Method for evaluating crude oil utilization rate during in-situ heating modification mining of shale oil

Abstract

The invention discloses a method for evaluating the crude oil utilization rate during shale oil in-situ heating modification exploitation, and is applied to the field of oil development. The method comprises the following steps: (1) constructing a three-dimensional grid model of shale oil reservoirs between two horizontal wells, and determining parameters such as initial temperature, initial fluid pressure, initial porosity, initial oil saturation, initial gas saturation, initial water saturation and initial dissolved gas volume of three-dimensional grid units of each reservoir; (2) determining the pressure of each reservoir three-dimensional grid unit when the fluid pressure is balanced according to the shale oil layer section bottom hole pressure and the reservoir displacement pressure gradient; (3) according to the characteristics of a temperature field, a pressure field and the like of the in-situ heating shale oil reservoir, obtaining three-dimensional grid unit temperature and instantaneous fluid pressure parameters of each reservoir, and determining porosity and fluid saturation at each time point; and (4) according to the instantaneous fluid pressure and the balanced fluid pressure of the three-dimensional grid unit of each reservoir, determining the oil, gas and water production quantity and the production rate of the grid unit of each reservoir in combination with the oil, gas and water saturation.

Description

Technical Field

[0001] The present invention relates to the technical field of oil exploration and development, and a method for evaluating the crude oil recovery rate during in-situ heating and upgrading for shale oil production. Background Art

[0002] Due to problems such as high viscosity and poor mobility of most shale oil resources, there are problems such as high investment, low output, and rapid decline in single-well production in horizontal well volume fracturing of shale oil. Many scholars at home and abroad have proposed technologies such as in-situ heating and upgrading and in-situ heating conversion for shale oil production. That is, in-situ heating is carried out on underground shale oil reservoirs (without collecting shale oil reservoirs to the ground). Among them, the in-situ heating temperature is relatively low, and basically no kerogen hydrocarbon generation or crude oil cracking into natural gas occurs. Moreover, the production method mainly by heating to reduce the viscosity of shale oil and increase its mobility is in-situ heating and upgrading; the in-situ heating temperature is relatively high, and the production method mainly for kerogen in immature-low mature source rocks to generate hydrocarbons is in-situ heating conversion.

[0003] The main in-situ heating methods for shale oil production are heat conduction (electric heating rods, steam circulation pipes, dielectric heating, etc.), convection + conduction (injecting steam, hot organic gases, and CO 2 ) and radiation + conduction (electric fields, electromagnetic waves, microwaves, etc.). Due to the low permeability of shale oil reservoirs, it is difficult and costly to inject hot fluids into shale oil reservoirs. Many scholars at home and abroad have carried out relevant research on unconventional oil and gas reservoirs such as low-frequency electric fields (belonging to dielectric heating), microwaves, and high-frequency electromagnetic fields for heating heavy oil, oil sands, shale oil, and shale gas. Oil companies such as Shell have conducted on-site tests on the large-scale heating of shale oil reservoirs using heating pipes in several blocks for shale oil production.

[0004] The in-situ heating and upgrading method for shale oil production can reduce the viscosity of shale oil, increase the reservoir fluid pressure, form fractures to increase the seepage capacity, increase the production of shale oil wells, and reduce the cost of shale oil production, that is, carry out viscosity reduction, pressure increase, permeability increase, production increase, and cost reduction for shale oil. In this way, shale oil production does not require staged hydraulic fracturing, and basically eliminates the need for water resources; only a large amount of electric energy is required, but there is no requirement for the stability of electric energy. In the northwestern region of China where wind energy and solar energy resources are rich, there is a broad prospect for promotion, and it is expected to break through the technical bottleneck of shale oil production.

[0005] There are several core issues in the in-situ heating and upgrading for shale oil extraction: during the process of increasing the temperature of the shale oil reservoir, the evaluation of the dynamic pressure field of the shale oil reservoir; the variation characteristics of the pore fluid pressure in the shale oil reservoir; the characteristics of the utilization of oil and gas resources in the shale oil reservoir, etc. These issues respectively determine whether the shale oil reservoir can be heated over a large area, whether a large-area fluid overpressure can be formed in the reservoir to drive the shale oil resources, the recoverable amount and utilization rate of the shale oil resources, and whether it is economically feasible, and jointly affect the success of in-situ heating and upgrading for shale oil extraction. Domestic scholars have studied the first two core issues, but there is still a lack of research on the characteristics of the utilization of oil and gas resources in the shale oil reservoir during the in-situ heating and upgrading for shale oil extraction.

[0006] For this reason, the present invention proposes a method for evaluating the utilization rate of crude oil during in-situ heating and upgrading for shale oil extraction. This method can quantitatively evaluate the characteristics of the utilization rate of shale oil during the in-situ heating and upgrading for shale oil extraction, provide important technical parameters for in-situ heating and upgrading for shale oil extraction, and provide support for breaking through the technical bottleneck of shale oil extraction. Summary of the Invention

[0007] The object of the present invention is: a method for evaluating the utilization rate of crude oil during in-situ heating and upgrading for shale oil extraction, which can quantitatively evaluate the variation characteristics of the pressure field of the shale oil reservoir with the temperature field during the in-situ heating and upgrading for shale oil extraction, provide important technical parameters for in-situ heating and upgrading for shale oil extraction, and provide support for breaking through the technical bottleneck of shale oil extraction.

