RU2542030C1 - Method of regulating well operation in regard to initial water separation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes measuring oil and water density, delivering raw oil with associated gas to the well killed by a packer through a spool, measuring quantity of delivered raw oil with associated gas as well as water-cut of raw oil, determining quantity of delivered dehydrated oil, discharging partially dehydrated oil and associated gas from annular space of the well, removing discharged water through inner annulus, measuring quantity of discharged water, measuring pressure of raw oil with associated gas at the well input, pressure of partially dehydrated oil with associated gas at the output from annular space of the well and pressure of discharged water at the output from inner annulus. Regulation is carried out by changing square area of the flow areas at the well input, at the output from annular space and at the output from inner annulus, for example, by means of gates, wherein at one or more of the above areas integral water-cut and height of these areas is measured, volumes of these areas are measured, quantity of dehydrated oil is calculated for these areas and compared with quantity of dehydrated oil delivered to the well.

EFFECT: improved reliability of the well operation control.

3 cl, 1 dwg

Description

The claimed invention relates to the field of equipment for the oil industry, and in particular to installations for separating the production of oil wells into oil and water.

A known method of operating a preliminary water discharge well, including measuring oil and gas densities, supplying crude oil with oil gas to a well plugged by a packer through a pipe insert, measuring the amount of supplied crude oil and gas, as well as the water content of crude oil, removing partially dehydrated oil and oil gas from the annulus of the well, discharge of discharged water through the inner string, measuring the amount of discharged water, the regulation is carried out by changing the area of the flow sections at the entrance to the well zhinu at the outlet from the annulus and the outlet of the inner column, for example by means of valves / VF Shayakberov Downhole installation of water discharge for well clusters // Equipment and technologies for the oil and gas complex. - M., 2009. - No. 3. - S.15-16 /.

The disadvantage of this method is the lack of reliability associated with the lack of control over the presence of oil along the wellbore, which can lead to its ingress into the inner string, as well as measuring the pressure of crude oil with oil gas at the entrance to the well, the pressure of partially dehydrated oil and oil gas the exit from the annulus of the well and the pressure of the discharged water at the exit from the inner string, which can lead to "locking" of the working part.

The closest in technical essence and the achieved result to the claimed invention is a method for regulating a preliminary water discharge well, including measuring oil and water densities, supplying crude oil with oil gas to a well plugged by a packer through a pipe insert, measuring the amount of crude oil and oil gas supplied, as well as the water cut of crude oil, determine the amount of incoming dehydrated oil, the removal of partially dehydrated oil and oil gas from the annulus of the well, the discharge of drainage water flow through the inner string, measuring the amount of water being discharged, measuring the pressure of crude oil with petroleum gas at the inlet to the well, the pressure of partially dehydrated oil and petroleum gas at the outlet of the annulus of the well and the pressure of the discharged water at the outlet of the inner string, the regulation is carried out by changing cross-sectional areas at the entrance to the well, at the exit from the annulus and at the exit from the inner string, for example, using gate valves / Shayakberov V.F., Latypov I.A. et al. Technology of preliminary cluster water discharge using decommissioned wells // Scientific and Technical Bulletin of Rosneft Oil Company. - M., 2011. - No. 3. - S. 36-37 /.

The disadvantage of this method is the lack of reliability associated with the lack of control over the presence of oil along the wellbore, which can lead to its ingress into the inner string.

The aim of the invention is to increase the reliability of regulation of the operation of the well by reducing the possibility of oil entering the inner column.

This goal is achieved in that in a method for regulating the operation of a preliminary water discharge well, including measuring oil and water densities, supplying crude oil with oil gas through a pipe insert to a well plugged by a packer, measuring the amount of supplied crude oil and oil gas, and also the water cut of crude oil, determining the amount of incoming dehydrated oil, the removal of partially dehydrated oil and gas from the annulus of the well, the discharge of discharged water through the inner string, measuring the amount discharged water, determining the content of residual oil products and mechanical impurities in the discharged water and comparing them with the geological conditions of the formation into which water is pumped, measuring the pressure of crude oil with oil gas at the well entrance, the pressure of partially dehydrated oil and oil gas at the exit of the annulus wells and pressure of discharged water at the outlet of the inner column. Determining the internal geometry of the working part, regulating the operation of the well by changing the area of the bore sections at the entrance to the well, and / or at the exit of the annulus, and / or at the exit of the inner column, for example using valves, according to the invention determine the compatibility of the discharged water with water the reservoir into which the injection is carried out, the wellbore is divided in height into one or more sections, the integrated water content in one or more sections is measured, as well as the height and volumes of these sections, determines t dehydrated oil quantity in these areas and comparing it with the incoming amount to dehydrated oil well. In addition, the hydrostatic pressure drop is measured in the method for regulating the operation of the preliminary water discharge well in sections, the integral water cut in the section is determined by the formula

