellbore and the formation include the geothermal gradient g e , well depth h, bottom hole temperature and ground temperature T0; the movement parameters of the core during lifting, including lifting speed v and lifting time t z .

[0008] Optionally, a radial heat transfer model between the inner and outer barrel wall structures is established based on the barrel wall structures and the corresponding basic parameters, including: calculating the process parameters of the radial heat transfer model between the barrel wall structures based on the basic parameters; wherein the process parameters include the volume V of each barrel wall structure of the coring barrel and the heat transfer coefficients U of the inner core steel barrel, the insulation layer, the water between the inner and outer core steel barrels, and each part of the outer core steel barrel; based on the basic parameters and the obtained process parameters, radial heat transfer equations of each barrel wall structure are respectively constructed to obtain a radial heat transfer model.

[0009] Optionally, calculating the process parameters of the radial heat transfer model between the cylinder wall structures based on the basic parameters includes: obtaining the volume of each cylinder wall structure according to the height and the radius parameter of the basic parameters of each cylinder wall structure, wherein the core is a cylinder and the volume is described by the formula:

[0010] V1=πr1 2 L,

[0011] Wherein, V1 is the core volume, in m3, r1 is the core radius, in m, L is the core height, in m; the inner core steel cylinder, the insulation layer, the water between the inner and outer core steel cylinders, and the outer core steel cylinder are all cylindrical walls, and their volumes are described by public description:

[0012]

[0013] Where i is the number of the structure of each part of the core barrel from the inside to the outside, i = 2, 3, 4, 5, Vi is the volume of the corresponding part, the unit is m 3 , r i is the outer diameter of the corresponding part, in m, r i-1 is the inner diameter of the corresponding part, in m 3 According to the thermal conductivity λ of the inner core steel cylinder, the insulation layer, the water between the inner and outer core steel cylinders, and the outer core steel cylinder i+1 The heat transfer coefficient U corresponding to each cylinder wall structure is calculated separately i , described by the formula:

[0014]

[0015] Where U i For the corresponding r i Radius and r i+1 Heat transfer coefficient at radius, unit is W / (m 2 ·℃);λ i+1 is the thermal conductivity of the corresponding part, and its unit is W / (m·℃).

[0016] Optionally, radial heat transfer equations of each barrel wall structure are respectively constructed based on the basic parameters and the obtained process parameters to obtain a radial heat transfer model, including: segmenting the time for the core barrel to move from the bottom of the well to the wellhead, and when the time step is short enough, presetting radial steady-state heat transfer between the various parts of the core barrel; based on the calculation that the heat transfer amount between two adjacent barrel wall structures is the same as the change in the internal energy of the corresponding barrel wall structure, a radial heat transfer model is constructed according to the basic parameters and the obtained process parameters.

[0017] Optionally, based on the calculation that the amount of heat transferred between two adjacent cylinder wall structures is the same as the change in the internal energy of the corresponding cylinder wall structures, a radial heat transfer model is constructed according to the basic parameters and the obtained process parameters, including: within the segmented time step, according to the basic parameters of the core and the process parameters, calculating the heat radially transferred from the core to the inner core steel cylinder and the change in the internal energy of the core itself, and constructing the radial heat transfer equation of the core based on the transfer of heat being the same as the change in its own internal energy; within the segmented time step, according to the basic parameters of the water between the inner core steel cylinder, the insulation layer, and the outer core steel cylinder, respectively calculating the heat radially transferred between the adjacent inner core steel cylinder, the insulation layer, and the outer core steel cylinder and the change in the internal energy of the core itself; The changes in the internal energy of the inner core steel cylinder, the insulation layer, and the outer core steel cylinder are respectively constructed based on the fact that the transferred heat is the same as the change in the internal energy of the inner core steel cylinder, the insulation layer, and the outer core steel cylinder radial heat transfer equations; within the segmented time step, the heat radially transferred from the outer core steel cylinder to the annular water and the change in the internal energy of the outer core steel cylinder are calculated according to the basic parameters of the outer core steel cylinder and the process parameters, and the radial heat transfer equation of the outer core steel cylinder is constructed based on the fact that the transferred heat is the same as the change in the internal energy of the outer core steel cylinder, wherein the annular water represents the water filled between the coring cylinder and the well wall; based on the constructed radial heat transfer equations of each barrel wall structure, a radial heat transfer model of each barrel wall structure is obtained to determine the radial variation law of the core temperature.

