WIDE RANGE MULTI-PHASE FLOW METER

A multiphase flow meter (MPFM) for determining component flowrates of multiple component phases within a multiphase mixture having a multiphase flowrate is disclosed. The MPFM may include a first venturi having a first constriction diameter; a second venturi having a second constriction diameter; a gamma ray tomograph fluidly connected to the first venturi and the second venturi; and a tomography controller communicably connected to the gamma ray tomograph. The tomography controller may be configured to calculate a first venturi multiphase flowrate using a first pressure change sensed across the first venturi and a second venturi multiphase flowrate using a second pressure change sensed across the second venturi. Additionally, the tomography controller may be configured to determine the component flowrates of the multiple component phases using a multiphase flowrate calculated from the first venturi multiphase flowrate and the second venturi multiphase flowrate.

BACKGROUND

In oil and gas, it is often important to know the volume or mass of each constituent phase within a multiphase fluid mixture. For example, it may be very important to know the relative fractions of water, oil, and gas being produced from a well as well as their individual flowrates. Traditionally, to determine the fraction of each component phase within an overall fluid, the phases first had to be separated using large, slow, expensive pressure vessel separators such as a three-phase separator.

Alternatively, multi-phase flow meters (MPFMs) may instead be used to simultaneously measure the individual fluid flowrates and volume fractions of multiple phases within a multiphase fluid mixture. These MPFMs rely on a variety of modern characterization techniques, including electromagnetic methods such as microwaves, SONAR, gamma ray densitometry, and others.

SUMMARY OF INVENTION

Some embodiments may describe a multiphase flow meter (MPFM) for determining component flowrates of multiple component phases within a multiphase mixture having a multiphase flowrate. The MPFM may comprise a first venturi having a first constriction diameter; a second venturi having a second constriction diameter; a gamma ray tomograph fluidly connected to the first venturi and the second venturi; and a tomography controller communicably connected to the gamma ray tomograph. In some embodiments, the tomography controller may be configured to calculate a first venturi multiphase flowrate using a first pressure change sensed across the first venturi and a second venturi multiphase flowrate using a second pressure change sensed across the second venturi. In some embodiments, the tomography controller may also be configured to determine the component flowrates of the multiple component phases using a multiphase flowrate calculated from the first venturi multiphase flowrate and the second venturi multiphase flowrate.

In some embodiments, the multi-phase flow meter may further comprise a fluid inlet into which the multiphase mixture enters the MPFM and a fluid outlet out of which the multiphase mixture exits the MPFM.

In some embodiments, the multi-phase flow meter may further comprise a blind T-bend that is fluidly connected to and upflow from the gamma ray tomograph. In some embodiments, the blind T-bend may be configured such that the multiphase mixture flows roughly vertically upward when downflow from the blind T-bend.

In some embodiments, the first constriction diameter may be smaller than the second constriction diameter.

In some embodiments, the multi-phase flow meter may further comprise a first pressure sensor disposed proximate to a first venturi inlet; a second pressure sensor disposed within or proximate to a first constriction; a third pressure sensor disposed proximate to a second venturi inlet; and a fourth pressure sensor disposed within or proximate to a second constriction. In some embodiments, the first pressure change may be determined between the second pressure sensor and the first pressure sensor. In some embodiments, the second pressure change may be determined between the fourth pressure sensor and the third pressure sensor.

In some embodiments, the gamma ray tomograph may comprise a gamma ray source disposed adjacent to one of the first or the second venturi that generates a gamma ray orthogonal to a flow direction in the one of the first or the second venturi. In some embodiments, the gamma ray tomograph may also comprise a gamma ray detector disposed so as to detect the gamma ray generated by the gamma ray source.

In some embodiments, the gamma ray tomograph may comprise a gamma ray source disposed adjacent to a sensor tube of the gamma ray tomograph that generates a gamma ray orthogonal to a flow direction in the sensor tube. In some embodiments, the gamma ray tomograph may also comprise a gamma ray detector disposed so as to detect the gamma ray generated by the gamma ray source.

In some embodiments, the tomography controller may determine a water volume fraction, a gas volume fraction, and an oil volume fraction of the multiphase mixture.

In some embodiments, the first venturi may be a supplemental venturi that is added to the second venturi that may be previously installed in a wellbore.

In some embodiments, a ratio between the first and second venturi constriction diameters may be between 0.10 and 0.80.

In some embodiments, a ratio between the first constriction diameter and a first inlet diameter may be between 0.10 and 0.70.

In some embodiments, a ratio between the second constriction diameter and a second inlet diameter may be between 0.40 and 0.90.

Some embodiments may describe a method for operating a multi-phase flow meter (MPFM) to determine component flowrates of multiple component phases within a multiphase mixture having a multiphase flowrate. Some embodiments of the method may comprise flowing the multiphase mixture through the MPFM into a fluid inlet, through a first venturi, a gamma ray tomograph, and a second venturi, and out a fluid outlet of the MPFM. Some embodiments of the method may also comprise calculating a first venturi multiphase flowrate using a first pressure change measured across the first venturi, calculating a second venturi multiphase flowrate using a second pressure change measured across the second venturi, and determining the multiphase flowrate using the first and the second venturi multiphase flowrates. Some embodiments of the method may comprise determining the component flowrates of the multiple component phases using the multiphase flowrate and a gamma ray data signal generated by a gamma ray detector of the MPFM.

In some embodiments, a range of measurement of the multiphase flowrate by the MPFM may be between 500 barrels per day (BPD) and 14,000 BPD.

In some embodiments, determining the multiphase flowrate may further comprise applying a predetermined flowrate threshold to select the first or the second venturi multiphase flowrates to determine the multiphase flowrate.

In some embodiments, determining the multiphase flowrate may further comprise applying a predetermined pressure change threshold to select the first or the second venturi multiphase flowrates to determine the multiphase flowrate.

In some embodiments, determining the multiphase flowrate may further comprise determining a difference between the first venturi multiphase flowrate and the second venturi multiphase flowrate and using the difference to select between the first venturi multiphase flowrate and the second venturi multiphase flowrate to determine the multiphase flowrate.

In some embodiments, determining the multiphase flowrate may further comprise equating the multiphase flowrate with one of the first or the second multiphase flowrate reflecting a larger constriction diameter and equating the multiphase flowrate with an other of the first or the second multiphase flowrate after the first and the second multiphase flowrates diverge.

In some embodiments, determining the multiphase flowrate may further comprise equating the multiphase flowrate with one of the first or the second multiphase flowrate reflecting a larger constriction diameter and equating the multiphase flowrate with an other of the first or the second multiphase flowrate after the first and the second multiphase flowrates converge.

In some embodiments, determining the multiphase flowrate may further comprise applying input from an electric submersible pump fluidly connected to the MPFM to select the first or the second multiphase flowrate.

Throughout the figures, similar numbers are typically used for similar components.

In the figures, down is toward or at the bottom and up is toward or at the top of the figure. “Up” and “down” are generally oriented relative to a local vertical direction. However, as used throughout this disclosure, the terms “upflow” and “downflow” may refer to a position relative to the general direction of process or fluid flow, with upflow indicating a direction or position closer to start of the process and downflow referring to the direction or position closer to the end of the process. One of ordinary skill in the art would readily understand that an object or a process may be upflow or downflow of another object or process while having no general relation to the position relative to vertical orientation unless otherwise specifically stated.

