CN105160161B

CN105160161B - Method and device for determining thermal parameters in shaft

Info

Publication number: CN105160161B
Application number: CN201510504682.4A
Authority: CN
Inventors: 杨清玲; 何金宝; 吕孝明; 朱静; 徐宇; 金璐; 冯紫微; 邹杨; 霍艳皎; 周轶青; 蒋国庆; 李复
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2015-08-17
Filing date: 2015-08-17
Publication date: 2018-08-10
Anticipated expiration: 2035-08-17
Also published as: CN105160161A

Abstract

The invention discloses a method and a device for determining thermal parameters in a shaft, wherein the method comprises the following steps: obtaining calculation parameters, wherein the calculation parameters comprise: measuring the pressure and temperature of steam and the distance between two adjacent measuring points; and according to the calculation parameters, carrying out linearization processing on the steam pressure and the temperature of the two adjacent measuring points, and determining the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft. The method and the device for determining the thermal parameters in the shaft can accurately calculate the steam thermal parameters at any position in the shaft.

Description

Method and device for determining thermal parameters in shaft

Technical Field

The invention relates to the field of thickened oil thermal recovery in the field of oil exploitation, in particular to a method and a device for determining thermal parameters in a shaft.

Background

Heavy oil refers to high viscosity heavy crude oil having a viscosity of greater than 50mp · s (millipascal · s) under formation conditions, or a viscosity of the degassed crude oil at reservoir temperature of 1000 to 10000mp · s. Because the thick oil has high viscosity, the thick oil has poor flowing property and even can not flow under certain oil layer conditions, and the thick oil is difficult to recover. In the oil exploitation of oil fields, because thick oil has the characteristics of special high viscosity and high freezing point, the thick oil has poor mobility in reservoirs and mineshafts, and the conventional exploitation recovery ratio is low, namely normal economic yield cannot be ensured. To ensure reasonable recovery, oil is often recovered by reducing the viscosity of the crude oil.

Because the viscosity of the thick oil is very sensitive to the temperature, the viscosity is greatly reduced along with the increase of the temperature, and the flow resistance is reduced, in order to recover the thick oil, one of the common methods for recovering the thick oil at present is a steam injection thermal recovery technology, including steam stimulation, steam flooding and SAGD (steam assisted gravity drainage). Specifically, the steam injection thermal recovery technology is mainly characterized in that high-temperature high-pressure wet saturated steam generated by a boiler is transmitted to a wellhead through a ground pipeline and then is injected into a thick oil layer after being transmitted through a shaft from the wellhead, so that the purpose of reducing the viscosity of the thick oil is achieved.

Thermal parameters such as pressure, temperature, dryness, etc. of the steam may vary due to heat loss and pressure loss generated during wellbore transport.

The heat loss directly influences the thermodynamic state of steam injected into the bottom of the well barrel, so that the steam injection thermal recovery effect is determined. The dryness is the mass percentage of dry steam contained in each kilogram of wet steam, and for steam injection thermal recovery, the higher the dryness, the more beneficial the steam injection thermal recovery effect is. During steam injection thermal recovery, thermodynamic parameters of steam in a shaft need to be calculated: pressure, temperature, dryness factor, heat loss, based on the calculated thermodynamic parameters, the shaft is improved to reduce the heat loss in the steam migration process to the maximum extent, and the steam dryness factor is improved, thereby improving the effect of exploiting the heavy oil by injecting steam.

In the method for calculating the steam thermodynamic parameter in the shaft, a commonly adopted technology is to establish a control equation of the steam pressure drop gradient in the shaft according to the momentum conservation law. And then calculating the steam temperature according to the one-to-one correspondence relationship of the saturated steam temperature and the saturated steam pressure. However, in actual production, the pressure and the temperature calculation result obtained by relying on the pressure and the pressure are greatly deviated from the temperature and the pressure in the field monitoring data. Furthermore, in the prior art method, the dryness and heat loss solving formula is only based on the steam pressure in the shaft, and when the pressure has a large error, the dryness and heat loss can easily cause the result to deviate from the true value. Therefore, there is a need for methods and apparatus that accurately calculate thermal parameters in a wellbore.

Disclosure of Invention

The invention aims to provide a method and a device for determining thermal parameters in a shaft, which can accurately calculate steam thermal parameters at any position in the shaft.

The above object of the present invention can be achieved by the following technical solutions:

a method of thermal parameter determination within a wellbore, comprising;

obtaining calculation parameters, wherein the calculation parameters comprise: measuring the pressure and temperature of steam and the distance between two adjacent measuring points;

and according to the calculation parameters, carrying out linearization processing on the steam pressure and the temperature of the two adjacent measuring points, and determining the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft.

In a preferred embodiment, the step of linearizing the steam pressure and temperature of two adjacent measuring points according to the measuring point parameters to determine the steam pressure and temperature at any position between the adjacent measuring points in the wellbore comprises:

establishing a calculation equation of pressure and temperature in the steam injection process along the shaft:

(p-p_i)/(p_i+1-p_i)＝(z-z_i)/(z_i+1-z_i)

(T-T_i)/(T_i+1-T_i)＝(z-z_i)/(z_i+1-z_i)

in the above formula, p is the pressure of steam in the shaft at any position between the ith and the (i + 1) th measuring points, p_iFor the pressure of steam in the wellbore at the ith station, p_i+1The pressure of steam in a shaft at the (i + 1) th measuring point is respectively in megapascals; t is the temperature of steam in the shaft at any position between the ith and the (i + 1) th measuring points_iFor the temperature, T, of steam in the shaft at the ith measuring point_i+1The temperature of steam in a shaft at the (i + 1) th measuring point is measured in centigrade degrees; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N; n is the number of measured data and the known quantity;

determining the steam pressure at any position between adjacent measuring points in the well bore according to the following formula:

p＝p_i+(p_i+1-p_i)(z-z_i)/(z_i+1-z_i)

in the above formula, p is the pressure of steam in the shaft at any position between the ith and the (i + 1) th measuring points, p_iFor the pressure of steam in the wellbore at the ith station, p_i+1The pressure of steam in a shaft at the (i + 1) th measuring point is respectively in megapascals; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N; n is the number of measured data and the known quantity;

determining the steam temperature at any position between adjacent measuring points in the shaft according to the following formula:

T＝T_i+(T_i+1-T_i)(z-z_i)/(z_i+1-z_i)

in the above formula, T is the temperature of steam in the shaft at any position between the ith and (i + 1) th measuring points_iFor the temperature, T, of steam in the shaft at the ith measuring point_i+1The temperature of steam in a shaft at the (i + 1) th measuring point is measured in centigrade degrees; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N; and N is the number of measured data and is a known quantity.

A method of thermal parameter determination within a wellbore, comprising:

obtaining calculation parameters, wherein the calculation parameters comprise: steam dryness at a well mouth, pressure and temperature of steam measured points, distance between two adjacent measured points, structural parameters of a shaft and environmental parameters;

according to the pressure and the temperature of the steam of the measuring points and the distance between two adjacent measuring points, the steam pressure and the temperature of the two adjacent measuring points are subjected to linearization treatment, and the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft are determined;

and dividing a shaft infinitesimal section on the length of the shaft according to the distance between the two adjacent measuring points, establishing an energy control equation, and determining the dryness and heat loss of the steam at any position of the shaft by using the steam dryness of the well head as an initial condition and through the iterative calculation of mutually coupled heat loss, temperature and dryness.

