EA042424B1 - METHOD FOR DETERMINING HYDRAULIC CONDUCTIVITY OF OIL RESERVOIR AND DEVICE FOR ITS IMPLEMENTATION - Google Patents

Description

The invention relates to the oil industry, in particular to hydrodynamic methods of well testing, and can be used in determining the parameters of the reservoir.

A known method for determining the hydraulic conductivity of an oil reservoir (1), which consists in using a nonlinear law of filtration during non-stationary redistribution of pressure in the reservoir and changes in the elastic reserve of the reservoir and fluid associated with starting or stopping the well, changing its operating modes. At the same time, during transient filtration in the reservoir, the hydraulic conductivity coefficient changes with a change in the pressure gradient on the well wall and reservoir drawdown. In this method, the problem of determining the formation hydraulic conductivity (HP) is solved according to the bottomhole pressure recovery curve to the formation pressure (PBU) with continued fluid inflow after it has been stopped. The conditional size of disturbances in the formation area from the shutdown of the well is determined depending on the logarithm of the function of the influence of fluid inflow into the well on the propagation of the perturbation front in the formation, which has a polynomial form of the 6th degree. The disadvantage of this method is that it does not show how GP is determined by pressure build-up.

A known method for determining the hydraulic conductivity of the reservoir (2), including stopping the well at the lower position of the pumping unit plunger, tracking the rate of recovery of bottomhole pressure at regular intervals in an unsteady filtration mode after stopping the well, plotting a curve for restoring bottomhole pressure to reservoir pressure in semilogarithmic coordinates, which is described the following formula

РзЮ ⁼ Pjc ~ (Р _to - P _o )exp(-Onty ⁺¹ ) where P _k - pressure in the formation feeding circuit; followed by the calculation of the hydraulic conductivity according to the known formula (1).

The method makes it possible to determine the HP with high accuracy, but the main disadvantage of this method is that the well is stopped for a certain period (10-15 days) to determine the HP, which is inexpedient from an economic and technical point of view.

There is a known method (3) for determining the HP, in which the change in bottomhole pressure is measured after stopping or starting the well, determining the value of the formation permeability coefficient Kf depending on the bottomhole pressure during well operation, measuring the formation thickness (h) and oil viscosity (pH), building bottomhole pressure recovery curve (PBU) in semi-logarithmic coordinates and calculate the value of the hydraulic conductivity of the oil reservoir using the well-known formula

Dia

The disadvantage of this method is that in most cases, especially for marginal wells, due to the limited capabilities of the mathematical apparatus used in the method for determining the hydrodynamic (filtration) characteristics of the reservoir by pressure build-up, this method leads to significant errors in determining the HP. And, in addition, the use of this method is also possible only when the well is shut down.

Closest to the claimed invention is a method for determining the hydraulic conductivity of the formation (4) consisting in determining the value of the formation permeability coefficient Kf depending on the bottomhole pressure during well operation, measuring the formation thickness and oil viscosity. Sampling of oil liquid is carried out, it is subjected to separation from accompanying water and gas, and the intensity of infrared radiation incident and passing through the layer of separated oil is measured. The optical density of oil is calculated, the exponential dependence of the permeability coefficient on the optical density D is determined, the absolute permeability Kf and the dynamic viscosity pH of the oil are determined, the characterizing optical density Dx is found, and the value of the hydraulic conductivity of the oil reservoir is calculated using the formula hK. ch^exp^-^gradp ξ = --- =----------------μ _Η a exp(bD) where ξ - formation hydraulic conductivity, cP;

h is the thickness (thickness) of the formation, m;

a, b, c - coefficients of conformity, which are determined experimentally;

K ₀ - the value of the permeability coefficient in the initial period of operation, determined by the core;

Dx - characterizing optical density, determined by the method of tangents to the curve of exponential dependence (Kf) on D;

grad P - pressure gradient determined taking into account the reservoir drawdown and the distance from the supply contour to the wellhead.

The disadvantage of this method is that in it ξ - GP is determined using grad Р - a parameter, the numerical value of which is determined only indirectly from the exponential dependence curve, which creates certain difficulties in determining ξ.

- 1 042424

The objective of the invention is a method for determining the HP in the well operation mode, simplifying the procedure for determining the dependence of hydraulic conductivity on drawdown pressure in a production well.

The essence of the claimed invention consists in a method for determining the hydraulic conductivity of an oil reservoir, in which a test sampling of an oil liquid is carried out, it is subjected to separation from accompanying water and gas, and the intensity of the incident J0 and the infrared radiation transmitted J through the separated oil layer is measured. The optical density of oil is calculated, the curve of the exponential dependence of the permeability coefficient on the optical density D is plotted, the absolute permeability Kf and the dynamic viscosity pH of the oil are determined, the characterizing optical density Dx is found, the pressure at the mouths of the casing string of the production and injection wells is additionally measured, and the hydraulic conductivity of the formation is calculated using the formulas:

/ Dx^P

C-fe^exp^g-)-;Ia exp(bD)

ΔΡ \u003d ρ "- p / p ₃ \u003d p,5 (n + |l) + p _y ^\u003d PzhZ^zh + where ξ is the hydraulic conductivity of the formation, m ³ / Pa-s;

h is the thickness (thickness) of the formation, m;

a, b, c - coefficient of conformity, which is determined experimentally;

K0 - the value of the permeability coefficient in the initial period of operation, determined by the core, m ² ;

D _x - characterizing optical density, determined by the method of tangent to the curve of exponential dependence (Kf) on D;

ΔΡ - pressure drop, defined as the difference between the bottomhole pressures of the injection and production wells, Pa;

P ⁿ R ^d ,, ^{g C} t ^g C - respectively, the bottomhole pressure of the injection and production wells, Pa;

pH pD y y - pressure at the mouths of the casing string (OK) of the injection and production wells, Pa;

r _in , Rzh - density of water, and oil (reservoir) fluid, kg/m ³ ;

h, H - the height of the perforation zone and the height from the mouth to the perforation zone of the OK of the injection well, m;

g - free fall acceleration, kg/s ² ;

l is the distance between the injection and production wells.