DETAILED DESCRIPTION

Multi-phase flow meters (MPFM) often rely on gamma ray tomography to dynamically measure droplet size and velocity within a flowing fluid. These tomography results along with other measurements such as density, pressure, temperature, and overall fluid flowrate may be entered into specialized fluid flow models to determine the individual flowrates of each component.

Gamma ray MPFMs are superior to other MPFM technologies because they may be used with multiphase mixtures having a gas volume fraction (GVF) over 95% percent, can more accurately determine the GVF, can directly measure fluid density, and can improve interpretation of intermittent flow (for example, plug and slug type flows).

Embodiments disclosed herein describe a gamma ray tomography-based, dual venturi MPFM. Specifically, the MPFM includes a gamma ray tomograph located between two venturi having different inner diameters to accommodate a wider range for measuring three phase fluid rates. Further, one or more embodiments propose to install double venturis in existing single venturi MPFMs to accommodate high and low range flowrate measurement, without the need to replace or resize existing meters.

An MPFM may be located in line with a production well to measure the composition of the production effluent. Thus, MPFMs may be deployed adjacent to or near a well, such as on the well pad or subsea. The MPFM may be located within about 50 meters from a well head.

FIG. 1depicts an embodiment of a MPFM100through which a multiphase mixture flows, as is depicted with an arrow101.

Fluid of the multiphase mixture101enters MPFM100via a fluid inlet110and ultimately exists the MPFM100via a fluid outlet180. Fluidly connected between the fluid inlet110and the fluid outlet180are a first venturi120, a gamma ray tomograph140, and a second venturi160. A tomography control system190including a tomography controller191is communicably connected to the gamma ray tomograph140via a data connection193.

The direction of the multiphase mixture flow is indicted with arrows101at both the fluid inlet110and the fluid outlet180. Thus, in one or more embodiments, the multiphase mixture101flows through the MPFM100sequentially through the fluid inlet110, the first venturi120, the gamma ray tomograph140, the second venturi160, and the fluid outlet180.

A venturi is a region of a pipe where fluid flow is restricted or choked. Due to Bernoulli's principle, a flow restriction results in a reduction of the fluid pressure within the restriction that is mathematically related to the flowrate of the fluid through the restriction. Consequently, a venturi may be used to measure the flowrate of a fluid, such as a multiphase mixture flowing through such a device. A flow meter that employs a venturi to measure the flowrate of a fluid may be called a venturi meter.

In the MPFM100, the first venturi120has a first venturi throat121with a first constriction diameter Dc1. Similarly, the second venturi160has a second venturi throat161with a second constriction diameter Dc2. InFIG. 1, the first constriction diameter Dc1is smaller than the second constriction diameter Dc2. Those skilled in the art will appreciate that although the first venturi120is shown with the smaller diameter, the MPFM100may be arranged such that the first venturi120has a larger diameter than the second venturi160.

The gamma ray tomograph140is located between the first venturi120and the second venturi160. The gamma ray tomograph140as depicted inFIG. 1includes a sensor tube141, a gamma ray source151, and a gamma ray detector153. The sensor tube141of the gamma ray tomograph140fluidly connects the first venturi120to the second venturi160.

The number and the energy of the gamma rays that successfully transmit from the gamma ray source151to the gamma ray detector153depend on the composition of the multiphase mixture101flowing within the sensor tube141. To that end, water is a strong absorber of gamma rays and gas is a weak absorber of gamma rays. Consequently, the gamma ray tomograph140generates a data signal that reflects the transmitted gamma rays. This data signal may be one of the inputs used to determine the composition of the multiphase mixture101. Additional details about this calculation are discussed below.

InFIG. 1, the gamma ray source151is located adjacent to the sensor tube141and generates a gamma ray that may be detected by the gamma ray detector153. Specifically, the gamma ray source151generates a gamma ray roughly orthogonal to the direction of the multiphase mixture101flow. In one or more embodiments, the gamma ray source151may use any radioactive, gamma ray producing materials known in the art to generate the gamma ray, such as americium241, barium133, cesium137, or a combination.

The gamma ray detector153is configured to detect the transmitted gamma rays. In one or more embodiments, the gamma ray detector153may be located across the sensor tube141from the gamma ray source151. The gamma ray detector153may detect some fraction of the gamma rays generated by the gamma ray source151. The gamma rays detected by the gamma ray detector153may have a different energy than the source gamma rays emitted by the gamma ray source151. In one or more embodiments, the gamma ray detector153is configured to generate a gamma ray data signal depending upon the detected gamma rays and transmit the gamma ray data signal to the tomography controller191.

The gamma ray tomograph140disclosed herein may employ various technologies in the gamma ray source151, the gamma ray detector153, or both. In one or more embodiments, the gamma ray tomograph140may be a scanning tomograph. Thus, in one or more embodiments, the gamma ray source151may be configured to emit gamma rays through a range of angles around the sensor tube141, and the gamma ray detector153may be configured to detect gamma rays through a range of angles around the sensor tube141. Alternatively, in one or more embodiments, the gamma ray tomograph140may be an instant, non-scanning tomograph. In one or more embodiments, the gamma ray tomograph140may include more than one gamma ray source151, and correspondingly, more than one gamma ray detector153.

The sampling frequency is the frequency at which measurements are performed by a measurement device. In the depiction ofFIG. 1, the sampling frequency is the frequency at which gamma rays are measured by the gamma ray detector153. The sampling frequency of the gamma ray detector153may vary. In one or more embodiments, the sampling frequency of the gamma ray detector153may be once per second or faster.

In one or more embodiments, the gamma ray source151, the gamma ray detector153, or both may essentially occupy a single point, a wider arc, or essentially the entire circumference around the sensor tube141.

Gamma ray absorption is the energy difference between the incoming gamma ray from the gamma ray source151and the detected gamma ray at the gamma ray detector153. In one or more embodiments, the gamma ray tomograph140may rely on single or multiple gamma ray absorption.

InFIG. 1, the tomography control system190is communicatively connected to the gamma ray tomograph140(specifically the gamma ray detector153) via the data connection193. As depicted inFIG. 1, in one or more embodiments, the tomography control191may be communicably connected to the gamma ray detector153via the data connection193. In one or more embodiments, the gamma ray detector153may send a gamma ray data signal to the tomography controller191. In one or more embodiments, the tomography controller191may be communicably connected to the gamma ray source151via a data connection (not depicted). In one or more embodiments, the tomography controller191may control the gamma ray source151. In one or more embodiments, the tomography controller191may be communicably connected to both the gamma ray source151and the gamma ray detector153via one or more data connections (not depicted).

In one or more embodiments, although not shown, the tomography control system190includes one or more processors and a computer-readable medium that stores computer instructions executable by the processors. The tomography control system190includes the tomography controller191that interprets the received measurement data into outputs relating to fluid characteristics of the multiphase mixture, such as density, temperature, pressure, viscosity, a combination of these characteristics, or other characteristics.

In one or more embodiments, the tomography control system190, the tomography controller191, or both may be a microcontroller, a computer (such as a personal computer, minicomputer, workstation, or mainframe), a dedicated controller (such as a programmable logic controller), or a combination thereof.

In one or more embodiments, the data connection191may be a wire, a data cable (such as a coaxial cable, a multi-core cable, a ribbon cable, an Ethernet cable, a token ring cable, an optical fiber cable, a serial cable, or a USB cable), a wireless connection (such as Wi-Fi or Bluetooth) or any other wired or wireless data connection191known in the art.