In a preferred embodiment, the determination of the dryness and heat loss of steam at any position of the well bore comprises the following steps:

setting dryness drop of steam in the wellbore infinitesimal section and total heat transfer coefficient of the wellbore infinitesimal section;

calculating the total thermal resistance of the wellbore micro-element section through the total heat transfer coefficient of the wellbore micro-element section, and calculating the steam heat loss of the wellbore micro-element section through the total thermal resistance of the wellbore micro-element section;

repeatedly iterating, and when the calculated value of the total heat transfer coefficient of the wellbore micro-element section and the set value meet a first preset precision, determining the total heat transfer coefficient of the wellbore micro-element section to obtain the steam heat loss of the wellbore micro-element section;

calculating the steam dryness according to an energy balance law, repeatedly iterating, and determining the dryness drop of the steam in the infinitesimal section of the shaft when the calculated value of the steam dryness drop in the infinitesimal section of the shaft and a set value meet a second preset precision;

and (4) circulating and calculating to the whole shaft, and determining dryness and heat loss of steam at any position of the shaft.

In a preferred embodiment, said calculating the steam quality according to the law of energy balance comprises:

the following energy control equation is established:

steam dryness x of well head₀As an initial condition, solving the equation to obtain a calculation expression of the steam dryness at any position of the shaft:

wherein

C₁＝G(h_g-h_l)

In the above formula, h_gIs the enthalpy of saturated steam, h_lThe enthalpy of saturated water is expressed in kilocalories/kilogram; x is the steam dryness; g is saturated steam mass flow, unit kilogram/hour; q is the heat loss of the shaft in unit length in unit time, and the unit is kilocalorie/(hour meter); rho_mSaturated wet steam density in kilograms per cubic meter; a is the cross-sectional area of the shaft in square meters; theta is a shaft inclination angle and a unit degree;

enthalpy h of the saturated water_lThe relationship with the steam temperature T is as follows:

enthalpy h of the saturated steam_gThe relationship with the steam temperature T is as follows:

h_g＝12500+1.88T-3.7×10^-6T^3.2

the above-mentionedρ_mThe saturated wet steam density calculation formula is as follows:

ρ_m＝H_gρ_g+(1-H_g)ρ_l

in the above formula rho_lThe density of saturated water is related to the steam temperature T as follows:

ρ_l＝0.9967-4.615×10^-5T-3.063×10^-6T²

in the above formula rho_gThe calculation formula for the density of saturated steam is as follows:

in the above formula, T is the steam temperature in centigrade; p is steam pressure in mpa;

zg is the compression factor of saturated steam, and is related to the steam temperature T by the following formula:

Z_g＝1.012-4.461×10^-4T+2.98×10^-6T²-1.663×10^-8T³

H_gthe volume vapor content of the saturated vapor is calculated according to the following formula:

in the above formula, x is steam dryness without dimensional quantity; rho_gIs the density of saturated steam, in kilograms per cubic meter; rho_lIs the density of saturated water in kilograms per cubic meter.

In a preferred embodiment, the heat loss in the wellbore micro-element section comprises: the heat loss transferred from the center of the oil pipe to the outer edge of the cement sheath and the heat loss transferred from the outer edge of the cement sheath to the stratum,

and establishing a heat transfer continuity equation according to the fact that the heat transferred from the center of the oil pipe to the outer edge of the cement sheath is equal to the heat transferred from the outer edge of the cement sheath to the stratum: dQ₁＝dQ₂。

In a preferred embodiment, the calculation formula of the heat loss from the center of the oil pipe to the outer edge of the cement sheath is as follows:

wherein:

in the above formula, dQ₁Is the heat change on the shaft with dz length in unit time, and has the unit of kilocalories/(hour); t is_sThe steam temperature in the shaft is in centigrade; t is_hThe temperature of the outer edge of the cement sheath is in centigrade unit; r is the thermal resistance on the shaft with the dz length, and the unit is [ kilocalorie/(meter-hour-degree centigrade)]^-1(ii) a dz is the length of the wellbore in meters; h is_fIs the convective heat transfer coefficient of the liquid film layer, h_pIs the convective heat transfer coefficient of the fouling layer, h_fcThe heat transfer coefficient in the annular space is expressed in kilocalories/(square meter, hour and centigrade); lambda [ alpha ]_tubIs heat conductivity coefficient of heat insulation oil pipe, lambda_insIs a thermal conductivity coefficient of the thermal insulation layer material, lambda_casIs the sleeve heat conductivity coefficient, lambda_cemThe cement sheath thermal conductivity coefficient is expressed in kilocalories/(meter.h.degree centigrade); r is₁Is the inner radius of the inner pipe of the heat insulation oil pipe, r₂For insulating the outer radius of the inner pipe of the tubing, r₃Is the inner radius of the outer pipe of the heat insulation oil pipe, r₄Is the outer radius of the outer pipe of the heat insulation oil pipe, r_coIs the outer radius of the casing, r_ciIs the inner radius of the casing, r_hThe outer radius of the cement sheath is meter;

the heat transfer coefficient in the annular space comprises a natural convection heat transfer coefficient and a radiation heat transfer coefficient, and the calculation formula is as follows:

h_fc＝h_r+h_c

the calculation formula of the radiation heat exchange coefficient in the annular space is as follows:

in the above formula, σ is Stefan-Boltzmann constant, and has a value of 4.8755.67 × 10^-8Kilocalories/(square meter hour kelvin)⁴)；ε₄The blackness of the outer wall of the outer pipe of the heat insulation oil pipe is known; epsilon_ciBlackness of the inner wall of the casing, known amount; t is₄The temperature of the outer wall of the outer pipe of the heat insulation oil pipe is measured in centigrade degrees; t is_ciThe temperature of the inner wall of the sleeve is measured in centigrade;

the calculation formula of the natural convection heat transfer coefficient in the annular space is as follows:

wherein:

in the above formula, g is the gravity acceleration in meters per square second; rho_anIn grams per cubic centimeter of the density of the annulus fluid at average temperature β_anIs the volumetric thermal expansion coefficient of the annular space fluid, β_an＝1/T_an ^*，T_an ^*＝T_an+273，1/K；T_anIs the mean temperature of the fluid in the annular space, T_an＝(T₄+T_ci) 2, unit degree centigrade; mu.s_anViscosity of the annulus fluid at average temperature in centipoise; c_anIs the heat capacity of the annular space fluid at average temperature, in kilocalories/(kilogram-degree centigrade); lambda [ alpha ]_haThe thermal conductivity of the fluid in the annular space at the average temperature is given in kilocalories/(square meter hour DEG C);

the calculation formula of the heat loss from the outer edge of the cement sheath to the stratum is as follows:

in the above formula, T_eIs the initial formation temperature, T_e＝T_m+a·z，T_mIs the surface temperature, T_hThe temperature of the outer edge of the cement sheath is measured in centigrade degrees; a is the ground temperature gradient, and the temperature is in degrees centigrade per meter; z is well depth, meter; lambda [ alpha ]_eThe formation thermal conductivity coefficient is kilocalorie/(square meter hour DEG C); f (t) is a dimensionless time function of formation conduction;

the dimensionless stratum heat conduction time function is selected according to different steam injection times:

when the steam injection time is not less than 7 days, f (t) adopts a Ramey empirical formula as follows:

