Water Cut Measurement Research Articles

Oil-Water Flowing Experiments and Water-Cut Range Classification Approach Using Distributed Acoustic Sensing

Summary The accurate measurement of dynamic water cut is of great interest for analyzing reservoir performance and optimizing oilwell production. Downhole water-cut measurement is a very challenging work. Moreover, the surface-measured water cut is a comprehensive indicator of commingled producing well and it is difficult to use this parameter to deduce the downhole water cut of each contributing layer. In this paper, we propose to use distributed fiber-optic acoustic sensing (DAS) technology for the classification of water-cut range. DAS can dynamically monitor the entire wellbore by “listening” to the acoustic signals during flow. A large number of laboratory experimental data from DAS have been collected and analyzed using wavelet time scattering transform and short-time Fourier transform (STFT). The extracted low-variance scattering feature, short time-frequency feature, and fusion feature (combination of two extracted features) were learned with backpropagation (BP) neural network, decision tree (DT), and random forest (RF) algorithm. Then, a classification method of water-cut range in oil-water flow was established with machine learning. Field DAS data were collected from two oil wells to verify the effectiveness of the proposed method. The classification accuracies for the vertical well (Well A) are 92.4% and 87.4% by DT and RF model, respectively. For the horizontal well (Well B), the average classification accuracy exceeds 90% for all three methods. Water shutoff measure was conducted in Well B, and an obvious water decrease was realized. The result shows that the fusion feature overweighs single feature in machine learning with DAS data. This study provides a novel way to identify downhole water-cut range and detect water entry location in horizontal, vertical, and deviated oil-producing wells.

Water-Cut Measurement Techniques in Oil Production and Processing—A Review

Water cut is a vital monitoring and surveillance parameter with great significance in oil production operations and processing. Water-cut measurements are also challenging due to the significant variations and the harsh measurement environment. The objective of this article is to review the current water-cut measurement techniques and suggest future areas that are expanding to overcome existing measurement challenges. Commercially available online methods such as capacitance-based sensors, tomography techniques, gamma densitometry, ultrasonic meters and infrared meters, and the traditional laboratory offline methods, are discussed, along with their principle of operation, detection range, and sensing resolution. Also, the discussed techniques are summarized, highlighting their main advantages and limitations. Furthermore, future trends and research areas, such as Artificial Intelligence (AI), soft computing, Metamaterials, and Nuclear Magnetic Resonance (NMR), which are integrated with water-cut measurements, are briefly mentioned. The current research hotspots are directed toward integrating full-range measurements with multi-parameter detection, high sensitivity, and reliability.

On-line determination of the water cut and chlorine impurities in crude oil using a pulsed beam of fast neutrons

A neutron-based sensor has been developed able to measure the water cut and the chlorine content in crude oil. The sensor is based upon the use of a pulsed fast neutron source. Two different cases were studied. Case ‘‘A’’: chlorine detection with no water present and case ‘‘B’’: water cut measurements with no chlorine present. The minimum detection limits for case A and case B were found to be (62 ± 6) mg/L and (2 ± 2) vol%, respectively.

A Dual-Parameter Measurement Method for Oil–Water Flow Based on a Venturi Embedded With Microwave Transmission Line Sensor

Accurate and real-time measurement of water cut (WC) and flowrate of oil–water flow is a critical factor in achieving intelligent digital oil field. In this article, a dual-parameter (WC and water flowrate) measurement method for oil–water flow is proposed based on a Venturi embedded with microwave transmission line sensor (V&MS). Dynamic experiments of horizontal fine dispersed oil–water flow are conducted. A two-dimensional finite element simulation model for V&MS under the fine dispersed flow is developed to simulate microwave phase outputs at 0%–100% WC. The simulation results agree with the experiments, providing a low-cost alternative to expensive oil–water dispersed flow tests. Furthermore, it is found that the flow patterns for 0%–10% WC and 40%–100% WC are water-in-oil and oil-in-water flows, respectively, but the flow patterns for 10%–40% WC are dispersions of water-in-oil and oil-in-water flow, and 20% WC is the transition point of the dominant continuous phase. When the water phase is continuous, V&MS has a higher sensitivity to phase signals. Finally, a WC prediction model (40%–100%) is developed by combining a modified Bruggeman model with microwave transmission line theory. Then, a discharge coefficient model is developed and the water flowrate is obtained by combining the pressure drop and the predicted WC. The absolute average relative deviation (AARD) of the predicted WC and water flowrate is 1.49% and 1.54%, respectively. The results suggest that appropriate sensing technology integration can offer a powerful solution for accurate and real-time determination of dual-parameter in oil–water flow systems.