[0008] The technical solution adopted by the present invention is: a method for evaluating the utilization rate of crude oil during in-situ heating and upgrading for shale oil extraction, characterized in that:

[0009] Step 1: Construct a three-dimensional grid model of the shale oil reservoir between two horizontal wells. The length, width, and height of each reservoir grid unit are all L, and determine the initial temperature T x,y,z,0 、initial fluid pressure P x,y,z,0 、initial porosity Ф x,y,z,0 、initial oil saturation S o,x,y,z,0 、initial gas saturation S g,x,y,z,0 、initial water saturation S w,x,y,z,0 、initial dissolved gas volume V dis-g,x,y,z,0 、initial coefficient of thermal expansion of the rock skeleton β r,x,y,z,0 、initial coefficient of thermal expansion of crude oil β o,x,y,z,0 、initial coefficient of thermal expansion of natural gas β g,x,y,z,0 and initial coefficient of thermal expansion of water β w,x,y,z,0, where x, y, and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis, and z-axis in the three-dimensional space respectively. The units of the length, width, and height of the reservoir grid cells are all m, the unit of temperature is K, the unit of pressure is MPa, the unit of porosity is %, and the units of oil saturation, gas saturation, and water saturation are %. The unit of the dissolved gas volume in crude oil is m 3 / m 3 , and the unit of the volume thermal expansion coefficient is K -1 , where x, y, and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis, and z-axis in the three-dimensional space respectively;

[0010] Step 2: According to the reservoir displacement pressure gradient P x,y,z,d and the wellbore fluid pressure P z,t of the shale oil reservoir section at time t, determine the pore fluid pressure P x,y,z,t when the fluid pressure in each three-dimensional reservoir grid cell is in equilibrium at time t;

[0011]

[0012] In the formula, P x,y,z,t is the pore fluid pressure when the fluid pressure of the reservoir grid cell numbered x, y, z is in equilibrium at time t, P x,y,z,0 is the initial fluid pressure of the reservoir grid cell numbered x, y, z, P z,t is the wellbore fluid pressure corresponding to the depth of the reservoir grid cell numbered z in the vertical direction at time t in the shale oil reservoir section, P x,y,z,d is the displacement pressure gradient of the reservoir grid cell numbered x, y, z. x, y, and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis, and z-axis in the three-dimensional space respectively. ox, oy, and oz are all integers, which are the numbers of the reservoir grid cells where the wellbore closer to the evaluated reservoir grid cell is located on the x-axis, y-axis, and z-axis respectively. i, j, and k are all integers, and their ranges are ox - x, oy - y, and oz - z respectively. L is the length of each reservoir grid cell. The unit of pressure is MPa, and the unit of the length of the reservoir grid cell is m;

[0013] Step 3: According to the characteristics of the temperature field, fluid pressure field, etc. of the in-situ heated shale oil reservoir, obtain the temperature T x,y,z,t of each reservoir grid cell at heating time t, and determine the porosity Ф x,y,z,t , oil saturation S o,x,y,z,t , gas saturation S g,x,y,z,t , water saturation S w,x,y,z,t , and dissolved gas volume V dis-g,x,y,z,t of each reservoir grid cell at time t;

[0014] Ф x,y,z,t = Ф x,y,z,0 – β r,x,y,z,t(T x,y,z,t –T x,y,z,0 )(1–Ф x,y,z,0 )

[0015] S o,x,y,z,t =S’ o,x,y,z,t / (S’ o,x,y,z,t +S’ g,x,y,z,t +S’ w,x,y,z,t )

[0016] S g,x,y,z,t =S’ g,x,y,z,t / (S’ o,x,y,z,t +S’ g,x,y,z,t +S’ w,x,y,z,t )

[0017] S w,x,y,z,t =S’ w,x,y,z,t / (S’ o,x,y,z,t +S’ g,x,y,z,t +S’ w,x,y,z,t )

[0018] V dis-g,x,y,z,t =2.4ρ rel-g (P x,y,z,0 ﹒exp(1.77 / ρ oil –0.001638T x,y,z,t –1.67)) 1.205

[0019] Wherein,

[0020] S’ o,x,y,z,t =S o,x,y,z,0 (1+β o,x,y,z,t (T x,y,z,t –T x,y,z,0 ))

[0021] S’ g,x,y,z,t =S g,x,y,z,0 (1+β g,x,y,z,t (T x,y,z,t –T x,y,z,0 ))+ΔV dis-g,x,y,z,t / Ф x,y,z,t

[0022] S’ w,x,y,z,t =S w,x,y,z,0 (1+β w,x,y,z,t (T x,y,z,t –T x,y,z,0 ))

[0023] ΔV dis-g,x,y,z,t =(V dis-g,x,y,z,0 –V dis-g,x,y,z,t )Ф x,y,z,t S o,x,y,z,t P c Tx,y,z,t / P x,y,z,t / T c