[0018] Optionally, before constructing the radial heat transfer model, preset conditions are also included, specifically including: based on the fact that the core length is much smaller than the wellbore depth, the center point of the core is taken as the temperature calculation point; based on the fact that the core is in motion in the wellbore with a slow speed, frictional heat generation and longitudinal heat transfer are ignored; it is preset that the coring barrel is always centered, and the wellbore wall and annulus water temperatures are the same as the formation temperature.

[0019] Optionally, setting the model boundary conditions based on the model and initializing the model parameters according to the relevant parameters includes: considering the lifting process of the coring barrel from the bottom of the well to the wellhead as a uniform motion, obtaining the relationship between the lifting speed and the lifting time, and describing it by the formula:

[0020]

[0021] Where, v is the lifting speed in m / s, t z is the total movement time, in seconds, and h is the well depth, in meters. The initial temperature of each part of the coring barrel is set equal to the coring formation temperature, which is described by the formula:

[0022] T i 0 =T0+ge h,

[0023] Where, T i 0 is the initial temperature of the corresponding part of the core barrel, in °C, T0 is the ground temperature, in °C, g e is the geothermal gradient, in ℃ / m; the annular water temperature in contact with the mth time period is set to be equal to the formation temperature, which is described by the formula:

[0024]

[0025] Where, T i 0 is the initial temperature of the corresponding part of the core barrel, in °C, T0 is the ground temperature, in °C, g e is the geothermal gradient in °C / m; calculate the maximum value of the time segment, and the number of time segments is described by the formula:

[0026]

[0027] Where M is the maximum value of the time segment, t z is the total movement time, and △t is the time step.

[0028] Optionally, the process of lifting the coring barrel from the bottom of the well to the wellhead is regarded as uniform motion, and the temperature distribution of the core along the entire wellbore is determined according to the radial heat transfer model, so as to obtain the change law of the core temperature with the lifting time, including: based on the radial heat transfer model, the temperature field of each part of the coring barrel in different time periods is obtained from the inside to the outside and from the bottom to the top to obtain the temperature distribution of the core along the entire wellbore; according to the relationship between the motion parameters of the coring barrel and the well depth, the change law of the core with the lifting time is obtained.

[0029] In the second aspect, the present application provides a core temperature calculation system during the coring and lifting process of drilling, the system comprising: an acquisition module, used to divide the coring barrel into a multi-layer barrel wall structure, and obtain the basic parameters of each barrel wall structure, the wellbore and formation related parameters and the motion parameters during the core lifting process, wherein the barrel wall structure includes the core, the inner core steel barrel, the insulation layer, the water between the inner and outer core steel barrels, and the outer core steel barrel; a model construction module, used to establish a radial heat transfer model between the barrel wall structures from the inside to the outside based on the each barrel wall structure and the corresponding basic parameters; an initialization module, used to set the model boundary conditions based on the radial heat transfer model and initialize the model parameters according to the wellbore and formation related parameters; a processing module, used to regard the lifting process of the coring barrel from the bottom of the well to the wellhead as a uniform motion, determine the temperature distribution of the core along the entire wellbore according to the radial heat transfer model, and obtain the change law of the core temperature with the lifting time.

[0030] In a third aspect, the present application also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-described method when executing the computer program.

[0031] In a fourth aspect, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above-mentioned method are implemented.

[0032] This application has at least the following advantages:

[0033] The coring barrel is divided into a multi-layer barrel wall structure, and the basic parameters of each barrel wall structure, the wellbore and formation related parameters, and the movement parameters during the core lifting process are obtained. According to the obtained multi-layer barrel wall structure and combined with the obtained parameters of each barrel wall, a radial heat transfer model between the barrel walls is constructed based on the calculation that the heat transfer between two adjacent barrel wall structures is the same as the change in the internal energy of the corresponding barrel wall structure. The dynamic change of the core temperature during the coring process is calculated based on the constructed radial heat transfer model, which overcomes the influence of core movement, annular fluid and formation contact, obtains the temperature distribution of the core along the entire wellbore, determines the dynamic change law of the core temperature in the entire well section and during the lifting process, and improves the coring accuracy, thereby providing a basis for coring optimization design and improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A diagram showing an application environment of a method for calculating core temperature during a coring and lifting process in a well drilling according to an embodiment;

[0035] Figure 2 A schematic flow chart showing the steps of a method for calculating core temperature during a coring and lifting process in a well drilling according to an embodiment;

[0036] Figure 3 A schematic diagram showing the structure of a coring barrel in one embodiment;

[0037] Figure 4 A schematic flow chart showing the steps of constructing a radial heat transfer model in one embodiment;

[0038] Figure 5 A structural block diagram showing a core temperature calculation system during the coring and lifting process in a well drilling embodiment;

[0039] Figure 6 FIG. 4 is a schematic structural diagram of a computer device in one embodiment. DETAILED DESCRIPTION

[0040] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when "including" and / or "comprising" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0042] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in the embodiments of the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The markings of the following embodiments are for convenience of description and should not constitute any limitation to the specific implementation of the present application. The various embodiments can be combined with each other and quoted from each other without contradiction.

