Hi Khaldoon

The most complex challenge could be the high degree of varying spatial distributions of the different phases with respect to flow path

Best wishes

Omar

Hi Khaldoon

The most complex challenge could be the high degree of varying spatial distributions of the different phases with respect to flow path

Best wishes

Omar

I will provide general physical ideas since I am not a specialist in this field. If I understood correctly, you need to measure quantities of flow of some substance that consists from different phases (like mix of liquid and gas). Since the density of gas and liquid differ substantially, it is important to measure what share of volume is occupied by different phases. If your metering include several devices in different location of the flow profile that measure density and velocity, then by summing those products you can estimate the flow. The problem is that flow profile can be quite heterogeneous and you cannot measure all the details, and have to approximate and thus  have some measurement error. If there are some physical theorem about how this  flow is separated in phases (like 60% of volume blow is always liquid and 40% above is always gas) - this can make estimation easier.

Different phases in a multiphase flow may travel with different velocities. Furthermore spatial distribution of different phases depends on so many parameters such as size, density, viscosity etc. Hence it is very difficult to measure all the phases simultaneously. Please look at some papers on my page on multiphase flow measurement.

The main challenge is if you use it with crude oil. Apart from different phases and travel with different velocities, they will change from one form to another continuously over time. The formation of permanent emulsion, deposition of wax etc. when dealing with waxy crude oil will be a great challenge to multiphase flow metering.  

I went offshore a few times, helped With setting up offshore pumping loop for well treatments, thus knowing a little on some of the multi-phase flow metering Devices.

The accuracy of measurements is confined for two main reasons: first, the rapidly changing conditions in the pipeline, like pressure, temperature, phase behavior and varying compositons, physical Properties like viscosity and flow rate, whether in laminar flow or transient, or turbulent, everything is on an ever-changing mode leading to big Challenge to the metering Devices, thus not easy to achieve precise real time and / or average Readings.

at the same time, the metering Devices themselves have their own measuring limitations, like proper working conditions, under too low temperatre or too hgih pressure for example they dont work propery, partly due to their designed work mechanism. One typical example is the turbine flow meter, an industral flow meter commonly used offshore, quite often does not give any reading values if the flow rate is say, below 600 liter / min. You simply can do nothing With this but wait until higher flow rate is obtained and maintained:) This type of device limit may cause lost data recording from time to time.

The development of multiphase metering technology for oil/gas/water flow started in the early eighties. Several multiphase testing units have been introduced in the past years to measure oil, gas and water rates and it has been said that “the application of multiphase flow meters in company operations if successful will provide continuous online well production and monitoring and will also eliminate large conventional test separators, portable test units and well test lines (Al-Taweel and Barlow, 1997-1998).

The real-time model based multiphase flow metering is an advanced technology for production allocation and monitoring for smaller and marginal fields. These real-time MPFMs technology have been around for about two decades and most of them are on a steady state approach but some are also dynamic, meaning that the system could have a solution also in transient conditions. The real-time metering systems have computers which are located either on the multiphase flow meters (MPFMs) or located remotely in a control room with basic principle of such systems are mostly been pipeline model reaching from well to inlet facilities on a production unit enabling it to simulate process states in the pipeline in real time.

Multiphase flow metering (MPFM) is a challenging complex topic in many engineering applications, particularly in Oil&Gas industry and offshore production sites..For instance we did not reach high accuracy as .Algorithms behind all MPFM commercial devices rely on empirical correlations see link:

https://www.linkedin.com/.../do-you-understand-how-multiphase-f...

experimental mesurements are linked to mathematical models and type of averaging (space, time, ensemble) to simplify equations ....No one can imagine the complexity of coupling turbulent Multiphase flow structures with interface deformations...

Here is an interesting link to Kahila Mokhtari paper on VFM (Virtual Flow Metering) models which can provide accurate predictions for multiphase flow metering.

Conference Paper Performance evaluation of multiphase flow models applied to ...

Regards

Kamal

Multiphase flow metering has become very important to the development of marginal oil and gas fields, since the economics of producing these fields do not justify the construction of new platforms; instead, they are tied back to existing infrastructure. In such cases, several fields are tied back to common facilities requiring each unprocessed stream to be measured prior to comingling. Multiphase flow metering is also a promising alternative to traditional test separators in those cases where having a large vessel is not feasible, and in the production of heavy oils where separation represents a big challenge.