[0024] In the formula, Ф x,y,z,t and Ф x,y,z,0 are the porosities of the reservoir grid cells at time t and initially, respectively, and β r,x,y,z,t is the volume thermal expansion coefficient of the rock skeleton of the reservoir grid cell numbered x, y, z at time t, and β o,x,y,z,t , β g,x,y,z,t and β w,x,y,z,t are the volume thermal expansion coefficients of oil, gas and water in the reservoir grid cells numbered x, y, z at time t, respectively. T x,y,z,t and T x,y,z,0 are the temperatures of the reservoir grid cells numbered x, y, z at time t and initially, respectively. S o,x,y,z,t , S g,x,y,z,t and S w,x,y,z,t are the oil saturation, gas saturation and water saturation in the reservoir grid cells numbered x, y, z at time t, respectively. S’ o,x,y,z,t , S’ g,x,y,z,t and S’ w,x,y,z,t are the oil volume factor, gas volume factor and water volume factor in the reservoir grid cells numbered x, y, z at time t, respectively. S o,x,y,z,0 , S g,x,y,z,0 and S w,x,y,z,0 are the initial oil saturation, initial gas saturation and initial water saturation in the reservoir grid cells numbered x, y, z, respectively. V dis-g,x,y,z,0 and V dis-g,x,y,z,t are the volumes of the original natural gas dissolved in the crude oil in the reservoir grid cells numbered x, y, z at the initial time and at time t, respectively, under standard conditions. ΔV dis-g,x,y,z is the volume of the natural gas that has changed from the dissolved state to the free state in the crude oil in the reservoir grid cells numbered x, y, z from the initial time to time t, under the reservoir temperature and pressure conditions. ρ rel-g and ρ oil are the relative density of natural gas and the relative density of crude oil, respectively. P c and T c are the pressure and temperature under standard conditions, respectively. P x,y,z,t is the pore fluid pressure at fluid pressure equilibrium in the reservoir grid cells numbered x, y, z at time t. x, y and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis and z-axis in the three-dimensional space, respectively. The unit of porosity is %, the unit of volume thermal expansion coefficient is K -1 , the unit of temperature is K, the unit of pressure is MPa, the unit of saturation is %, the unit of volume factor is %, and the unit of natural gas volume is m 3 / m3 , i.e., m 3 (natural gas) / m 3 (reservoir). The relative density of natural gas and the relative density of crude oil are dimensionless parameters, and the unit of pressure is MPa;

[0025] Step 4: Based on the instantaneous fluid pressure and equilibrium fluid pressure of each reservoir three-dimensional grid cell, combined with the oil, gas, and water saturations and reservoir temperature, determine the oil, gas, and water production and utilization rates per unit volume of the reservoir in each reservoir grid cell at time t for in-situ electric field heating and upgrading to extract shale oil;

[0026] ΔQ o,x,y,z,t = Q o,x,y,z,0 - Q o,x,y,z,t

[0027] = Ф x,y,z,0 S o,x,y,z,0 (1 + β o,x,y,z,0 (T x,y,z,0 - T c )) - Ф x,y,z,t S o,x,y,z,t (1 + β o,x,y,z,t (T x,y,z,t - T c ))

[0028] ΔQ g,x,y,z,t = Q g,x,y,z,0 - Q g,x,y,z,t

[0029] =(Ф x,y,z,0 S g,x,y,z,0 (1 + β g,x,y,z,0 (T x,y,z,0 - T c )) + V dis-g,x,y,z,0 ) – (Ф x,y,z,t S g,x,y,z,t (1 + β g,x,y,z,t (T x,y,z,t - T c )) + V dis-g,x,y,z,t )

[0030] ΔQ w,x,y,z,t = Q w,x,y,z,0 - Q w,x,y,z,t

[0031] = Ф x,y,z,0 S w,x,y,z,0 (1 + β w,x,y,z,0 (T x,y,z,0 - T c )) - Ф x,y,z,t S w,x,y,z,t (1 + β w,x,y,z,t (T x,y,z,t - T c ))

[0032] E o,x,y,z,t = ΔQ o,x,y,z,t / (Ф x,y,z,0 S o,x,y,z,0 (1 + β o,x,y,z,0 (T x,y,z,0 - T c )))

[0033] E g,x,y,z,t = ΔQ g,x,y,z,t / (Ф x,y,z,0 S g,x,y,z,0 (1 + β g,x,y,z,0 (T x,y,z,0 - T c )) + V dis-g,x,y,z,0 )

[0034] E w,x,y,z,t = ΔQ w,x,y,z,t / (Ф x,y,z,0 S w,x,y,z,0 (1 + β w,x,y,z,0 (T x,y,z,0 - T c )))

[0035] In the formula, ΔQ o,x,y,z,t , ΔQ g,x,y,z,t and ΔQ w,x,y,z,t are respectively the oil, gas, and water production amounts per unit volume of the reservoir in the reservoir grid cells numbered x, y, and z at time t. E o , E g and E w are respectively the oil, gas, and water utilization rates per unit volume of the reservoir in the reservoir grid cells numbered x, y, and z at time t. Q o,x,y,z,0 , Q g,x,y,z,0 and Q w,x,y,z,0 are respectively the initial oil content, initial gas content, and initial water content per unit volume of the reservoir in the reservoir grid cells numbered x, y, and z. Q o,x,y,z,t , Q g,x,y,z,t and Q w,x,y,z,t are respectively the oil, gas, and water contents per unit volume of the reservoir in the reservoir grid cells numbered x, y, and z at time t. S o,x,y,z,0 , S g,x,y,z,0 and S w,x,y,z,0 are respectively the initial oil saturation, initial gas saturation, and initial water saturation in the reservoir grid cells numbered x, y, and z. β o,x,y,z,0 , β g,x,y,z,0 and β w,x,y,z,0 are respectively the initial oil thermal expansion coefficient, initial gas thermal expansion coefficient, and initial water thermal expansion coefficient in the reservoir grid cells numbered x, y, and z. T x,y,z,0 and T care the initial temperature and the temperature under standard conditions of the reservoir grid cells numbered x, y, and z, respectively, V dis-g,x,y,z,0 and V dis-g,x,y,z,t are the volumes of the original natural gas dissolved in the crude oil in the reservoir grid cells numbered x, y, and z at the initial time and at time t under standard conditions, respectively. x, y, and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis, and z-axis in the three-dimensional space, respectively. The units of the oil, gas, and water production volumes are all m 3 , and the units of the oil, gas, and water utilization rates are all %, and the units of the oil, gas, and water contents are all m 3 , the units of the oil, gas, and water saturations are all %, and the units of the oil, gas, and water thermal expansion coefficients are all K -1 , the unit of temperature is K, and the unit of the volume of the original natural gas dissolved in the crude oil under standard conditions is m 3 / m 3 , that is, m 3 (natural gas) / m 3 (reservoir). x, y, and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis, and z-axis in the three-dimensional space, respectively.

