CN-122014185-A - Underground electric heating energy supply and demand matching calculation method and device for heavy oil reservoir

CN122014185ACN 122014185 ACN122014185 ACN 122014185ACN-122014185-A

Abstract

The embodiment of the application provides a method and a device for calculating underground electric heating energy supply and demand matching of a heavy oil reservoir and a storage medium. The method comprises the steps of obtaining a thick oil starting temperature-pressure plate, defining a starting temperature threshold and a starting pressure gradient threshold required by thick oil to start flowing under the conditions of specific reservoir permeability and temperature, establishing a heat transfer and seepage coupling numerical model from a shaft to a target stratum, carrying out iterative calculation by taking the starting temperature threshold and the starting pressure gradient threshold as target conditions through the heat transfer and seepage coupling numerical model, solving the minimum thermal power required by the shaft to enable the temperature and the pressure of the target stratum to reach the target conditions, carrying out compensation calculation on heat loss from the ground to the target stratum according to the minimum thermal power, and determining matched operation power required by a ground electric heating system.

Inventors

LIU ZHEYU
LI YIQIANG
WANG ZHIPENG
YAN ZHIQIAN
CHAI MAOJIE

Assignees

中国石油大学(北京)

Dates

Publication Date: 20260512
Application Date: 20251219

Claims (10)