;

;

where n _n is the integrated water cut (volumetric moisture content of crude oil); ρ _n - oil density; ρ _in is the density of water; Δρ _W - hydrostatic pressure drop over a fluid column in a section of a well bore with a hug height - acceleration of gravity. In addition, the chemical composition of the dissolved gas and the concentration of the components in the dissolved gas are determined, and then the volume fraction of the dissolved gas α _{g is found} , and the integral water cut in the area is determined by the formula:

.

.

Determination of the content of residual oil products and mechanical impurities in the discharged water is carried out, for example, by sampling the discharged water and their subsequent analysis. The permissible content of residual oil products and mechanical impurities in the injected water depends on the geological conditions of the formation and is determined by the permeability of the pores. If the quality of the discharged water is satisfied by the geological conditions of the formation, it can be pumped. Otherwise, you can’t upload it.

The determination of the internal geometry of the working part is necessary for calculating the flow in it. Velocity is defined as the ratio of volumetric flow rate to flow area. Dwell time is defined as the ratio of length to speed.

Water injected into the reservoir must be compatible with the water in the reservoir. The discharge of discharged water into the reservoir is possible when they are compatible.

Breakdown of the borehole in height into one or more sections allows you to determine the content of crude oil in these areas, which increases reliability.

Measurement of the integrated water cut in these areas makes it possible to determine the content of dehydrated oil on them, which ensures an increase in reliability.

Measurement of the height and volume of the plots makes it possible to measure the amount of dehydrated oil on them, which ensures increased reliability.

Determine the amount of dehydrated oil in these areas and compare it with the amount of dehydrated oil entering the well, which provides increased reliability, since this allows you to adjust the height of the column of partially dehydrated oil in the well.

Compare the amount of dehydrated oil that enters the well and which is in the areas. From this comparison, the height (depth) of the “tongue” of oil in the well is determined. If it is distributed before entering the inner column, then there is oil in the discharged water and it is unsuitable for the needs of PPD. With an increase in the amount of dehydrated oil above the amount of oil located in the section (s) of the well, a regulatory action is performed - a decrease in the amount of VNE supplied to the well, with a significant decrease - an increase in the amount of VNE. The amount of VE supplied is difficult to change in practice (you need to either stop one or more production wells; or change the operating mode of the pumps of production wells). It is simpler if there is a lot of VNE, then it is necessary to increase the amount of discharged crude oil; if VNE is small, then reduce the amount of partially dehydrated oil discharged.

For example, by determining the water cut (volumetric moisture content of crude oil) n _p under laboratory conditions, the density of the liquid - oil-water emulsion ρ _w can be calculated depending on the densities of oil ρ _n and water ρ _in :

Note that when determining n _n in laboratory conditions, the change in water cut over time is not taken into account, as well as the fact that the water cut of the sample (local) is not necessarily equal to the real (integral) water cut of the emulsion.

On the other hand, the density of the oil-water emulsion can be determined by the difference in hydrostatic pressure Δρ _W , the height of the liquid column in the borehole section h and the acceleration of gravity g:

From formulas (1) and (2) we obtain the expression for finding the integrated water content of the emulsion by the difference in its hydrostatic pressure Δρ _w at the height of the liquid column h as:

From (3) it follows that the accuracy of determining water cut increases with increasing h. To ensure a sufficient height of the liquid column, it is advisable to perform the installation in the form of a piping.

From (3) it is seen that the main absolute error in determining the integral water cut is constant regardless of the flow rate, and it can be reduced by increasing the height of the meter.

It should be noted that in contrast to the moisture meter, which determines the water content in some small place, the claimed invention determines the integral water content of partially dehydrated oil located in the borehole section. At the same time, the cost of the differential pressure sensor is much less than a hydrometer.