The claimed invention differs from the prototype in that the pressure is additionally measured at the mouths of the casing of the production and injection wells. The inventors found that the pressure gradient can be determined by the ratio of the value of the measured pressure drop (ΔΡ) between two points located at the mouth of the injection and production wells to the distance between these points (L) grad P=ΔΡ/Π.

The method is carried out as follows.

The oil liquid is sampled into a container and subjected to separation from associated water and gas. The intensity of the incident infrared radiation J0 and the radiation J passed through the vessel with oil is measured, the optical density (D) of the light-absorbing medium (oil) is calculated, according to the well-known formula D=lg(J ₀ /J), an exponential dependence curve (Fig. 1) of the coefficient permeability at the initial moment of time K0 on the optical density D, from which the characterizing optical density Dx is found by the tangent method, the absolute permeability Kf and the dynamic viscosity pH of the oil are determined by the formulas

K _f = K _o exp(-A\ μ _Η = α exp(bD);

according to the well-known formula for determining the hydraulic conductivity of the reservoir

L - ^hK *>

' ~ Рн' and taking into account the obtained values of the absolute permeability Kf and dynamic viscosity pH of the measured values of the bottomhole injection pressure in the production well, the formation hydraulic conductivity is calculated according to the stated formulas.

To implement this method, a slightly modernized well-known (4) device is used, in which pressure sensors are additionally installed at the mouths of the casing string.

Claims (4)

cabbage soup and injection wells. The schematic block diagram of the proposed device is shown in Fig. 2. The device contains: a sampler - 1 located on the flow line of the well, and a separator - 2 connected in series with it for separating oil from associated water and gas, and a container - 5 for separated oil. On both sides of the tank with oil, there is a source and receiver of infrared radiation - 3 and 4, respectively; infrared signal converters -6 and 6', the outputs of which are connected to the control and indication unit - 7. Pressure sensors - 14 and 18, with the corresponding converters - 17 and 19, installed at the mouths of the production and injection wells; liquid level sensor - 14 with transducer -15 installed in the production well casing. The outputs of the sensors are connected to the BUI, where the measured and calculated parameters determine the hydraulic conductivity of the reservoir and display on the indicator. The device uses standard and well-known devices, such as: infrared source - TSAL6100; infrared receiver - TSOP1738; signal amplification unit - AD7787; microprocessor - ATMEGA or PIC 16F877; indicator - AL304; loop - flat ribbon cable FRC 1-09-31; bracelet - plastic. TSAL6100 source frequency - up to 300 kHz. TSOP1738 receiver frequency - 38 kHz (carrier frequency). An example of the implementation of the method: a=11.09; b=1.4208; D=1; K ₀ =1-10 ^-12 µm ² ; D _x =0.5; h=10 m; ΔΡ I \u003d 1.2 Pa; c=5.18 / D\hP Ιμ _Η a exp(bD) 11.09 exp(l,421 D) 5.18 0.135 10' ¹² m ³ 1.2 10 ¹² m ³ D* cm = ---------------------- = 55.56 -------= 5.556-----15.21 10 ^-3 Pa s ' Pa-s ' cP where D*=10 ^-12 m ² - Darcy; cP - centipoise, Pa-s - Pascal - second. The technical effect of the claimed invention is to improve the previously stated method of hydrodynamic study of an oil reservoir, which uses the identified dependence of the permeability coefficient and viscosity of oil on optical density under the influence of infrared radiation on oil, which consists in simplifying the procedure for determining the dependence of hydraulic conductivity on drawdown on the reservoir in a production well. The method allows to measure the hydraulic conductivity of the oil reservoir without shutting down the well. The results of the obtained calculations show that the proposed method really reflects the processes of filtration in the oil reservoir. Literature 1) Patent of the Russian Federation No. 2301886, 08/17/2006, Method for determining the hydraulic conductivity of the formation. 2) Eurasian application No. 201400794, 10.2015, Method for determining formation hydraulic conductivity. 3) Robert Erlager Hydrodynamic methods of well research. Moscow-Izhevsk, 2006, 512. 4) Eurasian application No. 030391, 31.07.208. A method for determining the hydraulic conductivity of an oil reservoir and a device for its implementation, (Aliev T.A., Rzaev Ab.G., Rasulov S.R., Kelbaliyev G.I.). CLAIM A method for determining the hydraulic conductivity of an oil reservoir, in which a test sampling of an oil liquid is carried out, it is subjected to separation from associated water and gas, and the intensity of the incident J ₀ and infrared radiation passing through the separated oil layer J is measured, the optical density of the oil is calculated, and a curve of the exponential dependence of the permeability coefficient on optical density D, determine the absolute permeability Kf and dynamic viscosity μ _H of oil, find the characterizing optical density D _x , characterized in that they additionally measure the pressure at the mouths of the casing string of the injection and production wells and calculate the hydraulic conductivity of the reservoir using the formulas: -