[0036] Advantages of the present invention: A method for evaluating the oil utilization rate during in-situ heating and upgrading for shale oil production according to the present invention is easy to operate and implement. This method can quantitatively evaluate the reservoir oil and gas utilization characteristics during in-situ heating and upgrading for shale oil production, provide important technical parameters for in-situ heating and upgrading for shale oil production, and provide support for breaking through the technical bottleneck of shale oil production. Description of the Drawings

[0037] Figure 1 is a schematic flow chart of the method for evaluating the oil utilization rate during in-situ heating and upgrading for shale oil production according to the present invention.

[0038] Figure 2 is a layout plan of horizontal wells for in-situ heating and upgrading for shale oil production using an electric field.

[0039] Figure 3 is the pressure field at equilibrium of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ heating and upgrading for shale oil production using an electric field.

[0040] Figure 4 is the porosity characteristic of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ heating and upgrading for shale oil production using an electric field.

[0041] Figure 5 is the oil saturation characteristic of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ heating and upgrading for shale oil production using an electric field.

[0042] Figure 6It is the gas saturation characteristics of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production.

[0043] Figure 7 It is the water saturation characteristics of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production.

[0044] Figure 8 It is the oil recovery rate characteristics of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production.

[0045] Figure 9 It is the gas recovery rate characteristics of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production.

[0046] Figure 10 It is the water recovery rate characteristics of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production. Detailed implementation manners

[0047] Example 1: As Figure 1 described, a method for evaluating the crude oil recovery rate during in-situ heating and upgrading for shale oil production comprises the following steps:

[0048] Step 1: Under the Figure 2 well layout plan, construct a three-dimensional grid model of the shale oil reservoir between two horizontal wells. The length, width, and height of each three-dimensional grid unit are all 5 m. The length of the three-dimensional grid model is equal to the length of the horizontal section of the horizontal well, the width is not less than twice the distance between the horizontal sections of the two wells, the distance between the horizontal sections of the two wells is 60 m, and the height is equal to the thickness of the shale oil reservoir. The length, width, and height of this three-dimensional grid model are 1000 m, 200 m, and 200 m respectively, and determine the initial temperature T x,y,z,0 to be 363.15 K, the initial pressure P x,y,z,0 to be 30 MPa, the initial porosity Ф x,y,z,0 to be 2%, the initial oil saturation S o,x,y,z,0 to be 50%, the initial gas saturation S g,x,y,z,0 to be 0%, the initial water saturation S w,x,y,z,0 to be 50%, the initial dissolved natural gas volume of crude oil V dis-g,x,y,z,0 to be 50 m 3 / m 3 , the initial volumetric thermal expansion coefficient of the rock skeleton β r,x,y,z,0 to be 3.0×10 -7 K -1 , the initial thermal expansion coefficient of crude oil β o,x,y,z,0 to be 2.0×10 -4 K-1 、The initial natural gas thermal expansion coefficient β g,x,y,z,0 is 2.0×10 -3 K -1 and the initial water thermal expansion coefficient β w,x,y,z,0 is 3.0×10 -4 K -1 , where x, y, and z are all integers, which are the numbers of the grid cell on the x-axis, y-axis, and z-axis in the three-dimensional space respectively. The unit of temperature is K, the unit of pressure is MPa, the unit of porosity is %, the units of oil saturation, gas saturation, and water saturation are %, and the unit of the dissolved natural gas volume in crude oil is m 3 / m 3 . The unit of the volume thermal expansion coefficient is K -1 .

[0049] Step 2: The displacement pressure gradient P x,y,z,d of the reservoir is 0.2 MPa / m and the wellbore fluid pressure P z,t of the shale oil layer section at time t is 20 MPa. Determine the pore fluid pressure P x,y,z,t at fluid pressure equilibrium of each three-dimensional grid cell of the reservoir at time t. Figure 3 is the pressure field at equilibrium of the two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production.

