Monitoring flow of single or multiple phase fluids

Various embodiments include apparatus and methods to monitor flow of single and multiple phase fluids. Sensors of a tool can be dispersed along the tool to collect measurements to be processed using an autocorrelation operation on the collected measurements to provide information relative to the phases of the fluid. Additional apparatus, systems, and methods are disclosed.

TECHNICAL FIELD

The invention relates generally to systems having well logging capability.

BACKGROUND

In drilling wells for oil and gas exploration, understanding the structure and properties of the geological formation surrounding a borehole provides information to aid such exploration. However, the environment in which the drilling tools operate is at significant distances below the surface and measurements to manage operation of such equipment are made at these locations. Further, the usefulness of such measurements may be related to the precision or quality of the information derived from such measurements.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawings that show, by way of illustration, various example embodiments of the invention. These embodiments are described in sufficient detail to enable those skilled in the art to practice these and other embodiments. Other embodiments may be utilized, and structural, logical, and electrical changes may be made to these embodiments. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The following detailed description and accompanying drawings are, therefore, not to be taken in a limiting sense.

FIG. 1shows a block diagram of an example embodiment of a measurement system100operable in a borehole102to collect measurements in a fluid flow. Measurement system100includes a tool105and an analysis unit120. Tool105has a plurality of sensors110-1,110-1. . .110-(N−1),110-N dispersed along tool105. The plurality of sensors110-1,110-1. . .110-(N−1),110-N include sensors such that, in one or more combinations, the sensors are sensitive to all phases of the fluid in the flow. By sensitive to all phases of the fluid, it is meant that that the phases are present in sufficient amount to be measureable by one or more of sensors110-1,110-1. . .110-(N−1),110-N.

Analysis unit120can be configured to perform an autocorrelation operation on the collected measurements such that a factor of fluctuation per unit time is matched to each respective phase of the fluid. Analysis unit120can include a processor and a machine-readable storage medium having instructions stored thereon, which when executed by the processor, cause measurement system100to perform a number operations. The operations can include operations to determine a property of a phase of the fluid based on results from performing the autocorrelation operation. Properties determined based on results from performing the autocorrelation operation can include one or more of a volumetric flow rate of the phase, a mass flow rate of the phase, or other properties of the phase derivable from the volumetric flow rate and/or the mass flow rate. The autocorrelation operation on the collected measurements can use one or more techniques such as, but not limited to, time evolved factor analysis, general autocorrelation, multivariate curve resolution, histogram profiling, or other similar evaluation process.

Tool105and analysis unit120can be configured to be operable in various measurement configurations such as in a wireline system or in a measurements-while-drilling (MWD) system such as a logging-while-drilling (LWD) system. In addition, measurement system100may optionally include a fluid stream perturbing device107. Fluid stream perturbing device107can be disposed relative to sensors110-1,110-1. . .110-(N−1),110-N such that the fluid stream perturbing device107is operatively upstream relative to the flow of the fluid pass sensors110-1,110-1. . .110-(N−1),110-N. With the autocorrelation operation based on variations or fluctuations in the phases of the fluid over time, phases that are consistent over distance or mildly grading in composition and properties may be insensitive to the autocorrelation technique for determining flow rates of the phases. Fluid stream perturbing device107can inject a perturbation upstream of the sensors110-1,110-1. . .110-(N−1),110-N relative to a phase of the fluid, when the phase is flowing without sufficient variation at the respective measuring sensors absent the perturbation.

Though, in various embodiments, designs may include a fluid stream perturbing device configured to be placed upstream of multiple fluid sensors, natural perturbing instances may occur in the flow such that use of the fluid stream perturbing device may be reduced or eliminated in measurements. Examples of natural perturbing instances include, but are not limited to flow around the bend of an elbow, flow at a reducing or enlarging union, induction of a gas bubble, a change from laminar flow to turbulent flow, or other similar activities that accompany a change in flow. The arrangement of sensors and the evaluation of their measurements use perturbation that is observable by the fluid sensors employed.