In one or more embodiments, the multiphase mixture101passing through the MPFM100may be a mixture of multiple component phases. Each component phase of the multiphase mixture101has a component flowrate, a component volume fraction, and a component mass fraction. In one or more embodiments, the MPFM100may measure the component flowrate for each of the component phases within the multiphase mixture101flow. The method for determining the component flowrates of each component phase within the multiphase mixture101using the MPFM100is discussed in detail inFIG. 6below.

In one or more embodiments, the multiphase mixture101may contain a polar liquid, such as water. Specifically, the multiphase mixture101may contain water having a water volume fraction (WVF). The water within the multiphase mixture101may contain dissolved solids (such as dirt), ions (such as dissolved salts), or a combination thereof. In one or more embodiments, the multiphase mixture101may contain brackish water or ocean water.

In one or more embodiments, the multiphase mixture101may contain a gas having a gas volume fraction (GVF). “Gas” here may be used to describe a mixture of one or more gases, such as wet natural gas. In one or more embodiments, the gas within the multiphase mixture101may be a mixture of hydrocarbon gas(es) (such as methane or ethane) and non-hydrocarbon gas(es) (such as carbon dioxide or water vapor).

In one or more embodiments, the multiphase mixture101may contain a non-polar liquid, such as a non-aqueous liquid. In one or more embodiments, the multiphase mixture101may contain oil. “Oil” here may be used to describe a mixture of one or more hydrocarbon liquid(s) such as crude oil. In one or more embodiments, the multiphase mixture101may contain oil having an oil volume fraction (OVF).

In one or more embodiments, the multiphase mixture101that flows through the MPFM100may contain two or more immiscible component phases (for example, oil and water). In one or more embodiments, the multiphase mixture101may include two or more of a polar liquid (such as water), a non-polar liquid (such as oil), or a gas. One or more component phases of the multiphase mixture101may be a homogeneous mixture (for example, crude oil). In one or more embodiments, the multiphase mixture101may be may be a mixture of two or more immiscible component phases whose distribution is heterogeneous (for example, clustered bubbles of gas within a liquid). Alternatively, the multiphase mixture101may be a mixture of two or more immiscible component phases whose distribution is roughly homogeneous (for example, a mixture of oil and gas where the gas bubbles within the oil have a roughly uniform size and have a roughly even spatial distribution). In one or more embodiments, the multiphase mixture101may be a heterogeneous mixture composed of one or more homogeneous mixtures (for example, an immiscible mixture of brackish water in crude oil).

In one or more embodiments, the multiphase mixture101flowing through the MPFM100may be a three-phase mixture of water, gas, and oil. More specifically, the MPFM100may measure a water volume fraction (WVF), a gas volume fraction (GVF), and an oil volume fraction (OVF) of the multiphase mixture101. The method for determining the WVF, OVF, and GVF using the MPFM100will be discussed inFIG. 6below.

In one or more embodiments, the multiphase mixture101flowing through the MPFM100may have a steady-state flow, a variable flow, or an intermittent flow (for example, plug and slug type flows).

In one or more embodiments, MPFM100may include a blind t-bend. A blind t-bend is a fluid component where the incoming flow cannot continue directly ahead because of a dead-end and instead the flow must be rerouted through a900turn. A blind t-bend may be used to homogenize the multiphase mixture101. In one or more embodiments, the blind t-bend may be upflow from the gamma ray tomograph or the first venturi. The blind t-bend may be fluidly located between the fluid inlet and the first venturi or between the first venturi and the gamma ray tomograph.

In one or more embodiments, MPFM100may be configured such that, downflow from the blind t-bend (upon exiting the blind t-bend), the multiphase mixture101may be flowing roughly vertical. More generally, the multiphase mixture within at least one of the first venturi, the gamma ray tomograph, and the second venturi may be flowing roughly vertical. Here, “roughly vertical” may mean less than 100 off of vertical (such as less than 5° off of vertical, less than 7.5° off of vertical, less than 10 off of vertical, and so on).

As noted above, the MPFM ofFIG. 1depicts two venturis (120,160) before and after the gammy ray tomograph140. These venturis (120,160) have different constriction diameters Dl and Dc2. Details of the venturis and associated parameters and dimensions are shown inFIGS. 2A-2C, which depict various embodiments of a venturi220. Any of the embodiments depicted inFIGS. 2A-2Ccould be a first venturi (for example,120inFIG. 1), a second venturi (for example,160inFIG. 1) or both (seeFIGS. 1 and 4). Each of the venturis220shown inFIGS. 2A-2Chas a venturi inlet223having a venturi inlet diameter Di and a venturi outlet229having a venturi outlet diameter Do. A multiphase mixture201entering the venturi220is indicated with an arrow.

When flowing from venturi inlet223to venturi outlet229, the maximum constriction of the multiphase mixture201occurs where the diameter of the venturi220is the smallest. The smallest diameter of the venturi220is located at a venturi constriction222. A venturi constriction diameter Dc is measured within the venturi constriction222. The venturi constriction222may be defined by many different components of venturi220. Thus, one or more embodiments of the venturi220and the venturi constriction222are depicted inFIGS. 2A-2Cand discussed below.

FIG. 2Adepicts an embodiment of the venturi220in the form of a “throat-type” venturi220. Here, a venturi throat221with an elongated shape serves to constrict the multiphase mixture201flow through the venturi220. Thus, the venturi constriction222is defined by the venturi throat221. The venturi constriction diameter Dc is measured within the venturi construction222and, thus, within the venturi throat221. A venturi inlet cone225directs fluid from the venturi inlet223and into the venturi throat221. A venturi outlet cone227directs fluid out of the venturi throat221into the venturi outlet229.

InFIG. 2A, the multiphase mixture201flows sequentially through the venturi220from the venturi inlet223, through the venturi inlet cone225, the venturi constriction222defined by the venturi throat221, and the venturi outlet cone227, and out the venturi outlet229.

A venturi throat length Lt may be measured along the venturi throat221. A venturi inlet angle Ai may be measured between the venturi inlet cone225and the venturi throat221. A venturi outlet angle Ao may be measured between the venturi outlet cone227and the venturi throat221. In one or more embodiments, venturi inlet angle Ai may be between about 5° and 30° (such as between 7° and 15°, between 9° and 12°, etc.). In one or more embodiments, venturi outlet angle Ao may be between about 10 and 30° (such as between 2.5° and 20°, 2.5° and 10°, etc.). In one or more embodiments, venturi throat length Lt may be between 50 millimeters (mm) and 75 mm.

One having ordinary skill in the art will appreciate that the venturi inlet angle Ai and the venturi outlet angle Ao may be designed so as to avoid undue aerodynamic drag through the venturi220. In one or more embodiments, venturi inlet angle Ai may be greater than, less than, or roughly equal to the venturi outlet angle Ao.

FIG. 2Bdepicts an embodiment of the venturi220in the form of a “notch-type” venturi220. Between the venturi inlet cone225and the venturi outlet cone227, a V-shaped notch forms the venturi constriction through which fluid flow passes. InFIG. 2B, the venturi inlet cone225directly, fluidly connects to the venturi outlet cone227at an interface224. In one or more embodiments, the interface224may be smooth or angular.

The smallest diameter of the venturi220is located at the interface224between the venturi inlet cone225and the venturi outlet cone227. Therefore, the venturi constriction222ofFIG. 2Bis defined by the interface224where the venturi inlet cone225meets the venturi outlet cone227. The venturi constriction diameter Dc is measured within the venturi constriction222and, thus, at the interface224.