Application of Microwave Transmission Sensors for Water Cut Metering under Varying Salinity Conditions: Device, Algorithm and Uncertainty Analysis.

The measurement of water cut in crude oil is an essential procedure in petroleum production and it is desirable to obtain these data through an automatic and real-time method. Microwave sensors can be used for the task, and they are safe, robust and can cover the whole water cut range. However, they are relatively susceptible to the water conductivity and temperature, and the algorithms for addressing these problems are still rare in the literature. In this paper, a microwave transmission sensor that can measure the water cut under varying salinity conditions is proposed, and the algorithm for solving the water cut and salinity simultaneously with the measured amplitude and phase is described in detail. Experiments under different water cut and salinity conditions are conducted, and the results are used to verify the model and algorithm. Finally, a simplified and fast method for uncertainty analysis is proposed and applied to the iteration algorithm under test conditions. It can be concluded that accuracy higher than 95% in the water cut measurements can be expected under the 0~100% water cut range, and an error of about 10% in the water conductivity is achievable under water-continuous flow conditions. The uncertainty analysis shows that the calculated water cut and salinity results are negatively correlated, and the water salinity uncertainty tends to be larger than the water cut uncertainty. When the water salinity is high, the water cut uncertainty tends to be high whereas the water salinity uncertainty tends to be low.

Water Cut Measurement of Horizontal Oil–Water Flow Using Trielectrode Capacitance Sensor

From the actual development and testing requirements of horizontal wells in domestic oilfields, according to the problems that the common sensors have relatively low resolution during the water cut measurement for the oil–water flow in the horizontal wells with medium and low production, a trielectrode capacitance sensor (TECS) is designed and a water cut measurement system based on TECS is developed for different conditions of horizontal oil–water flow. Specifically, the electrostatic field distribution of the annular measurement region is investigated under different conditions of horizontal stratified flow. Then, its equivalent capacitance on the electrodes is analyzed. Based on the simulated results, the effects of structural parameters on sensitivity distribution are analyzed, including the electrode length, the radius of the flow channel, and the thickness of the insulation, determining its optimal structure. Moreover, the static and dynamic experiments, as well as the field testing, validate the designed TECS, indicating that the TECS enables measuring the water cut of horizontal oil–water flow, especially under low flow rate and oil–water stratified conditions. The developed TECS could realize the water cut measurement with a wide flow rate range (3–60 m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^3$</tex-math></inline-formula> /d) and the full water cut range (0%–100%) for the horizontal oil–water flow.

A horn antenna with circular aperture for pipeline water cut measurement

AbstractA horn antenna with circular aperture is proposed and designed based on the variation of the attenuation amplitude and the attenuation of electromagnetic wave in pipeline in the present paper. The simulation and tests show that the gain of the antenna is 15 dB and the return loss is −12.5 dB. The simulation and experimental results of simulated pipeline water cut test also show that the antenna was used to measure the water content in the range of 0%–100% of the water and oil in the pipeline. The water cut measurement of water and oil is less affected by the mixing type of oil–water mixture in the pipeline, because the main lobe of the antenna is located in the pipeline and the antenna has good directivity. The design of antenna in microwave sensor is useful for the field‐testing and fundamental research.

Automated real-time solids content and salinity analysis of well construction fluids using in-line XRF measurements

Measurements and monitoring of solids content and salinity in fluids to maintain these at ideal levels is essential for optimum well construction operations during drilling, completion, workover and abandonment phases. Currently, API measurements are used for solids and salinity determination, which have certain drawbacks and are difficult to automate.As an alternative, a novel in-line X-ray fluorescence (XRF) measurement approach was investigated to make determination of solids content and salinity of well construction fluids much simpler and more efficient through automation. Laboratory experiments were conducted to generate a comprehensive dataset of X-ray photon counts from an in-line XRF setup coupled to a flow loop to evaluate common solids and solutes in well construction fluids. Using this dataset, calibration curves were generated to determine the high-gravity solids (HGS) and low-gravity solids (LGS) content as well as the salinity of water/brine, oil, and synthetic-based fluids at a high level of accuracy in real-time with full automation.It was observed that with the XRF measurements, certain solids can be measured and monitored by analyzing the concentration of certain elements in the compounds (i.e., barium (Ba) for barite concentration, potassium (K) for potassium chloride concentration, iron (Fe) for clay concentration). The mean average errors in estimating the HGS, LGS and salinity values were found to be less than 2%. Using this method together with automated rheology, density and water-cut measurements decreases these errors to significantly lower levels.The system presented here offers the possibility for real-time solids content management and optimization, opening the door to fully automated fluid measurements, maintenance, and solids control in well construction operations. This will benefit well construction efficiency (e.g. lowering drilling costs), quality, productivity (e.g. reducing reservoir impairment from unwanted solids) and safety (e.g. lowering incidence of well control and lost circulation events due to better equivalent circulating density (ECD) management in narrow margin drilling environments).