For instance, if an optical fluid sensor is employed, a perturbation may be induction of a gas bubble, a change from laminar flow to turbulent flow, or injection of an absorbing or fluorescing dye. A single perturbation most likely affects different phases differently. However, in the case that a perturbation does not affect a given phase at all, multiple perturbations (one for each independent phase) may be induced. Relative perturbations may be induced in the case that an absolute perturbation provides less than sufficient delineating characterization. For instance with an optical sensor, two dies may simultaneously be injected in different concentrations to induce a relative optical density ratio between two different optical band centers. Perturbations may also be varied temporally with characteristic frequencies, beats, or cords so as to lock the pattern. Many natural perturbations occur with regular frequency that can provide the measurable perturbations without inducing a perturbation using a perturbation injection device.

With known distance between multiple sensors and/or the perturbation point, an autocorrelation function of sensor responses can yield a linear velocity for each phase observed. This autocorrelation function may make use of various algorithms to perform an autocorrelation operation. Such autocorrelation algorithms may include, but are not limited to, time evolved factor analysis, general autocorrelation, multivariate curve resolution, or histogram profiling. To convert the linear flow, provided by the autocorrelation analysis of the data from the sensors, into volumetric flow, the fluid phase cross section can be determined at the sensor points. To convert the linear flow into volumetric flow, an average phase volume, determined for the regions near the sensors, can be determined with volume based sensors such as optical analyzers. Alternatively, mass based sensors may be used to determine mass flow. Mass flow and volumetric flow may be interconverted with known phase densities. Alternatively, if mass flow and volumetric flow are determined, then phase densities may be calculated. In addition, phase compressibility may be derived from sensors placed at points of differing pressures, or from flow velocities correlated over differing pressures, if phase velocities are known.

As fluid moves through a tool implemented with respect to drilling operations, there are several different conditions changing. Such changing conditions can include changing temperature, changing pressure, changing fluid density as the pressure changes, and other changing conditions. These changes can be accompanied with the pumping of a variety of different fluids through the tool at a particular rate. However, the rate of pumping may not actually be the same as the rate the fluid is leaving the tool for a single phase fluid. In addition, different phases of a multiphase fluid can be flowing through the tool at different rates with respect to each over and at different rates relative to the selected pump rate.

In an example measurement situation, a tool touches the wall of a well bore and fluid is withdrawn into the tool. The fluid that is in the well bore is at a higher hydrostatic pressure than the core pressure of the formation and there is a general pressure grading when trying to pump filtrate into the formation. Filtrate is the liquid portion of the slurry, which is referred to as drilling mud. To bring fluid into the tool, suction is created for the internal plumbing of the tool to withdraw fluid first from the mud cake, out of the formation, and bring it up into the tool. There is a pressure change, since the formation was initially broached by the well, associated with filtrate being pushed out into the system. As the material is drawn into the tool, there may be a compositional gradient that starts with the filtrate. The compositional gradient moves to a mixture of reservoir fluids and, at some time after pulling in the material, the collected material may be identifiable as original reservoir fluid. However, the reservoir fluid can be an oil, a gas, a water based material, or combinations thereof. Though an ideal objective would be to have a single phase material, as fluid is withdrawn into the tool, changes in composition are observed because of the filtrate gradient. Other observed changes include changes in terms of temperature, since the well drilling process has been circulating mud from surface temperature to the down hole temperature, including extracting heat. As a result of these changes, there can be many gradients in the measurement system. The longer that fluid is pumped into the tool, more gradients and asymptotes of the gradients are going to be observed. At some point in time, a steady state of filtrate may be attained providing an increased quantity of reservoir fluid such that the temperature of the material coming into the tool would be sufficiently close to the reservoir temperature at some distance from where it was perturbed.

The phases of a multiphase fluid can occur in different forms. In addition to a gas and a liquid, there can be a liquid/liquid system. There can be an oil phase having a gas saturation within it. There can be an aqueous phase with gas dissolved in it. Solid particles may float in the fluid system.

A temperature sensor responds differently in a heat transfer manner with respect to gas or liquid. Within a fluid, one phase may carry more heat than another phase. Each individual phase has a different heat capacity, which indicates the amount of thermal energy that can be absorbed for a change in temperature, such that the temperature of the multiphase fluid is driven by the heat capacity of the individual phases in the fluid. For a fluid, a temperature sensor at one location may have observed temperature fluctuations that may be similar to temperature fluctuations at another temperature sensor downstream. This allows for the correlation of pulses in the temperature of the flowing fluid over a unit of time over unit length, which provides a mechanism for a flow meter.