1. The underground electric heating energy supply and demand matching calculation method for the heavy oil reservoir is characterized by comprising the following steps of: Acquiring a thick oil starting warm-pressing plate, wherein the thick oil starting warm-pressing plate defines a starting temperature threshold value and a starting pressure gradient threshold value required for starting the flow of thick oil under the conditions of specific reservoir permeability and temperature; establishing a heat transfer and seepage coupling numerical model from a shaft to a target stratum; Performing iterative computation by taking the starting temperature threshold and the starting pressure gradient threshold as target conditions through the heat transfer and seepage coupling numerical model, and solving the minimum thermal power required to be input by a shaft for enabling the temperature and the pressure of the target stratum to reach the target conditions; And carrying out compensation calculation on the heat loss from the ground to the target stratum according to the minimum thermal power, and determining the matched operating power required to be provided by the ground electric heating system.
2. The method of claim 1, wherein the heat transfer and seepage coupling numerical model comprises a wellbore axial one-dimensional energy conservation model that accounts for convective heat transfer of fluids within the wellbore, radial heat transfer through a tubing string and a formation, and latent heat of steam condensation phase change, wherein the wellbore axial one-dimensional energy conservation model is expressed as follows: Wherein, the For wellbore fluid temperature, the unit is K; the coupling temperature is the outer surface coupling temperature of the well wall, wherein the unit is K, t is time, the unit is s, z is the axial coordinate of the well shaft, and the unit is m; The fluid density is in kg.m -3 , A is the fluid flow sectional area in the shaft, and the unit is m 2 ; The constant pressure specific heat capacity of the fluid is given in the unit of J.kg -1 ·K -1 , the Q is the volume flow rate in the unit of m 3 ·s -1 , the U is the total heat transfer coefficient after the conversion of the convection in the well and the radial heat conduction of the sleeve pipe/cement ring/near-well stratum, the unit is W.m -2 · K -1 , the P is the circumference of the inner wall, and the unit is m; represents the latent heat of condensation of steam, and the unit is J.kg -1 ; the unit represents the mass of water converted from steam phase to liquid phase in a unit length of shaft, and the unit is kg.m -1 ·s -1 .
3. The method of claim 1, wherein the heat transfer and seepage coupling numerical model further comprises a radial unsteady heat transfer model of a wellbore to a formation, the radial unsteady heat transfer model being used to solve for a wellbore wall coupling temperature and a near-wellbore formation temperature field, wherein the radial unsteady heat transfer model is expressed as follows: Wherein, the The convection heat exchange coefficient in a shaft is expressed in W.m -2 ·K -1 ; The convection heat transfer coefficient outside the shaft is expressed in W.m -2 ·K -1 ; Represents the outer radius of the j layers of the shaft, and the unit is m; The unit of the radius of the inner layer of the j layers of the shaft is m, L represents the length of the shaft along the path, and the unit of the length of the shaft along the path is m; The j-th layer heat conductivity coefficient is expressed in W.m -1 ·K -1 ; The rock density is expressed in kg.m -3 ; the specific heat capacity of the rock is expressed in J.kg -1 ·K -1 , the temperature of the stratum is expressed in T, the time is expressed in T, and the unit is s; The fluid density is kg.m -3 ; the specific heat capacity of the fluid is expressed in J.kg -1 ·K -1 ; The radial seepage velocity is m.s -1 ; Representing radial coordinates in m; The unit of the body heat source generated by the electric heating body or chemical reaction is W.m -3 , wherein The unit is W.m -1 ·K -1 for effective heat conductivity; , For wellbore fluid temperature, the unit is K; The unit is K for the coupling temperature of the outer surface of the well wall.
4. The method of claim 1, wherein the heat transfer and seepage coupling numerical model further comprises a formation radial seepage drawdown model for calculating a near-well formation pressure profile, wherein the formation radial seepage drawdown model is expressed as follows: Wherein, the Representing formation porosity; representing the comprehensive compression coefficient, wherein the unit is Pa -1 ; Represents formation pressure in Pa; represents viscosity in mPa.s, k represents reservoir permeability in mD; Representing radial coordinates in m; the term "equivalent pressure source term" means a rate of change in pressure due to injection or production of fluid in a unit volume of a formation per unit time, and is expressed in pa·s -1 .
5. The method of claim 1, wherein solving for the minimum thermal power input by the wellbore required to bring the temperature and pressure of the target formation to the target condition comprises: setting a plurality of ground heating powers as initial input values; Calculating the temperature distribution and the pressure distribution of the target stratum under each heating power based on the heat transfer and seepage coupling numerical model; judging whether the temperature distribution reaches the starting temperature threshold value or not and whether the pressure distribution reaches the starting pressure gradient threshold value or not; and iteratively adjusting the ground heating power until the minimum heating power which simultaneously meets the temperature threshold and the pressure threshold is found and is used as the minimum heating power.
6. The method of claim 1, wherein the compensating for heat loss from the surface to the target formation based on the minimum thermal power comprises: taking the minimum thermal power as an effective thermal demand of the target formation; Establishing an energy transfer link model from the surface to the target formation, the model for calculating the total heat loss of surface supplied energy during transfer to the target formation; adding the minimum thermal power to the total thermal loss calculated by the model to obtain theoretical thermal power required to be provided by the ground electric heating system; and converting the theoretical thermal power into an equivalent electric power value as the matched operation power of the ground electric heating system.
7. The method of claim 1, wherein the obtaining a thick oil start-up warm-pressing plate comprises: Measuring the starting pressure gradient of the thick oil in the rock core under the conditions of different displacement speeds and different temperatures through a rock core displacement experiment; based on experimental data, establishing a relation curve of injection speed and pressure gradient, and determining a pressure gradient to be started through an intersection point of a reverse extension line of the relation curve and a pressure gradient coordinate axis; repeating the experiment under the rock cores with different permeabilities and different temperature conditions to obtain a plurality of groups of pressure gradient data to be started; And constructing the thick oil starting warm-pressing plate according to the gradient data.
8. A heavy oil reservoir downhole electrical heating energy supply and demand matching computing device, the device comprising: A memory configured to store instructions; A processor configured to recall the instructions from the memory and, when executed, enable the method for heavy oil reservoir downhole electrical heating energy supply and demand matching calculation according to any one of claims 1 to 7.
9. The apparatus of claim 8, further comprising an experimental device for determining a thickened oil start-up pressure, the experimental device comprising: high-precision injection pump, piston container, constant-temperature box, pressure monitoring system, six-way valve, core holder, metering test tube and pressure surrounding pump.
10. A machine-readable storage medium having instructions stored thereon, which when executed by a processor, cause the processor to be configured to perform the method for electrical heating energy supply and demand matching downhole for heavy oil reservoirs according to any one of claims 1 to 7.

