RU2055170C1 - Method for stimulation of oil recovery - Google Patents

Abstract

FIELD: oil production. SUBSTANCE: method for stimulation of oil recovery consists in injection of aqueous solution and gas into formation. Arranged on the oil field is plant for oil processing, e.g., including unit for electric desalting, electric dewatering and atmospheric distillation, unit for thermocontact cracking, and unit for hydrogenation. Sewage water and flue gas are withdrawn from the plant. Sewage water is heated by flue gases and injected into oil formation for stimulation of oil recovery under continuous or cyclic conditions. EFFECT: higher efficiency. 3 cl, 1 dwg, 3 tbl

Description

 The invention relates to the oil industry and can be used in oil production.

A known method of oil production by creating a rim of steam in the oil reservoir and the subsequent displacement of steam and oil with cold water [1]
The disadvantages of this method are the cooling of steam and its condensation in the process of advancing the rim along the formation, insufficient heating of pressure cold water in the process of injection and a decrease in the temperature of the formation as a result.

 A known method of oil production by injection into the oil reservoir of aqueous solutions of salts [2] the Use of solutions helps to reduce the viscosity of the produced oil.

 The disadvantages of the method are the significant consumption of salts, waterflooding of oil deposits, environmental damage from man-caused mineralization of groundwater.

 Closest to the proposed method is a gas displacement using dilute solutions of surfactants [3] In this method, an aqueous surfactant solution is pumped into the oil reservoir to intensify oil production, and then this solution is displaced towards the production well using gas.

 The disadvantage of this method is the low oil recovery due to thermal effects on the reservoir simultaneously with the action of surfactants and displacement, the need for costs for the supply and consumption of gas and surfactant solution.

 The objective of the invention is the enhancement of oil recovery, the elimination of the consumption of surfactants, water and gas.

 This is achieved by using wastewater as the working agent, and flue gases taken from the oil processing plant located in the field, including the unit for electric desalination, electric dewatering, atmospheric distillation, thermal contact cracking and hydrogenation followed by heating the waste water with flue gases, as a working agent. and pumping them hot into the oil reservoir, hot wastewater and flue gases are pumped into the oil reservoir sequentially or in the form of a pre-prepared mixture of frantically or cyclically.

 As wastewater use industrial and rainwater. Flue gas is taken from the coke heater of the thermocontact cracking unit or from the recovery boiler for burning coke, pitch or cracked residue obtained during thermal oil refining.

 The drawing shows a diagram of the method of intensification of oil production.

In a field including one or more injection and one or more production wells, an oil processing unit 1 is placed, in which, according to the technological scheme, wastewater and flue gases are provided. The waste water 2 is heated by the heat of the flue gases in the heat exchanger 1a. Wastewater temperature rises to ^about 98, while the flue gas temperature is reduced to 300 ° ^C. Hot effluent water through flow line 3 and is pumped into the injection well 4 into the oil reservoir 5 to make contact between the oil and hot water. Then, flue gases begin to be injected into the formation 6. Heat of water and gases is transferred to the oil formation, oil and rocks expand. Oil viscosity decreases, oil recovery increases and oil recovery 7 through production well 9. Additionally, the increase in the production rate of the production well is influenced by the pressure of the injected gases on the rim of the wastewater and oil. The advance of the displacement front in the oil reservoir is accompanied by the injection of hot flue gas, due to which the temperature of the water rim remains high. At the same time, partial or complete mixing of wastewater with reservoir oil occurs. The resulting mixture has a high temperature and low viscosity and acts on the reservoir oil as a heat transfer solvent. CO ₂ and SO ₂ contained in the flue gases are partially dissolved in wastewater and form acids, which additionally reduce the surface tension forces in the pore space of the formation and lower the viscosity of the oil.