[0043] Figure 2 A flow chart of a method for calculating the core temperature during the coring process provided in an embodiment of the present application is provided. The method can be performed as follows: Figure 1 The user space file server is executed in the system shown. Figure 2 , Figure 3 As shown, the method may include the following steps:

[0044] S201, dividing the coring barrel into a multi-layer barrel wall structure, and obtaining basic parameters of each barrel wall structure, wellbore and formation related parameters, and movement parameters during the core lifting process, wherein the barrel wall structure includes the core, the inner core steel barrel, the insulation layer, the water between the inner and outer core steel barrels, and the outer core steel barrel;

[0045] S202, establishing a radial heat transfer model between the cylinder wall structures from the inside to the outside based on the cylinder wall structures and corresponding basic parameters;

[0046] S203, setting model boundary conditions based on the radial heat transfer model and initializing model parameters according to wellbore and formation related parameters;

[0047] S204. Based on the motion parameters and according to the radial heat transfer model, the temperature distribution of the core along the entire wellbore is determined to obtain the variation pattern of the core temperature with the lifting time.

[0048] The coring barrel is divided into a multi-layer barrel wall structure, and the basic parameters of each barrel wall structure, the wellbore and formation related parameters, and the movement parameters during the core lifting process are obtained. According to the obtained multi-layer barrel wall structure and combined with the obtained parameters, a radial heat transfer model between the barrel walls is constructed. The model is initialized and based on the constructed radial heat transfer model, the temperature distribution of the core along the entire wellbore is calculated. According to the relationship between the movement speed, well depth and time, the change law of the core temperature with the lifting time is obtained, and the coring accuracy is improved, thereby providing a basis for the coring optimization design and improving work efficiency.

[0049] The following is a detailed description of each step:

[0050] Please refer to Figure 2 , Figure 3 As shown, step S201, dividing the coring barrel into a multi-layer barrel wall structure, and obtaining basic parameters of each barrel wall structure, wellbore and formation related parameters, and movement parameters during the core lifting process;

[0051] In this embodiment, it should be noted that the barrel wall structure includes a core, an inner core steel barrel, an insulation layer, water between the inner and outer core steel barrels, and an outer core steel barrel. The coring barrel is inserted into the well as a whole, and the coring barrel is located on the center line of the entire well, and moves vertically up and down along the well. The outer side of the outer core steel barrel of the coring barrel and the well wall are also filled with annular water. According to the divided multi-layer structure of the coring barrel, the basic parameters of each barrel wall structure, the parameters related to the wellbore and the formation, and the movement parameters during the core lifting process are obtained. The basic parameters include the density ρ, specific heat capacity C, height L, radius r, and thermal conductivity λ of each barrel wall structure; the parameters related to the wellbore and the formation, including the geothermal gradient g e , well depth h, bottom hole temperature and ground temperature T0, where the geothermal gradient represents the parameter of the uneven distribution of temperature inside the earth. It is usually expressed in degrees Celsius of temperature increase per 100 meters of vertical depth. The movement parameters during the core lifting process include the lifting speed v and the lifting time t z , based on the various parameters obtained, provide a data basis for subsequent calculation and processing.

[0052] Please continue to refer to Figure 2-Figure 4 As shown, step S202, based on each cylinder wall structure and the corresponding basic parameters, a radial heat transfer model between each cylinder wall structure from the inside to the outside is established, specifically including:

[0053] Step S2021, calculating the process parameters of the radial heat transfer model between each cylinder wall structure based on the basic parameters;

[0054] In this embodiment, it should be noted that, specifically, the process parameters include the volume V of each barrel wall structure of the coring barrel and the heat transfer coefficient U of each part of the inner core steel barrel, the insulation layer, the water between the inner and outer core steel barrels, and the outer core steel barrel; the volume of each barrel wall structure is obtained according to the height and radius parameters of the basic parameters of each barrel wall structure, wherein the core is a cylinder, and the volume is described by formula (1):

