Drilling circulating temperature modeling method, system, and apparatus for drill string eccentric effects

Abstract

This invention discloses a method, system, and equipment for simulating drilling circulation temperature based on the drill string eccentricity effect, belonging to the field of petroleum drilling engineering technology. The simulation method includes: acquiring the parameters of the target well; establishing thermal models for various heat source items in the horizontal section of the target well, including drill bit rock breaking heat source item, drill string-wellbore friction heat source item, drill string vibration heat source item, viscous heat dissipation heat source item, and electronic component working heat source item, based on the horizontal section drill string eccentricity effect and thermal model; establishing a wellbore heat balance model under the horizontal section drill string eccentricity effect; and solving the wellbore heat balance model under the horizontal section drill string eccentricity effect. This invention provides fundamental theoretical and applicable methodological support for drilling circulation temperature simulation research considering the horizontal section drill string eccentricity effect and complex heat source items. It is applicable to deep shale gas wells and has high practical value and application prospects.

Description

Technical Field

[0001] This invention belongs to the field of oil drilling engineering technology, and specifically relates to a method, system and equipment for simulating drilling circulation temperature based on drill string eccentricity effect. Background Technology

[0002] The bottom-hole circulating temperature in the horizontal section of deep shale gas wells generally exceeds 135℃, severely challenging the reliability of downhole tools operating under high-temperature conditions for extended periods. During long horizontal drilling operations, rotary steerable tools frequently fail due to high temperatures, leading to increased trips, low drilling efficiency, and prolonged drilling cycles. Therefore, accurately predicting the wellbore temperature distribution during horizontal well drilling is a prerequisite for overcoming this technical challenge.

[0003] Methods for calculating wellbore temperature fields mainly include analytical and numerical methods. Analytical methods, primarily represented by the analytical mathematical model of wellbore temperature fields established by Hasan and Kabir, can accurately simulate the steady-state temperature field of the wellbore. Numerical methods, on the other hand, are typically based on the numerical model of wellbore temperature fields established by Raymond and Marshall et al., with continuous modifications and improvements to the model, resulting in higher simulation accuracy and wider application. Existing analytical and numerical methods for wellbore temperature fields, when dealing with horizontal section temperatures, often rely on idealized concentric annulus heat transfer models of the drill string and do not consider heat source terms, leading to significant discrepancies with actual operating conditions.

[0004] Patent (CN115293066A) discloses a method for calculating the temperature field of a gas well that considers the heat transfer effect of formation seepage. Its wellbore temperature field heat balance model only includes three parts: heat generated by the drill bit breaking rocks, heat transfer from the formation seepage field, and heat balance of the drilling fluid. It ignores the comprehensive influence of other important heat sources such as heat loss due to the viscosity of the drilling fluid flow, heat generated by friction between the drill string and the well wall, heat generated by drill string vibration and heat generated by the operation of electronic components.

[0005] To address the inaccurate calculation of wellbore temperature distribution under the influence of drill string eccentricity in horizontal sections and complex heat source terms, it is urgent to develop a drilling circulation temperature simulation method. Summary of the Invention

[0006] To address the above problems, this invention discloses a method for simulating drilling circulation temperature based on drill string eccentricity, comprising:

[0007] Obtain the parameters of the target well;

[0008] Based on the parameters of the target well and the influence of various heat source items in the horizontal section of the target well, thermal models are established for the drill bit rock breaking heat source item, drill string and well wall friction heat source item, drill string vibration heat source item, viscous heat dissipation heat source item, and electronic component working heat source item, respectively.

[0009] Based on the horizontal section drill string eccentricity effect and the aforementioned heat model, a wellbore heat balance model under the horizontal section drill string eccentricity effect is established.

[0010] The heat balance model of the wellbore under the eccentric effect of the drill string in the horizontal section is solved.

[0011] Furthermore, the thermal model for the frictional heat source term between the drill string and the wellbore is as follows:

[0012] Q f =2π′RPS′μrwΔSsina

[0013] Where RPS—rotations per second, r / s; w—float weight, kN / m; μ—friction coefficient; —drill pipe outer diameter, m; DS—friction section, m; a—well inclination angle, °; Q f —Frictional heat between drill string and wellbore, W.

[0014] Furthermore, the thermal model for the drill string vibration heat source term is as follows:

[0015]

[0016] Among them, T N —Axial force of drill string, kN; m st —Weight of the drill string element, kg; x—lateral displacement of the drill string, m; z—spatial step, m; t—time, s; I a —Drill string moment of inertia, kg·m 2 E a —Elastic modulus of drill string, Pa; L a — Drill string length, m; dz — Drill string element length, m; Q -1 — Drill string thermoelastic damping; A — Cross-sectional area, m 2 Qz—Drill string vibration heat, W.