Description

Underground electric heating energy supply and demand matching calculation method and device for heavy oil reservoir Technical Field The application relates to the technical field of heavy oil reservoir development, in particular to a heavy oil reservoir underground electric heating energy supply and demand matching calculation method, a device and a storage medium. Background In the field of heavy oil reservoir development, the underground electric heating technology is used as a new low-carbon thermal recovery method, and the core of the method is that electric energy is accurately converted into heat energy to directly act on a shaft and a near-well reservoir so as to reduce the viscosity of heavy oil and start the flow of the heavy oil. The prior art scheme generally comprises three parts, namely firstly, obtaining thick oil starting pressure gradients under different temperature and permeability conditions through an indoor core displacement experiment, secondly, estimating the approximate electric heating power required for maintaining a certain temperature of a shaft based on a simplified steady-state heat conduction model or an empirical formula, and finally, setting fixed heating power or adjusting empirically by combining geology and engineering parameters. The technical path solves the basic requirements of thickened oil heating viscosity reduction to a certain extent, and forms the main basis of current underground electric heating design and operation. However, the above prior art scheme is characterized by isolated and static thick oil starting capability, and the "starting pressure gradient" parameter obtained by the implementation is not dynamically coupled into the formation temperature-pressure field real-time calculation model, so that the temperature and pressure double threshold conditions which are necessary for the "thick oil actually starts to flow" and are changed with space and time cannot be scientifically defined. Secondly, the energy transfer process from the well bore to the stratum is greatly simplified, the existing steady-state model or the empirical formula cannot be simultaneously coupled with the complex physical processes of non-isothermal flow in the well bore, radial non-steady-state heat transfer and reservoir non-darcy seepage, so that serious distortion is calculated on heat input from the well bore to the stratum and the minimum accurate thermal power meeting the starting condition cannot be solved. When the ground electric heating power is determined, the conventional method lacks a systematic calculation method for reversely and accurately compensating the heat loss of the full link by taking the minimum heat requirement of the stratum as constraint, and can only make rough estimation or 'overcomplete' design, so that real-time, accurate and self-adaptive matching of the underground heat energy dynamic requirement and ground electric energy supply cannot be realized. Disclosure of Invention The embodiment of the application aims to solve the problem that in the conventional energy meter algorithm based on a steady-state heat conduction model or an empirical formula, in the process of developing heavy oil by underground electric heating, the energy supply and demand mismatch is caused by the fact that a dynamic starting condition cannot be coupled with multi-physical-field energy transmission, and provides a heavy oil reservoir underground electric heating energy supply and demand matching calculation method, a device and a storage medium. In order to achieve the above purpose, the present application provides a method for calculating underground electric heating energy supply and demand matching of heavy oil reservoirs, comprising: acquiring a thick oil starting warm-pressing plate, wherein the thick oil starting warm-pressing plate defines a starting temperature threshold value and a starting pressure gradient threshold value required by the thick oil to start flowing under the conditions of specific reservoir permeability and temperature; establishing a heat transfer and seepage coupling numerical model from a shaft to a target stratum; Taking a starting temperature threshold value and a starting pressure gradient threshold value as target conditions, carrying out iterative calculation through a heat transfer and seepage coupling numerical model, and solving the minimum thermal power required to be input by a shaft for enabling the temperature and the pressure of a target stratum to reach the target conditions; And carrying out compensation calculation on the heat loss from the ground to the target stratum according to the minimum thermal power, and determining the matched operating power required to be provided by the ground electric heating system. In the embodiment of the application, the heat transfer and seepage coupling numerical model comprises a shaft axial one-dimensional energy conservation model, wherein the shaft axial one-dimensional energy conserv