The venturi inlet cone225directs fluid from the venturi inlet223into the venturi constriction222The venturi outlet cone227serves both to direct fluid from the venturi constriction222into the venturi outlet229and to define the venturi constriction222.

InFIG. 2B, the multiphase mixture201flows sequentially through the venturi220from the venturi inlet223, through the venturi inlet cone225, the venturi constriction222defined by the interface224, and the venturi outlet cone227, and out the venturi outlet229.

In the venturi design ofFIG. 2B, the venturi inlet angle Ai may be measured between the venturi inlet cone225and a line tangent to the interface224. The venturi outlet angle Ao may be measured between the venturi outlet cone227and a line tangent to the interface224.

FIG. 2Cdepicts an embodiment of a venturi220in the form of a “orifice-type” venturi220. This venturi220differs from the venturi220depicted inFIGS. 2A and 2Bin that it lacks the venturi inlet cone225, the venturi throat221, and the venturi outlet cone227. Instead, located between the venturi inlet223and the venturi outlet229is a venturi orifice plate226perforated by an orifice228. In one or more embodiments, the orifice228boundary may be smooth or angular.

The smallest diameter of the venturi220the orifice228defined by the venturi orifice plate226. Therefore, inFIG. 2C, the venturi constriction222is equivalent to the orifice228. Additionally, the venturi constriction222is similarly defined by the venturi orifice plate226. The venturi constriction diameter Dc is measured within the venturi constriction222and, thus, is equal to the diameter of the orifice228. For clarity, the orifice228points to the boundary of the orifice228as defined by the venturi orifice plate226, while the venturi constriction222points to the opening in the venturi orifice plate226.

InFIG. 2C, the multiphase mixture201flows sequentially through the venturi220from the venturi inlet223, through the venturi constriction222defined by the venturi orifice plate226, and out the venturi outlet229.

In addition to the configurations depicted inFIGS. 2A-2C, further configurations of the venturi220and the venturi constriction222will be apparent to one having skill in the art. Any suitable venturi220configuration, now known or later developed, may be employed in the MPFM described herein and shown inFIGS. 1 and 4.

Continuing withFIGS. 2A-2C, in one or more embodiments, within a single venturi220, venturi inlet diameter Di may be essentially equal to the venturi outlet diameter Do. Alternatively, in one or more embodiments, within a single venturi220, the venturi inlet diameter Di may not be equal to the venturi outlet diameter Do, and may be smaller or larger than the venturi outlet diameter Do. In one or more embodiments, the venturi inlet diameter Di may be between 75 mm and 125 mm. In one or more embodiments, the venturi outlet diameter Do may be between 75 mm and 125 mm.

In one or more embodiments, within a single venturi220, the venturi constriction diameter Dc may be less than the venturi inlet diameter Di, the venturi outlet diameter Do, or both. In one or more embodiments, the venturi constriction diameter Dc may be between 10 mm and 90 mm (such as between 15 and 75 mm, between 20 mm and 65 mm, etc.). In one or more embodiments, the venturi constriction diameter Dc may be between 10% and 90% smaller than the venturi inlet diameter Di (such as between 15% and 75% smaller, between 20% and 65% smaller, etc.). In one or more embodiments, the venturi constriction diameter Dc may be between 10% and 90% smaller than the venturi outlet diameter Do (such as between 15% and 75% smaller, between 20% and 65% smaller, etc.).

Some embodiments of the venturi220ofFIG. 2A-2Cmay include one or more transitions such as those between the venturi inlet223and the venturi inlet cone225, between the venturi inlet cone225and the venturi throat221, between the venturi throat221and the venturi outlet cone227, and/or between the venturi outlet cone227and the venturi outlet229. In one or more embodiments, transitions within the venturi220may be smooth, angular, or a combination.

FIGS. 3A-3Cdepict various forms of venturis320as depicted inFIGS. 2A-2C: a throat-type venturi, a notch-type venturi, and an orifice-type venturi, respectively. Similar toFIGS. 2A-2C, inFIGS. 3A-3Ca multiphase mixture301flows into a venturi inlet323and out a venturi outlet329. A venturi constriction322indicates the location of the narrowest diameter within the venturi320.FIGS. 3A and 3Binclude a venturi inlet cone325and a venturi outlet cone327.FIG. 3Adepicts the venturi320where the venturi constriction322is defined by a venturi throat321, an elongated structure in the center of the venturi320.FIG. 3Bdepicts the venturi220where the venturi constriction322is defined by an interface324between the venturi inlet cone325and the venturi outlet cone327.FIG. 3Cdepicts the venturi320that includes a venturi orifice plate326perforated by an orifice328where the venturi constriction322is equivalent to the orifice328. Such a venturi320as depicted inFIGS. 3A-3Cmay be a first venturi, a second venturi, or both as depicted inFIGS. 1 and 4.

FIGS. 3A-3Cdepict potential locations of multiple pressure sensors that may be incorporated into one or more embodiments of the venturi320. For example,FIGS. 3A-3Cdepict a venturi inlet pressure sensor333that measures a venturi inlet pressure Pi, a venturi outlet pressure sensor339that measures a venturi outlet pressure Po, and a venturi constriction pressure sensor332that measures a venturi constriction pressure Pc. Again, similar to the location of the venturi constriction322, the venturi constriction pressure sensor332may be located within the narrowest section of the venturi320, whether or not the venturi320has a discrete venturi throat321.

Venturi320may include one or more pressure sensors332,333,339that measure the venturi inlet pressure Pi, the venturi outlet pressure Po, the venturi throat pressure Pt, or a combination. In one or more embodiment, the pressure sensors (332,333,339) may have a sampling rate of one or more times per second.

In one or more embodiments, the pressure sensor(s)333,332,339in the venturi320may be able to measure pressures ranging from between 1 pound per square inch (psi) and 100 psi (such as between 2 psi and 75 psi, between 3 psi and 40 psi, etc.).

The pressure sensor(s)333,332,339within the venturi320may be of any suitable type. For example, the pressure sensor(s)333,332,339within the venturi320may be piezoresistive strain gauge, capacitive, electromagnetic, strain-gauge, optical, potentiometric, force balancing, resonant, thermal, ionization, or any suitable combination thereof.

One having ordinary skill in the art will appreciate how one or more types of pressure sensor(s)333,332,339may be implemented in the venturi320. In one or more embodiments, one or more pressure sensor(s)333,332,339within the venturi320may be an absolute pressure sensor, a gauge pressure sensor, a vacuum pressure sensor, a differential pressure sensor, a sealed pressure sensor, or a combination. Further, one having ordinary skill in the art will readily understand that the locations of the pressure sensors are not limited to the arrangement shown inFIGS. 3A-3C. The pressure sensors may be located anywhere inside or outside the venturi, without departing from the scope as disclosed herein, as long as the pressure in desired areas is able to be measured. In one or more embodiments, one or more of the pressure sensor(s)333,332,339may be a differential pressure sensor that measures a pressure difference between the venturi inlet pressure Pi and the venturi outlet pressure Po, between the venturi inlet pressure Pi and the venturi constriction pressure Pc, between the venturi constriction pressure Pc and the venturi outlet pressure Po, or a combination. In one or more embodiments, the pressure sensor(s)333,332,339may be absolute pressure sensor(s), vacuum pressure sensor(s), or a combination of such sensors that measure an absolute pressure (relative to vacuum) for the venturi inlet pressure Pi, the venturi constriction pressure Pc, the venturi outlet pressure Po, or a combination. In one or more embodiments, the pressure sensor(s)333,332,339may be gauge pressure sensor(s), sealed pressure sensor(s), or a combination that measure a pressure relative to a common standard (such as atmospheric pressure or another reference pressure) for the venturi inlet pressure Pi, the venturi throat pressure Pt, the venturi outlet pressure Po, or a combination.