[0017] Furthermore, the thermal model for the viscous heat dissipation source term is as follows:

[0018]

[0019] Where P is the pressure drop due to flow friction, in kPa; R is the pressure drop due to flow friction. w — Frictional pressure drop ratio; q—Drilling fluid flow rate, m³ 3 / s; L—unit length, m; ρ m —Fluid density, kg / m³ 3 f—friction coefficient; v—drilling fluid velocity, m / s; d—equivalent diameter, m; μ r —Relative viscosity; c f —Drilling fluid liquid phase content; c p —Drilling fluid solids content; ρ f—Drilling fluid liquid phase density, kg / m³ 3 ;ρ p —Drilling fluid solid density, kg / m³ 3 Q n —Drilling fluid viscosity consumes heat (W).

[0020] Furthermore, the thermal model for the operating heat source term of the electronic component is as follows:

[0021]

[0022] Where, I1—operating current of the first downhole instrument, A; R1—operating resistance of the first downhole instrument, Ω; I2—operating current of the second downhole instrument, A; R2—operating resistance of the second downhole instrument, Ω; I n —The operating current of the nth downhole instrument, A; R n —The operating resistance of the nth downhole instrument, in Ω; Q a —Heat of downhole instrument electronic components, W.

[0023] Furthermore, the thermal model for the drill bit rock-breaking heat source term is as follows:

[0024]

[0025] Where WOB is the drilling pressure (kN); ROP is the drilling rate (m / h); J is the Joule constant; ω is the rotational speed (RPM); and M is the drilling speed. bit —Drill bit torque, kN·m; r b —Drill bit outer diameter, mm; Q bit —Heat generated by the drill bit breaking rock, W.

[0026] Furthermore, the wellbore heat balance model includes a heat balance model of the drilling fluid inside the drill string under the eccentric effect of the horizontal section drill string, a heat balance model of the upper drill string wall under the eccentric effect of the horizontal section drill string, a heat balance model of the lower drill string wall under the eccentric effect of the horizontal section drill string, a heat balance model of the annulus at the upper end under the eccentric effect of the horizontal section drill string, a heat balance model of the annulus at the lower end under the eccentric effect of the horizontal section drill string, and a heat balance model of the annulus at the bottom of the well.

[0027] The heat balance model of the drilling fluid inside the drill string under the eccentric effect of the horizontal section drill string is as follows:

[0028]

[0029] Where ρ0 is the drilling fluid density, kg / m³ 3 c0—Specific heat capacity of drilling fluid, J / (kg·℃); T0—Drilling fluid temperature inside the drill string, ℃; T1—Trill string wall temperature at the upper end of the horizontal section, ℃; T1'—Trill string wall temperature at the lower end of the horizontal section, ℃; h0—Convective heat transfer coefficient at the upper end of the drill string inner wall, W / (m²)2 ·℃); q0—drilling fluid flow rate in the drill string, m 3 / s;Q n 1 —Heat dissipation due to the viscosity of drilling fluid inside the drill string, W; e—Drill string eccentricity, m; r0—Drill string inner diameter, m; r1—Drill string outer diameter, m; h'0—Convective heat transfer coefficient at the lower end of the drill string inner wall, W / (m²) 2 ·℃).

[0030] Furthermore, the heat balance model of the upper end of the drill string wall under the eccentric effect of the horizontal section drill string is as follows:

[0031]

[0032] Where ρ1 is the density of the drill string, kg / m³ 3 c1—Specific heat capacity of drill string, J / (kg·℃); T2—Temperature of drilling fluid in the annulus at the upper end of the horizontal section, ℃; h1—Convective heat transfer coefficient of the outer wall of the drill string at the upper end of the horizontal section, W / (m²) 2 ·℃); λ1—thermal conductivity of the drill string, W / (m·℃); α1—radial thermal diffusivity of the drill string, m 2 / s;

[0033] The heat balance model of the lower end of the drill string wall under the eccentric effect of the horizontal section drill string is as follows:

[0034]

[0035] Where h1' is the convective heat transfer coefficient of the drill string wall at the lower end of the horizontal section, in W / (m²). 2 ·℃); T2'—Temperature of drilling fluid in the annulus at the lower end of the horizontal section, ℃.

[0036] Furthermore, the annular heat balance model at the upper end of the horizontal drill string under the eccentric effect is as follows:

[0037]

[0038] Wherein, ρ2—density of drilling fluid in the annulus, kg / m³ 3 c2—Specific heat capacity of drilling fluid in the annulus, J / (kg·℃); T3—Wellbore temperature, ℃; α2—Thermal diffusivity of drilling fluid in the annulus, m 2 / s; h1—convective heat transfer coefficient of the upper well wall of the horizontal section, W / (m²) 2 ·℃); q1—Drilling fluid flow rate in the annulus, m 3 / s; r2—well radius, m;

[0039] The annular heat balance model at the lower end of the horizontal drill string under the eccentric effect is as follows:

[0040]

[0041] Where h'2 is the convective heat transfer coefficient of the lower end of the horizontal section well wall, W / (m²). 2 ·℃).