The increasing need for energy, combined with depleting worldwide light oil resources, has generated substantial interest in heavy oil reserves. Heavy oil applications involve low API gravity oils which are also very viscous. The production, transport, metering, and processing of heavy oils present a number of challenges associated with the increased resistance to flowing given the high-viscosity characteristics of heavy oils and the tendency to form emulsions. The hydrodynamics of high-viscosity oils presents various challenges in multiphase flow metering, including dependence of the discharge coefficient on the viscosity of the oil at low Reynolds numbers on Venturi-type meters used in commercially-available multiphase flow meters (MPFMs). Other issues are also related to the tendency of heavy oils of forming emulsion and the effect of complex fluids on the performance of the meters.

This paper presents a review on heavy oil, multiphase flow metering, and the challenges faced by multiphase flow meters in heavy oil applications. The purpose of this review paper is to provide relevant information that can be used in the selection of multiphase flow meters for heavy oil applications. While other studies on the subject have focused on one specific problem or flow metering technology, this paper provides a general overview of the various issues across existing flow metering technologies. Special focus is given to in-line multiphase flow meters, since they provide some advantages over other types of MPFMs in heavy oil applications. In-line MPFMs have the ability to measure the oil, water, and gas flow rates directly in the multiphase flow stream without separation of the phases. The inherent characteristics and physical properties of heavy oils impose additional constraints to MPFMs, as well as the enhanced recovery methods employed for the production of heavy oils. The main issue is associated with the tendency of heavy oil to form complex mixtures (emulsions, foam, etc.) as they can lead to inaccurate measurement of phase fraction and flow rates. The additional water or steam added to the reservoir to increase recovery rates can result in flow instabilities, high water cuts, and changes on the continuous phase. Thermal production methods can also cause inaccurate readings and compromise the integrity of the meters.

Multiphase flow metering has become very important to the development of marginal oil and gas fields, since the economics of producing these fields do not justify the construction of new platforms; instead, they are tied back to existing infrastructure. In such cases, several fields are tied back to common facilities requiring each unprocessed stream to be measured prior to comingling. Multiphase flow metering is also a promising alternative to traditional test separators in those cases where having a large vessel is not feasible, and in the production of heavy oils where separation represents a big challenge.

The increasing need for energy, combined with depleting worldwide light oil resources, has generated substantial interest in heavy oil reserves. Heavy oil applications involve low API gravity oils which are also very viscous. The production, transport, metering, and processing of heavy oils present a number of challenges associated with the increased resistance to flowing given the high-viscosity characteristics of heavy oils and the tendency to form emulsions. The hydrodynamics of high-viscosity oils presents various challenges in multiphase flow metering, including dependence of the discharge coefficient on the viscosity of the oil at low Reynolds numbers on Venturi-type meters used in commercially-available multiphase flow meters (MPFMs). Other issues are also related to the tendency of heavy oils of forming emulsion and the effect of complex fluids on the performance of the meters.

This paper presents a review on heavy oil, multiphase flow metering, and the challenges faced by multiphase flow meters in heavy oil applications. The purpose of this review paper is to provide relevant information that can be used in the selection of multiphase flow meters for heavy oil applications. While other studies on the subject have focused on one specific problem or flow metering technology, this paper provides a general overview of the various issues across existing flow metering technologies. Special focus is given to in-line multiphase flow meters, since they provide some advantages over other types of MPFMs in heavy oil applications. In-line MPFMs have the ability to measure the oil, water, and gas flow rates directly in the multiphase flow stream without separation of the phases. The inherent characteristics and physical properties of heavy oils impose additional constraints to MPFMs, as well as the enhanced recovery methods employed for the production of heavy oils. The main issue is associated with the tendency of heavy oil to form complex mixtures (emulsions, foam, etc.) as they can lead to inaccurate measurement of phase fraction and flow rates. The additional water or steam added to the reservoir to increase recovery rates can result in flow instabilities, high water cuts, and changes on the continuous phase. Thermal production methods can also cause inaccurate readings and compromise the integrity of the meters.