in the above formula, α is thermal diffusivity in square meter/hour, t is steam injection time in hour, r is_hThe distance from the well shaft to the outer edge of the cement sheath is meter;

when the steam injection time is less than 7 days, f (t) adopts the Liu article empirical formula as follows:

when K' is 0.1,

when K' ≠ 0.1,

in the above formula, t' ═ α t/r_h ²Time in dimension one; k' ═ r₁U/λ_eThermal conductivity in dimension one;

substituting the heat loss transferred from the center of the oil pipe to the outer edge of the cement sheath and the heat loss transferred from the outer edge of the cement sheath to the stratum into the heat transfer continuity equation to obtain various unknown quantities, wherein the method comprises the following steps:

the calculation formula of the outer edge temperature of the cement sheath is as follows:

in the above formula, λ_eThe formation thermal conductivity is expressed in kilocalories/(meter.h.degree centigrade); t is_eIs the initial formation temperature in degrees celsius; t is_sThe steam temperature in the shaft is measured in degrees centigrade; r is₂The radius of the inner pipe and the outer pipe of the heat insulation oil pipe is unit meter; f (t) is the dimensionless formation conduction time function; u is the total heat transfer coefficient from the center of the oil pipe to the outer edge of the cement sheath, and the unit is kilocalories/(square meter.h.degree centigrade), and the calculation formula is as follows:

in the above formula, h_fIs the convective heat transfer coefficient of the liquid film layer, h_pIs the convective heat transfer coefficient of the fouling layer, h_cNatural convection heat transfer coefficient, h, in the annular space_rThe radiation heat exchange coefficient in the annular space is kilocalorie/(square meter, hour and centigrade); lambda [ alpha ]_tubIs heat conductivity coefficient of heat insulation oil pipe, lambda_insIs a thermal conductivity coefficient of the thermal insulation layer material, lambda_casIs the sleeve heat conductivity coefficient, lambda_cemThe cement sheath thermal conductivity coefficient is expressed in kilocalories/(meter.h.degree centigrade); r is₁Is the inner radius of the inner pipe of the heat insulation oil pipe, r₂For insulating the outer radius of the inner pipe of the tubing, r₃Is the inner radius of the outer pipe of the heat insulation oil pipe, r₄Is the outer radius of the outer pipe of the heat insulation oil pipe, r_coIs the outer radius of the casing, r_ciIs the inner radius of the casing, r_hThe outer radius of the cement sheath is meter;

temperature T of inner surface of the sleeve_ciThe calculation formula is as follows:

in the above formula, T_ciIs the temperature of the inner wall of the casing, T_hIs the temperature of the outer edge of the cement sheath, T_sThe steam temperature in the shaft is measured in centigrade degrees; r is₂For insulating the outer radius of the inner pipe of the tubing, r_coIs the outer radius of the casing, r_ciIs the inner radius of the casing, r_hThe outer radius of the cement sheath is meter; lambda [ alpha ]_casIs the sleeve heat conductivity coefficient, lambda_cemThe cement sheath thermal conductivity coefficient is expressed in kilocalories/(meter.h.degree centigrade); u is the total heat transfer coefficient from the center of the oil pipe to the outer edge of the cement sheath, and the unit is kilocalories/(square meter, hour and centigrade);

the temperature T of the outer wall of the outer pipe of the heat insulation oil pipe₄The calculation formula is as follows:

in the above formula, T₄For the outer wall temperature, T, of the outer tube of the heat-insulating tube_hIs the temperature of the outer edge of the cement sheath, T_sThe steam temperature in the shaft is measured in centigrade degrees; h is_fIs the convective heat transfer coefficient of the liquid film layer, h_pThe convective heat transfer coefficient of the dirt layer is expressed in kilocalories/(square meter, hour and centigrade); lambda [ alpha ]_tubIs heat conductivity coefficient of heat insulation oil pipe, lambda_insThe thermal conductivity coefficient of the thermal insulation layer material is kilocalorie/(meter.h.degree centigrade); r is₁Is the inner radius of the inner pipe of the heat insulation oil pipe, r₂For insulating the outer radius of the inner pipe of the tubing, r₃Is the inner radius of the outer pipe of the heat insulation oil pipe, r₄The outer radius of the outer pipe of the heat insulation oil pipe is meter; u is the total heat transfer coefficient from the center of the oil pipe to the outer edge of the cement sheath, and the unit is kilocalories/(square meter, hour and centigrade);

and respectively substituting the obtained unknown quantity into a calculation formula of heat loss from the center of the oil pipe to the outer edge of the cement sheath and a calculation formula of heat loss from the outer edge of the cement sheath to the stratum so as to determine the heat loss in the steam injection process in the shaft.

In a preferred embodiment, the step of linearizing the steam pressure and the steam temperature of two adjacent measuring points according to the steam pressure and the steam temperature of the measuring points and the distance between the two adjacent measuring points to determine the steam pressure and the steam temperature at any position between the adjacent measuring points in the shaft comprises:

(p-p_i)/(p_i+1-p_i)＝(z-z_i)/(z_i+1-z_i)

(T-T_i)/(T_i+1-T_i)＝(z-z_i)/(z_i+1-z_i)

in the above formula, p is the pressure of steam in the shaft at any position between the ith and the (i + 1) th measuring points, p_iFor the pressure of steam in the wellbore at the ith station, p_i+1For steam in the (i + 1) th holeThe pressure at the measuring point is in megapascals; t is the temperature of steam in the shaft at any position between the ith and the (i + 1) th measuring points_iFor the temperature, T, of steam in the shaft at the ith measuring point_i+1The temperature of steam in a shaft at the (i + 1) th measuring point is measured in centigrade degrees; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N; n is the number of measured data and the known quantity;

p＝p_i+(p_i+1-p_i)(z-z_i)/(z_i+1-z_i)

T＝T_i+(T_i+1-T_i)(z-z_i)/(z_i+1-z_i)

in the above formula, T is the temperature of steam in the shaft at any position between the ith and (i + 1) th measuring points_iFor the temperature, T, of steam in the shaft at the ith measuring point_i+1The temperature of steam in a shaft at the (i + 1) th measuring point is measured in centigrade degrees; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N; n is the number of measured data and is a known quantity.

An apparatus for determining a thermal parameter in a wellbore, comprising:

a calculation parameter obtaining module, configured to obtain calculation parameters, where the calculation parameters include: measuring the pressure and temperature of steam and the distance between two adjacent measuring points;

and the pressure and temperature determining module is used for performing linearization processing on the steam pressure and the temperature of the two adjacent measuring points according to the calculation parameters to determine the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft.

An apparatus for determining a thermal parameter in a wellbore, comprising:

a calculation parameter obtaining module, configured to obtain calculation parameters, where the calculation parameters include: steam dryness at a well mouth, pressure and temperature of steam measured points, distance between two adjacent measured points, structural parameters of a shaft and environmental parameters;

the pressure and temperature determining module is used for carrying out linearization processing on the steam pressure and the temperature of two adjacent measuring points according to the steam dryness of the wellhead, the pressure and the temperature of the steam of the measuring points and the distance between the two adjacent measuring points, and determining the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft;

and the dryness heat loss determining module is used for dividing the shaft infinitesimal sections on the length of the shaft according to the distance between the two adjacent measuring points, establishing an energy control equation, and determining the dryness and heat loss of the steam at any position of the shaft by using the steam dryness of the wellhead as an initial condition and through iterative calculation of mutually coupled heat loss, temperature and dryness.