[0042] Furthermore, the annular heat balance model at the bottom of the well is as follows:

[0043]

[0044] This invention also discloses a drilling circulation temperature simulation system for drill string eccentricity effect, comprising:

[0045] Acquisition unit, used to acquire parameters of the target well;

[0046] A unit is established to create thermal models for the drill bit rock breaking heat source, drill string and well wall friction heat source, drill string vibration heat source, viscous heat dissipation heat source, and electronic component working heat source, based on the parameters of the target well and the influence of various heat source items in the horizontal section of the target well.

[0047] The model unit is used to establish a wellbore heat balance model under the horizontal section drill string eccentricity effect based on the horizontal section drill string eccentricity effect and the aforementioned heat model.

[0048] The solver unit is used to solve the wellbore heat balance model under the eccentricity effect of the drill string in the horizontal section.

[0049] The present invention also discloses an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described method for simulating drilling circulation temperature based on drill string eccentricity.

[0050] Compared with the prior art, the embodiments of the present invention have at least the following advantages: The present invention proposes a thermal model for five complex heat source terms and establishes a wellbore heat balance model considering the eccentricity effect of the drill string in the horizontal section, forming a drilling circulation temperature simulation method for the drill string eccentricity effect, which can accurately simulate and calculate the drilling circulation temperature under the drill string eccentricity effect during the drilling of the horizontal section of a horizontal well; The present invention provides basic theoretical and applicable method support for the research on drilling circulation temperature simulation considering the drill string eccentricity effect and complex heat source terms in the horizontal section, promotes the innovative development of drilling technology, is applicable to deep shale gas wells, and has high practical value and application prospects.

[0051] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 (a) shows a schematic diagram of radial heat transfer in the wellbore considering the eccentricity effect of the drill string in the horizontal section according to an embodiment of the present invention;

[0054] Figure 1 (b) shows a schematic diagram of axial heat transfer in the wellbore considering the eccentricity effect of the drill string in the horizontal section according to an embodiment of the present invention;

[0055] Figure 2 A flowchart of the model solving process according to an embodiment of the present invention is shown;

[0056] Figure 3 A wellbore mesh partitioning diagram under the horizontal segment eccentricity effect according to an embodiment of the present invention is shown;

[0057] Figure 4 A wellbore structure diagram according to an embodiment of the present invention is shown;

[0058] Figure 5 A comparison graph of drilling temperature curves under the influence of viscous heat dissipation heat source terms according to an embodiment of the present invention is shown;

[0059] Figure 6 A comparison diagram of drilling temperature curves under the influence of the drill bit rock-breaking heat source term according to an embodiment of the present invention is shown;

[0060] Figure 7 A comparison diagram of drilling temperature curves under the influence of the frictional heat source term between the drill string and the wellbore, according to an embodiment of the present invention, is shown.

[0061] Figure 8 A comparison diagram of drilling temperature curves under the influence of vibration heat source terms according to an embodiment of the present invention is shown;

[0062] Figure 9 A comparison graph of drilling temperature curves under the influence of the working heat source of electronic components according to an embodiment of the present invention is shown.

[0063] Figure 10 A comparison diagram of annular temperature curves under the influence of drill string eccentricity according to an embodiment of the present invention is shown. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] like Figure 1 (a) Figure 1 (b) and Figure 2 As shown, the present invention proposes a method for simulating drilling circulation temperature based on drill string eccentricity, comprising the following steps:

[0066] Obtain the parameters of the target well; these parameters include operational parameters, environmental parameters, well structure parameters, and thermal parameters.

[0067] Based on the parameters of the target well and the influence of various heat source items in the horizontal section of the target well, thermal models are established for the drill bit rock breaking heat source item, drill string and well wall friction heat source item, drill string vibration heat source item, viscous heat dissipation heat source item, and electronic component working heat source item, respectively.

[0068] Based on the horizontal section drill string eccentricity effect and the aforementioned heat model, a wellbore heat balance model under the horizontal section drill string eccentricity effect is established.

[0069] The heat balance model of the wellbore under the eccentric effect of the drill string in the horizontal section is solved.

[0070] Among them, after solving the wellbore heat balance model, the downhole temperature distribution data is output.

[0071] Operating parameters include drilling fluid density, drilling fluid injection temperature, mechanical drilling rate, drilling pump displacement, drilling pressure, and rotational speed.