In addition, it can be noted that not only can temperate data be observed to fluctuate as a phase passes by sensors separate over some distance, other data can be observed to fluctuate. Fluctuations in capacity, resistivity, and density can be observed in different sensors fluctuating as the phases pass by them. In an arrangement with a number of different sensors, these different sensors observe fluctuating in these different phases in the multiphase fluid, where some of the sensors are more sensitive to one phase than another. For instance, a resistivity sensor may be more sensitive to the water phase than other phases such as oil or gas. A density sensor may be sensitive to the density contrast between the phases. A capacitance sensor may provide an overall average flowing fraction being the phases. These different property observations use multiple different types of sensors distributed throughout a measurement tool, all of which respond very differently to different phases, and observe different phases differently. In addition, there can be a transverse dispersion function operative relative to the different properties of the different phases.

A transverse dispersion function takes into account changes in phases at cross-sections of the flow fluid due to the interaction between the phases of the fluid. These interactions may be viewed as one or more phases of a fluid pulling on and providing forces to other phases of the fluid in the flow such that changes in cross section of the phases in the fluid flow may occur. Such changes may occur between the various sensors of the tool as the fluid passes. The transverse dispersion function characterizes the mixing of the phases along the fluid flow from an initial mixing location. In various embodiments, the mixing can be characterized by a linear function in the flow direction away from the place of initial mixing. The transverse dispersion function may be applied to provide target models of the fluid flow to be observed at the sensors following the initial sensor. The transverse dispersion function may be applied in an iterative process for application of the autocorrelation operation with respect to the sensors.

In various embodiments, an autocorrelation operation can be applied to signals from a number of sensors dispersed across the flow measurement tool. Using autocorrelation on the data collected on the fluid flow as it passes the sensors distributed across the tool, factors that fluctuate across unit time can be generated, where the number of factors identifies the number of phases in the multiphase fluid. The autocorrelation operations provide a mechanism to look at variations across the sensors. An example of an autocorrelation operation can be realized by application of a time evolved factor analysis. In the time evolved factor analysis, each of the sensors can be considered to be a different channel. An auto correlation function provided by the time evolved factor analysis provides a technique designed to match factors with factors of fluctuation across unit time. In a time evolved factor analysis system, a number of different factors may be determined, for example, two different factors or three different factors. These factors are equivalent to the number of phases of the fluid. The factor fluctuation per unit time can yield a flow rate for these different phases. If distance is known, such a flow rate can be calculated as a volumetric flow rate. With known densities of the composition of the fluid, the factor fluctuation per unit time can yield a flow rate that translates to mass. In such an analysis, the number of sensors dispersed throughout the system such that they are sensitive to the different phases in the fluid. A combination of sensors, which yield enough to degrees of freedom to physically provide the data of the different phases, can be used such that each sensor need not be sensitive to all phases.

FIG. 2shows an example embodiment of a measurement apparatus200including a tool205and an analysis unit220operable in a borehole202. Tool205includes a fluid inlet section206that can draw in fluid from a formation201using probes208-1and208-2that can be arranged to contact formation201. The number of probes to draw in the fluid can range from one to any number greater than one depending on the particular situation in which tool205is applied. Tool205can include a sensor section212disposed near fluid inlet. Sensor section212can include a plurality of sensors, which may be a number of different types of sensors. Such sensor types can include temperature sensors and pressure sensors. Other types of sensors that can measure properties of a fluid as the fluid flows by the sensors can be used. These types of sensors can include fiber optic based sensors, sensors to measure resistivity, sensors to measure density, sensors to measure capacitance, and other sensors capable of measuring properties of fluid phases. Tool205also includes a pump section208that functions to draw in fluid through probes208-1and208-2. Following pump section209is another sensor section214. Sensor section209can also include a plurality of sensors, which may be a number of different types of sensors. The components of tool205can be arranged and configured in a number of different combinations. These components may have fixed geometries and fixed distances. Alternatively, these components may be arranged such that there are a limited number of fixed geometries and fixed distances for a design of tool205.