Research Status and Development Trend of Water Cut Detection Methods for Crude Oil

Water cut detection of crude oil plays a very important role in the petroleum and petrochemical industry. At present, the existing crude oil water cut detection methods include capacitance method, conductance method, radio frequency method, Ray method, spectrum method. Firstly, the measuring principle, application conditions, advantages and disadvantages of the existing methods are summarized, and the factors affecting the measuring accuracy of the existing methods are analyzed. Afterwards, the latest development of water cut measurement technology of crude oil is mentioned, such as multi-sensor information fusion technology, tomography technology, neural network technology. With the emergence of new technology and new method, the development trend of crude oil water cut measurement technology is towards full range, high precision, intelligence, multi-parameter fusion, safety, energy saving, environmental protection and so on.

Wet gas metering using a vortex cross-correlation meter based on fluctuating pressure measurement

A solution for wet gas metering was developed with a vortex meter by using pressure sensors and correlation technology. For the fluctuating pressure measurement, the micro pressure sensors, especially the probe-transducer systems, were designed to acquire reliable vortex signals. For the experiments, an annular mist flow loop with a film metering system was established, and the tests were conducted on various pressure, gas velocity and liquid flowrate conditions. Then, the dimensionless convection velocity, named convection coefficient, and the peak value of the normalized cross-correlation function, named correlation coefficient were calculated. A piecewise function was developed for the convection coefficient with modified Weber number where the segmentation was determined by the correlation coefficient. Finally, the wet gas measurement model was developed and realized by iterative algorithm. Under the present conditions, the ±5% error bands contain 91% of the relative errors for gas flowrate prediction, the mean absolute percentage error is 2.54%, and the uncertainty of gas flowrate prediction is 2.85%. The primary advantage of the proposed method is that the convection coefficient is almost independent of liquid fraction, no extra systems are necessary for watercut measurement, hence providing a cost-effective solution for wet gas metering.

A parallel-wire microwave resonant sensor for measurement of water holdup in high water-cut oil-in-water flows

In the present study, we propose a parallel-wire microwave resonant sensor (PMRS) with transmission-through configuration for water holdup measurement in high water-cut oil-in-water flows. Through the finite element method (FEM) analysis using HFSS software, the variations of sensor responses for changing water holdup and salinity are investigated. In this manner, the optimum working frequency of microwave resonant sensor is tuned to 1.8 GHz. With the designed PMRS measurement system, an experimental test of vertical high water-cut oil-in-water flows is conducted in a 20 mm inner diameter pipe, through which the relationship among dimensionless normalized phase output of PMRS which reflects the water holdup information, water-cut and total flow rate are investigated. The results show that PMRS presents a high resolution in measurement of water holdup. By establishing statistics models, water-cut can be accurately predicted. Besides, PMRS can still retain high resolution under the circumstance of high salinity. To conclude, PMRS can possess high resolution in measurement of water holdup with both high water-cut and salinity variation in oil-in-water flows, and satisfactory water-cut measurement results can be achieved.

Derivative-free parameter tuning for a well multiphase flow simulator

The analysis of multiphase flow from wells is periodically performed in test separators, producing data on fluid and reservoir properties such as the gas–oil ratio, water cut, pressure, and temperature measurements from sensors. Such data enables the tuning of multiphase flow simulators to reflect the prevailing conditions of reservoir and production processes. Besides meeting demands from the regulatory agency, a well-adjusted model empowers engineers to plan production and derive representative models for production optimization. This work proposes the use of derivative-free optimization methods for tuning an in-house multiphase flow simulator widely used by Petrobras. The tuning algorithm was coupled to the simulation software to free engineers from lengthy analyses, allowing the timely update of processes that are key in decision making and production optimization.