[0055] V1=πr1 2 L (1),

[0056] Where V1 is the core volume, in m 3 ; r1 is the core radius, in m, L is the core height, in m; the inner core steel cylinder, the insulation layer, the water between the inner and outer core steel cylinders, and the outer core steel cylinder are all cylindrical walls, and their volumes are described by formula (2):

[0057]

[0058] Where i is the number of each part of the core barrel from the inside to the outside, i = 2, 3, 4, 5, V i is the volume of the corresponding part, in m 3 , r i is the outer diameter of the corresponding part, in m, r i-1 is the inner diameter of the corresponding part, in m 3 ;

[0059] In addition, in one example, according to the thermal conductivity λ corresponding to the inner core steel cylinder, the insulation layer, the water between the inner and outer core steel cylinders, and the outer core steel cylinder i+1 The heat transfer coefficients U of the inner core steel cylinder, the insulation layer, and the water between the inner and outer core steel cylinders are calculated respectively. i , described by formula (3):

[0060]

[0061] Where i is the number of each part of the core barrel from the inside to the outside, i = 2, 3, 4, 5, U i For the corresponding r i Radius and r i+1 Heat transfer coefficient at radius, unit is W / (m 2 ·℃);λ i+1 is the thermal conductivity of the corresponding part, in W / (m·℃). For example, U2 is the thermal conductivity of the inner core steel tube, corresponding to the heat transfer coefficient at the radius of the inner core steel tube and the radius of the insulation layer.

[0062] Step S2022: Based on the basic parameters and the obtained process parameters, the radial heat transfer equation of the core, the energy equation of the water between the inner core steel cylinder, the insulation layer and the outer core steel cylinder, and the radial heat transfer equation of the outer core steel cylinder are respectively constructed to obtain a radial heat transfer model.

[0063] In this embodiment, it should be noted that the time for the core barrel to move from the bottom of the well to the wellhead is segmented. When the time step is short enough, it can be considered that steady-state heat transfer occurs between the various parts of the core barrel. Therefore, the radial heat transfer equation of the core is constructed based on the fact that the heat radially transferred to the inner core steel cylinder is the same as the change in the internal energy of the core itself.

[0064] In one example, the radial heat transfer equation of the core is constructed based on the density of the basic parameters of the core, the specific heat capacity of the core, and the volume and heat transfer coefficient of the process parameters, and is described by formula (4):

[0065]

[0066] Where m is the number of the time segment, m = 0, 1, 2, 3.........; T1 m+1 is the temperature of the core in the m+1th time period, in °C, T1 m is the temperature of the core in the mth time period, in °C, and ρ1 is the density of the core, in kg / m 3 ; C1 is the core specific heat capacity, unit is J / (kg·℃), is the temperature of the inner core steel cylinder in the mth time period, in °C, and △t is the time step, in s.

[0067] Within the segmented time step, the radial heat transferred by the water between the inner core steel cylinder, the insulation layer and the outer core steel cylinder and the change in their own internal energy are calculated according to the basic parameters of the water between the inner core steel cylinder, the insulation layer and the outer core steel cylinder as well as the process parameters. The radial heat transfer equations of the inner core steel cylinder, the insulation layer and the outer core steel cylinder are constructed according to the fact that the transferred heat is the same as the change in their own internal energy.

[0068] Specifically, the energy equation of the water between the inner core steel cylinder, the insulation layer, and the outer core steel cylinder is constructed according to the density of the basic parameters of the water between the inner and outer core steel cylinders, the core specific heat capacity parameter, and the volume and heat transfer coefficient parameters of the process parameters, which is described by formula (5):

[0069]

[0070] Where, T i m+1 is the temperature of the corresponding part in the m+1th time period, in °C, T im is the temperature of the corresponding part in the mth time period, in °C; ρ1 is the density of the corresponding part, in kg / m 3 , C1 is the specific heat capacity of the part, the unit is J / (kg·℃), is the temperature of the response part in the mth time period, in °C.

[0071] In the segmented time step, the heat radially transferred from the outer core steel cylinder to the annular water and the change in the internal energy of the outer core steel cylinder itself are calculated according to the basic parameters of the outer core steel cylinder and the process parameters. The radial heat transfer equation of the outer core steel cylinder is constructed based on the fact that the transferred heat is the same as the change in its own internal energy.

