RU2023145C1 - Method for heat generation at field with residual oil - Google Patents

Abstract

FIELD: mining, processing of oil at its occurrence to produce power energy with use of steam generated in underground steam generator. SUBSTANCE: injected into reservoir is excessive amount of air for complete oxidation of oil and required amount of water in compliance with respective mathematical expression. EFFECT: higher efficiency in use of nonconditional oil reservoirs by power steam production.

Description

 The invention relates to mining, in particular to the utilization of the energy potential of substandard oil reserves.

There is a method of producing steam at a coal bed, developed by the National Institute of Mining in Belgium (E.V. Kreinin et al. Underground coal gasification. - M .; Nedra, 1982, 109-115 pp.). This method involves the drilling of a system of wells — air-injection and gas-vapor producing, their failure, ignition, underground production of low-calorie generator gas, the removal of this gas from the bottom to the Earth’s surface with an uninsulated central pipe elevator, the injection of water into the annulus of the well, and the extraction of water vapor from the annulus temperature 220-250 ^{° C} at the wellhead, and finally heat recovery steam and lean gas to the surface. At the same time, pyrolysis of the surrounding coal seams, if any, is also provided.

The main disadvantages of this known method are:
overheating of the casing pipe downhole high temperature steam to 220-250 ^{° C,} due to the high thermal conductivity losses, and leads to thermal stresses between the pipe and the cement sheath, and finally to the loss of integrity of the wellbore.

 Low efficiency of heat transfer from the gas stream in the central pipes through the walls of these pipes to the steam stream in the annulus, which significantly limits the specific power of the useful heat transfer and leads to large dimensions of the heat exchanger; the remoteness of the underground gas generator in the coal seam from vaporization in the wellbore, which excludes the possibility of operational control of the combustion process as a whole and coordination of the operating modes of individual vaporization units; as a result of these shortcomings, the structure’s operating life is low, the well’s reliability is low, there is no possibility to control the underground process, hence the extremely low efficiency of the steam formation process as a whole.

 A known method of producing steam using geothermal technology (Mangushev K. I. Problems of the development of gas energy in the world. - M.; Nauka, 1981, pp. 85-91, Fig. 5.1-5.2), including drilling a system of wells, the formation of a heat exchanger using nuclear explosions in the form of a mass of a fragmented array, supply of a cold coolant through the annular space of a coaxial pipe system to the upper part of the underground heat exchanger and steam extraction. The main disadvantages of this method are: the need for expensive nuclear explosions; carrying out a number of additional special measures before a nuclear explosion, including anti-seismic and protective measures against radiation; the process of heat and mass transfer is ultimately difficult to control and uncontrollable.

There is also a method of producing a gas-vapor mixture during underground gasification of coal (autosw. N 941587), which includes the formation of a well system, gas supply towards the face of the fire, and discharge of the gas-vapor mixture obtained by supplying cold water to the gas-vented space. The main disadvantages of this method are:
low efficiency of coal processing, since the distance between the face of the fire and the exhaust well is constantly increasing, which leads to both heat loss and gas leakage, which can reach 15% or more;
the need for additional well drilling due to a change in the location of the degassed space, where cold water is provided;
technical difficulties in maintaining technological interrelated parameters - critical pressure of water and supplied air and water in the fire face.

The closest in technical essence and the achieved result to the proposed method is a method of oil production using in-situ combustion, designed to heat the oil reservoir in order to displace from the reservoir [1]. The essence of this method is as follows. Initially, the conditions necessary for initiating and forming a stable combustion front are created in the bottomhole zone of the incendiary well. After the formation of the combustion front, an oxidizing agent (air, oxygen-enriched air or an oxygen-containing gas mixture, etc.) is injected into the formation from the surface in an amount necessary to maintain the thermochemical reaction and to move the combustion front through the formation. At the same time, part of the reservoir oil (up to 15%) burns out, and the heat generated, acting on the reservoir, contributes to the displacement of oil from the reservoir. Process products (oil, combustion gases, hydrocarbon gases, water) are extracted through production wells. The main disadvantages of this method are:
up to 50% of the oil remains in the bowels, and up to 80-85% of its geological reserves in the layers of high-viscosity oil;
low efficiency of recovery of heavy oil, reaching 10-20%;
limited supply of oxidizer, due to the speed of movement of the front of highly viscous oil in the reservoir;
the difficulty of controlling the combustion zone, as when oil is extracted by the in situ combustion method, it is necessary to burn only a certain part of the oil (up to 15%);
low efficiency of using the generated heat during oil combustion, as Only one component of heat loss is used for heating oil, which coincides with the direction of motion of the combustion front. Under this condition, most of the heat goes to the roof, soil and to heat the skeleton of the rock, from which oil has already been displaced.

 The aim of the invention is to increase the effective development of oil fields for the production of water vapor.

 This is achieved by supplying an excess amount of air to complete oil oxidation, water supply in an amount determined in accordance with the formula and separation on the surface of the gas-vapor mixture for the disposal of by-products, and the working steam is sent to the turbine to generate electricity.

Thus, the essential features of the invention are:
complete oxidation of oil by supplying air to the reservoir in an amount established by the calculation formula.