Determination of the phases and properties of the phases from data collected in sensor sections212and214can be conducted using analysis unit220. Analysis unit220includes a processor222, memory224, and a communications interface226. Signals from tool205received at communications interface226provide data to analysis unit220, where analysis unit uses the data that exhibits the variation of the fluid phases at the sensors in sensor sections212and214. Memory224can include algorithms and data to perform autocorrelation operations on the received data under control of processor222. Processor222can be realized as one or more processors. Analysis unit220may be realized as an integrated unit with tool205operable downhole. Analysis unit220made be realized as a surface unit that communicates downhole over conventional communication vehicles for a drilling operation. Analysis unit220made be realized as a distributed unit with some components or portions of components locatable downhole and other components or portions of components locatable at the well surface.

Analysis unit220can operate relative to fluctuations in the fluid flow. If the measured signals at the sensors of sensor sections212and214are absence a sufficient degree of fluctuation to determine the phases and their properties, perturbation device207can be used to induce a perturbation into the fluid flow. Such a perturbation can be the generation of a pressure pulse to flow through one or more of the sensors.

FIG. 3shows features of an embodiment of a method300of monitoring flow of phases of a fluid. At310, measurements in a flow of a fluid are collected from different sensors of a tool in a borehole. The sensors are dispersed along the tool such that the sensors in one or more combinations are sensitive to all phases of the fluid. At320, an autocorrelation operation is performed on the collected measurements. Such autocorrelation operation can provide a factor of fluctuation per unit time that is matched to a respective phase of the fluid. The number of factors resulting from the autocorrelation operation can equal the number of phases of the fluid in the flow. Performing an autocorrelation operation on the collected measurements can be conducted using one or more of a time evolved factor analysis, a general autocorrelation, a multivariate curve resolution, or a histogram profiling. With the autocorrelation operation based on variations or fluctuations in the phases of the fluid over time, phases that are consistent over distance or mildly grading in composition and properties may be insensitive to the autocorrelation technique for determining flow rates of the phases. A perturbation upstream of the sensors can be injected relative to a phase of the fluid flowing, absent the perturbation, without variation at the sensors sensitive to this phase. A number of perturbations can be injected equal to or greater than the number of phases in the fluid. An iterative process can be conducted to provide sufficient fluctuations for the autocorrelation operation.

At330, a property of a phase of the fluid is determined based on results from performing the autocorrelation operation. The determined properties of a phase of the fluid can include a volumetric flow rate of the phase, a mass flow rate of the phase, or other properties of the phase derivable from the volumetric flow rate and/or the mass flow rate. Such properties can be determined for each phase of the fluid. The fluid can be a single phase or a multiple phase fluid. A drilling operation may be directed based on determined properties from performing the autocorrelation operation on the collected measurements. Methods similar to or identical to method300can be conducted using tools and analysis units similar to or identical to tools and analysis units discussed herein.

In various embodiments, volumetric flow/mass flow measurement systems, including distributed sensors and an analysis unit to conduct autocorrelation operations on data collected from these sensors over distance and over time based on perturbation in the observed flow, provide a mechanism to determine flow of single and multiple phase fluids. This mechanism can provide determinations with a more stable average than conventional flow meters, which attempt to make use of a single point sensor to provide an all in one answer to determine flow of multiple phase fluids. Some of these conventional flow meters can often be complicated.

Typically, monitoring multiphase flow in a pump out operation is important, for example, in wireline sampling jobs. In various embodiments, a volumetric flow/mass flow measurement system, similar to or identical to tools and analysis units discussed herein, can provide measurements of such flow in straight forward manner. Using volumetric flow/mass flow measurement systems as discussed herein, bubble point and dew point may be directly determined, pump out rates may be maximized, and cleanup can be monitored for multiphase contamination such as water based drilling fluid in a normal petroleum sampling job. Using volumetric flow/mass flow measurement systems as discussed herein in production monitoring, the fraction of the total flow rate produced from a well that is due to water for flooding operations may be determined. Using volumetric flow/mass flow measurement systems as discussed herein in production monitoring, the fraction of the total flow rate produced from a well that is due to gas can be determined for enhanced oil recovery. Using volumetric flow/mass flow measurement systems as discussed herein in production monitoring, artificial lift or particulates content may be determined for sand loss control.