[0050]

[0051] In the formula, P x,y,z,t is the pore fluid pressure at fluid pressure equilibrium of the reservoir grid cell numbered x, y, z at time t, P x,y,z,0 is the initial fluid pressure of the reservoir grid cell numbered x, y, z, P z,t is the wellbore fluid pressure of the shale oil layer section corresponding to the depth of the reservoir grid cell numbered z vertically at time t, P x,y,z,d is the displacement pressure gradient of the reservoir grid cell numbered x, y, z. x, y, and z are all integers, which are the numbers of the grid cell on the x-axis, y-axis, and z-axis in the three-dimensional space respectively. ox, oy, and oz are all integers, which are the numbers of the reservoir grid cell where the wellbore closer to the evaluated reservoir grid cell is located on the x-axis, y-axis, and z-axis respectively. i, j, and k are all integers, and their ranges are ox - x, oy - y, and oz - z respectively. L is the length of each reservoir grid cell. The unit of pressure is MPa, and the unit of the length of the reservoir grid cell is m;

[0052] Step 3: According to the characteristics of the temperature field, fluid pressure field, etc. of the in-situ heated shale oil reservoir, obtain the temperature T x,y,z,t of each reservoir grid cell at heating time t, and determine the porosity Ф x,y,z,t, oil saturation \(S\) o,x,y,z,t , gas saturation \(S\) g,x,y,z,t , water saturation \(S\) w,x,y,z,t , dissolved gas volume \(V\) dis-g,x,y,z,t . Figure 4 is the porosity characteristic of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production. Figure 5 is the oil saturation characteristic of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production. Figure 6 is the gas saturation characteristic of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production. Figure 7 is the water saturation characteristic of a two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production.

[0053] \(\varPhi\) x,y,z,t \(=\varPhi\) x,y,z,0 –\(\beta\) r,x,y,z,t (\(T\) x,y,z,t –\(T\) x,y,z,0 )(1–\(\varPhi\) x,y,z,0 )

[0054] \(S\) o,x,y,z,t \(=S'\) o,x,y,z,t / ( \(S'\) o,x,y,z,t +\(S'\) g,x,y,z,t +\(S'\) w,x,y,z,t )

[0055] \(S\) g,x,y,z,t \(=S'\) g,x,y,z,t / ( \(S'\) o,x,y,z,t +\(S'\) g,x,y,z,t +\(S'\) w,x,y,z,t )

[0056] \(S\) w,x,y,z,t \(=S'\) w,x,y,z,t / ( \(S'\) o,x,y,z,t +\(S'\) g,x,y,z,t +\(S'\) w,x,y,z,t )

[0057] \(V\) dis-g,x,y,z,t \(=2.4\rho\) rel-g ( \(P\) x,y,z,0 ﹒exp(1.77 / \(\rho\) oil –0.001638\(T\) x,y,z,t –1.67)) 1.205

[0058] Among them,

[0059] \(S'\) o,x,y,z,t \(=S\) o,x,y,z,0 (1+\(\beta\) o,x,y,z,t(T x,y,z,t –T x,y,z,0 ))

[0060] S’ g,x,y,z,t =S g,x,y,z,0 (1 + β g,x,y,z,t (T x,y,z,t –T x,y,z,0 )) + ΔV dis-g,x,y,z,t / Ф x,y,z,t

[0061] S’ w,x,y,z,t =S w,x,y,z,0 (1 + β w,x,y,z,t (T x,y,z,t –T x,y,z,0 ))

[0062] ΔV dis-g,x,y,z,t =(V dis-g,x,y,z,0 –V dis-g,x,y,z,t ) Ф x,y,z,t S o,x,y,z,t P c T x,y,z,t / P x,y,z,t / T c

[0063] Where Ф x,y,z,t and Ф x,y,z,0 are the porosities of the reservoir grid cells at time t and initially, respectively, β r,x,y,z,t is the coefficient of volume thermal expansion of the rock skeleton of the reservoir grid cell numbered x, y, z at time t, β o,x,y,z,t , β g,x,y,z,t and β w,x,y,z,t are the coefficients of volume thermal expansion of oil, gas, and water in the reservoir grid cells numbered x, y, z at time t, respectively, T x,y,z,t and T x,y,z,0 are the temperatures of the reservoir grid cells numbered x, y, z at time t and initially, respectively, S o,x,y,z,t , S g,x,y,z,t and S w,x,y,z,t are the oil saturation, gas saturation, and water saturation in the reservoir grid cells numbered x, y, z at time t, respectively, S’ o,x,y,z,t , S’ g,x,y,z,t and S’ w,x,y,z,t are the oil formation volume factor, gas formation volume factor, and water formation volume factor in the reservoir grid cells numbered x, y, z at time t, respectively, S o,x,y,z,0 , S g,x,y,z,0 and S w,x,y,z,0 are the initial oil saturation, initial gas saturation, and initial water saturation in the reservoir grid cells numbered x, y, z, respectively, V dis-g,x,y,z,0 and V dis-g,x,y,z,tare the volumes of the original natural gas dissolved in the crude oil in the reservoir grid cells numbered x, y, and z at the initial time and at time t under standard conditions, respectively, ΔV dis-g,x,y,z is the volume of the natural gas that has changed from the dissolved state to the free state in the crude oil in the reservoir grid cells numbered x, y, and z from the initial time to time t under the reservoir temperature and pressure conditions, ρ rel-g and ρ oil are the relative density of natural gas and the relative density of crude oil, respectively, P c and T c are the pressure and temperature under standard conditions, respectively, P x,y,z,t is the pore fluid pressure at fluid pressure equilibrium in the reservoir grid cells numbered x, y, and z at time t. x, y, and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis, and z-axis in the three-dimensional space, respectively. The unit of porosity is %, and the unit of the volume thermal expansion coefficient is K -1 , the unit of temperature is K, the unit of pressure is MPa, the unit of saturation is %, the unit of the volume coefficient is %, and the unit of the natural gas volume is m 3 / m 3 , that is, m 3 (natural gas) / m 3 (reservoir). The relative density of natural gas and the relative density of crude oil are dimensionless parameters, and the unit of pressure is MPa;

[0064] Step 4: Based on the instantaneous fluid pressure and equilibrium fluid pressure of each reservoir three-dimensional grid cell, combined with the oil, gas, and water saturations and reservoir temperature, determine the oil, gas, and water production and utilization rates per unit volume of the reservoir in each reservoir grid cell after 1 hour of in-situ electric field heating and upgrading for shale oil production. Figure 8 is the oil utilization rate characteristic of the two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production. Figure 9 is the gas utilization rate characteristic of the two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production. Figure 10 is the water utilization rate characteristic of the two-dimensional reservoir grid profile perpendicular to the projection of the horizontal well section plane after 1 hour of in-situ electric field heating and upgrading for shale oil production.