;
утилизация на поверхности побочных продуктов, а перегретый пар высоких параметров после сепарации направляют в турбину для выработки электроэнергии.water is supplied to the underground steam generator through injection wells in the amount of:
M _water =

;
utilization of by-products on the surface, and superheated steam of high parameters after separation is sent to the turbine to generate electricity.

 Thus, the proposed solution satisfies the criterion of "significant differences", because when studying analogues, the authors did not find analogues of identical solutions for the purpose of increasing the efficiency of oil field development.

 The method is as follows. The opening of the oil reservoir from the surface is carried out by vertical wells. The mining and geological conditions for the occurrence of an oil deposit are determined, as well as the physicochemical properties of the oil and surrounding rocks. From these conditions, the required excess air is calculated according to the well-known formula (In the book. Ed. By V.K. Zaporozhets. Handbook for engineers, technicians and students. M-L., Vol. 1, 1936, p. 649-650).

Q _water = 9.6 (C + 3h).

After ignition of the formation downhole injection wells and establishing stable combustion front (which is recorded a high temperature combustion products T _g = 300-650 ^C. mining hole) into the oil reservoir supplying water to a quantity which is determined by the claims.

; а образующуюся парогазовую смесь отводят через добычные скважины в сепаратор на поверхности. Далее очищенный пар направляют в турбину для выработки электроэнергии, а побочные продукты утилизируют на поверхности для последующей химической переработки.M _water =

; and the resulting vapor-gas mixture is diverted through production wells to a surface separator. Next, the purified steam is sent to the turbine to generate electricity, and by-products are disposed of on the surface for subsequent chemical processing.

 Thus, the oil recovery processing ratio reaches 90%.

PRI me R. Legend:
Depth of oil reservoir N = 1000 m
Oil porosity P = 12% Oil saturation σ = 80%
Calorific value of oil q _Н = 10500 kcal Oil composition С - 85.5% h (Н ₂ ) -14.2%, others - 0.3% Formation capacity m = 6 m Number of wells in a row N = 4
The distance between the wells L = 500 m in a row B = 200 m
The coverage coefficient of the deposit To _oh = 0.7
The velocity of the combustion front is V _fg. = 0.5 m / day Heat capacity of water С _b = 1 kcal / kg
Heat capacity of wet steam With _int . = 0.47 kcal /
/ kg ^o C
The heat of the phase transition
stroke (water evaporation) r = 595 kcal / kg
The specific gravity of oil ρ _n = 0.94 kg / DM ³
Coefficient taking into account
total heat loss to the surrounding massif K _p = 0.7
A consumer of energy produced in the form of steam is a steam turbine with initial parameters for a pair of t _p = 300 ^° C and a pressure of 220 atm. At a speed of movement of the combustion front of 0.5 m / day = 0.02 m / h, we determine the amount of oil burned in the contour unit per unit time:
V _H = N _b V _fg n σK _OHV K ρ _H H _n =
4˙200˙6˙0.02˙0.12˙0.8˙940˙0.7 =
= 6064 kg / h.

The amount of heat released during the combustion of such an amount of oil:
Q _n = q _n ˙V _n = 10500˙6064 = 64˙10 ⁶ kcal / h.

=

= 81 т/ч
Таким образом
M_воды =

;
Необходимое количество воздуха для полного окисления нефти:
Q_возд = 9,6 (С + 3L), м³
Q_возд. = 9,6 (0,855 + 3 0,142) = 12,29 м³/кг
Q_{общее возд.} = 12,29˙ 60 ˙64 = 72572,6 м³/ч.Amount of water supplied to the underground steam generator:
M _water =

=

= 81 t / h
In this way
M _water =

;
The required amount of air for the complete oxidation of oil:
Q _air = 9.6 (C + 3L), m ³
Q _air = 9.6 (0.855 + 3 0.142) = 12.29 m ³ / kg
Q _{total air} = 12.29 ˙ 60 ˙64 = 722572.6 m ³ / h.

 Thus, the oil refining efficiency reaches 90%.

Claims (1)

METHOD FOR PRODUCING HEAT IN RESIDUAL OIL FIELDS including opening a deposit by drilling wells, preliminary increasing the permeability of the array, igniting the deposit, supplying part of the wells to the air and water reservoir, selection of combustion products from another part of the wells, characterized in that, in order to obtain thermal energy or energy vapor, hard-to-recover oil is burned in the reservoir until the combustible components are completely oxidized, and excess air is supplied in a mass ratio to the residual oil of 16: 1, and the water is supplied into the combustion zone in an amount determined by the expression
M _water =

,
where q _n is the calorific value of oil, kcal / kg;
N - the number of wells in a row, units;
B is the distance between the wells in a row, m ,;
m is the thickness of the oil reservoir, m;
V _fg - the velocity of the combustion front, m / h;
P - formation porosity,%;
σ is oil saturation,%;
K _ohw - the coverage coefficient of the reservoir,%;
B _n - oil density, kg / m;
To _p - loss coefficient;
C _in and C _VP - heat capacity of water and wet steam, kcal / kg, ^o C;
Δt _in and Δt _VP - change in temperature of water and wet steam, ^o C;
r is the heat of evaporation of water, kcal / kg.