 The method can also be implemented by pre-mixing wastewater and flue gas. In this case, the wastewater and the substances contained in them turn into a vapor state, and the flue gas is cooled to a temperature sufficient to use the discharge equipment. The resulting hot mixture is pumped into the oil reservoir in a continuous mode and the oil is displaced towards production wells. In a cyclic production method, hot steam is pumped into the well. At the second stage of the cycle, the well is shut off and held for the time necessary to transfer heat from the combined cycle gas to oil. In the third stage, heated oil is extracted from the wells in a mixture with water and flue gases.

 The extracted oil goes to the oil refinery. Refined petroleum products are transported to consumers. Petroleum coke is burned in a recovery boiler. All sewage and flue gases of the unit are pumped into the oil reservoir to intensify oil production.

The advantages of injecting hot wastewater and flue gases into the oil reservoir are as follows: intensification of oil production; large environmental effect from the use of effluents containing oil products and sodium salts, and flue gases containing CO ₂ , SO ₂ , nitrogen oxides, hydrocarbons, hydrogen sulfide.

 The advantages of locating an oil refinery in the field are the absence of costs for water supply, the absence of costs for supplying and consuming gas to displace oil from the reservoir, the absence of special costs for heating water and gas, and the reduction of environmental damage by reducing the length of transport streams of solutions and gases .

 The advantage of using a thermal contact cracking unit as part of an oil refining unit is to obtain a significant amount of hot flue gas from a coke heater unit.

When processing 100 thousand tons of viscous oil per year, 36 thousand tons of flue gas can be obtained on a coke heater of a thermocontact cracking unit, and during gasification of the coke obtained 135 thousand tons. About 2 thousand tons of SO ₂ will be transferred to the composition of gases in the oil reservoir. As part of 92 thousand tons of wastewater, up to 5 tons of oil products will be transferred to the reservoir in a year.

 PRI me R. An oil refinery is installed at the field, including an electric dehydration, electric desalination and atmospheric distillation unit (ELOU-AT), a thermal contact cracking unit (TKK), including a recovery boiler and a hydrogenation unit (HG). During the production and processing of 100,000 tons of oil per year, production effluents with a total volume of 89414 tons are formed. The origin and characteristics of the effluents are given in Table 1.

The effluents are sent to a heat exchanger, where they are heated to 98 ^° C with flue gases and plant heat and pumped into an oil reservoir.

 Flue gas obtained in the coke heater 36 thousand tons per year is taken from the TKK unit, and 135 thousand tons during coke gasification in the recovery boiler in year. The composition of the flue gases is given in table.2.

The flue gases are purified, if necessary, and cooled ^to 300 ° C and pumped into the oil reservoir. At the same time, reservoir pressure is maintained. As a result of injection of wastewater and flue gases, the temperature of the oil and rocks of the formation increases and the viscosity of the oil decreases in the ratio given in Table. 3.

Oil Viscosity at 20 ° ^C of 864.8 MPa · s. Increasing the temperature of the reservoir to 50 ^about C reduces the viscosity of the oil to 138 MPa · s. The intake of hot flue gas prevents the rim of the wastewater from cooling as it moves into the formation. By reducing the viscosity of the oil in the reservoir and the pressure of the displacement increases the production rate of production wells, increases oil recovery. Depending on the temperature and the amount of injected gases and water, the pace of field development will vary.

Claims (3)

 1. METHOD OF INTENSIFICATION OF OIL PRODUCTION, including the injection of a working agent and gas into the oil reservoir and oil displacement, characterized in that waste water is used as the working agent, and flue gases taken from the oil processing facility located in the field are used as gas; including blocks of electric desalination, electric dehydration, atmospheric distillation, thermal contact cracking and hydrogenation, followed by heating the waste water with flue gases and pumping them hot into the oil reservoir.  2. The method according to claim 1, characterized in that the injection into the oil reservoir of hot wastewater and flue gases is carried out sequentially.  3. The method according to claim 1, characterized in that the injection into the oil reservoir of hot wastewater and flue gases is carried out in the form of a pre-prepared mixture continuously or cyclically.

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