[0065] ΔQ o,x,y,z,t =Q o,x,y,z,0 -Q o,x,y,z,t

[0066] =Ф x,y,z,0 S o,x,y,z,0 (1 + β o,x,y,z,0 (T x,y,z,0 -T c )) - Ф x,y,z,t S o,x,y,z,t (1 + β o,x,y,z,t (Tx,y,z,t -T c ))

[0067] ΔQ g,x,y,z,t =Q g,x,y,z,0 -Q g,x,y,z,t

[0068] =(Ф x,y,z,0 S g,x,y,z,0 (1 + β g,x,y,z,0 (T x,y,z,0 -T c )) + V dis-g,x,y,z,0 ) – (Ф x,y,z,t S g,x,y,z,t (1 + β g,x,y,z,t (T x,y,z,t -T c )) + V dis-g,x,y,z,t )

[0069] ΔQ w,x,y,z,t =Q w,x,y,z,0 -Q w,x,y,z,t

[0070] =Ф x,y,z,0 S w,x,y,z,0 (1 + β w,x,y,z,0 (T x,y,z,0 -T c )) - Ф x,y,z,t S w,x,y,z,t (1 + β w,x,y,z,t (T x,y,z,t -T c ))

[0071] E o,x,y,z,t =ΔQ o,x,y,z,t / (Ф x,y,z,0 S o,x,y,z,0 (1 + β o,x,y,z,0 (T x,y,z,0 -T c )))

[0072] E g,x,y,z,t =ΔQ g,x,y,z,t / (Ф x,y,z,0 S g,x,y,z,0 (1 + β g,x,y,z,0 (T x,y,z,0 -T c )) + V dis-g,x,y,z,0 )

[0073] E w,x,y,z,t =ΔQ w,x,y,z,t / (Ф x,y,z,0 S w,x,y,z,0 (1 + β w,x,y,z,0 (T x,y,z,0 -T c )))

[0074] In the formula, ΔQ o,x,y,z,t , ΔQ g,x,y,z,t and ΔQ w,x,y,z,t are respectively the oil, gas, and water production amounts per unit volume of the reservoir in the reservoir grid cells numbered x, y, and z at time t. E o , E g and E w are respectively the oil, gas, and water utilization rates per unit volume of the reservoir in the reservoir grid cells numbered x, y, and z at time t. Q o,x,y,z,0 , Q g,x,y,z,0 and Q w,x,y,z,0 are respectively the initial oil content, initial gas content, and initial water content per unit volume of the reservoir in the reservoir grid cells numbered x, y, and z. Q o,x,y,z,t , Q g,x,y,z,t and Q w,x,y,z,t are respectively the oil, gas, and water contents per unit volume of the reservoir in the reservoir grid cells numbered x, y, and z at time t. S o,x,y,z,0 , S g,x,y,z,0 and S w,x,y,z,0 are respectively the initial oil saturation, initial gas saturation, and initial water saturation in the reservoir grid cells numbered x, y, and z. β o,x,y,z,0 , β g,x,y,z,0 and β w,x,y,z,0 are respectively the initial oil thermal expansion coefficient, initial gas thermal expansion coefficient, and initial water thermal expansion coefficient in the reservoir grid cells numbered x, y, and z. T x,y,z,0 and T c are respectively the initial temperature and the temperature under standard conditions in the reservoir grid cells numbered x, y, and z. V dis-g,x,y,z,0 and V dis-g,x,y,z,t are respectively the volume of the original natural gas dissolved in the crude oil in the reservoir grid cells numbered x, y, and z at the initial moment and at time t under standard conditions. x, y, and z are all integers, which are respectively the numbers of the grid cells on the x-axis, y-axis, and z-axis in the three-dimensional space. The units of the oil, gas, and water production amounts are all m 3 , the units of the oil, gas, and water utilization rates are all %, the units of the oil, gas, and water contents are all m 3 , the units of the oil, gas, and water saturations are all %, the units of the oil, gas, and water thermal expansion coefficients are all K -1 , the unit of temperature is K, and the unit of the volume of the original natural gas dissolved in the crude oil under standard conditions is m 3 / m 3 , that is, m 3 (natural gas) / m 3 (reservoir). x, y, and z are all integers, which are respectively the numbers of the grid cells on the x-axis, y-axis, and z-axis in the three-dimensional space.