The invention has the characteristics and advantages that: according to the method for determining the steam thermal force parameter in the shaft, steam pressure and temperature of two adjacent measuring points are subjected to linearization processing through the measuring point parameters, the pressure and the temperature of the steam at any position between the two adjacent measuring points in the shaft are determined, compared with the existing mode, a control equation of steam pressure drop gradient in the shaft is established according to the momentum conservation law, and then the steam pressure in the whole shaft is solved, so that the steam pressure at a certain position of the shaft is suddenly changed, and when the steam pressure does not accord with the pressure gradient equation, the pressure between the measuring points is restrained through the pressure parameters of the two adjacent measuring points, and the calculation error of the steam pressure in the whole shaft is effectively controlled.

In addition, the temperature of the steam in the shaft is subjected to linearization processing by acquiring the temperature of the steam of two adjacent measuring points, and the temperature of the steam at any point along the shaft is determined by establishing a calculation equation of the temperature in the process of injecting the steam along the shaft.

Furthermore, because the heat loss and the dryness fraction are calculated based on a temperature function, an energy control equation is established according to an energy balance law by relying on the obtained accurate temperature in the method for determining the steam thermal parameters in the shaft, and the heat loss and the dryness fraction of steam at any position in the shaft are solved through circulating calculation. Compared with the existing dryness and heat loss solving formula, the method only depends on the steam pressure in the pipeline, when the pressure has a large error, the dryness and heat loss can easily cause the result to deviate from the true value, and the calculated heat loss and dryness precision are high.

Drawings

FIG. 1 is a diagram illustrating the steps of a method for determining thermal parameters of steam in a wellbore in accordance with an embodiment of the present invention;

FIG. 2 is a diagram illustrating the steps of a method for determining thermal parameters of steam in a wellbore in accordance with an embodiment of the present invention;

FIG. 3 is a diagram illustrating steps in a method for determining dryness and heat loss of steam in a wellbore in accordance with an embodiment of the present invention;

FIG. 4 is a schematic representation of a wellbore configuration in an embodiment of the present invention;

FIG. 5 is a graph of steam pressure versus well depth in a wellbore in an embodiment of the present invention;

FIG. 6 is a graph of steam temperature versus well depth in a wellbore in accordance with an embodiment of the present invention;

FIG. 7 is a graph of dryness of steam versus depth in a wellbore in accordance with an embodiment of the present invention;

FIG. 8 is a graph of steam heat loss versus well depth in a wellbore in accordance with an embodiment of the present invention;

FIG. 9 is a schematic illustration of a steam thermodynamic parameter determination device within a wellbore in accordance with an embodiment of the present invention;

FIG. 10 is a schematic diagram of a steam thermodynamic parameter determination device within a wellbore in accordance with an embodiment of the present invention.

Detailed Description

The technical solutions of the present invention will be described in detail with reference to the accompanying drawings and specific embodiments, it should be understood that these embodiments are merely illustrative of the present invention and are not intended to limit the scope of the present invention, and various equivalent modifications of the present invention by those skilled in the art after reading the present invention fall within the scope of the appended claims.

The invention provides a method and a device for determining thermal parameters in a shaft, which can accurately calculate the thermal parameters of steam at any position in the shaft so as to reduce the heat loss in the steam injection process to the maximum extent and improve the dryness of the steam at the bottom of an injection shaft, thereby improving the effect of extracting thick oil by injecting steam.

Fig. 1 is a flowchart illustrating a method for determining a steam thermodynamic parameter in a wellbore according to an embodiment of the present invention. The method for determining the steam thermodynamic parameter in the shaft comprises the following steps:

step S10: obtaining calculation parameters, wherein the calculation parameters comprise: measuring the pressure and temperature of steam, and the distance between two adjacent measuring points.

In this embodiment, the test points may be obtained by setting a certain time interval for taking points during a test process of a test instrument, and the distances between the test points may be different due to different lowering speeds during the test process of the test instrument.

The pressure and temperature of the steam at the measuring point can be obtained by a testing instrument from the wellhead to the bell mouth in the process of testing along the shaft.

Step S12: and according to the calculation parameters, carrying out linearization processing on the steam pressure and the temperature of the two adjacent measuring points, and determining the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft.

In this embodiment, according to the measurement point parameters, linearizing the steam pressure and temperature of two adjacent measurement points, and determining the steam pressure and temperature at any position between the adjacent measurement points in the wellbore may specifically include:

(p-p_i)/(p_i+1-p_i)＝(z-z_i)/(z_i+1-z_i)

(T-T_i)/(T_i+1-T_i)＝(z-z_i)/(z_i+1-z_i)

in the above formula, p is the pressure of steam in the shaft at any position between the ith and the (i + 1) th measuring points, p_iFor the pressure of steam in the wellbore at the ith station, p_i+1The pressure of steam in a shaft at the (i + 1) th measuring point is respectively in megapascals; t is the temperature of steam in the shaft at any position between the ith and the (i + 1) th measuring points_iFor the temperature, T, of steam in the shaft at the ith measuring point_i+1The temperature of steam in a shaft at the (i + 1) th measuring point is measured in centigrade degrees; z is the shaft task between the ith and the (i + 1) th measuring pointsFree depth, z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N; and N is the number of measured data and is a known quantity.

p＝p_i+(p_i+1-p_i)(z-z_i)/(z_i+1-z_i)

in the above formula, p is the pressure of steam in the shaft at any position between the ith and the (i + 1) th measuring points, p_iFor the pressure of steam in the wellbore at the ith station, p_i+1The pressure of steam in a shaft at the (i + 1) th measuring point is respectively in megapascals; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N; and N is the number of measured data and is a known quantity.

T＝T_i+(T_i+1-T_i)(z-z_i)/(z_i+1-z_i)

According to the method for determining the steam thermal force parameter in the shaft, steam pressure and temperature of two adjacent measuring points are subjected to linearization processing through the measuring point parameters, the pressure and the temperature of the steam at any position between the two adjacent measuring points in the shaft are determined, compared with the existing mode, a control equation of steam pressure drop gradient in the shaft is established according to the momentum conservation law, and then the steam pressure in the whole shaft is solved, so that the steam pressure at a certain position of the shaft is suddenly changed, and when the steam pressure does not accord with the pressure gradient equation, the pressure between the measuring points is restrained through the pressure parameters of the two adjacent measuring points, and the calculation error of the steam pressure in the whole shaft is effectively controlled.

Referring to fig. 2, a method for determining a steam thermodynamic parameter in a wellbore according to an embodiment of the invention is shown. The method for determining the steam thermodynamic parameter in the shaft comprises the following steps:

step S20: obtaining calculation parameters, wherein the calculation parameters comprise: the steam dryness of the well mouth, the pressure and the temperature of the steam of the measuring points, the distance between two adjacent measuring points, the structural parameters of the shaft and the environmental parameters.

In this embodiment, the wellbore construction parameters may include: the inner diameter of the inner pipe of the heat insulation oil pipe, the outer diameter of the inner pipe of the heat insulation oil pipe, the inner diameter of the outer pipe of the heat insulation oil pipe, the outer diameter of the outer pipe of the heat insulation oil pipe, the heat conductivity coefficient of the heat insulation oil pipe, the inner diameter of the sleeve, the outer diameter of the cement sheath, the heat conductivity coefficient of the cement sheath, the blackness of.