[0072] Environmental parameters include formation depth, geothermal gradient, and surface temperature;

[0073] Wellbore structural parameters include well depth, wellbore diameter, drill string outer diameter, drill inner diameter, and well inclination angle;

[0074] Thermal parameters include drilling fluid specific heat capacity, drill string specific heat capacity, formation specific heat capacity, drilling fluid thermal conductivity, drill string thermal conductivity, and formation thermal conductivity;

[0075] This invention provides a drilling circulation temperature simulation method based on the drill string eccentricity effect. It simulates and analyzes the changes in drilling circulation temperature under the drill string eccentricity effect during the horizontal section drilling of a horizontal well, providing basic theoretical and applicable methodological support for the selection of key tools and the optimization of drilling process measures, thereby achieving "one-trip drilling".

[0076] like Figure 2As shown in the flowchart, the model solution process includes the following steps:

[0077] Initial parameter input;

[0078] Iterative calculation;

[0079] Determine if the current cell is eccentric;

[0080] If eccentric, calculate the unit temperature under the eccentricity of the horizontal segment; if not eccentric, calculate the unit temperature.

[0081] Determine if convergence has occurred;

[0082] If convergence is achieved, the unit temperature at the next time step is calculated; if convergence is not achieved, the calculation is repeated iteratively.

[0083] Output downhole temperature distribution.

[0084] In some embodiments, such as Figure 3 As shown, the thermal model is constructed based on the finite difference method. In the axial and radial directions, with the center of the drill string's inner circle as the baseline, the wellbore space is divided into eccentrically distributed upper and lower regions. Furthermore, based on the specific dimensions of different regions, it is further subdivided into discrete grid cells of different sizes, with each grid cell representing the temperature distribution at a specific point.

[0085] In some embodiments, the thermal model for the frictional heat source term between the drill string and the wellbore is as follows:

[0086]

[0087] Where RPS—rotations per second, r / s; w—float weight, kN / m; μ—friction coefficient; —drill pipe outer diameter, m; DS—friction section, m; a—well inclination angle, °; Q f —Frictional heat between drill string and wellbore, W.

[0088] In some embodiments, the thermal model of the drill string vibration heat source term is as follows:

[0089]

[0090] Among them, T N —Axial force of drill string, kN; m st —Weight of the drill string element, kg; x—lateral displacement of the drill string, m; z—spatial step, m; t—time, s; I a —Drill string moment of inertia, kg·m 2 E a —Elastic modulus of drill string, Pa; L a — Drill string length, m; dz — Drill string element length, m; Q -1 — Drill string thermoelastic damping, N·s / m; A— Cross-sectional area, m²2 Qz—Drill string vibration heat, W. In some embodiments, the heat model of the viscous heat dissipation source term is as follows:

[0091]

[0092] Where P is the pressure drop due to flow friction, in kPa; R is the pressure drop due to flow friction. w — Frictional pressure drop ratio; q—Drilling fluid flow rate, m³ 3 / s; L—unit length, m; ρ m —Fluid density, kg / m³ 3 f—friction coefficient; v—drilling fluid velocity, m / s; d—equivalent diameter, m; μ r —Relative viscosity; c f —Drilling fluid liquid phase content; c p —Drilling fluid solids content; ρ f —Drilling fluid liquid phase density, kg / m³ 3 ;ρ p —Drilling fluid solid density, kg / m³ 3 Q n —Drilling fluid viscosity consumes heat (W).

[0093] In some embodiments, the thermal model of the electronic component's operating heat source term is as follows:

[0094]

[0095] Where, I1—operating current of the first downhole instrument, A; R1—operating resistance of the first downhole instrument, Ω; I2—operating current of the second downhole instrument, A; R2—operating resistance of the second downhole instrument, Ω; I n —The operating current of the nth downhole instrument, A; R n —The operating resistance of the nth downhole instrument, in Ω; Q a —Heat of downhole instrument electronic components, W.

[0096] In some embodiments, the thermal model of the drill bit rock-breaking heat source term is as follows:

[0097]

[0098] Where WOB is the drilling pressure (kN); ROP is the drilling rate (m / h); J is the Joule constant; ω is the rotational speed (RPM); and M is the drilling speed. bit —Drill bit torque, kN·m; r b —Drill bit outer diameter, mm; Q bit —Heat generated by the drill bit breaking rock, W.

[0099] In some embodiments, the wellbore heat balance model includes a heat balance model of the drilling fluid inside the drill string under the eccentricity effect of the horizontal section drill string, a heat balance model of the upper drill string wall under the eccentricity effect of the horizontal section drill string, a heat balance model of the lower drill string wall under the eccentricity effect of the horizontal section drill string, a heat balance model of the annulus at the upper end under the eccentricity effect of the horizontal section drill string, a heat balance model of the annulus at the lower end under the eccentricity effect of the horizontal section drill string, and a heat balance model of the annulus at the bottom of the well.

