EA020663B1 - Method of measurement of well production rate - Google Patents

Abstract

The invention relates to oil production industry, to methods of measurement of well production rate, in particular, to methods of determining formation permeability and pressure buildup. The essence of the invention provides a method of measurement of well production rate which comprises measuring pressure, temperature and dynamic level of formation fluid and determining in a laboratory watering of formation liquid, oil viscosity, density of water and oil. According to the obtained values the change of bottom-hole pressure is calculated, a graph of pressure buildup is plotted and the obtained curve is approximated by the formulaand the expected value of pressure buildup and time for measuring the dynamic level are determined, the formation permeability index is calculated and the rate of oil, gas and water in an operation string are determined by the corresponding formulae. The technical effect of the claimed invention is characterized in that the method takes into account main formulation parameters and it allows to provide a well operation process adequately and to intensify oil production.

Description

The invention relates to the oil industry, relates to methods for measuring oil production, namely, methods for determining the permeability of the reservoir and the restoration of reservoir pressure.

During production well operation, a lot of geological, technological, physico-chemical and technical factors influence the formation-well-pump system and, consequently, the productivity of the well.

The known method (1) of measuring the production rate of oil wells, implemented in group measuring devices of the type AGM-3. This type of installation is intended for centralized control of oil production rates, which allows two-component production rates to be monitored from a control desk. Measurement of the flow rate of wells is carried out by alternating (if necessary, and extraordinary) cyclic connection of wells according to a given program. This method allows you to accurately measure the flow rate of the well in oil and produced water. However, it does not take into account the gas flow rate of the well, does not establish the dependence of the flow rate on the state of the oil reservoir, and does not allow efficiently and promptly controlling the production mode of the well.

The known method (2), in which at a given mode record the flow rate of the oil fluid, its water cut, dynamic level, overpressure at the wellhead. The flow rate of the well is measured using a group metering unit. The water content of the produced fluid is determined in the laboratory by a chemical-analytical method. Dynamic level - with the help of an echo sounder. Then, for each studied mode, the dependence of bottomhole pressure on the flow rate of the formation fluid is determined in the form of indicator diagrams by calculation.

This measurement method allows you to measure the flow rate of the well and to obtain the predicted value of the reservoir pressure to establish, in the form of indicator diagrams, the dependence of the bottomhole pressure on the flow rate of the reservoir fluid, which allows you to control the mode of operation of the well. The disadvantage of this method is that the flow rate is measured only for oil and produced water and does not take into account the flow rate for gas. In addition, permeability calculations, which are an important factor for managing well operation, are not taken into account in oil production calculations, and indicator charts are not reliable and reliable. In addition, for the construction of indicator charts, a change in the well flow rate in a given interval is required, which is often impossible in practice.

The objective of the invention is to create a reliable and reliable method of measuring the flow rate of the wells, determining the predicted value of the flow rate of the well in oil, gas and produced water and the permeability of the formation.

The essence of the invention consists in a method for measuring the flow rate of oil wells, which includes measuring pressure, temperature and the dynamic level of the reservoir fluid and determining in a laboratory way the water cut of the reservoir fluid, viscosity of oil, density of water and oil. According to the obtained values, the change in bottomhole pressure is calculated according to the formulas

DR ₃ (t) = AN (t) -rp _J -d + ARy (t)

Рпж = [^ Рв + (1-№) Рн] build a graph of reservoir pressure restoration and the resulting curve is approximated by the formula AN (g) = К _у Л (1-е ^{/ т / т} ); the predicted value of the reservoir pressure to be restored and time for conducting dynamic level measurements, calculating the permeability coefficient of the formation and calculating the flow rate of oil, gas and water in the production casing according to the following formulas:

2π ^ (Л „-Л),, 'σ” = β. ”Ά

Kk

/ ^ 273 + / (g)]

848 _ 848 ις 'ιςχ ^; where ΔΡ., (τ) is the change in bottomhole pressure;

AR _y (g) - change in pressure at the wellhead;

ΔΗ (τ) is the change in the level of reservoir fluid in the production string at time τ; d - acceleration of gravity;

-τ / Τ е - exponential change in the level of the liquid in the production string; p _pzh , r _n , Rv - the density of the reservoir fluid, oil and water, respectively;

№ - water cut of formation fluid;

P _PL - reservoir pressure;