The environmental parameters include: surface temperature, ground temperature gradient, formation heat conductivity coefficient and formation heat conductivity coefficient.

In addition, the calculating the parameters may further include: and (5) steam injection amount.

Step S22: and according to the pressure and the temperature of the steam of the measuring points and the distance between two adjacent measuring points, carrying out linearization treatment on the steam pressure and the temperature of the two adjacent measuring points to determine the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft.

In this embodiment, the determining the pressure and the temperature of the steam at any position along the adjacent measuring points in the wellbore by performing linearization processing on the pressure and the temperature of the steam at the two adjacent measuring points and the distance between the two adjacent measuring points may specifically include:

(p-p_i)/(p_i+1-p_i)＝(z-z_i)/(z_i+1-z_i)

(T-T_i)/(T_i+1-T_i)＝(z-z_i)/(z_i+1-z_i)

in the above formula, p is the pressure of steam in the shaft at any position between the ith and the (i + 1) th measuring points, p_iFor the pressure of steam in the wellbore at the ith station, p_i+1The pressure of steam in a shaft at the (i + 1) th measuring point is respectively in megapascals; t is the temperature of steam in the shaft at any position between the ith and the (i + 1) th measuring points_iFor the temperature, T, of steam in the shaft at the ith measuring point_i+1The temperature of steam in a shaft at the (i + 1) th measuring point is measured in centigrade degrees; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N; and N is the number of measured data and is a known quantity.

p＝p_i+(p_i+1-p_i)(z-z_i)/(z_i+1-z_i)

T＝T_i+(T_i+1-T_i)(z-z_i)/(z_i+1-z_i)

Step S24: and dividing a shaft infinitesimal section on the length of the shaft according to the distance between the two adjacent measuring points, establishing an energy control equation, and determining the dryness and heat loss of the steam at any position of the shaft by using the steam dryness of the well head as an initial condition and through the iterative calculation of mutually coupled heat loss, temperature and dryness.

Specifically, please refer to fig. 3, which is a step diagram of a method for determining dryness and heat loss of steam in a wellbore according to an embodiment of the present invention. In step S24, the determining dryness and heat loss of steam at any position of the wellbore includes the following sub-steps:

step S240: setting dryness drop of steam in the wellbore infinitesimal section and total heat transfer coefficient of the wellbore infinitesimal section;

in the embodiment, when setting the dryness fraction of the steam in the wellbore infinitesimal section, the dryness fraction can be set according to an empirical value, so as to reduce the number of iterations. For example, a range in which the dryness fraction decreases within a predetermined step is obtained statistically, and the dryness fraction decrease may be selected to be a value within the statistically obtained range. Specifically, for example, the dryness drop can be set to 0.015 by statistically reducing the dryness between two adjacent measuring points by 0.014 to 0.18.

When the total heat transfer coefficient of the wellbore infinitesimal section is set, the total heat transfer coefficient can be set according to an empirical value, so that the number of iterations is reduced. For example, a range of variation in the total heat transfer coefficient of the wellbore infinitesimal section within a predetermined step is statistically obtained, and the total heat transfer coefficient of the wellbore infinitesimal section may be selected to be a value within the statistically obtained range. Specifically, for example, the total heat transfer coefficient of the wellbore micro-element section can be set to 0.5 by counting that the total heat transfer coefficient of the wellbore micro-element section varies between two adjacent measuring points to be 0.4 to 0.6.

Step S242: and calculating the total thermal resistance of the wellbore micro-element section through the total heat transfer coefficient of the wellbore micro-element section, and calculating the steam heat loss of the wellbore micro-element section through the total thermal resistance of the wellbore micro-element section.

Fig. 4 is a schematic diagram of a wellbore structure according to an embodiment of the invention. The well bore center outward in sequence can be: the cement sheath comprises an inner pipe, an outer pipe, a sleeve and a cement sheath, wherein a heat insulating layer is arranged between the inner pipe and the outer pipe, and an air layer is arranged between the outer pipe and the sleeve.

The calculation formula of the heat loss from the center of the oil pipe to the outer edge of the cement sheath is as follows:

wherein:

in the above formula, dQ₁Is the length of dz in unit timeHeat change on the wellbore in kilocalories/(hour); t is_sThe steam temperature in the shaft is in centigrade; t is_hThe temperature of the outer edge of the cement sheath is in centigrade unit; r is the thermal resistance on the shaft with the dz length, and the unit is [ kilocalorie/(meter-hour-degree centigrade)]^-1(ii) a dz is the length of the wellbore in meters; h is_fIs the convective heat transfer coefficient of the liquid film layer, h_pIs the convective heat transfer coefficient of the fouling layer, h_fcThe heat transfer coefficient in the annular space is expressed in kilocalories/(square meter, hour and centigrade); lambda [ alpha ]_tubIs heat conductivity coefficient of heat insulation oil pipe, lambda_insIs a thermal conductivity coefficient of the thermal insulation layer material, lambda_casIs the sleeve heat conductivity coefficient, lambda_cemThe cement sheath thermal conductivity coefficient is expressed in kilocalories/(meter.h.degree centigrade); r is₁Is the inner radius of the inner pipe of the heat insulation oil pipe, r₂For insulating the outer radius of the inner pipe of the tubing, r₃Is the inner radius of the outer pipe of the heat insulation oil pipe, r₄Is the outer radius of the outer pipe of the heat insulation oil pipe, r_coIs the outer radius of the casing, r_ciIs the inner radius of the casing, r_hThe outer radius of the cement sheath is meter.

h_fc＝h_r+h_c

in the above formula, σ is Stefan-Boltzmann constant, and has a value of 4.8755.67 × 10^-8Kilocalories/(square meter hour kelvin)⁴)；ε₄The blackness of the outer wall of the outer pipe of the heat insulation oil pipe is known; epsilon_ciBlackness of the inner wall of the casing, known amount; t is₄The temperature of the outer wall of the outer pipe of the heat insulation oil pipe is measured in centigrade degrees; t is_ciIs the temperature of the inner wall of the casing in degrees centigrade.

wherein:

in the above formula, g is the gravity acceleration in meters per square second; rho_anIn grams per cubic centimeter of the density of the annulus fluid at average temperature β_anIs the volumetric thermal expansion coefficient of the annular space fluid, β_an＝1/T_an ^*，T_an ^*＝T_an+273，1/K；T_anIs the mean temperature of the fluid in the annular space, T_an＝(T₄+T_ci) 2, unit degree centigrade; mu.s_anViscosity of the annulus fluid at average temperature in centipoise; c_anIs the heat capacity of the annular space fluid at average temperature, in kilocalories/(kilogram-degree centigrade); lambda [ alpha ]_haIs the thermal conductivity of the fluid in the annular space at the average temperature, in kilocalories/(square meter hour degrees celsius).

in the above formula, T_eIs the initial formation temperature, T_e＝T_m+a·z，T_mIs the surface temperature, T_hThe temperature at the outer edge of the cement sheath is measured in unitsIs in degrees centigrade; a is the ground temperature gradient, and the temperature is in degrees centigrade per meter; z is well depth, meter; lambda [ alpha ]_eThe formation thermal conductivity coefficient is kilocalorie/(square meter hour DEG C); f (t) is a dimensionless function of the conduction time of the formation.

when K' is 0.1,

when K' ≠ 0.1,

in the above formula, t' ═ α t/r_h ²Time in dimension one; k' ═ r₁U/λ_eThe dimension is the thermal conductivity of one.

