scholarly journals A New Dynamic Model for Sealed Coring Saturation Correction in Hydrocarbon Reservoir

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Bin Tu ◽  
Jie Li
Keyword(s):  
Mathematical Model ◽  
Water Saturation ◽  
Correction Method ◽  
Fluid Viscosity ◽  
Dissolved Gas ◽  
Fractional Flow ◽  
Model Correction ◽  
Advantages And Disadvantages ◽  
Hydrocarbon Reservoir ◽  
The Impact

It is one of the most intuitive methods to analyze the formation of oil and water saturation by sealed coring. But this method is affected by a variety of factors, such as pore volume change, fluid compression, and separation of dissolved gas. In view of the impact of such factors on sealed coring test saturation, there are four kinds of correlation methods currently, namely, comprehensive coefficient correction method, experiment correlation method, mathematical statistics method, and mathematical model correction method, with their own advantages and disadvantages. Based on the analysis of physical change during core lifting process, this paper proposes the mathematical model for dynamic correction of core saturation based on dissolved gas drive filtration theory, multiphase flow fractional flow theory, and corresponding work flow. This method comprehensively considers the impact of relative permeability of three-phase fluid flow, elastic compression nature of fluid and rock, fluid viscosity, volume factor, solution GOR, and other high-pressure PVTs, so it features a wider adaptability, and the accuracy of model correction results satisfies the project requirements. This method provides a reliable basis for the true oil-water saturation of actual reservoir and has an important theoretical and practical significance.

Systematic Modelling of Unstable Displacement

2021 ◽  
Author(s):  
Arne Skauge ◽  
Kenneth Stuart Sorbie ◽  
Iselin Cecilie Salmo ◽  
Tormod Skauge
Keyword(s):  
Single Point ◽  
Viscous Fingering ◽  
Mobility Ratio ◽  
Fluid Viscosity ◽  
Fractional Flow ◽  
Fine Grid ◽  
Rock Heterogeneity ◽  
Unstable Displacement ◽  
The Impact ◽  
Adverse Mobility Ratio

Abstract Modelling unstable displacement is a challenge which may lead to large errors in reservoir simulations. Field scale coarse grid simulations therefore need to be anchored to more reliable fine grid models which capture fluid displacement instabilities in a physically correct manner. In this paper, a recently developed approach for accurately modelling viscous fingering has been applied to various types of unstable displacement. The method involves estimation of dispersivity of the porous medium and length scale of the model to determine the required size of the simulation grid cell. Fractional flow theory is then applied to obtain the correct saturation of the injected phase in the unstable fingers formed due to the adverse mobility ratio. Unstable displacement experiments have been history matched using 2D-imaging of in-situ saturation as a calibration of our method, before carrying out sensitivity calculations on the effect of fluid viscosity, and rock heterogeneity. Our modelling approach allows us to carry out simulations using a conventional numerical simulator using elementary numerical methods (e.g. single-point upstreaming). The methods used to model instability (Sorbie et al, 2020) was originally developed for immiscible water/oil systems. The current paper now presents new results applying this approach to unstable gas displacements, where adverse viscosity ratios may be even higher than in water/oil systems. The displacement with injected gas is shown to be influenced by mass exchanges between the gas and oil as the alternating fluids (water and gas) are injected in WAG processes. Swelling of fingers delay the gas front and WAG processes divert the injected gas and improve sweep efficiency. We have also modelled water-oil displacement at adverse mobility and shown the benefit which is obtained by reducing the instability by adding polymers to viscosify the injected water. The impact of rock heterogeneity has different effect depending on buoyancy forces and the degree of crossflow into the high permeable zones. This paper extends our novel approach to modelling the fine scale distribution of the injected fluids in adverse mobility ratio displacements. This approach has now been applied to both, gas/oil and water/oil systems where viscous fingering is present, either at extremely adverse mobility ratios and/or for reservoirs where the permeability field is very heterogeneous.

Understanding Protocol Performance: Impact of Test Performance

2013 ◽  
Vol 24 (10) ◽  
pp. 909-919
Author(s):  
Robert G. Turner
Keyword(s):  
Mathematical Model ◽  
Research Design ◽  
Test Performance ◽  
Negative Impact ◽  
Performance Impact ◽  
Advantages And Disadvantages ◽  
Protocol Performance ◽  
The Individual ◽  
The Impact ◽  
Test Correlation