[0072] Specifically, the radial heat transfer equation of the outer core steel cylinder is constructed according to the density of the basic parameters of the outer core steel cylinder, the specific heat capacity parameter of the outer core steel cylinder, and the volume and heat transfer coefficient parameters of the process parameters, which is described by formula (6):

[0073]

[0074] In the formula, is the temperature of the outer core steel cylinder in the m+1th time period, in °C, is the temperature of the outer core steel tube in the mth time period, in °C, and ρ5 is the density of the outer core steel tube, in kg / m 3 , C5 is the specific heat capacity of the outer core steel tube, in J / (kg·℃), is the annular water temperature that the outer core steel tube contacts in the mth time period, in °C;

[0075] According to the radial heat transfer equations of each structure of the coring barrel constructed above, a radial heat transfer model is obtained to determine the radial variation law of the core temperature.

[0076] Reference Figure 3 , Figure 4 As shown, step S202, before constructing the radial heat transfer model, preset conditions are also set, specifically including: based on the core length being much smaller than the wellbore depth, the center point of the core is taken as the temperature calculation point; based on the core being in motion in the wellbore at a slow speed, frictional heat generation and longitudinal heat transfer are ignored; it is preset that the coring barrel is always centered, and the temperature of the water filled in the wellbore wall and the annulus is the same as the formation temperature.

[0077] In this embodiment, it should be noted that before constructing the radial heat transfer model, preset conditions in advance, ignore the temperature difference of different parts of the core, take the center point of the core as the calculation point, find the calculation base point, and regard the obtained calculation point as the temperature of the entire core. At the same time, during the coring process, frictional heat will occur during the movement of the coring barrel along the wellbore. The effect of this part of heat is not significant and can be ignored. When each part of the entire coring barrel moves in the vertical direction, it is regarded as a point moving, ignoring its own longitudinal heat changes to ensure the rationality of the radial heat transfer model constructed by subsequent calculations. Finally, the coring barrel is always preset to be centered to ensure uniform radial heat transfer, and the well wall and annular water temperature are preset to be the same as the formation temperature so that the constructed model can be initialized later. The above preset conditions are all within the consideration range of constructing the entire radial heat transfer model to increase the accuracy of the constructed model.

[0078] Reference Figure 2-Figure 4 As shown, step S203, setting model boundary conditions based on the radial heat transfer model and initializing model parameters according to relevant parameters;

[0079] First, based on the assumption that the process of lifting the core barrel from the bottom of the well to the wellhead is uniform motion, the relationship between the lifting speed and the lifting time is obtained and described by formula (7):

[0080]

[0081] Where, v is the lifting speed in m / s, t z is the total movement time in seconds, h is the well depth in meters;

[0082] The initial temperature of each part of the coring barrel is set equal to the coring formation temperature, which is described by formula (8):

[0083] T i 0 =T0+g e h (8),

[0084] Where, T i 0 is the initial temperature of the corresponding part of the core barrel, in °C, T0 is the ground temperature, in °C, g e is the geothermal gradient, in °C / m;

[0085] The annular water temperature in contact with the mth time period is set to be equal to the formation temperature, which is described by formula (9):

[0086]

[0087] Where, T i 0is the initial temperature of the corresponding part of the core barrel, in °C, T0 is the ground temperature, in °C, g e is the geothermal gradient, in °C / m;

[0088] Calculate the maximum value of the time segment. The number of time segments is described by formula (10):

[0089]

[0090] Where M is the maximum value of the time segment, t z is the total movement time, and △t is the time step.

[0091] In this embodiment, it should be noted that the process of lifting the coring barrel from the bottom of the well to the wellhead is regarded as uniform motion, the average speed of the coring barrel is obtained, and the maximum value of the time segment is obtained according to the determined time step to determine the boundary conditions of the radial heat transfer model. At the same time, the initial temperature of each part of the coring barrel is set to be equal to the coring formation temperature, and the annular water temperature in contact in the mth time period is set to be equal to the formation temperature, and the parameters of the radial heat transfer model are initialized for subsequent calculation and processing.

[0092] Reference Figure 2 , Figure 3 As shown, step S204, based on the motion parameters, the temperature distribution of the core along the entire wellbore is determined according to the radial heat transfer model, and the change law of the core temperature with the lifting time is obtained.

[0093] In this embodiment, it should be noted that, according to the obtained radial heat transfer model and the set boundary conditions, the equation group is solved from the inside to the outside and from the bottom to the top. In the initial state, let m = 0, then let i = 1, first solve the temperature change of the core, then let i = i + 1 to solve the temperature change of other parts in turn, after solving the temperature field of all parts, calculate the temperature field of all parts in the next period, that is, m = m + 1, let i = 1 again, repeat the above steps until the core barrel is lifted from the bottom of the well to the wellhead, that is, m = M, and the calculation is terminated. Through the above steps, the temperature distribution of the core along the entire wellbore can be obtained, and then according to the relationship between the movement speed of the core barrel and the well depth and time, the specific change law of the core with the lifting time can be obtained.

