RU2237154C1 - Method for extraction of highly viscous oil - Google Patents

Abstract

FIELD: oil extractive industry.

SUBSTANCE: method includes drilling of system of product and force wells, opening of product wells by perforation, treatment of bed with acoustical pressure oscillations, generating acoustic well devices lowered into force wells and continuous extraction of oil from product wells. Pipes of force wells are not opened by perforation and are filled with working liquid. Treatment by acoustic oscillations of pressure is performed at two frequencies, main f₁ and additional f₂. Treatment is started at frequency f₁, which is selected based on condition for creation of pressure amplitude providing for pressure gradient for oil influx to product well and oil raising. Values of temperature T₀ and viscosity μ₀ are measured during the process, and frequency f₂ is selected 2-8 times higher than frequency f₁. During the process also measured is maximal increase of oil temperature and minimal value of its viscosity relatively to measured values T₀ and μ₀ respectively. With extraction of bed well device is moved downwards.

EFFECT: higher effectiveness of viscous oil extraction by lowering costs, higher debit and oil yield.

6 cl

Description

The invention relates to the oil and gas industry and can be used for the production of heavy viscous oil.

A known method of producing highly viscous oil (RF patent No. 2098613, E 21 B 43/24, publ. 10.12.97) by injecting water vapor into an injection well, creating a permeable zone between the injection and producing wells and the simultaneous extraction of oil from the producing well. This method is time consuming and energy intensive.

A known method of producing viscous oil (RF patent No. 2088749, E 21 B 43/00, published on 08.27.97), including the lifting of oil by a sucker rod pump in the annulus of tubing above the packer installed on them and feeding Low-viscosity fluid tubing with dosing into the annulus, with the formation of wall layers on the outer surface of the tubing and the inner surface of the production string, thereby reducing the hydrodynamic resistance when lifting viscous oil through the annulus.

This method is more economical, however, additional watering of the oil occurs when water is used as a low-viscosity liquid, and when using a special emulsion, it can be stratified and even increase the viscosity of the produced oil.

The closest taken as a prototype is the method of oil production (RF patent No. 2162516, E 21 B 43/16, published on January 21, 2001), which includes opening the oil reservoir with a system of production and injection wells, exposure of the reservoir to acoustic immersion devices through injection wells and oil recovery from production wells.

This method is economical, makes it possible to adjust the flow rate, however, it is not effective enough for the production of highly viscous oil.

The objective of the proposed method is to eliminate the water cut of the produced oil, and the technical result is to increase the efficiency of the production of highly viscous oil by reducing cost, increasing production rate and oil recovery.

The specified technical result is achieved due to the fact that in the method of oil production, including drilling a system of production and injection wells, opening production wells by perforation, exposure to the formation by acoustic pressure fluctuations excited by acoustic well devices immersed in injection wells and continuous lifting of oil from production wells pipes of injection wells are not opened by perforation and fill them with a working fluid, and the impact of acoustic pressure fluctuations is melt at two frequencies the main f ₁ and additional f ₂ , begin to act on the frequency f ₁ , which is selected from the conditions for creating a pressure amplitude that provides a pressure gradient for oil flow to the production well and oil rise, and the temperature T _o and viscosity are measured μ _o, and the frequency f ₂ is selected to 2-8 times higher than the frequency f _1, fixing the maximum increase of oil temperature and the minimum value of the viscosity thereof relative to the measured values T _o and μ _o, respectively, and generating at least a borehole formation is moved Noe device downward.

Water, glycerin, etc. are used as the working fluid, and acoustic well devices are immersed in injection wells at 70-80% of the reservoir power level, while production wells are opened with perforation also at a value of 70-80% of the reservoir thickness.

Acting on the oil reservoir of a field with high-viscosity oil by acoustic pressure fluctuations, according to the proposed method, two phenomena occur: the first is the transfer of elastic energy or the transition of the disturbed state of the medium from one particle to another due to the acoustic effect at the fundamental frequency and the second - the movement of particles as material points at an additional frequency. As a result of the first, a pressure gradient is formed, which is the basis of the course of the production process, as a result of the second, the oil viscosity index decreases due to the high values of particle accelerations in the wave. The resulting deformation of the pores of the rock matrix creates a condition for increasing the permeability of the formation, which increases the filtration rate, thereby increasing the oil flow rate.