[0100] The heat balance model of the drilling fluid inside the drill string under the eccentric effect of the horizontal section drill string is as follows:

[0101]

[0102] Where ρ0 is the drilling fluid density, kg / m³ 3 c0—Specific heat capacity of drilling fluid, J / (kg·℃); T0—Drilling fluid temperature inside the drill string, ℃; T1—Trill string wall temperature at the upper end of the horizontal section, ℃; T1'—Trill string wall temperature at the lower end of the horizontal section, ℃; h0—Convective heat transfer coefficient at the upper end of the drill string inner wall, W / (m²) 2 ·℃); q0—drilling fluid flow rate in the drill string, m 3 / s;Q n 1 —Heat dissipation due to the viscosity of drilling fluid inside the drill string, W; e—Drill string eccentricity, m; r0—Drill string inner diameter, m; r1—Drill string outer diameter, m; h'0—Convective heat transfer coefficient at the lower end of the drill string inner wall, W / (m²) 2 ·℃).

[0103] In some embodiments, the heat balance model of the upper drill string wall under the eccentric effect of the horizontal section drill string is as follows:

[0104]

[0105] Where ρ1 is the density of the drill string, kg / m³ 3 c1—Specific heat capacity of drill string, J / (kg·℃); T1—Terrain wall temperature at the upper end of the horizontal section, ℃; T2—Annular drilling fluid temperature at the upper end of the horizontal section, ℃; h1—Convective heat transfer coefficient of the outer wall of the drill string at the upper end of the horizontal section, W / (m²) 2 ·℃); λ1—drill string thermal conductivity, W / (m·℃); r1—drill string outer diameter, m; α1—drill string radial thermal diffusivity, m 2 / s;

[0106] The heat balance model of the lower end of the drill string wall under the eccentric effect of the horizontal section drill string is as follows:

[0107]

[0108] Where h1' is the convective heat transfer coefficient of the drill string wall at the lower end of the horizontal section, in W / (m²). 2·℃); T2'—Temperature of drilling fluid in the annulus at the lower end of the horizontal section, ℃.

[0109] In some embodiments, the annular heat balance model at the upper end of the horizontal drill string under the eccentric effect is as follows:

[0110]

[0111] Wherein, ρ2—density of drilling fluid in the annulus, kg / m³ 3 c2—Specific heat capacity of drilling fluid in the annulus, J / (kg·℃); T3—Wellbore temperature, ℃; α2—Thermal diffusivity of drilling fluid in the annulus, m 2 / s; h2—convective heat transfer coefficient of the upper well wall of the horizontal section, W / (m²) 2 ·℃); q1—Drilling fluid flow rate in the annulus, m 3 / s; r2—well radius, m.

[0112] The annular heat balance model at the lower end of the horizontal drill string under the eccentric effect is as follows:

[0113]

[0114] Where h'2 is the convective heat transfer coefficient of the lower end of the horizontal section well wall, W / (m²). 2 ·℃).

[0115] In some embodiments, the annular heat balance model at the bottom of the well is as follows:

[0116]

[0117] In calculating the bottom hole drilling temperature, it is necessary to consider the heat source terms of electronic components and the rock breaking heat source terms of the drill bit. The heat model of the annulus heat balance at the bottom hole should include the heat source terms of electronic components and the rock breaking heat source terms of the drill bit.

[0118] The initial and boundary conditions of the wellbore heat balance model are as follows:

[0119] ① Initially, the internal and external circulation temperatures of the drill string in the horizontal section are equal;

[0120] ② At the node at the top of the drill string, the temperature of the drilling fluid is always the injection temperature;

[0121] ③ At the bottom node, the circulating temperature of the drill string and the annulus is equal.

[0122] This embodiment is further configured as follows: the wellbore heat balance model is solved using an unconditionally stable fully implicit finite difference method to discretize the partial differential equations in space and time, and then the Gauss-Seidel iterative method is applied to iteratively solve the discrete algebraic equations. The discrete forms of each heat balance model are as follows:

[0123] The discrete formula for the heat balance model of drilling fluid inside the drill string under the eccentric effect of the drill string in the horizontal section is as follows:

[0124]

[0125] In the formula:

[0126]

[0127]

[0128] in, —Temperature of drilling fluid at the j-th point inside the drill string at time n+1; —Temperature at the j-th point on the upper end of the drill string wall of the horizontal segment at time n+1; —Temperature at the j-th point at the lower end of the horizontal section of the drill string at time n+1; —The temperature of the drilling fluid at the j-th point inside the drill string at time n.

[0129] Discrete form of the heat balance model of the upper drill string wall under the eccentric effect of the horizontal section drill string:

[0130]

[0131] In the formula:

[0132]

[0133] in, —Temperature at the upper end of the drill column wall at the (n+1)th time; —The temperature of the upper end of the annular drilling fluid at the same point j at time n+1; —Temperature at the top of the drill column wall at point j at time n.