Heat loss in the wellbore micro-element section includes: heat loss transferred from the center of the oil pipe to the outer edge of the cement sheath and heat loss transferred from the outer edge of the cement sheath to the stratum.

The heat loss of the micro-element section of the determined shaft is equal to that of the cement according to the heat transferred from the center of the oil pipe to the outer edge of the cement sheathAnd (3) establishing a heat transfer continuity equation according to the heat transferred from the outer edge of the ring to the stratum: dQ₁＝dQ₂。

in the above formula, λ_eThe formation thermal conductivity is expressed in kilocalories/(meter.h.degree centigrade); t is_eIs the initial formation temperature in degrees celsius; t is_sThe steam temperature in the shaft is measured in degrees centigrade; r is₂The radius of the inner pipe and the outer pipe of the heat insulation oil pipe is unit meter; f (t) is the dimensionless formation conduction time function; u is the total heat transfer coefficient from the center of the oil pipe to the outer edge of the cement sheath, kilocalories/(square meter-hour-centigrade), and the calculation formula is as follows:

in the above formula, h_fIs the convective heat transfer coefficient of the liquid film layer, h_pIs the convective heat transfer coefficient of the fouling layer, h_cNatural convection heat transfer coefficient, h, in the annular space_rThe radiation heat exchange coefficient in the annular space is kilocalorie/(square meter, hour and centigrade); lambda [ alpha ]_tubIs heat conductivity coefficient of heat insulation oil pipe, lambda_insIs a thermal conductivity coefficient of the thermal insulation layer material, lambda_casIs the sleeve heat conductivity coefficient, lambda_cemThe cement sheath thermal conductivity coefficient is expressed in kilocalories/(meter.h.degree centigrade); r is₁Is the inner radius of the inner pipe of the heat insulation oil pipe, r₂For insulating the outer radius of the inner pipe of the tubing, r₃Is the inner radius of the outer pipe of the heat insulation oil pipe, r₄Is the outer radius of the outer pipe of the heat insulation oil pipe, r_coIs the outer radius of the casing, r_ciIs the inner radius of the casing, r_hThe outer radius of the cement sheath is meter.

in the above formula, T_ciIs the temperature of the inner wall of the casing, T_hIs the temperature of the outer edge of the cement sheath, T_sThe steam temperature in the shaft is measured in centigrade degrees; r is₂For insulating the outer radius of the inner pipe of the tubing, r_coIs the outer radius of the casing, r_ciIs the inner radius of the casing, r_hThe outer radius of the cement sheath is meter; lambda [ alpha ]_casIs the sleeve heat conductivity coefficient, lambda_cemThe cement sheath thermal conductivity coefficient is expressed in kilocalories/(meter.h.degree centigrade); u is the total heat transfer coefficient from the center of the oil pipe to the outer edge of the cement sheath, and the unit is kilocalories/(square meter, hour and centigrade).

in the above formula, T₄For the outer wall temperature, T, of the outer tube of the heat-insulating tube_hIs the temperature of the outer edge of the cement sheath, T_sThe steam temperature in the shaft is measured in centigrade degrees; h is_fIs the convective heat transfer coefficient of the liquid film layer, h_pThe convective heat transfer coefficient of the dirt layer is expressed in kilocalories/(square meter, hour and centigrade); lambda [ alpha ]_tubIs heat conductivity coefficient of heat insulation oil pipe, lambda_insThe thermal conductivity coefficient of the thermal insulation layer material is kilocalorie/(meter.h.degree centigrade); r is₁Is the inner radius of the inner pipe of the heat insulation oil pipe, r₂For insulating the outer radius of the inner pipe of the tubing, r₃Is the inner radius of the outer pipe of the heat insulation oil pipe, r₄The outer radius of the outer pipe of the heat insulation oil pipe is meter; u is the total heat transfer coefficient from the center of the oil pipe to the outer edge of the cement sheath, and the unit is kilocalories/(square meter, hour and centigrade).

Step S244: and repeating iteration, and when the calculated value of the total heat transfer coefficient of the wellbore micro-element section and the set value meet first preset precision, determining the total heat transfer coefficient of the wellbore micro-element section to obtain the steam heat loss of the wellbore micro-element section.

In this embodiment, the first predetermined accuracy may be set according to actual accuracy requirements, and the smaller the value set by the first predetermined accuracy, the more accurate the obtained total heat transfer coefficient of the wellbore micro-element section is, and accordingly, the higher the accuracy of the obtained heat loss in the wellbore micro-element section is.

The iterative process specifically includes: and obtaining corresponding total thermal resistance through a set total heat transfer coefficient of the wellbore micro-element section, obtaining corresponding heat loss through the total thermal resistance, and obtaining a calculated value of the total heat transfer coefficient of the wellbore micro-element section through the obtained heat loss.

Step S246: and calculating the dryness according to an energy balance law, repeatedly iterating, and determining the dryness drop of the wellbore infinitesimal section when the dryness drop calculation value of the wellbore infinitesimal section and a set value meet a second preset precision.

In this embodiment, the calculating the dryness fraction according to the energy balance law includes:

the following energy control equation is established:

wherein

C₁＝G(h_g-h_l)

In the above formula, h_gIs the enthalpy of saturated steam, h_lThe enthalpy of saturated water is expressed in kilocalories/kilogram; x is the steam dryness; g is saturated steam mass flow, unit kilogram/hour; q is the heat loss of the shaft in unit length in unit time, and the unit is kilocalorie/(hour meter); rho_mSaturated wet steam density in kilograms per cubic meter; a is the cross-sectional area of the shaft in square meters; theta is the inclination angle of the shaft in units of degrees.

h_g＝12500+1.88T-3.7×10^-6T^3.2

the rho_mThe saturated wet steam density calculation formula is as follows:

ρ_m＝H_gρ_g+(1-H_g)ρ_l

ρ_l＝0.9967-4.615×10^-5T-3.063×10^-6T²

Z_g＝1.012-4.461×10^-4T+2.98×10^-6T²-1.663×10^-8T³

In this embodiment, the second predetermined precision may be set according to an actual precision requirement, and the smaller the value set by the second predetermined precision is, the more precisely the dryness reduction of the micro-element section of the pipeline is obtained.

Step S248: and (4) circulating and calculating to the whole shaft, and determining dryness and heat loss of steam at any position of the shaft.

In the embodiment, the circulation calculation to the whole shaft can be sequentially selected from the first measuring point and the second measuring point of the wellhead two by two.

In a specific embodiment, the calculation parameters are obtained, specifically, the inner diameter of the inner pipe of the thermal insulation oil pipe is 0.031 meter, the outer diameter of the inner pipe of the thermal insulation oil pipe is 0.0365 meter, the inner diameter of the outer pipe of the thermal insulation oil pipe is 0.0509 meter, the outer diameter of the outer pipe of the thermal insulation oil pipe is 0.0572 meter, the thermal conductivity of the thermal insulation oil pipe is 0.007 watt/meter.C, the inner diameter of the casing is 0.0807 meter, the outer diameter of the casing is 0.0889 meter, the outer diameter of the cement ring is 0.1236 meter, the thermal conductivity of the cement ring is 0.933 watt/meter.C, the blackness of the inner surface of the thermal insulation oil pipe is 0.8, the blackness of the inner surface of the casing is 1, the surface temperature is 15.6 deg.C, the ground temperature gradient^-07Square meter/second, steam injection amount of 7 tons/hour, well head dryness of 0.63243, shaft length of 800.5 meters, positions of each measuring point, and pressure and temperature corresponding to each measuring point. The pressure at any position in the shaft obtained by applying the method for determining the steam thermodynamic parameter in the shaft is in unit of megapascal (MPa); temperature units in degrees Celsius (. degree. C.); dryness; heat loss was accumulated in kilojoules per kilogram (Kj/Kg) as shown in Table 1.