[0094] The implementation principle of this embodiment: The above steps mainly divide the coring barrel into a multi-layer barrel wall structure, and obtain the basic parameters of each barrel wall structure, the wellbore and formation related parameters and the movement parameters during the core lifting process. According to the obtained multi-layer barrel wall structure and combined with the obtained basic parameters of each barrel wall and the obtained process parameters, a radial heat transfer model between the barrel walls is constructed based on the calculation that the heat transfer between two adjacent barrel wall structures is the same as the change in the internal energy of the corresponding barrel wall structure. The model is initialized and the dynamic change of the core temperature during the coring process is calculated based on the constructed radial heat transfer model, which overcomes the influence of core movement, annular space fluid and formation contact, and obtains the temperature distribution of the core along the entire wellbore. According to the relationship between the movement speed, well depth and time, the change law of the core temperature with the lifting time is obtained, and the coring accuracy is improved, thereby providing a basis for coring optimization design and improving work efficiency.

[0095] Reference Figure 5 As shown, the present application also provides a core temperature calculation system during the core extraction and lifting process, which may include: an acquisition module 301, a model building module 302, an initialization module 303, and a processing module 304. The main functions of each component module are as follows:

[0096] The acquisition module 301 is used to divide the coring barrel into a multi-layer barrel wall structure, and obtain the basic parameters of each barrel wall structure, the wellbore and formation related parameters, and the movement parameters during the core lifting process, wherein the barrel wall structure includes the core, the inner core steel barrel, the insulation layer, the water between the inner and outer core steel barrels, and the outer core steel barrel;

[0097] A model building module 302 is used to build a radial heat transfer model between the inner and outer wall structures based on the wall structures and corresponding basic parameters;

[0098] Initialization module 303, used to set model boundary conditions based on the radial heat transfer model and initialize model parameters according to wellbore and formation related parameters;

[0099] The processing module 304 is used to regard the lifting process of the coring barrel from the bottom of the well to the wellhead as uniform motion, determine the temperature distribution of the core along the entire wellbore according to the radial heat transfer model, and obtain the variation law of the core temperature with the lifting time.

[0100] like Figure 6 , is a block diagram of a computer device according to an embodiment of the present application. The computer device is intended to represent various forms of digital computers or mobile devices. The digital computer may include a desktop computer, a portable computer, a workbench, a personal digital assistant, a server, a mainframe computer, and other suitable computers. The mobile device may include a tablet computer, a smart phone, a wearable device, etc.

[0101] like Figure 6 As shown, the device 600 includes a computing unit 601, a ROM 602, a RAM 603, a bus 604, and an input / output (I / O) interface 605, and the computing unit 601, ROM 602 and RAM 603 are connected to each other through the bus 604. The input / output (I / O) interface 605 is also connected to the bus 604.

[0102] The computing unit 601 can perform various processes in the method embodiment of the present application according to the computer instructions stored in the read-only memory (ROM) 602 or the computer instructions loaded from the storage unit 608 to the random access memory (RAM) 603. The computing unit 601 can be various general and / or special processing components with processing and computing capabilities. The computing unit 601 may include, but is not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. In some embodiments, the method provided in the embodiment of the present application can be implemented as a computer software program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 608.

[0103] RAM 603 may also store various programs and data required for the operation of device 600. Part or all of a computer program may be loaded and / or installed on device 600 via ROM 602 and / or communication unit 609.

[0104] The input unit 606, output unit 607, storage unit 608 and communication unit 609 in the device 600 can be connected to the I / O interface 605. The input unit 606 can be, for example, a keyboard, a mouse, a touch screen, a microphone, etc. The output unit 607 can be, for example, a display, a speaker, an indicator light, etc. The device 600 can exchange information, data, etc. with other devices through the communication unit 609.

[0105] It should be noted that the device may also include other components necessary for normal operation, or may only include components necessary for implementing the solution of the present application, rather than all the components shown in the figure.

[0106] Various implementations of the systems and techniques described herein can be realized in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof.

[0107] The computer instructions for implementing the method of the present application can be written in any combination of one or more programming languages. These computer instructions can be provided to the computing unit 601, so that when the computer instructions are executed by the computing unit 601 such as a processor, the steps involved in the method embodiment of the present application are executed.