Claims

1. A method for evaluating the crude oil utilization rate when shale oil is mined by in-situ heating and reforming, characterized in that: Step 1: Construct a three-dimensional grid model of the shale oil reservoir between two horizontal wells. The length, width, and height of each reservoir grid unit are L. Determine the initial temperature T of each reservoir grid unit. x,y,z,0 , initial fluid pressure P x,y,z,0 , initial porosity Ф x,y,z,0 , initial oil saturation S o,x,y,z,0 , initial gas saturation S g,x,y,z,0 , initial water saturation S w,x,y,z,0 , initial dissolved gas volume V dis-g,x,y,z,0 , initial rock skeleton volume thermal expansion coefficient β r,x,y,z,0 , initial crude oil thermal expansion coefficient β o,x,y,z,0 , initial natural gas thermal expansion coefficient β g,x,y,z,0 and the initial water thermal expansion coefficient β w,x,y,z,0 , x, y and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis and z-axis in three-dimensional space respectively. The length, width and height of the reservoir grid cell are all in m, the unit of temperature is K, the unit of pressure is MPa, the unit of porosity is %, the unit of oil saturation, gas saturation and water saturation is %, and the unit of natural gas dissolved in crude oil is m 3 / m 3 The unit of volume thermal expansion coefficient is K -1 , x, y and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis and z-axis in three-dimensional space respectively; Step 2: Based on the reservoir displacement pressure gradient P x,y,z,d and the wellbore fluid pressure P of the shale oil layer at time t z,t , determine the pore fluid pressure P of each reservoir three-dimensional grid unit when the fluid pressure is balanced at time t x,y,z,t ; Where P x,y,z,t is the pore fluid pressure of the reservoir grid cells numbered x, y, and z when the fluid pressure is balanced at time t, P x,y,z,0 is the initial fluid pressure of the reservoir grid cells numbered x, y, and z, P z,t is the wellbore fluid pressure of the shale oil layer corresponding to the depth of the reservoir grid unit with vertical number z at time t, P x,y,z,d is the displacement pressure gradient of the reservoir grid cells numbered x, y, and z, where x, y, and z are all integers, and are the numbers of the grid cells on the x, y, and z axes in three-dimensional space, respectively; ox, oy, and oz are all integers, and are the numbers of the reservoir grid cells where the wellbore is located that is closer to the evaluated reservoir grid cell on the x, y, and z axes, respectively; i, j, and k are all integers, and their ranges are ox-x, oy-y, and oz-z, respectively; L is the length of each reservoir grid cell, the unit of pressure is MPa, and the unit of the length of the reservoir grid cell is m; Step 3: Based on the temperature field, fluid pressure field and other characteristics of the in-situ heated shale oil reservoir, obtain the temperature T of each reservoir grid unit when the heating time is t x,y,z,t , determine the porosity Ф of each reservoir grid unit at time t x,y,z,t , oil saturation S o,x,y,z,t , gas saturation S g,x,y,z,t , water saturation S w,x,y,z,t , dissolved gas volume V dis-g,x,y,z,t ; F x,y,z,t =F x,y,z,0 –β r,x,y,z,t (T x,y,z,t –T x,y,z,0 )(1–F x,y,z,0 ) S o,x,y,z,t =S’ o,x,y,z,t / (S’ o,x,y,z,t +S’ g,x,y,z,t +S’ w,x,y,z,t ) S g,x,y,z,t =S’ g,x,y,z,t / (S’ o,x,y,z,t +S’ g,x,y,z,t +S’ w,x,y,z,t ) S w,x,y,z,t =S’ w,x,y,z,t / (S’ o,x,y,z,t +S’ g,x,y,z,t +S’ w,x,y,z,t ) V dis-g,x,y,z,t =2.4p rel-g (P x,y,z,t ﹒exp(1.77 / ρ oil –0.001638T x,y,z,t –1.67)) 1.205 in, S’ o,x,y,z,t =S o,x,y,z,0 (1+β o,x,y,z,t (T x,y,z,t –T x,y,z,0 )) S' g,x,y,z,t =S g,x,y,z,0 (1+b g,x,y,z,t (T x,y,z,t –T x,y,z,0 ))+ΔV dis-g,x,y,z,t / F x,y,z,t S’ w,x,y,z,t =S w,x,y,z,0 (1+β w,x,y,z,t (T x,y,z,t –T x,y,z,0 )) ΔV dis-g,x,y,z,t =(V dis-g,x,y,z,0 –V dis-g,x,y,z,t )Ф x,y,z,t S o,x,y,z,t P c T x,y,z,t / P x,y,z,t / T c In the formula, Ф x,y,z,t and Φ x,y,z,0 are the porosity of the reservoir grid unit at time t and at the initial time, β r,x,y,z,t is the thermal expansion coefficient of the rock skeleton volume of the reservoir grid unit numbered x, y, z at time t, β o,x,y,z,t , β g,x,y,z,t and β w,x,y,z,t are the thermal expansion coefficients of oil, gas and water in the reservoir grid cells numbered x, y and z at time t, respectively. x,y,z,t and T x,y,z,0 are the temperatures of the reservoir grid cells numbered x, y, and z at time t and at the initial time, respectively, S o,x,y,z,t , S g,x,y,z,t and S w,x,y,z,t are the oil saturation, gas saturation and water saturation in the reservoir grid cells numbered x, y and z at time t, respectively, S' o,x,y,z,t , S' g,x,y,z,t and S' w,x,y,z,t are the oil volume coefficient, gas volume coefficient and water volume coefficient in the reservoir grid cells numbered x, y and z at time t, respectively. o,x,y,z,0 , S g,x,y,z,0 and S w,x,y,z,0 are the initial oil saturation, initial gas