In one or more embodiments, the pressure sensor(s)333,332,339within the venturi320may withstand and function under the environmental conditions present downhole in an oil and gas well. Some environmental conditions that may be present include an elevated temperature (up to 300° C.), a chemically corrosive environment, and other environmental conditions known to those of ordinary skill in the art.

A multiphase flowrate through the venturi320may be calculated using one or more equations, which vary depending upon the venturi320geometry and the location of the pressure sensors333,332,339. These equations relate a pressure change across the venturi320to the multiphase flowrate of the multiphase mixture301through said venturi320.

In one or more embodiments, the multiphase flowrate equations may depend on the overall configuration and geometry of venturi320. In one or more embodiments, these multiphase flowrate equations may differ for a venturi320in the form of a throat-type venturi as inFIG. 3A; a venturi320in the form of a notch-type venturi as inFIG. 3B; and a venturi in the form of an orifice-type venturi as inFIG. 3C. Further, the multiphase flowrate equations may depend on the placement of the pressure sensors333,332,339that measure a pressure change across a venturi320. In one or more embodiments, the multiphase flowrate equations may depend on the venturi inlet pressure Pi, the venturi constriction pressure Pc, or the venturi outlet pressure Po, or a combination.

In one or more embodiments, a pressure change across the venturi320may be calculated using the venturi inlet pressure Pi and the venturi outlet pressure Po. Alternatively, in one or more embodiments, a pressure change across the venturi320may be calculated using the venturi inlet pressure Pi and the venturi constriction pressure Pc. In one or more embodiments, a pressure change across the venturi320may be calculated using the venturi constriction pressure Pc and the venturi outlet pressure Po. Bernoulli's Principal may be used to calculate the multiphase volumetric flowrate (Q), using:

where ρ is the density of the multiphase fluid, Pi and Pc are the venturi inlet and constriction pressures, and Di and Dc are the venturi inlet and constriction diameters. One having skill in the art will appreciate how Bernoulli's principal may be adjusted to calculate the multiphase volumetric flowrate using venturi inlet pressure Pi and the venturi outlet pressure Po or venturi constriction pressure Pc and the venturi outlet pressure Po. Further, one having skill will appreciate how calculations based on Bernoulli's principal may be adjusted to compensate for the effects of molar mass, temperature, and pressure on density and concentration.

FIG. 4depicts a more detailed version of the MPFM ofFIG. 1. Many of the same measurements and values (e.g., diameters, angles, etc.) described inFIG. 1are shown with respect toFIG. 4. Those skilled in the art will appreciate that these values may be the same as those described above.

InFIG. 4, a multiphase mixture401enters a MPFM400via a fluid inlet410and ultimately exits the MPFM400via a fluid outlet480. Fluidly connected between the fluid inlet410and the fluid outlet480are a first venturi420, a sensor tube441of a gamma ray tomograph440, and a second venturi460. A tomography control system490including a tomography controller491is communicably connected to the gamma ray tomograph440via a data connection493. The gamma ray tomograph440also includes a gamma ray source451and a gamma ray detector453. Sensor tube441has a sensor tube diameter Ds.

In the MPFM400depicted inFIG. 4, both the first venturi420and the second venturi460have the form of a “throat-type venturi” as depicted inFIG. 2A. In one or more embodiments, the first venturi420, the second venturi460, of both may have the form a “throat-type venturi” as depicted inFIG. 2A, a “notch-type venturi,” as depicted inFIG. 2B, a “orifice-type venturi” as depicted inFIG. 2C, or any other venturi geometry known in the art.

The first venturi420has a first venturi inlet423with a first venturi inlet diameter Di1, a first venturi inlet cone425with a first venturi inlet angle Ai1, a first venturi throat421with a first venturi constriction diameter Dc1, a first venturi outlet cone427with a first venturi outlet angle Ao1, and a first venturi outlet429with a first venturi outlet Do1. Similarly, the second venturi460has a second venturi inlet463with a second venturi inlet diameter Di2, a second venturi inlet cone465with a second venturi inlet angle Ai2, a second venturi throat461with a second venturi constriction diameter Dc2, a second venturi outlet cone467with a second venturi outlet angle Ao2, and a second venturi outlet469with a second venturi outlet Do2.

Those skilled in the art will appreciate that the venturi inlet angle Ai1, Ai2may be the smaller than, equal to, or larger than the venturi outlet angle Ao1, Ao2. Further, those skilled in the art will appreciate that the first venturi angles Ai1, Ao1may smaller than, equal to, or larger than the second venturi angles Ai2, Ao2.

The first venturi throat421may have a first venturi throat length Lt1and the second venturi throat461may have a second venturi throat length Lt2. Those skilled in the art will appreciate that first venturi throat length Lt1may be the smaller than, equal to, or larger than the second venturi throat length Lt2.

As in MPFM400, in one or more embodiments, the first venturi outlet429, the sensor tube441, and the second venturi inlet463may be regions of the same tube located between the first venturi420and the second venturi. In one or more embodiments, the first venturi outlet diameter Do1, the sensor tube diameter Ds, and the second venturi inlet diameter Di2may be essentially equal.

InFIG. 4, apart from the restricted regions of a venturi, the diameter of the MPFM400is essentially constant. As inFIG. 4, in one or more embodiments, the first venturi inlet diameter Di1and outlet diameters Do1, the sensor tube diameter Ds, and the second venturi inlet and outlet diameters Di2, Do2may be essentially equal. In one or more embodiments, first venturi inlet diameter Di1, the first venturi outlet diameter Do1, the sensor tube diameter Ds, the second venturi inlet diameter Di2, and the second venturi outlet diameter Do2may be the same or different. In one or more embodiments, the first venturi outlet diameter Do1, the sensor tube diameter Ds, and the second venturi inlet diameter Di2may be essentially equivalent but may have a value different than the first venturi inlet diameter Di1, the second venturi outlet diameter Do2, or both.

The first venturi throat421may have a first venturi constriction diameter Dc1. Second venturi throat461may have a second venturi constriction diameter Dc2. InFIG. 4, first venturi constriction diameter Dc1is smaller than second venturi constriction diameter Dc2. In one or more embodiments, first venturi constriction diameter Dc1may be smaller than second venturi constriction diameter Dc2(as inFIG. 4) or may be larger than second venturi constriction diameter Dc2.

In one or more embodiments, the smaller constriction diameter (such as first venturi constriction diameter Dc1inFIG. 4) may be between 10 mm and 70 mm (such as between 15 and 40 mm, between 15 mm and 30 mm, etc.). In one or more embodiments, a ratio between the smaller constriction diameter (such as first venturi constriction diameter Dc1inFIG. 4) and the inlet diameter (such as first venturi inlet diameter Di1inFIG. 4) may be between 0.10 and 0.70 (such as between 0.15 and 0.40, between 0.15 and 0.30, etc.). In one or more embodiments, the larger constriction diameter (like second venturi constriction diameter Dc2inFIG. 4) may be between 40 mm and 90 mm (such as between 50 and 90 mm, between 50 mm and 65 mm, etc.). In one or more embodiments, a ratio between the larger constriction diameter (like second venturi constriction diameter Dc2inFIG. 4) and the inlet diameter (such as second venturi inlet diameter Di2inFIG. 4) may be between 0.40 and 0.90 (such as between 0.50 and 0.90, between 0.50 and 0.65, etc.). In one or more embodiments, a ratio between the smaller venturi constriction diameter (such as first venturi constriction diameter Dc1inFIG. 4) and larger constriction diameter (like second venturi constriction diameter Dc2inFIG. 4) may be between 0.10 and 0.80 (such as between 0.30 and 0.75, between 0.40 and 0.75, between 0.40 and 0.60, etc.).