In various embodiments, a machine-readable storage medium having instructions stored thereon, which when executed by a processor, causes a machine to perform operations, the operations comprising: collecting measurements in a flow of a fluid from different sensors of a tool in a borehole, the sensors dispersed along the tool such that the sensors in one or more combinations are sensitive to all phases of the fluid, the phases being measureable phases; performing an autocorrelation operation on the collected measurements such that a factor of fluctuation per unit time is matched to each respective phase of the fluid; and determining a property of a phase of the fluid from performing the autocorrelation operation. The instructions can include instructions to determine a volumetric flow rate of the phase. The instructions can include instructions to determine a volumetric flow rate of each of the phases of a multiple phase fluid. The instructions can include instructions to perform the autocorrelation operation on the collected measurements using one or more of a time evolved factor analysis, general autocorrelation, multivariate curve resolution, or histogram profiling. The instructions can include instructions to determine a mass flow rate of the phase. The instructions can include instructions to inject a perturbation upstream of the sensors relative to a phase of the fluid flowing without variation at one or more of the sensors absent the perturbation. The instructions can include instructions to operate the tool with the fluid being a single phase fluid or a multiphase fluid. The machine-readable medium can also store parameters used in execution of the instructions and can also store results from execution of the instructions. The form of machine-readable medium is not limited to any one type of machine-readable medium, but can be any machine-readable medium. For example, a machine-readable medium can include a data storage medium that can be implemented in a housing disposed in a collar of a drill string, in a wireline configuration, and/or in a system control center.

FIG. 4depicts a block diagram of features of an embodiment of a system400including a sensor tool405having a measuring tool and an analysis unit such that a phase of a single phase or a multiphase fluid can be monitored. The measuring tool includes a number of sensors dispersed along the tool, from which data can be collected for the analysis unit to conduct autocorrelations on the collected data to determine volumetric or mass flow rates of each of the phases of the fluid. Sensor405can be made robust to measure the fluid flow while downhole in a well. Sensor tool405can be realized in similar or identical manner to arrangements discussed herein.

System400can also include a controller462, a memory464, an electronic apparatus468, and a communications unit466. Controller462, memory464, and communications unit466can be arranged to operate sensor tool405to determine properties of the fluid being measured. Controller462, memory464, and electronic apparatus468can be realized to include control activation of individual sensors in sensor tool405and acquisition of data from the individual sensors in sensor tool405and to manage processing schemes in accordance with measurement procedures and signal processing as described herein. Communications unit466can include downhole communications in a drilling operation. Such downhole communications can include a telemetry system.

System400can also include a bus463, where bus463provides electrical conductivity among the components of system400. Bus463can include an address bus, a data bus, and a control bus, each independently configured. Bus463can also use common conductive lines for providing one or more of address, data, or control, the use of which can be regulated by controller462. Bus463can be configured such that the components of system400are distributed. Such distribution can be arranged between downhole components such as individual sensors of sensor tool405and components that can be disposed on the surface. Alternatively, the components can be co-located such as on one or more collars of a drill string or on a wireline structure.

In various embodiments, peripheral devices467can include displays, additional storage memory, and/or other control devices that may operate in conjunction with controller462and/or memory464. In an embodiment, controller462can be realized as one or more processors. Peripheral devices467can be arranged with a display that can be used with instructions stored in memory464to implement a user interface to manage the operation of sensor tool405and/or components distributed within system400. Such a user interface can be operated in conjunction with communications unit466and bus463. Various components of system400can be integrated with sensor tool405such that processing identical to or similar to the processing schemes discussed with respect to various embodiments herein can be performed downhole in the vicinity of the measurement.

FIG. 5depicts an embodiment of a system500at a drilling site, where system500includes a sensor apparatus505and electronics to monitor flow of single and multiple phase fluids. Sensor apparatus505can include a measuring tool and an analysis unit such that a phase of a single phase or a multiphase fluid can be monitored. The measuring tool includes a number of sensors dispersed along the tool, from which data can be collected for the analysis unit to conduct autocorrelations on the collected data to determine volumetric or mass flow rates of each of the phases of the fluid. Sensor apparatus505can be structured, fabricated, and operated in accordance with various embodiments as taught herein.