[0134] Discrete form of the heat balance model of the lower end of the drill string wall under the eccentric effect of the horizontal section drill string:

[0135]

[0136] In the formula:

[0137]

[0138]

[0139] in, —Temperature at the lower end of the drill column wall at the (n+1)th time; —Temperature of the lower end of the annular drilling fluid at the j-th point at time n+1; —Temperature at the lower end of the drill string at point j at time n.

[0140] Discrete form of the annular heat balance model at the upper end of the horizontal drill string under the eccentric effect:

[0141]

[0142] In the formula:

[0143]

[0144]

[0145] in, —Temperature of the upper end of the annular drilling fluid at the (j+1)th point at time n+1; —Well wall temperature at point j at time n+1; —Temperature of the upper end of the annular drilling fluid at point j at time n.

[0146] Discrete form of the annular heat balance model at the lower end of the horizontal drill string under the eccentricity effect:

[0147]

[0148] In the formula:

[0149]

[0150]

[0151] in, —Temperature of the lower end of the annular drilling fluid at the (j+1)th point at time n+1; —Temperature of the lower end of the annular drilling fluid at point j at time n.

[0152] This embodiment uses actual drilling data from a shale gas well in a certain area as the raw data, and verifies the transient heat transfer model based on the well structure and drilling parameters. Figure 4 The wellbore structure, basic parameters, and downhole medium thermophysical properties of the well are shown in Tables 1 and 2, respectively.

[0153] Table 1 Basic Parameters Table

[0154]

[0155] Table 2. Downhole Medium Thermophysical Properties Table

[0156]

[0157] Figure 5 A comparison chart of drilling temperature curves under the influence of viscous heat dissipation, as shown in the figure. Figure 5As shown, since the viscous heat loss of drilling fluid exists in the drill string and annulus, the temperature of drilling fluid is directly affected by the viscous heat loss. Its temperature is much higher than that of the model without complex heat source terms. The temperature difference at the bottom of the well reaches a maximum of 5.84℃, and the temperature returned from the wellhead is also 2.23℃ higher.

[0158] Figure 6 A comparison chart of drilling temperature curves under the influence of the drill bit rock-breaking heat source term, such as... Figure 6 As shown, after considering the influence of the drill bit rock-breaking heat source term, the temperature at the bottom of the well increases by 2.82℃ due to the large amount of heat generated by the drill bit friction against the rock. Overall, the bottom-hole temperature of the model considering the rock-breaking heat source term is 4.74℃ higher than that of the model without complex heat source terms.

[0159] Figure 7 This is a comparison chart of drilling temperature curves under the influence of the frictional heat source term between the drill string and the wellbore, such as... Figure 7 As shown, in the directional and horizontal sections, due to the high frequency of friction between the drill string and the well wall during circumferential rotation, a large amount of heat is generated. The temperature of the model containing the heat source term of drill string-well wall friction is significantly higher than that of the model without complex heat source term, with the temperature difference reaching up to 3.16℃.

[0160] Figure 8 A comparison chart of drilling temperature curves under the influence of vibration heat source term, such as... Figure 8 As shown, after considering the heat source term of drill string vibration, the drill string temperature rises the fastest, reaching a maximum increase of approximately 2.1℃. Simultaneously, this vibration-induced heat generation phenomenon indirectly affects the temperature distribution of the drilling fluid within the annulus. Compared to the case where the vibration-induced heat source is not considered, the temperature of the drilling fluid within the annulus also increases to some extent, by approximately 0.73℃. This temperature rise is particularly pronounced when drilling operations enter the horizontal section, due to the increased lateral load on the drill string and intensified vibration.

[0161] Figure 9 A comparison chart of drilling temperature curves under the influence of heat source terms of electronic components, such as... Figure 9 As shown, in the upper section, the temperature difference between the model with electronic components and the model without complex heat sources is almost zero, and the drilling fluid return temperature is the same, both at 37.24℃. However, in the horizontal section, the downhole electronic instruments generate heat, causing the drilling fluid temperature to rise by 0.38℃.

[0162] Figure 10 A comparison of annular temperature curves under the influence of drill string eccentricity, as shown in the figure. Figure 10 As shown, drill string eccentricity mainly affects the horizontal section of a horizontal well. Eccentricity increases frictional heat generation from the drill string and also causes a rapid rise in annular temperature. The eccentricity causes the bottom hole temperature to increase from 136.2℃ to 140.11℃; therefore, the drill string eccentricity effect cannot be ignored in wellbore temperature calculations.