TABLE 1

The thermodynamic parameters at the wellbore can be separately obtained from the data in table 1 above.

The thermal parameters of the measuring points corresponding to the well depth positions in the table 1 are selected from values close to the well mouth and two ends of the bell mouth at the bottom of the shaft, and the total length of the whole shaft reaches 800.5 meters, so that one example is not shown.

Specifically, a graph of steam pressure in the wellbore versus well depth is shown in fig. 5, wherein the abscissa represents well depth in meters; the ordinate represents the pressure of steam in mpa in the wellbore. The curve in the figure shows the steam pressure in the shaft with the well depth of 800.5 meters from the well head to the bell mouth at the bottom of the shaft when the well depth is 0. Compared with the prior art, the pressure of the whole shaft is solved from the wellhead through the pressure gradient equation, and the pressure calculation error of the whole shaft can be effectively controlled through the constraint of the pressure value of the measuring point of the shaft when the pressure of a certain section of the shaft is suddenly changed and does not accord with the pressure gradient equation.

Specifically, a graph of steam temperature in the wellbore versus well depth is shown in fig. 6, wherein the abscissa represents well depth in meters; the ordinate represents the steam temperature in degrees celsius within the wellbore. The graph shows the steam temperature at any position in the whole shaft from the well head with the well depth of 0 meter to the bell mouth at the bottom of the shaft and the well depth of 800.5 meters. By the method for determining the steam thermodynamic parameter in the shaft, the steam temperature at any position in the shaft can be obtained. Compared with the existing mode that the temperature depends on pressure calculation, the method can effectively avoid the influence on the calculation precision of the temperature when the pressure has errors.

Specifically, a graph of steam dryness versus well depth in the wellbore is shown in fig. 7, wherein the abscissa represents well depth in meters; the ordinate represents the dryness of the steam in the wellbore. The curve in the figure shows the steam quality at any position in the whole shaft from the well head with the well depth of 0 meter to the bell mouth at the bottom of the shaft of the well head and the well depth of 800.5 meters. Namely, the steam dryness at any position in the shaft can be obtained by the method for determining the steam thermodynamic parameter in the shaft.

Specifically, a graph of steam heat loss versus well depth in the wellbore is shown in fig. 8, wherein the abscissa represents well depth in meters; the ordinate represents steam heat loss in the wellbore in kilojoules per kilogram. The graph shows the steam heat loss from the well head with the well depth of 0 meter to the bell mouth at the bottom of the well shaft and the well depth of 800.5 meters at any position in the whole well shaft. Namely, the steam heat loss at any position in the shaft can be obtained by the method for determining the steam heat parameter in the shaft.

Because the calculation of the heat loss and the dryness fraction is based on a function of temperature, an energy control equation is established according to an energy balance law by relying on the obtained accurate temperature in the method for determining the steam thermal parameters in the shaft, and the heat loss and the dryness fraction of the steam at any position in the shaft are solved through circulating calculation. Compared with the existing dryness and heat loss solving formula, the method only depends on the steam pressure in the pipeline, when the pressure has a large error, the dryness and heat loss can easily cause the result to deviate from the true value, and the calculated heat loss and dryness precision are high.

In actual production, the temperature, pressure, dryness and heat loss of steam in the shaft are calculated, so that the change rule of steam parameters in the shaft and the heat loss condition of the whole steam injection process are known conveniently, and the steam flooding effect is predicted conveniently and quickly and the steam injection parameters are optimized. Furthermore, some improvement measures can be provided according to the calculated thermal parameters: for example, a low thermal conductivity, high thermal insulation pipe may be preferred, or steam injection parameters may be preferred to minimize heat loss and ensure sufficient dryness of the steam reaching the bottom of the well. Further, when a sudden change in at least one of temperature, pressure, dryness, heat loss is found at a location on the wellbore, further analysis can be performed for that location to see if a leak has occurred.

Referring to fig. 9, an apparatus 100 for determining a thermal parameter of steam in a wellbore includes:

a calculation parameter obtaining module 10, configured to obtain calculation parameters, where the calculation parameters include: and measuring the pressure and the temperature of steam and the distance between two adjacent measuring points.

And the pressure and temperature determining module 20 is used for performing linearization processing on the steam pressure and the temperature of the two adjacent measuring points according to the calculation parameters, and determining the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft.

According to the device 100 for determining the steam thermal force parameter in the shaft, steam pressure and temperature of two adjacent measuring points are subjected to linearization processing through the measuring point parameters, and the pressure and the temperature of the steam at any position between the two adjacent measuring points in the shaft are determined.

Referring to fig. 10, an apparatus 200 for determining a thermal parameter of steam in a wellbore includes:

a calculation parameter obtaining module 20, configured to obtain calculation parameters, where the calculation parameters include: steam dryness at a well mouth, pressure of steam at a measuring point, distance between two adjacent measuring points for temperature, structural parameters of a shaft and environmental parameters;

the pressure and temperature determining module 22 is used for performing linearization processing on the steam pressure and the temperature of the two adjacent measuring points according to the steam pressure and the temperature of the measuring points and the distance between the two adjacent measuring points, and determining the steam pressure and the temperature at any position between the adjacent measuring points in the shaft;

and the dryness heat loss determining module 24 is used for dividing the shaft infinitesimal sections on the length of the shaft according to the distance between the two adjacent measuring points, establishing an energy control equation, and determining the dryness and heat loss of the steam at any position of the shaft by using the steam dryness of the wellhead as an initial condition and through iterative calculation of mutually coupled heat loss, temperature and dryness.

According to the device 200 for determining the steam thermal force parameter in the shaft, steam pressure and temperature of two adjacent measuring points are subjected to linearization processing through the measuring point parameters, and the pressure and the temperature of the steam at any position between the two adjacent measuring points in the shaft are determined.

The above embodiments in this specification are all described in a progressive manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment is described with emphasis on being different from other embodiments. Especially for the device embodiment, since it is basically similar to the method embodiment, the description is simple, and the relevant points can be referred to the description of the method embodiment.