- 1 020663

P _s - pressure in the bottom hole;

1p - a symbol of the natural logarithm; π is the number pi = 180 or 3.14;

Oh, gas consumption;

To _y is the gain, which at τ ^ χ is equal to Α / ΔΡ (χ);

Ά = Δβ = β _Τ -β ₀ - an abrupt decrease in the production rate of the reservoir fluid from the current value of Ts _t to zero - Tso;

(Ω = Ω _Τ ) for τ <0; Ω = Ωο = Ο for τ>0;

τ is the current time;

T is a constant time;

О, _{| ж} - volumetric flow rate of formation fluid;

With _n , With _in - the mass flow, respectively, of oil and water; q _|| μ ,, is the viscosity of the reservoir fluid and oil (μΐ · _ιι -, _κ = μι _ιι (1 + 2.5 \ ν));

K is the permeability coefficient of the formation;

B _p is the thickness of the reservoir;

To _to , g _with - respectively, the radii of the power circuit and the well;

P0 is atmospheric pressure;

M _cf. - the average molecular weight of the gas;

With ₁ M ₁ - respectively, the content and molecular weight of the ί-th component of the gas;

K is the universal gas constant;

N _s - the distance from the bottom to the wellhead;

Η (τ) is the dynamic fluid level in the production string at time τ;

- temperature in the gas phase at time τ.

A comparative analysis of the claimed invention and the prototype showed that the claimed invention differs from the known new significant features: the calculation of the permeability of the formation, the predicted value of the flow rate of the well, as well as the determination of the recovery time of the reservoir pressure from a curve constructed on the basis of a mathematical model developed by the inventors.

A comparative analysis with other known solutions showed that the known solutions do not have a similar mathematical model, based on which a pressure recovery curve is constructed from the measured parameters and known formulas. Known models (3) used for this purpose, the curve is approximated only in individual sections, which does not give reliable results. In the claimed invention, according to the recovery curve of the dynamic level, both the magnitude of the restored pressure and the recovery time can be predicted. Moreover, the recovery time, in fact, is determined 4 times faster than expected. This saves time on idle wells, i.e. increase the efficiency of her work. The method allows to determine the permeability of the oil reservoir, which, in turn, makes it possible to act on the reservoir in order to intensify the recovery of the reservoir. Therefore, the claimed solution has novelty, and meets the criterion of inventive step, and can be recognized as an invention.

The method is implemented in a well production rate measurement system and is illustrated in FIG. 1 is a schematic diagram of an implementation of a method for measuring oil production rates, and FIG. 2 - pressure recovery curve.

The measurement system contains an injection well 1, a reservoir 2, a producing well 3, a production casing 4, a rocking machine 5, an actuator 6, an echo sounder 7, a reference 8, pressure sensors 9 and temperature 10, pressure transducers 11 and temperature 12, a transducer acoustic signal 13, the control unit and registration 14.

The method is as follows.

Before starting the measurement at the wellhead, samples are taken both by laboratory and chemical-analytical methods, the water cut of the formation fluid (Dean-Start method), the viscosity of oil and gas under formation conditions (at the current temperature and pressure in the formation), and the composition of the gas are determined. The current temperature and pressure of the formation 2 is measured by pressure sensors 9 and temperature 10 and their values through the pressure transducer 11 and the temperature transducer 12 are recorded in the control and recording unit 14. With a fish finder 7 measure the dynamic level of the reservoir fluid in the production casing 4, through the acoustic signal transducer 13 and using a benchmark 8 register in block 14 and through the actuator 6 stop the rocking machine 5. The measured values determine the change in bottomhole pressure according to the formula

ΔΡ. / ΤφΔΗίτμρ ,,. ,,, β + ΔΡ, / τ)

Рпж = [^ Рв + (1-ЮРн]

Based on the obtained measurement data, a dynamic level recovery curve is constructed (Fig. 2) and, approximating the graph curve by the formula

