RU2600075C2 - Method of determining parameters of borehole flow and device for its implementation - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: present invention relates to methods and devices for studying mixed flow of gas, liquid and solid particles. Gas and liquid can be represented by water, steam and different fractions of hydrocarbons. Application field of proposed technical solution is oil and gas industry. Method of determining parameters of downhole multiphase multicomponent flow involves passing through optical signal in the wavelength range from 850 to 2,000 nm, registration of signal after its interaction with the flow and computer processing of obtained results. Signal is transmitted on at least two different wavelengths, preliminarily dividing it on optical divider into two parts, one of which is the reference, parallel recording of reference signal is performed, and obtained results processing is carried out on the basis of comparison of both signal intensity and phase. In disclosed method processing obtained results is possible to carry out on the basis of calculating flow components speed, obtaining holographic pattern of flow. Device for determining parameters of downhole multiphase multicomponent flow contains measuring chamber in form of pipe, as well as additionally contains at least one source of optical signal, at least one optical signal detector arranged with its source on same axis, optical divider, optical system for delivery of reference signal to detector in bypass of measuring chamber and processing unit, wherein source and detector are separated by walls of measuring chamber, made from material transparent for optical signal.

EFFECT: technical result is possibility of determination of concentration of different phases of multi-phase flow in investigated area, construction of spatial distribution of fluids in investigated area, evaluation of dynamics of movement and obtaining data on volume fraction of flow components.

4 cl, 2 dwg

Description

A method for determining the parameters of a borehole multiphase multicomponent flow and a device for its implementation

The present invention relates to methods and devices for studying a mixed flow of gas, liquid and solid particles. Gas and liquid can be represented by water, steam and various fractions of hydrocarbons. The scope of the proposed technical solution is the oil and gas industry.

Well production during production comes to the surface in the form of a mixture through pipes. At the wellhead (on the surface), it is required to determine the parameters of a multicomponent flow to control production. Measurements are made for each well individually, and for groups of wells. Data on the production volumes of each component are used to analyze and predict the operation of wells.

The traditional solution to the problem of determining the component flow rate (flow rate) of a multiphase borehole flow are separators. The separation method consists in completely separating the phases and / or separating the gas component and measuring the proportion of water in the remaining liquid volume. To determine the presence of particulate matter and / or water, additional equipment is also used and / or samples are taken and analyzed. Many two and three-phase installations operate on this principle: Sputnik in various modifications (AM, D, etc.), MERA-Massomer, OZNA-Impulse, SPECTR, etc.

To obtain reliable measurement of flow rates using a separator, first of all, it is necessary to completely separate the gas from the liquid and, in most cases, carry out the subsequent separation of water from oil. Then, the separated components fall into single-phase flow meters at the outlet of the separator. Most single-phase flow meters are very sensitive to the presence of other components in the flow, which leads to unreliable measurements. In fields where operating conditions, flow rates, gas-liquid and water-liquid ratios are unstable, poor phase separation is observed. Moreover, field separators are often not equipped with multi-stage or duplicate measuring systems, therefore, any ablation of a liquid by a gas stream or gas breakthrough through a liquid line is not detected and is not determined, leading to very large errors in the final measurements.

In addition to the problems associated with phase separation, separators used as measuring instruments contain many sources of errors, including calibrations, mechanical malfunctions, the problematic state of fluids (e.g. emulsions), corrosion, particulate flows and human errors. All these factors significantly reduce the accuracy of measurements by separation plants in the field.

Additionally, the disadvantages of such technical solutions are: a long time of the research cycle, as a result, the impossibility of an operational reaction in real time; low accuracy at low fluid concentrations; high price of equipment and its maintenance; the large weight and dimensions of the devices greatly complicate and increase the cost of delivery, installation and maintenance; the disadvantages include the incorrect choice of the averaging interval with a dynamically changing mode of operation of the well, which leads to significant errors, inoperability in conditions of high volume fractions of the gas component [1].