Background: This is the second of two articles that examine the factors that determine protocol performance. The objective of these articles is to provide a general understanding of protocol performance that can be used to estimate performance, establish limits on performance, decide if a protocol is justified, and ultimately select a protocol. The first article was concerned with protocol criterion and test correlation. It demonstrated the advantages and disadvantages of different criterion when all tests had the same performance. It also examined the impact of increasing test correlation on protocol performance and the characteristics of the different criteria. Purpose: To examine the impact on protocol performance when individual tests in a protocol have different performance. This is evaluated for different criteria and test correlations. The results of the two articles are combined and summarized. Research Design: A mathematical model is used to calculate protocol performance for different protocol criteria and test correlations when there are small to large variations in the performance of individual tests in the protocol. Results: The performance of the individual tests that make up a protocol has a significant impact on the performance of the protocol. As expected, the better the performance of the individual tests, the better the performance of the protocol. Many of the characteristics of the different criteria are relatively independent of the variation in the performance of the individual tests. However, increasing test variation degrades some criteria advantages and causes a new disadvantage to appear. This negative impact increases as test variation increases and as more tests are added to the protocol. Conclusions: Best protocol performance is obtained when individual tests are uncorrelated and have the same performance. In general, the greater the variation in the performance of tests in the protocol, the more detrimental this variation is to protocol performance. Since this negative impact is increased as more tests are added to the protocol, greater test variation indicates using fewer tests in the protocol.

A new approach to water cut forecasting based on results of capacitance resistance modeling

2020 ◽  
Vol 6 (1) ◽  
pp. 192-207 ◽  
Author(s):  
Alexander D. Bekman ◽  
Tatiana A. Pospelova ◽  
Dmitry V. Zelenin
Keyword(s):  
Mathematical Model ◽  
Injection Well ◽  
Adaptation Algorithm ◽  
Injection Wells ◽  
Operational Analysis ◽  
Operating Modes ◽  
Advantages And Disadvantages ◽  
Stage Of Development ◽  
Water Cut ◽  
The Impact

For oil fields that are at a late stage of development, urgent tasks are the operational analysis of the development and optimization of the operating modes of injection wells. The demand for responsiveness often forces one to abandon the use of three-dimensional hydrodynamic models in favor of analytical ones such as CRMP. Using CRMP models allows you to quickly assess the trends in the impact of injection wells on producing wells and build reliable short-term forecasts for fluid production. Supplementing the traditional (single-phase) CRMP model with a water cut model also allows predicting oil production rates for producing wells and expands the capabilities of an operational analysis of the existing development system. In addition, an adequate water cut model allows using the CRMP model to solve the problem of optimizing the operating modes of the injection well stock. This article discusses the main known water cut models used in conjunction with the CRMP model, provides a brief analysis of their advantages and disadvantages. A new authorial mathematical model of water cut (“multi-characteristic model”) is proposed, which allows to establish the role of each injection well in changing the water content of the considered producer. An adaptation algorithm is also described, that is, the selection of unknown model coefficients implemented in Ariadna software (developed by Tyumen Petroleum Research Center LLC). The low computational complexity of the algorithm allows you to quickly simulate areas containing up to several hundred wells. The results of experiments on the use of a new mathematical model on a synthetic model of an oil reservoir are presented. The results of predicting water cut are compared with the results of previously known methods. The restrictions for using the new model, as well as directions for its development are indicated.

scholarly journals Rocket tracking impact point prediction using α-β, standard Kalman, extended, Kalman, and unscented Kalman filters: a comparative analysis

2020 ◽  
Vol 9 (3) ◽  
pp. e42932022
Author(s):  
José Alano Peres de Abreu ◽  
Roberto Célio Limão de Oliveira ◽  
João Viana da Fonseca Neto
Keyword(s):  
Mathematical Model ◽  
Kalman Filter ◽  
Comparative Analysis ◽  
Unscented Kalman Filter ◽  
Target Position ◽  
Accurate Information ◽  
Impact Point ◽  
Advantages And Disadvantages ◽  
Tracking Algorithms ◽  
The Impact

Accurate information about the impact point (IP) of a suborbital rocket on Earth’s surface during a launch is an important requirement for range safety operations. Four different estimators, i.e., the α-β filter, standard Kalman filter (SKF), extended Kalman filter (EKF), and unscented Kalman filter (UKF), are considered for the suborbital rocket tracking problem, whose data are used specifically for improving the accuracy of the IP prediction (IPP) of these vehicles. This paper presents a comparative analysis between the results of the estimators. Rocket flight data are discussed to demonstrate the advantages and disadvantages of the estimators and to determine the inherent limitations in predicting the aerodynamic effects found in certain flight situations. We discuss the appropriate mathematical model of a filter capable of running the real-time algorithm for the estimation of target position and velocity. This work uses actual data from a radar sensor to evaluate the tracking algorithms. We insert the filter result into the mathematical model developed to predict the rocket IP on Earth's surface. The main goal of this study is to evaluate the performance of four different estimators when specifically applied for the improvement of the IPP of suborbital rockets. It is demonstrated that the UKF outperforms all other tracking algorithms in terms of the accuracy and robustness of IP estimation.