Повышение эффективности определения обводненности добывающих скважин

Повышение эффективности определения обводненности добывающих скважин

Method of eliminating the effect of a free gas on the measurement of water cut three-phase oil-water emulsion by the flow microwave water-cut meter

A method is proposed for eliminating the influence of free gas on the measurement of the water-cut of a three-phase oil-water emulsion (OWE) with an in-line microwave water-cut meter by in-troducing a specialized statistical processing of the current water-cut meter readings. The useful effect is to increase the accuracy of water cut measurements and to reduce the requirements for degassing the OWE at the stage of preliminary preparation. Additionally, it is possible to esti-mate quantitatively the extent of homogeneity violation of the working environment.

ТЕХНИЧЕСКИЕ РЕШЕНИЯ ПО ОЦЕНКЕ ОБВОДНЕННОСТИПРОДУКЦИИНЕФТЕДОБЫВАЮЩИХ СКВАЖИН

Актуальность исследования определена необходимостью стандартизации способов и методик по определению обводненности продукции нефтедобывающих скважин. Цель: оценить причины и условия возникновения систематической погрешности при определении состава скважинной продукции, минимизировать ошибки в измерениях обводненности путем создания новых технологий. Объектом исследования являются нефтедобывающие скважины и процессы, протекающие при движении пластовой продукции от забоя скважины до штатного пробоотборника на выкидной линии устьевой арматуры. Методы исследования основаны на отборе устьевых проб продукции скважин до и после гомогенизации жидкости в выкидной линии скважины. По технологии отбора объемных скважинных проб жидкости оценивалась толщина слоя нефти над водной фазой с помощью разработанного устройства, в котором фиксированный объем нефти переводится в делительную воронку путем снижения давления и добавления в нефть органического растворителя. Установлено, что в высокообводненных скважинах наблюдается гравитационное разделение скважинной жидкости на прослои с различным содержанием нефти и воды. Следствием этого становится поступление в пробоотборную тару жидкости, не соответствующей составу скважинной продукции. Рассмотрены возможные решения существующей проблемы пробоотбора: скважинный поток необходимо гомогенизировать перед штатным пробоотборником или отбирать объемные пробы в течение длительного периода времени. Относительная погрешность измерения доли нефти и воды в объемных пробах с помощью разработанного устройства не превышает 0,1 % для высокообводненных скважин. Рассмотрен альтернативный способ оценки обводненности скважинной продукции, основанный на применении двух датчиков давления в колонне лифтовых труб над электроцентробежным насосом, соответствующий требованиям репрезентативности оцениваемых дискретных проб скважинной жидкости.

A Novel Combined Conductance Sensor for Water Cut Measurement of Low-Velocity Oil-Water Flow in Horizontal and Slightly Inclined Pipes

This paper studied conductance-based method for water cut measurement to dynamically monitor the horizontal oil-producing wells. Existing conductance tools cannot obtain the response values corresponding to the water phase in horizontal wells due to the characteristics of the ring-shaped electrode structure and the horizontal well structure. In order to tackle this issue, this paper designed a novel Combined Conductance Sensor (CCS), which mainly consists of the Ring-Shaped Conductance Probe (RSCP) and the novel Clock-like Conductance Probe Array (CCPA). Specifically, we first established the structure model of CCS, optimized the geometry of CCPA by analyzing the uniformity of electric field distribution generated by the exciting electrodes of CCPA and then analyzed the local sensitivity field region of the optimized CCPA. Then we studied the flow pattern distribution of the horizontal oil-water two-phase flow and analyzed the response characteristics and the linear relation between RSCP and CCPA. In addition, this research developed the CCS-based tool and conducted the experiments about different inclined angles in horizontal and slightly inclined pipes. Extensive experiments demonstrated that the developed CCS can cover the three-quarter scale of water cut measurement(25%-100%) in horizontal and slightly inclined pipes, and the experimental results verified the validity of CCS for the water cut measurement. Comparing to the existing methods, the proposed CCS is more suitable for water cut measurement with the advantages of simple structure and low cost for the horizontal oil wells with the characteristics of the low production, which could be used widely in the actual logging.