ΔΗ (τ) = ^ Ά (1- € ^{-τ / Τ} ), determine the reservoir pressure recovery curve. Using this formula, the predicted value of reservoir pressure and the time required to restore pressure are determined. To determine the actual time of the measurement at the starting point of the graph curve, a tangent is drawn until it intersects with the line corresponding to the new steady-state value of the dynamic level (point a). Then the projection of the segment of the tangent along the time axis will be the desired value of T. Moreover, according to the schedule, the transition process time (with a probability of 0.95) will be determined as 4T. Therefore, after 4T from the beginning of the measurement with an echo sounder, the final value of the dynamic fluid level H in the production casing 4 of the well is recorded. Given the obtained value of H (4T), k _[; (4T). determine the value of reservoir pressure P _PL (4T) by the formula

P _P l (4T) = P ₃ (1o) + AR (4T) where P _s (£ ₀ ) is the bottomhole pressure at time 1 ₀ (the closing moment of actuator 6 at the wellhead). Based on the obtained Rpl value (4T), the permeability coefficient of formation 2 is determined and the production rate of the formation fluid, oil and gas is calculated using the formulas

I (r) = I (t ₀₎ + AH (z) = I (r ₀₎ + X n (1- _e - ^{r 'z);}

I (r) = ^Hp t.

The technical effect of the claimed invention lies in the fact that the method takes into account the main parameters of the reservoir and this allows you to adequately control the process of well operation and to intensify oil production.

Literature

1. T.M. Aliev, A.G. Mamikonov, A.M. Melik-Shakhnazarov, Information Systems in the Oil Industry, M., Nedra Publishing House, 1972, 240 pp.

2. V.A. Ivanov, V.Ya. Soloviev, Hydrodynamic studies of waterlogged oil wells at established selection modes, journal Oil and Gas Economy No. 1, 2010 (prototype).

Claims (1)

A method for determining the flow rate of oil wells, in which the water cut of the formation fluid, the viscosity of the oil and the density of water and oil are measured by laboratory methods, the pressure, temperature and dynamic level of the formation fluid are measured, and the gas flow rate, constant time, an abrupt decrease in the rate of formation fluid, and the radius of the loop are measured supply and wells, the average molecular weight of the ί-th gas component and the distance from the bottom to the wellhead and the obtained values are calculated and the recovery curve of the reservoir is built about pressure, which determine the predicted value of the restored reservoir pressure, and the recovery curve of the reservoir pressure is built according to the formulas AR ₃ (t) = AN (t) -rp _J -d + ARu (t) Рпж = [No.Рв + (1-ЮРн], the resulting curve is approximated by the formula - 3,020,663 AN (t) = K _at A (1 ^{t / t} ) and from it determine the predicted value of the reservoir pressure and the pressure recovery time, and to calculate the flow rate of the well in oil, gas and reservoir fluid, the permeability coefficient of the reservoir is preliminarily determined by the formula and calculated well production rate according to the formulas where ΔΡ ₃ (τ) is the change in bottomhole pressure; ΔΡ ,,. (Τ) is the change in pressure at the wellhead; ΔΗ (τ) is the change in the level of reservoir fluid in the production string at time τ; d - acceleration of gravity; -τ / Τ е - exponential change in the level of the liquid in the production string; p _pzh , r _n , p _{in the} density, respectively, of the reservoir fluid, oil and water; go - the water content of the reservoir fluid; P _PL - reservoir pressure; P _s - pressure in the bottom hole; 1p - a symbol of the natural logarithm; π is the number pi = 180 or 3.14; Oh, gas consumption; To _y is the gain, which at τ ^ χ is equal to Α / ΔΡ (χ); Λ = ΔΟ = 0 _Τ -Ο ₀ - an abrupt decrease in the production rate of the reservoir fluid from the current value of O _t to zero - Tso; (Ω = Ω _Τ ) for τ <0; Ω = Ωο = Ο for τ>0; τ is the current time; T is a constant time; О, _{| ж} - volumetric flow rate of formation fluid; О _н , О _ь - mass flow rate, respectively, of oil and water; C _{|| W} , μ - viscosity of the reservoir fluid and oil ( _{C pzh} = _{C n} (1 + 2.5go)); K is the permeability coefficient of the formation; B _p is the thickness of the reservoir; To _to , g _with - respectively, the radii of the power circuit and the well; P0 is atmospheric pressure; M _cf. - the average molecular weight of the gas; With ₁ M ₁ - respectively, the content and molecular weight of the ί-th component of the gas; K is the universal gas constant; N _s - the distance from the bottom to the wellhead; Η (τ) is the dynamic fluid level in the production string at time τ; ΐ is the temperature in the gas phase at time τ.