scholarly journals ДОСЛІДЖЕННЯ РОБОТИ СИСТЕМ КЕРУВАННЯ ДОЗУВАЛЬНИМ ОБЛАДНАННЯМ БЕЗПЕРЕРВНОЇ ДІЇ З «ПІ» ТА «ПІД» РЕГУЛЯТОРАМИ

2022 ◽  
pp. 18-27
Author(s):  
VOLODYMYR NICHEGLOD ◽  
OLEKSANDR BURMISTENKOV ◽  
VOLODYMYR STATSENKO
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Operating Time ◽  
Pid Controllers ◽  
Engine Operation ◽  
Continuous Action ◽  
Advantages And Disadvantages ◽  
Plate Feeder ◽  
The Impact ◽  
Continuous Dosing

Purpose. Investigation of transients in the control system of continuous dosing equipment for bulk materials using PI and PID regulators and evaluation of their impact on the quality of work elements.Method. Using the Mathlab: Simulink software environment to develop a mathematical model, conduct experimental research and assess the impact on the working bodies of the control system of continuous dosing equipment.Researchresults. Control of motor parameters (motor characteristics) by means of standard regulators of their comparison of advantages and disadvantages. described in many standards and scientific papers. However, modeling the engine operation process in dosing systems is significantly complicated due to the inertness and adhesion of bulk material dosed in the core of the hopper, it can significantly affect the final result of the finished mixture. continuous operation equipment using PI and PID controllers, an experiment was performed on a mathematical model using PI and PID controllers to assess their impact on the control system of the plate feeder continuous action. The results of the simulation can be used to decide on the type of controller control of transient characteristics of the engine, at development of control system of plate feeders in mixing complexes of continuous action.Scientificnovelty. Scientific novelty. The parameters influencing the frequency with which the motor of the plate feeder of continuous action rotates are determined. The time of the transient process of engine operation and the value of the maximum dynamic deviation are determined. The expediency of using regulators of one or another type for certain modes of operation of feeders is proved.Practical significance. The obtained results will reduce the transient time in the operation of the feeder motor and increase the operating time until the failure of the entire system. Design changes are proposed that will reduce the amount of ripple and improve the performance of continuous dosing equipment.

The Impact of Light Polarisation on Light Field of Scenes with Multiple Reflections

2020 ◽  
pp. 108-115 ◽  
Author(s):  
Vladimir P. Budak ◽  
Anton V. Grimaylo
Keyword(s):  
Mathematical Model ◽  
Light Field ◽  
Global Illumination ◽  
Multiple Reflections ◽  
Software Environment ◽  
The Monte Carlo Method ◽  
Mueller Matrices ◽  
Volume Integration ◽  
The Impact

The article describes the role of polarisation in calculation of multiple reflections. A mathematical model of multiple reflections based on the Stokes vector for beam description and Mueller matrices for description of surface properties is presented. On the basis of this model, the global illumination equation is generalised for the polarisation case and is resolved into volume integration. This allows us to obtain an expression for the Monte Carlo method local estimates and to use them for evaluation of light distribution in the scene with consideration of polarisation. The obtained mathematical model was implemented in the software environment using the example of a scene with its surfaces having both diffuse and regular components of reflection. The results presented in the article show that the calculation difference may reach 30 % when polarisation is taken into consideration as compared to standard modelling.

The Management of Post-Tonsillectomy Morbidity in Patients With Sleep Apnoea

2019 ◽  
Vol 70 (10) ◽  
pp. 3738-3740
Keyword(s):  
Day Surgery ◽  
Sleep Apnoea ◽  
Integrative Approach ◽  
Multicenter Studies ◽  
Therapeutic Modalities ◽  
Advantages And Disadvantages ◽  
Obstructive Sleep ◽  
Wide Range ◽  
The Impact ◽  
Surgery Center

The Tonsillectomy in children or adults is an intervention commonly encountered in the ENT (Ear Nose and Throat) and Head and Neck surgeon practice. The current tendency is to perform this type of surgery in major ambulatory surgery centers. Two objectives are thus pursued: first of all, the increase of the patient quality of life through the reintegration into the family as quickly as possible and secondly, the expenses associated with continuous hospitalization are reduced. Any tertiary (multidisciplinary) sleep center must ensure the complete diagnosis and treatment (including surgery) of sleep respiratory disorders. Under these conditions the selection of patients and especially the implementation of the specific protocols in order to control the postoperative complications it becomes essential. The present paper describes our experience of tonsillectomy as treatment for selected patients with chronic rhonchopathy (snoring) and mild to moderate obstructive sleep apnoea. It was presented the impact of antibiotics protocols in reducing the main morbid outcomes following tonsillectomy, in our day surgery center. The obtained results can also be a prerequisite for the integrative approach of the patients with sleep apnoea who were recommended surgical treatment. Considering the wide range of therapeutic modalities used in sleep apnoea, each with its specific advantages and disadvantages, more extensive and multicenter studies are needed. Keywords: post-tonsillectomy morbidity, day surgery center, sleep disorders