[0163] This invention proposes thermal models for five complex heat source terms and establishes a wellbore heat balance model considering the eccentricity effect of the drill string in the horizontal section. This results in a method for simulating drilling circulation temperature under the eccentricity effect of the drill string, which can accurately simulate and calculate the drilling circulation temperature during horizontal drilling in the horizontal section of a horizontal well. This invention provides fundamental theoretical and applicable methodological support for the simulation of drilling circulation temperature considering the eccentricity effect of the drill string in the horizontal section and complex heat source terms, promoting the innovative development of drilling technology. It is applicable to deep shale gas wells and has high practical value and application prospects.

[0164] Based on the above-mentioned method for simulating drilling circulation temperature due to drill string eccentricity, this embodiment proposes a drilling circulation temperature simulation system for drill string eccentricity, comprising:

[0165] Acquisition unit, used to acquire parameters of the target well;

[0166] A unit is established to create thermal models for the drill bit rock breaking heat source, drill string and well wall friction heat source, drill string vibration heat source, viscous heat dissipation heat source, and electronic component working heat source, based on the parameters of the target well and the influence of various heat source items in the horizontal section of the target well.

[0167] The model unit is used to establish a wellbore heat balance model under the horizontal section drill string eccentricity effect based on the horizontal section drill string eccentricity effect and the aforementioned heat model.

[0168] The solver unit is used to solve the wellbore heat balance model under the eccentricity effect of the drill string in the horizontal section.

[0169] The present invention also proposes an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described method for simulating drilling circulation temperature based on drill string eccentricity.

[0170] The present invention also proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described method for simulating drilling circulation temperature due to drill string eccentricity.

[0171] The present invention also proposes a computer program product, including computer instructions, which, when executed by a processor, implement the above-mentioned drilling circulation temperature simulation method for the drill string eccentricity effect.

[0172] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for simulating drilling circulation temperature based on drill string eccentricity effect, characterized in that, include: Obtain the parameters of the target well; Based on the parameters of the target well and the influence of various heat source items in the horizontal section of the target well, thermal models are established for the drill bit rock breaking heat source item, drill string and well wall friction heat source item, drill string vibration heat source item, viscous heat dissipation heat source item, and electronic component working heat source item, respectively. Based on the horizontal section drill string eccentricity effect and the aforementioned heat model, a wellbore heat balance model under the horizontal section drill string eccentricity effect is established. The heat balance model of the wellbore under the eccentric effect of the drill string in the horizontal section is solved.

2. The drilling circulation temperature simulation method for drill string eccentricity effect according to claim 1, characterized in that, The thermal model for the frictional heat source term between the drill string and the wellbore is as follows: Q f =2π×RPS×μrwΔSsina Where RPS—rotations per second, r / s; w—float weight, kN / m; μ—friction coefficient; —drill pipe outer diameter, m; DS—friction section, m; a—well inclination angle, °; Q f —Frictional heat between drill string and wellbore, W.

3. The drilling circulation temperature simulation method for drill string eccentricity effect according to claim 1, characterized in that, The thermal model for the drill string vibration heat source term is as follows: Among them, T N —Axial force of drill string, kN; m st —Weight of the drill string element, kg; x—lateral displacement of the drill string, m; z—spatial step, m; t—time, s; I a —Drill string moment of inertia, kg·m 2 E a —Elastic modulus of drill string, Pa; L a — Drill string length, m; dz — Drill string element length, m; Q -1 — Drill string thermoelastic damping; A — Cross-sectional area, m 2 Qz—Drill string vibration heat, W.

4. The drilling circulation temperature simulation method for drill string eccentricity effect according to claim 1, characterized in that, The heat model for the viscous heat dissipation source term is as follows: Where P is the pressure drop due to flow friction, in kPa; R is the pressure drop due to flow friction. w — Frictional pressure drop ratio; q—Drilling fluid flow rate, m³ 3 / s; L—unit length, m; ρ m —Fluid density, kg / m³ 3 f—friction coefficient; v—drilling fluid velocity, m / s; d—equivalent diameter, m; μ r —Relative viscosity; c f —Drilling fluid liquid phase content; c p —Drilling fluid solids content; ρ f —Drilling fluid liquid phase density, kg / m³ 3 ;ρ p —Drilling fluid solid density, kg / m³ 3 Q n —Drilling fluid viscosity consumes heat (W).

5. The drilling circulation temperature simulation method for drill string eccentricity effect according to claim 1, characterized in that, The heat model for the working heat source of the electronic component is as follows: Where, I1—operating current of the first downhole instrument, A; R1—operating resistance of the first downhole instrument, Ω; I2—operating current of the second downhole instrument, A; R2—operating resistance of the second downhole instrument, Ω; I n —The operating current of the nth downhole instrument, A; R n —The operating resistance of the nth downhole instrument, in Ω; Q a —Heat of downhole instrument electronic components, W.