Another more modern way are non-separation or flow methods, which have a common name - multiphase flow measurement. Measurements are made without phase separation on a multiphase flow. This method has a number of significant advantages compared with the separation method both in terms of operational characteristics and in terms of data quality [2].

Measurements are taken at the wellhead by passing the test stream through the measuring chamber. The basic principle is the measurement of well fluid by various physical fields directly in the flow without significant changes in its volume, pressure and temperature (under the so-called linear conditions). The key advantage of all flow-through multiphase flow meters is high information content, good time resolution and the ability to receive data in real time, which allows us to solve a number of serious technical problems that were previously unsolvable [3]. The data obtained are the basis for making important operational decisions, such as, for example, choosing the moment of closing a loss-making well or issues of geological and technological measures at the well [2].

However, depending on the applied physical principle or combination of methods, multiphase flow meters determine the flow rate of flow components with different accuracy under different conditions.

The accuracy of the flow meters also greatly depends on the parameters of the oil density and the concentration of the liquid in the mixture. These factors limit the scope of this type of flow meter, for example, in wells with a high volumetric gas factor in linear conditions (GVF or Gas Volume Factor - the ratio of gas and liquid volumes under linear conditions of the measuring cell) when the fraction of the liquid phase is very small. Most often this occurs in gas condensate fields. To date, the greatest difficulties are measurements in the range of 80-100% GVF. All applications declared for operation in this range are either modifications of single-phase (gas) flow meters to take into account the presence of liquid in the stream, or modifications of multiphase (oil) flow meters adapted for high GVF. This approach leads to low accuracy in gas and gas condensate wells, where optimization of the extraction of light liquid hydrocarbons is especially relevant. Known modifications of single-phase flow meters, not being multiphase, have fundamental disadvantages that allow the use of such flow meters only in combination with other devices under control and with constant recalibration to reference devices.

Known devices that implement the principle of cross-correlation for a set of parameters (density, electromagnetic). An example of such a solution is the Roxar 1900 VI [4]. The disadvantages of this device are the high demands on the heterogeneity of the flow: the recorded physical field must exhibit characteristic inhomogeneities used to estimate the flow rate; the inability to detect droplets of liquid hydrocarbons in a gas stream; these systems are not capable of operating at high GVF values.

Known devices using radioactive sources of densitometry. The most famous flow meter from Schlumberger is PhaseWatcherVx. Key components of the installation: a gamma-density meter based on a radioactive source Barium-133 and a narrowing device. The temperature and pressure drop data on the constriction device (Venturi pipe) determine the total flow rate of the mixture, and the absorption spectrum of gamma rays allows you to determine the relative volume fractions of gas, oil and water [5]. These devices were developed for measuring oil with low GVF, then the technology was refined and expanded to higher GVF for gas and gas condensate studies. The disadvantages of such devices are serious difficulties in calibrating for a clean environment; great dependence on the PVT properties of the fluid, both for the transition from linear to standard conditions, and for calculations in linear conditions; the need to obtain the results of laboratory studies of the fluid before providing final information on flow rates; a long period from taking measurements to obtaining final results; high uncertainty in the vicinity of the gas point at low contents of the liquid phase; the presence of a radioactive source makes special demands on the maintenance and transportation of the device.

As a prototype of the claimed device selected tomographic section of a multiphase flowmeter FMC Tech MPM [6]. In it, the mass flow rate is calculated using differential pressure sensors installed in the venturi. Based on the method of 3-dimensional radio-frequency measurement of dielectric constant, the phase distribution in the multicomponent stream is determined. Measurements are taken in various planes. In each plane, measurements are carried out at several frequencies in a wide range. The density of a multiphase medium is determined by a gamma-density meter.

The selected prototype has a high sensitivity to changes in water cut. However, it has the following disadvantages: firstly, the need for preliminary preparation of the flow before measurement, since otherwise the tomographic principles used in the device will not work; secondly, in the low resolution of the device, associated with the specifics of the detection system and a small number of sensors [7].