The absence of opening of the injection well with perforation prevents the working fluid from entering the formation, the working fluid transfers the acoustic pressure from the acoustic emitters of the acoustic well device through its entire volume through the column wall and cement stone into the formation, the fluid and the fluid filling it. This pressure is excessive in relation to the reservoir pressure, and therefore, the conditions for the flow of oil are created, while the volume of the working fluid is sharply reduced in comparison with traditional methods of oil production using large volumes of water to squeeze out oil. The method is also effective in cases where there is no possibility of a direct impact on the residual oil reserves that are more than 100 m from the wells or located in separate clusters of "pillars", that is, enhanced oil recovery.

In contrast to the analogue in which the production of viscous oil is carried out on the basis of the method of reducing the hydraulic resistance when it is raised along the tubing by injecting a less viscous fluid into the well, the proposed method changes the state of the oil: reduces its viscosity. This is achieved by exposing the formation to acoustic pressure fluctuations simultaneously at two different frequencies, including a second higher frequency. The frequency range f _{2 is} selected from the conditions for creating a cavitation mode in the reservoir during operation of the acoustic emitter, leading to a change in the physical state of the oil: temperature increase and viscosity decrease.

The method is as follows.

A system of producing and injection wells is arranged in the deposits in the form of an equilateral triangle, at the tops of which there are injection wells (HC), and in the center is a production well (DS). DS open perforation in the amount of 70-80% of the capacity of the reservoir. After the natural reservoir pressure is established in the wells, the reservoirs are filled with water and acoustic downhole devices are lowered into them at a level of 70-80% of the reservoir power and produce an acoustic effect on the reservoir with a power of 12 kW at the main operating frequency f ₁ = 2-4 kHz and record the response in the DS. After 3-4 hours of operation, the value of viscosity μ _o and oil temperature T _o are measured, after which the acoustic effect is added at a higher frequency f ₂ = 10-30 kHz, choosing a frequency from this interval at which a maximum temperature increase of 10-15 ° C from the value of T _o and a decrease in the viscosity of the oil to a value of μ = (10-40)% μ _o . The production process is carried out with the continuous selection of oil from the reservoir and, as the formation develops, the downhole device is moved from top to bottom.

When an acoustic wave passes from one medium to another, namely from a working fluid through a column of cement slab, the cement stone into the formation changes in the wavelength, the calculated value of which in the formation with an acoustic frequency equal to f ₁ = 3 kHz is λ = (1.35- 1.50) m.

раз, где R - расстояние от акустической нагнетательной скважины НС до эксплуатационной добывающей скважины ДС. Избыточный по отношению к пластовому градиент давления

- создаваемый воздействием на пласт акустическими колебаниями давления на частоте f₁=3 кГц определяется по формулеA NS column filled with water is a “linear wave source” and creates a cylindrical mechanical wave in the formation. The value of the maximum amplitude of the acoustic pressure transmitted by the cylindrical wave decreases asymptotically as it propagates in

times, where R is the distance from the acoustic injection well NS to the production production well DS. Excessive in relation to the reservoir pressure gradient

- created by the impact on the reservoir by acoustic pressure fluctuations at a frequency f ₁ = 3 kHz is determined by the formula

where P _PL = 2,256 ATM - the amplitude of the acoustic pressure in the reservoir;

R = 500 m is the distance from the acoustic injection well NS to the production production well DS;

λ / 2 = 1.35 / 2 = 0.675 m is the part of the wavelength in the formation at which the maximum pressure change in the medium occurs.

составитIn the traditional method of oil production by injection of water, the pressure gradient

will make

where P is _pumping = 250 atm is the pressure of discharge in NS;

P _zab = 190 atm - pressure in the bottom of the DS;

L = 500 m - the distance between the NS and the DS.