saturation and initial water saturation in the reservoir grid cells numbered x, y and z respectively, V dis-g,x,y,z,0 and V dis-g,x,y,z,t are the volumes of the original natural gas dissolved in the crude oil in the reservoir grid cells numbered x, y, and z at the initial moment and time t under standard conditions, ΔV dis-g,x,y,z is the volume of natural gas that is converted from dissolved state to free state in the crude oil of the reservoir grid unit numbered x, y, z under the reservoir temperature and pressure conditions from the initial to time t, ρ rel-g and ρ oil are the relative density of natural gas and crude oil, P c and T c The pressure and temperature under standard conditions, P x,y,z,t is the pore fluid pressure of the reservoir grid unit numbered x, y, z when the fluid pressure is balanced at time t. x, y, and z are all integers, which are the numbers of the grid unit on the x-axis, y-axis, and z-axis in three-dimensional space, respectively. The unit of porosity is %, and the unit of volume thermal expansion coefficient is K. -1 The unit of temperature is K, the unit of pressure is MPa, the unit of saturation is %, the unit of volume coefficient is %, and the unit of natural gas volume is m 3 / m 3 , that is, m 3 (Natural gas) / m 3 (reservoir), the relative density of natural gas and crude oil are dimensionless parameters, and the unit of pressure is MPa; Step 4: According to the instantaneous fluid pressure and equilibrium fluid pressure of each reservoir three-dimensional grid unit, combined with the oil, gas, water saturation and reservoir temperature, determine the oil, gas, and water production and utilization rate of each unit volume of the reservoir in each reservoir grid unit when the time of electric field in-situ heating reforming and exploitation of shale oil is t; ΔQ o,x,y,z,t =Q o,x,y,z,0 -Q o,x,y,z,t =Ф x,y,z,0 S o,x,y,z,0 (1+β o,x,y,z,0 (T x,y,z,0 -T c ))-Ф x,y,z,t S o,x,y,z,t (1+β o,x,y,z,t (T x,y,z,t -T c )) ΔQ g,x,y,z,t =Q g,x,y,z,0 -Q g,x,y,z,t =(Ф x,y,z,0 S g,x,y,z,0 (1+β g,x,y,z,0 (T x,y,z,0 -T c ))+V dis-g,x,y,z,0 )–(Ф x,y,z,t S g,x,y,z,t (1+β g,x,y,z,t (T x,y,z,t -T c ))+V dis-g,x,y,z,t ) ΔQ w,x,y,z,t =Q w,x,y,z,0 -Q w,x,y,z,t =Ф x,y,z,0 S w,x,y,z,0 (1+β w,x,y,z,0 (T x,y,z,0 -T c ))-Ф x,y,z,t S w,x,y,z,t (1+β w,x,y,z,t (T x,y,z,t -T c )) E o,x,y,z,t =ΔQ o,x,y,z,t / (Ф x,y,z,0 S o,x,y,z,0 (1+β o,x,y,z,0 (T x,y,z,0 -T c ))) E g,x,y,z,t =ΔQ g,x,y,z,t / (Ф x,y,z,0 S g,x,y,z,0 (1+β g,x,y,z,0 (T x,y,z,0 -T c ))+V dis-g,x,y,z,0 ) E w,x,y,z,t =ΔQ w,x,y,z,t / (Ф x,y,z,0 S w,x,y,z,0 (1+β w,x,y,z,0 (T x,y,z,0 -T c ))) Where ΔQ o,x,y,z,t , ΔQ g,x,y,z,t and ΔQ w,x,y,z,t are the oil, gas and water production per unit volume of the reservoir in the reservoir grid cells numbered x, y and z at time t, respectively. o 、E g and E w are the oil, gas and water utilization rates per unit volume of the reservoir in the reservoir grid cells numbered x, y and z at time t, respectively, and Q o,x,y,z,0 , Q g,x,y,z,0 and Q w,x,y,z,0 are the initial oil content, initial gas content, and initial water content per unit volume of the reservoir in the reservoir grid cells numbered x, y, and z, respectively. Q o,x,y,z,t , Q g,x,y,z,t and Q w,x,y,z,t are the oil, gas and water contents per unit volume of the reservoir in the reservoir grid cells numbered x, y and z at time t, respectively. o,x,y,z,0 , S g,x,y,z,0 and S w,x,y,z,0 are the initial oil saturation, initial gas saturation and initial water saturation of the reservoir grid cells numbered x, y and z, respectively, and β o,x,y,z,0 , β g,x,y,z,0 and β w,x,y,z,0 are the initial oil thermal expansion coefficient, initial gas thermal expansion coefficient and initial water thermal expansion coefficient of the reservoir grid cells numbered x, y and z, respectively. x,y,z,0 and T c are the initial temperature and standard temperature of the reservoir grid cells numbered x, y, and z, respectively, V dis-g,x,y,z,0 and V dis-g,x,y,z,t are the volumes of the original natural gas dissolved in the crude oil in the reservoir grid units numbered x, y, and z at the initial moment and time t, respectively. x, y, and z are all integers, which are the numbers of the grid units on the x-axis, y-axis, and z-axis in three-dimensional space, respectively. The units of oil, gas, and water production are all m 3 The unit of oil, gas and water utilization rate is %, and the unit of oil, gas and water content is m 3 The unit of oil, gas and water saturation is %, and the unit of thermal expansion coefficient of oil, gas and water is K. -1 The unit of temperature is K, and the unit of volume of the original natural gas dissolved in crude oil under standard conditions is m 3 / m 3 , that is, m 3 (Natural gas) / m 3 (reservoir), x, y and z are all integers, which are the numbers of the grid cells on the x-axis, y-axis and z-axis in the three-dimensional space respectively.

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