InFIG. 4, the first venturi420includes a first venturi inlet pressure sensor433that measures a first venturi inlet pressure Pi1; a first venturi outlet pressure sensor439that measures a first venturi outlet pressure Po1, and a first venturi constriction pressure sensor432that measures a first venturi constriction pressure Pc1. The second venturi460includes a second venturi inlet pressure sensor473that measures a second venturi inlet pressure Pi2; a second venturi outlet pressure sensor479that measures a second venturi outlet pressure Po2; and a second venturi constriction pressure sensor472that measures a second venturi constriction pressure Pc2. The sensor tube includes a sensor tube pressure sensor443that measures a sensor tube pressure Ps.

In one or more embodiments, the first outlet pressure Po1, the second inlet pressure Pi2, and the sensor tube pressure Ps may be approximately equivalent.

One or more embodiments of the MPFM400may include some combination of the first venturi inlet pressure sensor433, the first venturi constriction pressure sensor432, the first venturi outlet pressure sensor439, the second venturi inlet pressure sensor473, the second venturi constriction pressure sensor472, the second venturi outlet pressure sensor479, and the sensor tube pressure sensor443. One or more embodiments of the MPFM400may include fewer pressure sensors than depicted inFIG. 4. One or more embodiments of the MPFM400may include the first venturi inlet pressure sensor433; the first venturi outlet pressure sensor439, the second venturi inlet pressure sensor473, and/or the sensor tube pressure sensor443; and the second venturi outlet pressure sensor479. In such an embodiment, the first pressure change across the first venturi420may reflect the first venturi inlet pressure sensor433along with the first venturi outlet pressure sensor439, the second venturi inlet pressure sensor473and/or the sensor tube pressure sensor443, while the second pressure change across the second venturi460may reflect the second venturi outlet pressure sensor479along with the first venturi outlet pressure sensor439, the second venturi inlet pressure sensor473and/or the sensor tube pressure sensor443, and. One or more embodiments of the MPFM400may include the first venturi inlet pressure sensor433, the first venturi constriction pressure sensor432, the second venturi inlet pressure sensor473, and the second venturi constriction pressure sensor472. In such an embodiment, the first pressure change across the first venturi420may reflect the first venturi inlet pressure sensor433and the first venturi constriction pressure sensor432, while the second pressure change across the second venturi460may reflect the second venturi inlet pressure sensor473, and the second venturi constriction pressure sensor472. Such a double venturi MPFM disclosed herein provides a wider range for measuring three phase fluid rates. Over time, the liquid rate decreases in producing oil wells. As a result, a single venturi based MPFM may need to be replaced to accommodate for the lower flowrates. With embodiments disclosed herein, based on the measured pressure across both venturis of the double venturi MPFM, the system is able to automatically detect (without the need to manually switch) the right venturi size and use that venturi for measuring the total flowrate passing through it.

In one or more embodiments, the MPFM400may include the tomography control system490having the tomography controller491that receives the measurements from the gamma ray detector453, from the pressure sensors associated with the two or more venturis420,460, and from any other sensor residing downhole in the wellbore as part of the MPFM400or elsewhere in the wellbore.

In one or more embodiments, the pressure sensors433,432,439,443,473,472,479of the MPFM400including those associated with the first venturi (such as the first venturi inlet pressure sensor433, the first venturi constriction pressure sensor432, the first venturi outlet pressure sensor439, or a combination); the second venturi (such as the second venturi inlet pressure sensor473, the second venturi constriction pressure sensor472, the second venturi outlet pressure sensor479, or a combination); the gamma ray tomograph (the sensor tube pressure sensor443), or a combination may be communicably connected to tomography controller491within tomography control system490. In one or more embodiments, the pressure sensors433,432,439,443,473,472,479of the MPFM400may provide pressure data, temperature data, or both, of the multiphase flow401to the tomography controller491. In one or more embodiments, the pressure sensors433,432,439,443,473,472,479may generate one or more pressure data signals that are transmitted from the pressure sensors433,432,439,443,473,472,479to the tomography controller491. In one or more embodiments, the tomography controller491may receive sensor input from the pressure sensors433,432,439,443,473,472,479in substantially real time.

In one or more embodiments, the tomography control system490includes one or more processors and a computer-readable medium that stores computer instructions executable by the one or more processors. The tomography control system490includes the tomography controller491that interprets the received measurement data into outputs relating to fluid characteristics of the multiphase mixture401, such as volume fraction, mass fraction, flowrate, density, temperature, pressure, viscosity, a combination of these characteristics, or other characteristics.

In one or more embodiments, a second venturi may be added to an existing MPFM system that already has one venturi. For example, a second, smaller venturi may be installed in the existing MPFM to accommodate a wider range of flowrate using the same meter. Thus, the MPFM system may be able to operate within a larger range of multiphase mixture flowrates. More specifically, the smaller venturi may be installed to accommodate lower rate wells, in which overall flowrates have reduced over time. Advantageously, such a double venturi MPFM leads to better data quality for lower rate wells, and also saves in the cost to replace/upgrade the existing MPFMs when liquid rates decrease at the producing wells or in adding second single venturi meter to the producing well. Furthermore, a supplemental venturi system would allow a commercially-available gamma ray tomography-based MPFM to be accurate over a larger range of flowrates.

FIG. 5depicts an embodiment of an MPFM500. Included in MPFM500is a supplemental venturi509and a gamma ray tomography-based MPFM549. Here, the embodiment is configured such that a supplemental venturi509may be placed in-line with a commercially-available gamma ray tomography-based MPFM549to increase the range of accurately-measured flowrates.

Supplemental venturi509includes a first venturi inlet523, a first venturi inlet cone525, a first venturi throat521having a constriction diameter Dc1, a first venturi outlet cone527, and a first venturi outlet529. Supplemental venturi509also includes a first venturi inlet pressure sensor533that measures a first venturi inlet pressure Pi1, and a first venturi constriction pressure sensor532that measures a first venturi constriction pressure Pc1for calculating a first multiphase fluid flowrate, as detailed previously. Finally, supplemental venturi509includes a supplemental MPFM control system510having a supplemental tomography controller511.

Gamma ray tomography-based MPFM549also includes a second venturi inlet563; a second venturi inlet cone565; a second venturi throat561having a constriction diameter of Dc2; a second venturi outlet cone567; and a second venturi outlet469with a second venturi outlet Do2. Gamma ray tomography-based MPFM549also includes a gamma ray source551and a gamma ray detector553located around second venturi throat561that also serves as a sensor tube. Further, gamma ray tomography-based MPFM549includes a second venturi inlet pressure sensor573and a second venturi constriction pressure sensor572for calculating a second multiphase fluid flowrate, as detailed previously.

A multiphase mixture501enters MPFM500via a fluid inlet510and ultimately exits the MPFM500via a fluid outlet580. Fluidly connected between fluid inlet510and fluid outlet580are the supplemental venturi509and the gamma ray tomography-based MPFM549.