From the point of view of increasing the accuracy of research under conditions of high GVF values, optical methods of investigation look attractive. Optical methods make it possible to obtain images of objects in a gas stream instead of registering fields (as it is today implemented in various methods of multiphase flow metering above). Therefore, the sensitivity of optical methods to insignificant inclusions of impurities in the gas stream allows one to obtain a much higher accuracy of measurements in the liquid phase (liquid droplets in the gas stream). The most accurate methods are a 3-dimensional method of digital tracer visualization (or DPIV) and a method of digital holography, since they allow you to restore the flow structure and get a three-dimensional picture.

The DPIV method is used to study the spatial distribution of particles, drops, bubbles in a stream (hereinafter referred to as particles), as well as to determine their speed of movement and size [8]. A laser is used as the radiation source, and at each hole there is a photosensitive matrix recording the scattered radiation. Particle coordinates are determined numerically, and using the standard cross-correlation method (double measurement with a fixed time difference), the speed of movement is calculated. The particle size is calculated based on the intensity of the scattered radiation. The disadvantages of this method are the difficulty of accounting for errors in the calculation of coordinates, the inability to determine the phases in cases of multiphase flow and the need for laborious calibration to measure particle sizes. In addition, the minimum size of the measured particle is 200 μm, which is a significant limitation.

Digital holography is also used to visualize plankton in a water stream [9]. In the measurement scheme, the object beam is a laser beam of light diffracting at the object of study, and the reference beam is a beam that freely passed through the volume of the medium under study. The device detects the interference pattern of the object and reference beam, called a hologram. Further, processing algorithms allow reconstructing images of oceanic plankton from reconstructed images and calculating the trajectory of objects of interest directly from holograms. The disadvantages of the installation, created by the authors, is the ability to work only with two-phase media in which the density of the second phase does not distort the collimated beam of light. In addition, this method, like the one described above, does not allow phase separation in a multiphase flow.

Based on the sources described above, we can say that the prototype of the proposed method is a technical solution for visualizing plankton by holographic methods.

The objective of the proposed technical solution is to develop a method for high-precision determination of the concentration of phase components in multiphase flows and devices for its implementation.

The technical results of the invention are the ability to determine the concentration of various phases of the multiphase flow in the study area, the construction of the spatial distribution of fluids in the study area, the assessment of the dynamics of motion and obtaining data on the volume fractions of the components of the stream.

Technical results are achieved due to the fact that in the method for determining the parameters of a borehole multiphase multicomponent stream, including passing an optical signal through the stream in the wavelength range from 850 to 2000 nm, registering the signal after it interacts with the stream and computer processing the results, the signal is sent to less than two different wavelengths, after dividing it on an optical divider into two parts, one of which is the reference, parallel registration of the reference on signal and processing of results performed by comparing the signals of both the intensity and phase, yielding a holographic picture stream.

In the inventive method, the processing of the obtained results can be carried out on the basis of calculating the speed of the flow components.

Technical results are also achieved due to the fact that the device for determining the parameters of the borehole multicomponent stream, containing a measuring chamber in the form of a pipe, additionally contains at least one optical signal source, at least one optical signal detector with the possibility of obtaining a holographic picture of the stream located with its source on one axis, an optical divider, an optical system for delivering a reference signal to the detector bypassing the measuring chamber and the processing unit, while the source and the detector are separated by the walls of the measuring chamber made of a material transparent to the optical signal.

The device may further comprise a scattered radiation signal detector located at a predetermined distance from the optical signal detector along the axis.

The essence of the claimed device for determining the parameters of a borehole multiphase multicomponent flow is illustrated by drawings, where in Fig. 1 schematically shows a longitudinal section, in Fig. 2 is a cross-sectional view of the device.

The device comprises a measuring chamber 1 in the form of a pipe, an optical signal source 2, an optical divider 3, an optical signal detector 4, an optical system 5 for delivering a reference signal, and a wall 6 made of optically transparent material.