и при заводнении

показывает, что при акустическом воздействии на пласт на выбранной частоте f₁=3 кГц обеспечивается градиент давления, достаточный для подъема нефти, т.к. он выше в 1.24 раза градиента давления при традиционном способе добычи нефти нагнетанием воды.Acoustic Pressure Gradient Comparison

and when flooding

shows that when acoustic stimulation of the formation at a selected frequency f ₁ = 3 kHz provides a pressure gradient sufficient for lifting oil, because it is 1.24 times higher than the pressure gradient in the traditional method of oil production by injection of water.

Exposure at a higher frequency reduces the viscosity index μ, and mainly increases the permeability index k, which is a power function of porosity, as part of volumetric deformation, because in the sound wave, with increasing frequency, the elastic forces dominate the viscosity forces. When the frequency of exposure increases, the main acting factor is the acceleration of particles in the wave and, as a result, deformation of the pores of the rock matrix. Stresses and deformations arising in the matrix of the rock, as well as the speed and acceleration of the particles of the matrix and fluid create conditions for increasing the permeability of the formation due to increments of shear deformation, leading to a change in configuration, size, increase in volume and lumen of the pores. The velocities and volumes of fluid flow to the drain significantly increase, which can significantly increase the flow rate and oil recovery.

The release of rock pores from the fluid during oil production leads to the formation of a free volume of pores not filled with water, in which the chaotic movement of fluid residues increases both under the influence of acoustic pressure oscillations at the fundamental frequency, and mainly under the influence of oscillations at the second increased frequency, due to high accelerations of particles and the emerging phenomenon of cavitation. Multiple reflection of fluid microparticles from the inner walls of the pores of the rock leads to heating of the rock and fluid and to a decrease in the viscous density of oil. Thus, according to the viscosity characteristic μ, which can be from 10 to 40% of its natural value, the fluid filtration rate increases during the production process.

The effectiveness of the proposed method can be judged by the value of the filtration flow rate W

where k _o (1.5) - increased by 50% permeability;

μ _o (0,6) - reduced by 40% viscosity;

h is the thickness of the reservoir;

- градиент давления.

- pressure gradient.

Using this method allows you to increase the speed of the filtration flow by 2.5 times or more, and hence the productivity of the wells.

Thus, the proposed method for the production of highly viscous oil with lower energy costs will increase the oil production rate, increase oil recovery and reduce the watering of the extraction products. Reducing the grid of wells and choosing their optimal layout will make it possible to additionally increase the filtration flow by 2–3 times.

In addition, this method can be used to extract water in arid regions that do not have large ground and underground water sources, given that in the form of separate clusters of "pillars" water is present everywhere in the bowels of the globe.

Claims (6)

1. A method of producing highly viscous oil, including drilling a system of production and injection wells, opening production wells by perforation, impacting the formation with acoustic pressure fluctuations excited by acoustic well devices immersed in injection wells, and continuous lifting of oil from production wells, characterized in that the pipes injection wells are not opened by perforation and filled with a working fluid, and the impact of acoustic pressure fluctuations is carried out at two frequencies, the main oval f ₁ and additional f ₂ , and begin to influence at a frequency f ₁ , which is selected from the conditions for creating a pressure amplitude that provides a pressure gradient for oil flow to the production well and oil rise, and the temperature T ₀ and oil viscosity μ ₀ are measured and then begin to impact on the frequency f _2, which is selected from the interval 2-8 times the frequency f _1, fixing the maximum increase of oil temperature and the minimum value of the viscosity thereof relative to the measured values of T μ ₀ and _0, respectively, and by measures generating a formation downhole tool is moved downwards. 2. The method according to claim 1, characterized in that water is used as the working fluid. 3. The method according to claim 1, characterized in that glycerol is used as the working fluid. 4. The method according to claim 1, characterized in that the acoustic downhole device is immersed in the injection well at 70-80% of the reservoir power level. 5. The method according to claim 1, characterized in that the producing wells are opened by perforation in the amount of 70-80% of the power level of the reservoir. 6. The method according to claim 1, characterized in that the element of the well placement system is an equilateral triangle, in the center of which is placed the producing, and on the tops injection wells.