InFIG. 5, gamma ray tomography-based MPFM549includes a tomography control system590(including a tomography controller591) that is connected to gamma ray detector553by data connection593. Further, supplemental venturi509includes a supplemental MPFM control system510having a supplemental tomography controller511connected to tomography control system590by a secondary data connection513. Some embodiments, as depicted inFIG. 5, may include a separate supplemental MPFM control system510connected to tomography control system590by a secondary data connection513. Some embodiments of an MPFM500that includes supplemental venturi509and gamma ray tomography-based MPFM549may lack a separate supplemental MPFM control system510, so the functions of supplemental tomography controller511may be performed by tomography controller591. In some embodiments, tomography controller591may be updated or augmented to perform the additional functions performed by supplemental tomography controller511.

In some embodiments, supplemental tomography controller511may receive data from tomography controller591, including a gamma ray data signal and a pressure data signal. Additionally, in some embodiments, supplemental tomography controller511may receive pressure data from first venturi inlet pressure sensor533and first venturi constriction pressure sensor532. By combining the data from gamma ray tomography-based MPFM549and supplemental venturi509, supplemental tomography controller511may determine a multiphase flowrate as detailed further. Thus, in some embodiments, supplemental venturi509may be installed in line with gamma ray tomography-based MPFM549(such as an existing, commercial MPFM) to increase the range where the calculated multiphase flowrate is accurate.

Supplemental tomography controller511may be upflow or downflow from gamma ray tomography-based MPFM549. Second venturi throat561constriction diameter Dc2may be larger or smaller than first venturi throat521constriction diameter Dc1. Pressure sensors in supplemental tomography controller511and gamma ray tomography-based MPFM549may be located in any location depicted inFIG. 4. While inFIG. 5, both supplemental tomography controller511and gamma ray tomography-based MPFM549have “throat-type,” supplemental tomography controller511and gamma ray tomography-based MPFM549may include any venturi type discussed previously. While not depicted inFIG. 5, the lengths and angles of the venturi within supplemental tomography controller511and gamma ray tomography-based MPFM549may be measured as discussed previously.

In some embodiments, gamma ray source151,451,551and gamma ray detector153,453,553may be located around second venturi throat161,461,561(as inFIG. 5), around a first venturi throat121,421, or around a sensor tube141,441that is not within a venturi (as inFIGS. 1 and 4). Locating the gamma ray source151,451,551and gamma ray detector153,453,553within a first or second venturi120,420,520,160,460,560may help make the overall MPFM100,400,500smaller and/or may decrease the cross-sectional area through which the gamma rays are transmitted before detection.

FIG. 6is a flow chart summarizing the method for using MPFM400to determine the component flowrates of the multiple component phases within the multiphase mixture. Specifically,FIG. 6illustrates the process by which component flowrates and/or an overall flowrate of the multiphase mixture are calculated at the time the fluid flows through the MPFM as shown inFIGS. 1 and 4, for example. As described above, embodiments disclosed herein provide a multi-venturi MPFM capable of providing a wider range of flowrate to measure (e.g., high and low range rate measurement). Based on the measured pressure across the ventures, the system should be able automatically (without the need to manually switch) to detect the right venturi size and use that detected venturi for measuring the total rate passing through it. One or more blocks inFIG. 6may be performed by one or more components as described above inFIGS. 1-4(e.g., pressure sensors, processor, etc.). One of ordinary skill in the art will appreciate that some or all of the blocks may be executed in a different order, may be combined or omitted, and some or all of the blocks may be executed in parallel. Furthermore, the blocks may be performed actively or passively.

In step S1, the multiphase mixture flows through the MPFM from the fluid inlet to the fluid outlet. Specifically, the multiphase mixture enters the fluid inlet, traverses the first venturi, the gamma ray tomograph, and the second venturi, and flows out of the fluid outlet.

In step S2, using the pressure sensors of the MPFM, a first pressure change is determined across the first venturi and a first venturi multiphase flowrate R1is calculated.

Specifically, in one or more embodiments, the first venturi inlet pressure Pi1, the first venturi outlet pressure Po1, the first venturi constriction pressure Pc1, the sensor tube pressure Ps, or a combination thereof may be used to calculate a first multiphase pressure change. Using the equations discussed previously, in one or more embodiments, the tomography controller may calculate a first venturi multiphase flowrate R1from a first pressure change across the first venturi using one or more first venturi pressure data signals.

In step S3, using the pressure sensors of the MPFM, a second pressure change is determined across the second venturi and a second venturi multiphase flowrate R2is calculated.

In one or more embodiments, the second venturi inlet pressure Pi2, the second venturi outlet pressure Po2, the second venturi constriction pressure Pc2, the sensor tube pressure Ps, or a combination may be used to calculate a second pressure change across the second venturi. Using the equations discussed previously, in one or more embodiments, the tomography controller may calculate a second venturi multiphase flowrate R2from a second pressure change across a second venturi using one or more second venturi pressure data signals.

Step S4involves calculating a multiphase flowrate Rm of the multiphase mixture flowing through the MPFM based on the first venturi multiphase flowrate R1determined in S2and the second venturi multiphase flowrate R2determined in S3.

In one or more embodiments, tomography controller491may use the first venturi multiphase flowrate R1and the second venturi multiphase flowrate R2to calculate a multiphase flowrate Rm.

In one or more embodiments, a correct value for the multiphase flowrate Rm may be equal to the first venturi multiphase flowrate R1at some real flowrates and equal to the second venturi multiphase flowrate R2at other real flowrates. In one or more embodiments, the tomography controller491may apply a predetermined pressure change threshold or predetermined multiphase flowrate threshold to select the first or second venturi multiphase flowrates R1, R2when calculating the multiphase flowrate Rm. In some embodiments, tomography controller491may apply a predetermined first pressure/flowrate threshold to measurements from the first venturi and a predetermined second pressure/flowrate threshold to measurements from the second venturi.

In one or more embodiments, the multiphase flowrate Rm determined using the smaller-diameter venturi may be more accurate at lower flowrates, such as flowrates between 400 BPD and 4,000 BPD, while the multiphase flowrate Rm determined using the larger-diameter venturi may be more accurate at higher flowrates, such as flowrates between 4,000 BPD and 14,000 BPD. Thus, in one or more embodiments where the first venturi constriction diameter is smaller than the second venturi constriction diameter, the multiphase flowrate Rm determined using the first multiphase flowrate R1may be more accurate at flowrates between 400 BPD and 4,000 BPD, while the multiphase flowrate Rm determined using the second multiphase flowrate R2may be more accurate at flowrates between 4,000 BPD and 14,000 BPD.

Every Venturi has a threshold pressure drop across it where if that pressure is smaller than the threshold it will not be detected by the pressure sensors. However, if the rate is high rate and the throat is small, the flow regime will be turbulent (not laminar) and the measured pressure drop will not be representative thus the rate will have accuracy issues. In some embodiments, a multiphase flowrate calculated using an oversized, large diameter venturi may underestimate or overestimate the actual multiphase flowrate due to factors such as a small pressure change. Similarly, a multiphase flowrate calculated using an undersized, small diameter venturi may be in a turbulent flow regime (as opposed to laminar flow regime). Such a undersized venturi may underestimate or overestimate the actual flowrate due to factors such as turbulence.