Intelligent Completion in Laterals Becomes a Reality

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 183949, “Intelligent Completion in Laterals Becomes a Reality,” by Brett Bouldin, Robert Turner, Isidore Bellaci, and Yousif Abu Ahmad, Saudi Aramco, and Steven Dyer, Thales Oliveira, and Ali Bin Al-Sheikh, Schlumberger, prepared for the 2017 SPE Middle East Oil and Gas Show and Conference, Manama, Bahrain, 6–9 March. The paper has not been peer reviewed. A producer and a service company have collaborated to develop a downhole system to merge multilateral technology and intelligent completions to create “smart laterals.” This approach is known as the extreme-reservoir-contact (ERC) approach to reservoir management. The complete paper discusses ERC completion technology that segments laterals into multiple compartments to provide flow rate, pressure, temperature, and water-cut measurements, together with variable choking in each compartment. Technology-Development Program Even the most-experienced and -diligent development teams cannot deal with an “unknown unknown,” defined here as a serious problem so deeply hidden that it eludes discovery by all laboratory prototype test methods. Therefore, full-scale tests and preliminary field trials must be conducted early as part of the development exercise. This approach was used successfully in Well Trial 1, which verified well-construction practices, and Well Trial 2, which tested prototype electrical control valves. Executing Well Trials 1 and 2 revealed “unknown unknowns” in the pressure-gauge electronics and the assembly of the water-cut sensor. Because these were tool failures, they were relative-ly simple to correct. During Well Trial 3, an application failure was encountered when the drilling bottomhole assembly (BHA) tracked the liner outer diameter for several hundred feet after exiting the casing window. The resulting intersection of the electric umbilical on the outside of the 7-in. intelligent liner destroyed the downhole communications capability in the well. This problem could not have been prevented by effective planning; being an application failure, it could be discovered only in a field trial. The application failure caused a program halt. A team was formed to redevelop lateral exit methods and drilling-sensor usage. A new project plan was made that required three additional parallel trials. Well Trial 4 was planned to prove umbilical avoidance by use of resistivity logging and revised procedures; further details are contained in the ERC Well Construction subsection of this synopsis. Well Trial 5 was a reduced-scale trial. Well Trial 6 was a full-scale installation similar to that previously attempted in Well Trial 3 and is the primary focus of this paper.

Прогнозирование влияния солености воды на качество измерения обводненности нефти

Прогнозирование влияния солености воды на качество измерения обводненности нефти

Coreflood planning criteria for relative permeability computation by Welge-JBN method

Relative permeability computation is extensively applied in petroleum engineering through the Welge-JBN’s method in unsteady-state corefloods. The purpose of this work is to determine admissible coreflood parameters that could limit the application of the Welge-JBN method. These parameters are presented through theoretical and operational criteria. The theoretical criteria include capillary number and capillary–viscous ratio. The operational criteria consist of measurement precision for pressure, volume sampling for either of phases, water cut measurement precision, and number of samples taken during one pore volume injected. The minimum core length and fluid displacement velocity for specific rock and fluid properties could be determined through these criteria. A laboratory coreflood example was performed using the proposed parameters.

A stochastic approach for evaluating where On/Off zonal production control is efficient

Intelligent wells offer an efficient downhole completion able to increase oil production and reduce water or gas production, and to mitigate the unwanted fluid breakthrough thus reducing the production uncertainty. The flexibility of down-hole, active flow control allows field development optimisation on a day-by-day basis without costly and time consuming well intervention operations. The installation of On/Off, interval control valves (ICVs) is a simple and effective example of an active intelligent well (IW) completion. Many IW completions employ On/Off ICVs because they are efficient, (relatively) cheap and are more reliable than the more complex infinitely variable or multi-position, discrete ICVs. A clear understanding of the area in which On/Off ICVs provide sufficient zonal control will allow reducing a project’s capital investment while minimising possible future risks of production loss. This paper provides a stochastic, Monte-Carlo simulation-based approach for identifying the application area of On/Off ICVs by analysing how the completion performance is affected by changes in the inflow over a broad range of zonal reservoir and fluid properties such as productivity index, water cut, gas–oil ratio and layer pressure. The analysis confirms that On/Off control provides an optimal solution for the wide range of reservoir and fluid properties when the well is being produced by natural flow or gas-lift and the instantaneous oil rate maximisation is the control objective. It also shows that a multi-position valve is marginally better only in the cases of an intelligent well producing from multiple reservoirs with significantly different zonal pressures or gas–oil ratios. Let alone it is uncommon to have accurate, zonal water cut measurements which are required to take advantage of the better performance of multi-position ICVs. This paper confirms that On/Off control strategy has a wide application area where it achieves the maximum, or near maximum, instantaneous oil rate value. It also provides guidelines for identifying whether On/Off ICVs are applicable in a particular case. The resulting methodology can thus be used to guide informed choices on the ICV completion types.