The Good, the Bad and the Ugly
. A Broad look at the Adaptation of Technology in Education

2020 ◽  
Vol 2 (1) ◽  
pp. 31-44
Author(s):  
Vladislav Ilin
Keyword(s):  
Technology In Education ◽  
Advantages And Disadvantages ◽  
Standardized Method ◽  
Impact Of Technology ◽  
The Impact ◽  
The Way

Technology in education is a global phenomenon affecting learners of all ages. The breadth and variety of available tools make it difficult to implement a standardized method for assessing the impact of technology on learning. The lack of a consensus on good and bad practices results in inconsistent application and mixed learning results.   This article takes a look at the adaptation of technology to education and examines the various tools used to enhance learning. We discuss the advantages and disadvantages of using technology, as well as review methodologies for evaluating the impact.   The essay concludes by identifying several problems with the way technology is evaluated and offers suggestions for further research to address those problems.

Analyzing the Impact of Healthy Behavior on Weight Change with a Provable Mathematical Model (Preprint)

2020 ◽  
Author(s):  
Ayan Chatterjee ◽  
Ram Bajpai ◽  
Pankaj Khatiwada
Keyword(s):  
Physical Activity ◽  
Mathematical Model ◽  
Health Behavior ◽  
Weight Change ◽  
Simulated Data ◽  
Negative Behavior ◽  
Healthy Behavior ◽  
Healthy Habits ◽  
Lifestyle Diseases ◽  
The Impact

BACKGROUND Lifestyle diseases are the primary cause of death worldwide. The gradual growth of negative behavior in humans due to physical inactivity, unhealthy habit, and improper nutrition expedites lifestyle diseases. In this study, we develop a mathematical model to analyze the impact of regular physical activity, healthy habits, and a proper diet on weight change, targeting obesity as a case study. Followed by, we design an algorithm for the verification of the proposed mathematical model with simulated data of artificial participants. OBJECTIVE This study intends to analyze the effect of healthy behavior (physical activity, healthy habits, and proper dietary pattern) on weight change with a proposed mathematical model and its verification with an algorithm where personalized habits are designed to change dynamically based on the rule. METHODS We developed a weight-change mathematical model as a function of activity, habit, and nutrition with the first law of thermodynamics, basal metabolic rate (BMR), total daily energy expenditure (TDEE), and body-mass-index (BMI) to establish a relationship between health behavior and weight change. Followed by, we verified the model with simulated data. RESULTS The proposed provable mathematical model showed a strong relationship between health behavior and weight change. We verified the mathematical model with the proposed algorithm using simulated data following the necessary constraints. The adoption of BMR and TDEE calculation following Harris-Benedict’s equation has increased the model's accuracy under defined settings. CONCLUSIONS This study helped us understand the impact of healthy behavior on obesity and overweight with numeric implications and the importance of adopting a healthy lifestyle abstaining from negative behavior change.

Unfunded Public Employee Health Care Benefits and GASB No. 45

2007 ◽  
Vol 21 (3) ◽  
pp. 245-263 ◽  
Author(s):  
Elizabeth K. Keating ◽  
Eric S. Berman
Keyword(s):  
Health Care ◽  
Financial Reporting ◽  
Full Range ◽  
Financial Reports ◽  
Employment Benefits ◽  
Care Plans ◽  
Advantages And Disadvantages ◽  
Government Accounting ◽  
The Government ◽  
The Impact

The Government Accounting Standards Board (GASB) recently released Statement No. 45, Accounting and Financial Reporting by Employers for Post-Employment Benefits Other Than Pensions and its companion Statement No. 43 for pooled stand-alone health care plans, which will profoundly affect American governmental finance. The goal of this article is to encourage governments to consider carefully a full range of options in funding and restructuring other post-employment benefits (OPEB). This article will review Statement No. 45's potential impact on governments and review existing disclosures in financial reports as well as bond offering statements. The article will discuss the statement's impact on budgets and governmental operations, including collective bargaining. Funding options under Statement No. 45 will be detailed, including the advantages and disadvantages of irrevocable trusts and OPEB bonds. The article will also discuss the impact of Medicare Part D subsidies received by governments, as well as the bond rating implications of policy decisions surrounding OPEB. As the largest government entities are just now implementing GASB Statement No. 45, estimates of the magnitude of unfunded OPEB liabilities are limited as are the strategies likely to be adopted to cover these obligations. This article offers a summary of the unfunded OPEB liabilities reported by states and major cities and suggests some measures for assessing the ability of these entities to address these costs.

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