6. The drilling circulation temperature simulation method for drill string eccentricity effect according to claim 1, characterized in that, The thermal model for the drill bit rock-breaking heat source term is as follows: Where WOB is the drilling pressure (kN); ROP is the drilling rate (m / h); J is the Joule constant; ω is the rotational speed (RPM); and M is the drilling speed. bit —Drill bit torque, kN·m; r b —Drill bit outer diameter, mm; Q bit —Heat generated by the drill bit breaking rock, W.

7. The drilling circulation temperature simulation method for drill string eccentricity effect according to claim 1, characterized in that, The wellbore heat balance model includes the heat balance model of the drilling fluid inside the drill string under the eccentric effect of the horizontal section drill string, the heat balance model of the upper drill string wall under the eccentric effect of the horizontal section drill string, the heat balance model of the lower drill string wall under the eccentric effect of the horizontal section drill string, the heat balance model of the annulus at the upper end under the eccentric effect of the horizontal section drill string, the heat balance model of the annulus at the lower end under the eccentric effect of the horizontal section drill string, and the heat balance model of the annulus at the bottom of the well. The heat balance model of the drilling fluid inside the drill string under the eccentric effect of the horizontal section drill string is as follows: Where ρ0 is the drilling fluid density, kg / m³ 3 c0—Specific heat capacity of drilling fluid, J / (kg·℃); T0—Drilling fluid temperature inside the drill string, ℃; T1—Trill string wall temperature at the upper end of the horizontal section, ℃; T1'—Trill string wall temperature at the lower end of the horizontal section, ℃; h0—Convective heat transfer coefficient at the upper end of the drill string inner wall, W / (m²) 2 ·℃); q0—drilling fluid flow rate in the drill string, m 3 / s;Q n 1 —Heat dissipation due to the viscosity of drilling fluid inside the drill string, W; e—Drill string eccentricity, m; r0—Drill string inner diameter, m; r1—Drill string outer diameter, m; h'0—Convective heat transfer coefficient at the lower end of the drill string inner wall, W / (m²) 2 ·℃).

8. The drilling circulation temperature simulation method for drill string eccentricity effect according to claim 7, characterized in that, The heat balance model of the upper drill string wall under the eccentric effect of the horizontal section drill string is as follows: Where ρ1 is the density of the drill string, kg / m³ 3 c1—Specific heat capacity of drill string, J / (kg·℃); T2—Temperature of drilling fluid in the annulus at the upper end of the horizontal section, ℃; h1—Convective heat transfer coefficient of the outer wall of the drill string at the upper end of the horizontal section, W / (m²) 2 ·℃); λ1—thermal conductivity of the drill string, W / (m·℃); α1—radial thermal diffusivity of the drill string, m 2 / s; The heat balance model of the lower end of the drill string wall under the eccentric effect of the horizontal section drill string is as follows: Where h′1 is the convective heat transfer coefficient of the drill string wall at the lower end of the horizontal section, in W / (m²). 2 ·℃); T′2—Temperature of drilling fluid in the annulus at the lower end of the horizontal section, ℃.

9. The drilling circulation temperature simulation method for drill string eccentricity effect according to claim 7, characterized in that, The annular heat balance model at the upper end of the horizontal drill string under the eccentric effect is as follows: Wherein, ρ2—density of drilling fluid in the annulus, kg / m³ 3 c2—Specific heat capacity of drilling fluid in the annulus, J / (kg·℃); T3—Wellbore temperature, ℃; α2—Thermal diffusivity of drilling fluid in the annulus, m 2 / s; h2—convective heat transfer coefficient of the upper well wall of the horizontal section, W / (m²) 2 ·℃); q1—Drilling fluid flow rate in the annulus, m 3 / s; r2—well radius, m; The annular heat balance model at the lower end of the horizontal drill string under the eccentric effect is as follows: Where h'2 is the convective heat transfer coefficient of the lower end of the horizontal section well wall, W / (m²). 2 ·℃).

10. The drilling circulation temperature simulation method for drill string eccentricity effect according to claim 7, characterized in that, The annular heat balance model at the bottom of the well is as follows:

11. A drilling circulation temperature simulation system for drill string eccentricity effect, characterized in that, include: Acquisition unit, used to acquire parameters of the target well; A unit is established to create thermal models for the drill bit rock breaking heat source, drill string and well wall friction heat source, drill string vibration heat source, viscous heat dissipation heat source, and electronic component working heat source, based on the parameters of the target well and the influence of various heat source items in the horizontal section of the target well. The model unit is used to establish a wellbore heat balance model under the horizontal section drill string eccentricity effect based on the horizontal section drill string eccentricity effect and the aforementioned heat model. The solver unit is used to solve the wellbore heat balance model under the eccentricity effect of the drill string in the horizontal section.

12. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the drilling circulation temperature simulation method for the drill string eccentricity effect as described in any one of claims 1-10.

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