The productivity and thus the multiphase flowrate for a well typically decreases over time on average, as a formation becomes less productive. Furthermore, in some embodiments, the larger diameter venturi may be appropriately sized for the initial flowrate. Thus, in some embodiments, larger diameter venturi may be used to calculate an accurate multiphase flowrate early in a wells life when the multiphase flowrate is highest. Furthermore, since the larger diameter venturi is less accurate at low flowrates, the smaller diameter venturi may be used to calculate an accurate multiphase flowrate later in a wells life as the multiphase flowrate decreases.

ConsiderFIGS. 7 and 8which both depict schematic graphs of calculated flowrate as a function of time (meaning production time). In both idealized graphs, the actual flowrate follows a linear decrease. However, as discussed above, at high flowrates early in the well lifetime, the flowrate calculated using the small diameter venturi may not reflect the true flowrate. Similarly, at low flowrates late in the well lifetime, the flowrate calculated using the large diameter venturi may not reflect the true flowrate. Here, the assumption is that the small diameter venturi underestimates the flowrate at high flowrates and the large diameter venturi overestimates the flowrate at low flowrates.

The idealized graph depicted inFIG. 7is divided into three regions: Region I, where the large diameter venturi is accurate and the small diameter venturi underestimates the flowrate; Region II, where the calculated flowrates using the large and small diameter venturis are equal and both result in accurate measures; and Region III, where the small diameter venturi is accurate and the large diameter venturi overestimates the flowrate.

Thus, in some embodiments as depicted inFIG. 7, a tomography controller may compare the first and second venturi multiphase flowrates R1, R2to calculate the multiphase flowrate Rm.

Consider an MPFM400where constriction diameter Dc2of second venturi460is larger than constriction diameter Dc1of first venturi420, as depicted inFIG. 4. In Region I, at high flowrates tomography controller491may equate the multiphase flowrate Rm with the second venturi multiphase flowrate R2.

In Region II, as the first and second venturi multiphase flowrates R1, R2converge, the multiphase flowrate Rm may equal a combination of the first and second venturi multiphase flowrates R1, R2such as an average.

Finally, in Region III, the second venturi multiphase flowrate R2and the first venturi multiphase flowrate R1diverge. Specifically, when second venturi multiphase flowrate R2becomes greater than the first venturi multiphase flowrate R1and/or the difference between the first and second venturi multiphase flowrates R1, R2increases beyond a predetermined threshold, tomography controller491may equate the multiphase flowrate Rm with the first venturi multiphase flowrate R1.

One having ordinary skill in the art will appreciate how to determine appropriate predetermined thresholds for equivalence, divergence, and convergence between first and second venturi multiphase flowrates R1, R2.

Consider the schematic graph depicted inFIG. 8. Here, there is no significant region where the first and second venturi multiphase flowrates R1, R2converge. However, the first and second venturi multiphase flowrates R1, R2are equivalent at a single point where the two lines cross. In some embodiments, such a crossing may indicate Region I and Region III. As detailed above, the multiphase flowrate Rm may be calculated in Region I and Region III from the first and second venturi multiphase flowrates R1, R2.

In some embodiments, one or more mathematical functions may be used to determine when either the first or the second venturi multiphase flowrates R1, R2may be relied on to calculate the multiphase flowrate Rm. For example, in some embodiments, the transition point between Region I and Region III may be where the second time derivative of the calculated flowrate for the first and/or second venturi multiphase flowrates R1, R2equals zero or changes signs.

One having ordinary skill in the art will appreciate how to mathematically determine the transition point between Regions I and II; between Regions II and III; and between Regions I and III. Further, one having ordinary skill in the art will appreciate how the efficiency of an electric submersible pump (ESP) decreases when the ESP operates outside of a specific range of multiphase flowrates. Specifically, if the ESP is properly sized for the initial multiphase flowrate, the efficiency decreases as the multiphase flowrate decreases. Thus, one of ordinary skill can estimate the multiphase flowrate using pressure readings from the ESP to calculate the total dynamic head per stage.

In some embodiments, tomography controller491may receive input including pressure data from the ESP to estimate the multiphase flowrate. In some embodiments, tomography controller491may use the multiphase flowrate estimated from the ESP to determine whether to rely on the first or second venturi multiphase flowrate R1, R2when calculating a multiphase flowrate Rm. In some embodiments, tomography controller491may apply a total dynamic head threshold to determine whether to rely on the first or second venturi multiphase flowrate R1, R2when calculating a multiphase flowrate Rm.

Step S5combines the multiphase flowrate Rm and the gamma ray tomography data Gd to determine an individual flowrate Ri of each of the component phases in the multiphase mixture401. More specifically, in one or more embodiments, the tomography controller491uses the multiphase flowrate Rm and the gamma ray tomography data Gd to determine the individual flowrates Ri of each of the component phases in the multiphase mixture401.

In one or more embodiments, some fraction of the gamma rays generated by the gamma ray generator451may be detected by the gamma ray detector453. In one or more embodiments, the gamma ray detector453may detect some fraction of the gamma rays generated by the gamma ray generator451. In one or more embodiments, the gamma ray detector453may generate a gamma ray data signal Gd reflecting the gamma rays detected and transmit gamma ray signal Gd to the tomography controller491. In one or more embodiments, the tomography controller491may receive sensor input from the gamma ray detector453in substantially real time.

In one or more embodiments, the MPFM400may further include a temperature sensor, or other sensors that provide data to the tomography controller491. In one or more embodiments, the tomography controller491receives data input from additional sensors that provide one or more of pressure, temperature, viscosity, density, or other characteristics.

One having ordinary skill in the art will appreciate how to combine the multiphase flowrate Rm with the gamma ray tomography data Gd and additional sensor readings to determine the individual flowrates Ri of each of the component phases in the multiphase mixture401.

Unless defined otherwise, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which these systems, apparatuses, methods, processes and compositions belong.

It is noted that one or more of the following claims utilize the term “where” or “in which” as a transitional phrase. For the purposes of defining the present technology, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.” For the purposes of defining the present technology, the transitional phrase “consisting of” may be introduced in the claims as a closed preamble term limiting the scope of the claims to the recited components or steps and any naturally occurring impurities. For the purposes of defining the present technology, the transitional phrase “consisting essentially of” may be introduced in the claims to limit the scope of one or more claims to the recited elements, components, materials, or method steps as well as any non-recited elements, components, materials, or method steps that do not materially affect the novel characteristics of the claimed subject matter. The transitional phrases “consisting of” and “consisting essentially of” may be interpreted to be subsets of the open-ended transitional phrases, such as “comprising” and “including,” such that any use of an open ended phrase to introduce a recitation of a series of elements, components, materials, or steps should be interpreted to also disclose recitation of the series of elements, components, materials, or steps using the closed terms “consisting of” and “consisting essentially of.” For example, the recitation of a composition “comprising” components A, B, and C should be interpreted as also disclosing a composition “consisting of” components A, B, and C as well as a composition “consisting essentially of” components A, B, and C. Any quantitative value expressed in the present application may be considered to include open-ended embodiments consistent with the transitional phrases “comprising” or “including” as well as closed or partially closed embodiments consistent with the transitional phrases “consisting of” and “consisting essentially of.”

As used in the Specification and appended Claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly indicates the contrary. The verb “comprises” and its conjugated forms should be interpreted as referring to elements, components or steps in a non-exclusive manner. The referenced elements, components or steps may be present, utilized or combined with other elements, components or steps not expressly referenced.

“Optionally” means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

Ranges may be expressed as from about one particular value to about another particular value, inclusive. When such a range is expressed, it is to be understood that another embodiment is from the one particular value to the other particular value, along with all particular values and combinations thereof within the range.