The above description is only a few examples of the present invention, and although the embodiments of the present invention are described above, the above description is only for the convenience of understanding the present invention, and is not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for determining a thermal parameter in a wellbore, comprising:

according to the calculation parameters, carrying out linearization processing on the steam pressure and the temperature of two adjacent measuring points, and determining the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft; the step of carrying out linearization processing on the steam pressure and the temperature of two adjacent measuring points according to the calculation parameters, and determining the steam pressure and the temperature at any position between the adjacent measuring points in the shaft comprises the following steps:

(p-p_i)/(p_i+1-p_i)＝(z-z_i)/(z_i+1-z_i)

(T-T_i)/(T_i+1-T_i)＝(z-z_i)/(z_i+1-z_i)

p＝p_i+(p_i+1-p_i)(z-z_i)/(z_i+1-z_i)

T＝T_i+(T_i+1-T_i)(z-z_i)/(z_i+1-z_i)

2. A method for determining a thermal parameter in a wellbore, comprising:

according to the pressure and the temperature of the steam of the measuring points and the distance between two adjacent measuring points, the steam pressure and the temperature of the two adjacent measuring points are subjected to linearization treatment, and the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft are determined; the step of carrying out linearization processing on the steam pressure and the temperature of two adjacent measuring points according to the steam pressure and the temperature of the measuring points and the distance between the two adjacent measuring points to determine the steam pressure and the temperature at any position between the adjacent measuring points in the shaft comprises the following steps:

(p-p_i)/(p_i+1-p_i)＝(z-z_i)/(z_i+1-z_i)

(T-T_i)/(T_i+1-T_i)＝(z-z_i)/(z_i+1-z_i)

p＝p_i+(p_i+1-p_i)(z-z_i)/(z_i+1-z_i)

T＝T_i+(T_i+1-T_i)(z-z_i)/(z_i+1-z_i)

in the above formula, T is the temperature of steam in the shaft at any position between the ith and (i + 1) th measuring points_iFor the temperature, T, of steam in the shaft at the ith measuring point_i+1The temperature of steam in a shaft at the (i + 1) th measuring point is measured in centigrade degrees; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N; n is the number of measured data and is a known quantity;

3. The method of claim 2, wherein: the method for determining dryness and heat loss of steam at any position of the shaft comprises the following steps:

calculating the steam dryness according to an energy balance law, repeatedly iterating, and determining the dryness drop of the steam in the micro element section of the shaft when the calculated value of the steam dryness drop in the micro element section of the shaft and a set value meet a second preset precision;

4. The method of claim 3, wherein said calculating the dryness fraction according to the law of energy balance comprises:

the following energy control equation is established:

wherein,

C₁＝G(h_g-h_l)

in the above formula, z is the well depth in meters; h is_gIs the enthalpy of saturated steam, h_lThe enthalpy of saturated water is expressed in kilocalories/kilogram; x is the steam dryness; g is saturated steam mass flow, unit kilogram/hour; q is the heat loss of the shaft in unit length in unit time, and the unit is kilocalorie/(hour meter); rho_mSaturated wet steam density in kilograms per cubic meter; a is the cross-sectional area of the shaft in square meters; theta is a shaft inclination angle and a unit degree;

h_g＝12500+1.88T-3.7×10^-6T^3.2

the rho_mThe saturated wet steam density calculation formula is as follows:

ρ_m＝H_gρ_g+(1-H_g)ρ_l

ρ_l＝0.9967-4.615×10^-5T-3.063×10^-6T²

Z_g＝1.012-4.461×10^-4T+2.98×10^-6T²-1.663×10^-8T³

5. The method of claim 3, wherein heat loss in the wellbore microsection comprises: the heat loss transferred from the center of the oil pipe to the outer edge of the cement sheath and the heat loss transferred from the outer edge of the cement sheath to the stratum,

and establishing a heat transfer continuity equation according to the fact that the heat transferred from the center of the oil pipe to the outer edge of the cement sheath is equal to the heat transferred from the outer edge of the cement sheath to the stratum: dQ₁＝dQ₂Wherein Q is₁Representing the heat loss transferred from the center of the oil pipe to the outer edge of the cement sheath; q₂Indicating heat loss transferred from the outer edge of the cement sheath to the formation.

6. The method of claim 5, wherein:

wherein:

h_fc＝h_r+h_c

in the above formula, σ is Stefan-Boltzmann constant, and has a value of 4.8755.67 × 10^-8Kilocalories/(square meter hour kelvin)⁴)；ε₄The blackness of the outer wall of the outer pipe of the heat insulation oil pipe is known; epsilon_ciBlackness of the inner wall of the casing, known amount; t is₄The temperature of the outer wall of the outer pipe of the heat-insulating oil pipe is measured in centigrade；T_ciThe temperature of the inner wall of the sleeve is measured in centigrade;

wherein:

the calculation formula of the heat loss transferred from the outer edge of the cement sheath to the stratum is as follows:

in the above formula, T_eIs the initial formation temperature, T_e＝T_m+a·z，T_mIs the surface temperature, T_hThe temperature of the outer edge of the cement sheath is measured in degrees centigrade; a is the ground temperature gradient, and the temperature is in degrees centigrade per meter; z is well depth, meter;λ_ethe formation thermal conductivity coefficient is kilocalorie/(square meter hour DEG C); f (t) is a dimensionless time function of formation conduction;

when K' is 0.1,

when K' ≠ 0.1,

in the above formula, t' ═ α t/r_h ²The dimension is one, wherein α is the thermal diffusion coefficient in square meters per hour, and K' ═ r₁U/λ_eThermal conductivity in dimension one;

7. An apparatus for determining a thermal parameter in a wellbore, comprising:

the pressure and temperature determining module is used for carrying out linearization processing on the steam pressure and the temperature of two adjacent measuring points according to the calculation parameters to determine the pressure and the temperature of the steam at any position between the adjacent measuring points in the shaft; the step of carrying out linearization processing on the steam pressure and the temperature of two adjacent measuring points according to the calculation parameters, and determining the steam pressure and the temperature at any position between the adjacent measuring points in the shaft comprises the following steps:

(p-p_i)/(p_i+1-p_i)＝(z-z_i)/(z_i+1-z_i)

(T-T_i)/(T_i+1-T_i)＝(z-z_i)/(z_i+1-z_i)

p＝p_i+(p_i+1-p_i)(z-z_i)/(z_i+1-z_i)

in the above formula, p is the pressure of steam in the shaft at any position between the ith and the (i + 1) th measuring points, p_iFor the pressure of steam in the wellbore at the ith station, p_i+1The pressure of steam in a shaft at the (i + 1) th measuring point is respectively in megapascals; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; the number of bits where i is 0, 1,…, N; n is the number of measured data and the known quantity;

T＝T_i+(T_i+1-T_i)(z-z_i)/(z_i+1-z_i)

8. An apparatus for determining a thermal parameter in a wellbore, comprising:

the pressure and temperature determining module is used for carrying out linearization treatment on the steam pressure and the temperature of the two adjacent measuring points according to the steam pressure and the temperature of the measuring points and the distance between the two adjacent measuring points to determine the steam pressure and the temperature at any position between the adjacent measuring points in the shaft; the step of carrying out linearization processing on the steam pressure and the temperature of two adjacent measuring points according to the steam pressure and the temperature of the measuring points and the distance between the two adjacent measuring points to determine the steam pressure and the temperature at any position between the adjacent measuring points in the shaft comprises the following steps:

(p-p_i)/(p_i+1-p_i)＝(z-z_i)/(z_i+1-z_i)

(T-T_i)/(T_i+1-T_i)＝(z-z_i)/(z_i+1-z_i)

p＝p_i+(p_i+1-p_i)(z-z_i)/(z_i+1-z_i)

T＝T_i+(T_i+1-T_i)(z-z_i)/(z_i+1-z_i)

in the above formula, T is the temperature of steam in the shaft at any position between the ith and (i + 1) th measuring points_iFor the temperature, T, of steam in the shaft at the ith measuring point_i+1The temperature of steam in a shaft at the (i + 1) th measuring point is measured in centigrade degrees; z is any depth of the shaft between the ith measuring point and the (i + 1) th measuring point, and z_iIs the ith measurement point depth, z_i+1The depth of the (i + 1) th measuring point is measured in meters; i is 0, 1, …, N;n is the number of measured data and is a known quantity;