In the presence of dissolved gas in crude oil, the method for determining water cut from the differential pressure is supplemented by taking it into account. The molar mass of gas M _G is determined, for example, by its 6-component composition and the molar masses of the components M _{g, i} , and their concentrations k _{g, i} / USSR Author's Certificate No. 1835537, IPC ⁵ G05D 11/00. Declared: 07/04/1988. Published: 08/23/1993 /:

Relation (4) is used in the Mendeleev-Clapeyron equation to determine the volume fraction of dissolved gas α _g in crude oil.

After the statements, an expression is obtained to determine the water cut of crude oil with dissolved gas:

When α _r = 0, formula (5) is converted to (3).

The method is applicable at fields of a late stage of development, when the water cut of the produced VNE is more than 80% - this is high-water oil, where most of the water is kept in free form. According to the norms, samples from each producing well are taken every 2 weeks and oil and water densities, as well as water cut, are measured. The density of water usually varies in the range of 1000-1200 kg / m ³ . The inventive method is applicable for light (density up to 850 kg / m ³ ) and medium (density up to 890 kg / m ³ ) oils. The gas factor is any. The method of regulating the operation of the preliminary water discharge well is as follows. For selected samples in laboratory conditions, the densities of oil and water are measured. Then begins the flow of crude oil with oil gas into the well plugged by the packer through the pipe insert. Measure the amount of supplied crude oil and gas, as well as the water content of the crude oil. The amount of incoming water is defined as the product of water cut and the amount of crude oil. The amount of dehydrated oil is defined as the difference between the amounts of crude oil and water. At the exit of the tube insert, crude oil is divided into water and partially dehydrated oil. Partially dehydrated oil, together with gas, as lighter, rises up the annulus formed by the outer surface of the pipe insert and the inner surface of the well. Then, partially dehydrated oil and oil gas are removed from the annulus of the well. Water, as denser, flows down the wellbore. Discharged water is discharged through the inner column. In the inner column, the amount of discharged water is measured. The content of residual oil products and mechanical impurities in the discharged water is determined, as well as the compatibility of the discharged water with the formation water, for example, by sampling the discharged water and their subsequent analysis. If the content of residual oil products and mechanical impurities in the injected water meets the geological conditions of the reservoir and they are compatible, then this water can be injected. Otherwise, you can’t upload it. The internal geometry of the working part is determined.

At the installation, 160 m ³ / day of VNE with a water cut of 92% and an inlet pressure of 2-2.2 MPa was supplied from the article to the well with a 168 mm casing. Water was discharged 80 m ³ / day. The volume of partially dehydrated oil is 80 m ³ / day with a water cut of 84%. The pressure loss at the outlet is 0.1 MPa for partially dehydrated oil and 0.2 MPa for discharged water. Measure the pressure of crude oil with petroleum gas at the entrance to the well, the pressure of partially dehydrated oil and petroleum gas at the outlet of the annulus of the well and the pressure of the discharged water at the outlet of the inner string. The regulation is carried out by changing the area of the bore sections at the entrance to the well, and / or at the exit from the annulus, and / or at the exit from the inner column, for example, using valves.

One or more sections are distinguished in the wellbore, their height and volume are measured. In these areas, the integral water cut is measured, for example, by sampling or using densitometers. The known integrated watering of partially dehydrated oil and the volume of the site determine the amount of dehydrated oil in this area in the same way as it was done at the entrance to the well. Then, a comparison is made with the amount of dehydrated oil entering the well, according to the results of which the height of the column of crude oil in the well is regulated.

In addition, in some cases, in the method of regulating the preliminary water discharge well in sections, the differential pressure can be measured, and the integral water cut in the section is determined by the formula:

;

;

where n _n is the integrated water cut (volumetric moisture content of crude oil); ρ _n - oil density; ρ _in is the density of water; Δρ _W is the hydrostatic pressure drop over the fluid column in the section of the wellbore with a height of h and g is the acceleration of gravity.

In addition, in some cases, in the method of regulating the preliminary water discharge well, the chemical composition of the dissolved gas and the concentration of the components in the dissolved gas can be determined, and then the volume fraction of the dissolved gas α _{g can be found} , and the integral water cut in the area is determined by the formula:

.

.