System500can include a drilling rig502located at a surface504of a well506and a string of drill pipes, that is, drill string508, connected together so as to form a drilling string that is lowered through a rotary table507into a wellbore or borehole512. The drilling rig502can provide support for drill string508. The drill string508can operate to penetrate rotary table507for drilling a borehole512through subsurface formations514. The drill string508can include drill pipe518and a bottom hole assembly520located at the lower portion of the drill pipe518.

The bottom hole assembly520can include drill collar515, sensor apparatus505attached to drill collar515, and a drill bit526. The drill bit526can operate to create a borehole512by penetrating the surface504and subsurface formations514. Sensor apparatus505can be structured for an implementation in the borehole of a well as a MWD system such as a LWD system. The housing containing sensor apparatus505can include flow control components, such as a pump, to control collection of the fluid within sensor apparatus505for measurement of phases in the flow of the fluid. The housing containing sensor apparatus505can include electronics to activate sensors in sensor apparatus505and collect responses from the sensors in sensor apparatus505. Such electronics can include an analysis unit to analyze signals sensed by the sensors in sensor apparatus505using autocorrelation operations and provide measurement results to the surface over a standard communication mechanism for operating a well. Alternatively, electronics can include a communications interface to provide signals sensed by sensor apparatus505to the surface over a standard communication mechanism for operating a well, where these sensed signals are analyzed using autocorrelation operations at an analysis unit at the surface.

In various embodiments, sensor apparatus505may be included in a tool body570coupled to a logging cable574such as, for example, for wireline applications. Tool body570housing sensor apparatus505can include flow control components, such as a pump, to control collection of fluid within sensor apparatus505for measurement of phases in the flow of the fluid. Tool body570containing sensor apparatus505can include electronics to activate sensors in sensor apparatus505and collect responses from the sensors in sensor apparatus505. Such electronics can include an analysis unit to analyze signals sensed by sensors in sensor apparatus505using autocorrelation operations and provide measurement results to the surface over a standard communication mechanism for operating a well. Alternatively, electronics can include a communications interface to provide signals sensed by sensors of sensor apparatus505to the surface over a standard communication mechanism for operating a well, where these sensed signals are analyzed using autocorrelation operations at an analysis unit at the surface. Logging cable574may be realized as a wireline (multiple power and communication lines), a mono-cable (a single conductor), and/or a slick-line (no conductors for power or communications), or other appropriate structure for use in bore hole512.

During drilling operations, the drill string508can be rotated by the rotary table507. In addition to, or alternatively, the bottom hole assembly520can also be rotated by a motor (e.g., a mud motor) that is located downhole. The drill collars515can be used to add weight to the drill bit526. The drill collars515also can stiffen the bottom hole assembly520to allow the bottom hole assembly520to transfer the added weight to the drill bit526, and in turn, assist the drill bit526in penetrating the surface504and subsurface formations514.

During drilling operations, a mud pump532can pump drilling fluid (sometimes known by those of skill in the art as “drilling mud”) from a mud pit534through a hose536into the drill pipe518and down to the drill bit526. The drilling fluid can flow out from the drill bit526and be returned to the surface504through an annular area540between the drill pipe518and the sides of the borehole512. The drilling fluid may then be returned to the mud pit534, where such fluid is filtered. In some embodiments, the drilling fluid can be used to cool the drill bit526, as well as to provide lubrication for the drill bit526during drilling operations. Additionally, the drilling fluid may be used to remove subsurface formation514cuttings created by operating the drill bit526.

In various embodiments, volumetric and/or mass flow of a single or multiple phase fluids can be monitored. Such a flow meter can be implemented for harsh environment use in oil fields or oil well settings. Methods for implementing a flow meter may be realized in a well bore for permanent installation, in a wireline reservoir tool string, or in a measurement while drilling sampling tool. Alternatively, methods of implementing the flow meter can be used in a surface mounted pipeline installation.