[0108] The computer-readable storage medium provided in the present application may be a tangible medium that may contain or store computer instructions for executing the steps involved in the method embodiments of the present application. The computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, and other forms of storage media.

[0109] The above specific implementations do not constitute a limitation on the protection scope of this application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A method for calculating core temperature during the process of coring in drilling, characterized in that: The following steps are involved: The coring barrel is divided into a multi-layer barrel wall structure, and the basic parameters of each barrel wall structure, the wellbore and formation related parameters, and the movement parameters during the core lifting process are obtained, wherein the barrel wall structure includes the core, the inner core steel barrel, the insulation layer, the water between the inner and outer core steel barrels, and the outer core steel barrel; based on the barrel wall structures and the corresponding basic parameters, a radial heat transfer model between the barrel wall structures from the inner to the outer is established; Setting model boundary conditions based on the radial heat transfer model and initializing model parameters according to the wellbore and formation related parameters; Based on the movement parameters, the temperature distribution of the core along the entire wellbore is determined according to the radial heat transfer model, and the variation pattern of the core temperature with the lifting time is obtained.

2. The method for calculating core temperature during the core extraction process according to claim 1, characterized in that: The coring barrel is divided into a multi-layer barrel wall structure, and basic parameters of each barrel wall structure, wellbore and formation related parameters, and movement parameters during the core lifting process are obtained, including: the basic parameters include density ρ, specific heat capacity C, height L, radius r, and thermal conductivity λ of each barrel wall structure; The wellbore and formation related parameters include geothermal gradient g e , well depth h, bottom well temperature and ground temperature T0; The movement parameters of the core during lifting include lifting speed v and lifting time t z .

3. The method for calculating the core temperature during the core extraction process according to claim 2, characterized in that: The radial heat transfer model between the inner and outer cylinder wall structures is established based on the cylinder wall structures and the corresponding basic parameters, including: Calculate the process parameters of the radial heat transfer model between the cylinder wall structures based on the basic parameters; The process parameters include the volume V of each wall structure of the coring barrel, the inner core steel barrel, the insulation layer, the water between the inner and outer core steel barrels, and the heat transfer coefficient U of each part of the outer core steel barrel; Based on the basic parameters and the obtained process parameters, radial heat transfer equations of each cylinder wall structure are respectively constructed to obtain a radial heat transfer model.

4. The method for calculating core temperature during the core extraction process according to claim 3, characterized in that: The process parameters of the radial heat transfer model between the cylinder wall structures are calculated based on the basic parameters, including: The volume of each barrel wall structure is obtained according to the height and radius parameters of the basic parameters of each barrel wall structure, wherein the core is a cylinder and the volume is described by the formula: V1=πr1 2 L, Where V1 is the core volume, in m 3 , r1 is the core radius, in m, L is the core height, in m; The inner core steel cylinder, the insulation layer, the water between the inner and outer core steel cylinders, and the outer core steel cylinder are all cylindrical walls, and their volumes are described by the formula: Where i is the number of each part of the core barrel from the inside to the outside, i = 2, 3, 4, 5, V i is the volume of the corresponding part, in m 3 , r i is the outer diameter of the corresponding part, in m, r i-1 is the inner diameter of the corresponding part, in m 3 ; According to the thermal conductivity λ corresponding to the inner core steel cylinder, the insulation layer, the water between the inner and outer core steel cylinders, and the outer core steel cylinder i+1 The heat transfer coefficient U corresponding to each cylinder wall structure is calculated separately i , described by the formula: Where U i For the corresponding r i Radius and r i+1 Heat transfer coefficient at radius, unit is W / (m 2 ·℃);λ i+1 is the thermal conductivity of the corresponding part, and its unit is W / (m·℃).

5. The method for calculating core temperature during the core extraction process according to claim 3 or 4, characterized in that: The radial heat transfer equations of each cylinder wall structure are respectively constructed based on the basic parameters and the obtained process parameters to obtain a radial heat transfer model, including: The time for the core barrel to move from the bottom of the well to the wellhead is segmented, and when the time step is short enough, steady-state heat transfer is preset to occur radially between the parts of the core barrel; Based on the calculation that the amount of heat transfer between two adjacent cylinder wall structures is the same as the amount of change in the internal energy of the corresponding cylinder wall structures, a radial heat transfer model is constructed according to the basic parameters and the obtained process parameters.