One of the possible embodiments of the device for implementing the method of regulating the well preliminary discharge of water is shown in figure 1.

A device for implementing a method for controlling the operation of a preliminary water discharge well includes a well 1 plugged with a packer 2. A supply pipe 3 with a valve 4 is connected to a pipe insert 5 located inside the well 1. An oil discharge pipe 6 with a valve 7 is connected to the annulus of the well 1. Inside the pipe insert 5 is an inner column 8 with a valve 9. Inside the well 1 is a densitometer 10, which measures the change in the density of the liquid in height. The pipelines of the supply 3 and oil drain 6, as well as the inner column 8 are equipped with samplers 11, to which a pressure gauge can be connected.

в N точках по высоте плотномера 10, обводненность в этих точках определяется по формуле:A device for implementing a method of regulating the operation of a well of preliminary water discharge works as follows. Crude oil and petroleum gas are supplied through the supply pipe 3 to the pipe insert 5, from where they enter the inside of the well 1. Using a sampler 11, a sample is taken from pipeline 3 for laboratory analysis. The process of separation into partially dehydrated oil and water begins. Partially dehydrated oil and petroleum gas rise up the wellbore 1 through the annular space formed by the outer surface of the pipe insert 5 and the inner surface of the well 1 and are discharged through the oil discharge pipe 6. Water, as it is denser, flows down the wellbore 1 and is discharged along inner column 8. The height of the plot is equal to the height of the density meter 10. Using the density meter 10, a change in the density of partially dehydrated oil is determined by height. Provide a measurement of changes in the density of the liquid ρ _{W, i} $$\left(i=\overline{\mathrm{one},N}\right)$$

at N points along the height of the densitometer 10, the water cut at these points is determined by the formula:

The integrated water cut on the site is determined as the arithmetic average of local water cuts calculated by the formula (6). The volume of a section is defined as the volume of the internal cavity of the well in this section, minus the volumes of the inner string located in this section and the density meter. The well-known volume of the site and the integral water cut determines the amount of dehydrated oil in this area, which is compared with the flow into the well 1. Regulation is carried out by changing the area of the bore of the valves 4, 7 and 9.

If you measure in one area, then there will be an integrated water cut in this area. In reality, with increasing depth, water cut increases. When we measure in several areas, the change in water cut in depth is tracked more accurately. If at the lower (lower) section (s), the water cut is 100%, then the discharge capacity can be increased.

Claims (3)

1. A method of regulating the operation of a preliminary water discharge well, including measuring oil and water densities, supplying crude oil with oil gas through a pipe insert to a well plugged by a packer, measuring the amount of supplied crude oil and oil gas, as well as the water content of crude oil, determining the amount of incoming oil dehydrated oil, drainage of partially dehydrated oil and gas from the annulus of the well, discharge of discharged water through the inner string, measurement of the amount of discharged water, determination of the content I am in the discharged water of residual oil products and mechanical impurities and comparing them with the geological conditions of the formation into which the water is pumped, measuring the pressure of crude oil with oil gas at the inlet to the well, the pressure of partially dehydrated oil and oil gas at the outlet of the annulus of the well and the pressure discharged water at the outlet of the inner string, determining the internal geometry of the working part, regulating the operation of the well by changing the area of the flow cross sections at the entrance to the well, and / or at the exit of the mud the wafer space, and / or at the exit from the inner string, for example, using valves, characterized in that the compatibility of the discharged water with the water of the formation being injected is determined, the wellbore is divided in height into one or more sections, measured in one or in more areas, the integrated water cut, as well as the height and volume of these sections, determine the amount of dehydrated oil in these sections and compare it with the amount of dehydrated oil entering the well. 2. The method according to claim 1, characterized in that the hydrostatic pressure drop is measured in the sections, the integral water cut in the section is determined by the formula

;
where n _n is the integrated water cut (volumetric moisture content of crude oil); ρ _n - oil density; ρ _in is the density of water; Δp _w - hydrostatic pressure drop over the liquid column in the section of the wellbore with a height of h and g - gravity acceleration. 3. The method according to claims 1 and 2, characterized in that the chemical composition of the dissolved gas and the concentration of the components in the dissolved gas are determined, and then the volume fraction of the dissolved gas α _{g is found} , and the integral water cut in the area is determined by the formula

.

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