The implementation of the proposed method using this device to determine the parameters of the borehole multiphase multicomponent flow is as follows.

The studied stream is passed through the measuring chamber 1. The signal from the source 2 is fed to the optical divider 3, after which one part (object) is passed through the wall 6 into the chamber 1 and then through the multiphase multicomponent stream at a given angle. The optical signal passing through the multiphase multicomponent stream passes through the wall 6 to the detector 4. At the same time, the second part of the signal (reference) from the source 2, obtained on the optical divider 3 through the optical delivery system 5, is fed to the detection device of the processing unit. As such a detecting device, either a separate detector or a detector 4 can be used. Next, the optical signals (reference and reference) are compared with each other and the results are processed in the processing unit, resulting in data on the qualitative and quantitative composition of the studied stream in the form of holographic picture.

The inventive method and the device used for its implementation make it possible to distinguish between liquid droplets with various optical properties (oil, condensate or water). The presence of a separate optical delivery system for the reference signal allows you to get a holographic picture in conditions when the reference signal is not able to pass through the volume under study without hindrance.

Literature

1. The evolution of multiphase flow measurements and their impact on operational management. E. Toski, B.V. Hanssen, D. Smith, Schlumberger, 3 Phase Measurements, Bergen, Norway, B. Teuveny, Schlumberger, Cambridge, UK

(http://www.oilcapital.ru/edition/technik/archives/technik/technik_06_2003/66466/public/66502.shtml)

2. Devegowda, D. and S.L. Scott: "Assessment of Subsea Production Systems" paper presented at the SPE Annual Technical Meeting & Exhibition, Denver (Oct. 5-8, 2003), SPE J. of Petroleum Tech., 56-57 (http: //www.rogtecmagazine .com / PDF / Issue_011 / 06_Multiphase.pdf).

3. Mehdizadeh, P., B. Ghaempanah and S. L. Scott: "Impact of Data Quality on Production Allocation and Reserves Forecasting," paper presented at the SPE ATCE, San Antonio

4.http: //www2.emersonprocess. com / enus / brands / roxar / flowmetering / metermgsystems / pages / roxarmultiphasemeter.aspx.

5. Vx Technology Multiphase flow rate measurements without fluid separation (http: //www.slb.corn/~/media/Files/testing/brochures/multiphase/vx_technology_brochure.pdf)

6. MPM flowmeter (http://www.mpm-no.com/mpmproducts/)

7. Method and apparatus for tomographic multiphase flow measurements (US 20090126502 A1)

8. F. Pereira, M. Gharib and others "Defocusing digital particle image velocity: a 3-component 3-dimensional DPIV measurement technique. Application to bubbly flows."

9. J. A. Dominguez-Caballero, N. Loomis and others "Advances in Plankton Imaging using Digital Holograph"

Claims (4)

1. A method for determining the parameters of a borehole multiphase multicomponent stream, including passing an optical signal through the stream in the wavelength range from 850 to 2000 nM, registering the signal after it interacts with the stream and computer processing the results, characterized in that the signal is applied to at least two different wavelengths, having previously divided it into two parts on the optical divider, one of which is the reference one, parallel registration of the reference signal is performed, and processing is obtained x results are carried out based on a comparison of both signals in intensity and phase, obtaining a holographic picture of the stream. 2. The method according to p. 1, characterized in that the processing of the obtained results is carried out on the basis of calculating the speed of the flow components. 3. A device for determining the parameters of a borehole multiphase multicomponent stream, containing a measuring chamber in the form of a pipe, characterized in that it further comprises at least one optical signal source, at least one optical signal detector with the possibility of obtaining a holographic picture of the stream, located with its source on one axis, optical divider, optical system for delivering a reference signal to the detector bypassing the measuring chamber and the processing unit, while the source and detector from divided by the walls of the measuring chamber made of a material transparent to the optical signal. 4. The device according to p. 3, characterized in that it further comprises a scattered radiation signal detector located at a predetermined distance from the optical signal detector along the axis.

Images