6. The method for calculating the core temperature during the coring process according to claim 5, characterized in that: The calculation based on the heat transfer amount between two adjacent cylinder wall structures being the same as the change amount of the internal energy of the corresponding cylinder wall structures, constructing a radial heat transfer model according to the basic parameters and the obtained process parameters, includes: In the segmented time step, the heat radially transferred from the core to the inner core steel cylinder and the change in the core's own internal energy are calculated according to the basic parameters of the core and the process parameters, and the radial heat transfer equation of the core is constructed based on the fact that the transferred heat is the same as the change in its own internal energy; In the segmented time step, the heat radially transferred by the water between the inner core steel cylinder, the insulation layer and the outer core steel cylinder and the change in the internal energy of the inner core steel cylinder, the insulation layer and the outer core steel cylinder are calculated respectively according to the basic parameters of the water between the inner core steel cylinder, the insulation layer and the outer core steel cylinder and the process parameters, and the radial heat transfer equations of the inner core steel cylinder, the insulation layer and the outer core steel cylinder are constructed respectively according to the fact that the transferred heat is the same as the change in the internal energy; In the segmented time step, the heat radially transferred from the outer core steel tube to the annular water and the change in the internal energy of the outer core steel tube itself are calculated according to the basic parameters of the outer core steel tube and the process parameters, and the radial heat transfer equation of the outer core steel tube is constructed based on the fact that the transferred heat is the same as the change in its own internal energy, wherein the annular water represents the water filled between the coring tube and the well wall; Based on the constructed radial heat transfer equations of each barrel wall structure, a radial heat transfer model of each barrel wall structure is obtained to determine the radial variation law of the core temperature.

7. The method for calculating the core temperature during the core extraction process according to any one of claims 1 to 6, characterized in that: Before constructing the radial heat transfer model, preset conditions are also included, specifically including: Since the core length is much smaller than the wellbore depth, the center point of the core is taken as the temperature calculation point; since the core is in motion in the wellbore at a slow speed, frictional heat generation and longitudinal heat transfer are ignored; It is preset that the coring barrel is always centered, and the temperature of the well wall and annular water is the same as the formation temperature.

8. The method for calculating core temperature during the core extraction process according to claim 6, characterized in that: The step of setting a model boundary condition based on the radial heat transfer model and initializing model parameters according to the relevant parameters includes: Based on the fact that the lifting process of the coring barrel from the bottom of the well to the wellhead is regarded as uniform motion, the relationship between the lifting speed and the lifting time is obtained and described by the formula: Where, v is the lifting speed in m / s, t z is the total movement time, in seconds, and h is the well depth, in meters; The initial temperature of each part of the coring barrel is set equal to the coring formation temperature, which is described by the formula: T i 0 =T0+g e h, Where, T i 0 is the initial temperature of the corresponding part of the core barrel, in °C, T0 is the ground temperature, in °C, g e is the geothermal gradient, in °C / m; The annular water temperature in contact with the mth time period is set to be equal to the formation temperature, which is described by the formula: Where, T i 0 is the initial temperature of the corresponding part of the core barrel, in °C, T0 is the ground temperature, in °C, g e is the geothermal gradient, in °C / m; Calculate the maximum value of a time segment, the number of time segments is described by the formula: Where M is the maximum value of the time segment, t z is the total movement time, and △t is the time step.

9. The method for calculating core temperature during the core extraction process according to claim 8, characterized in that: The method of determining the temperature distribution of the core along the entire wellbore based on the motion parameters and the radial heat transfer model to obtain the variation law of the core temperature with the lifting time includes: Based on the radial heat transfer model, the temperature fields of the various parts of the coring barrel in different time periods are obtained from inside to outside and from bottom to top to obtain the temperature distribution of the core along the entire wellbore; According to the relationship between the movement parameters of the coring barrel and the well depth, the change law of the core with the lifting time is obtained.

10. A core temperature calculation system during the coring process of drilling, characterized in that: include: An acquisition module is used to divide the coring barrel into a multi-layer barrel wall structure and obtain the basic parameters of each barrel wall structure, the wellbore and formation related parameters, and the movement parameters during the core lifting process; The cylinder wall structure includes a rock core, an inner rock core steel cylinder, an insulation layer, water between the inner and outer rock core steel cylinders, and an outer rock core steel cylinder; A model building module is used to establish a radial heat transfer model between the inner and outer cylinder wall structures based on the cylinder wall structures and the corresponding basic parameters; An initialization module, used for setting model boundary conditions based on the radial heat transfer model and initializing model parameters according to the wellbore and formation related parameters; A processing module is used to determine the temperature distribution of the core along the entire wellbore based on the motion parameters and the radial heat transfer model, and obtain the change law of the core temperature with the lifting time.

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