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analytical model
Abstract Interpretation of reservoir boundary conditions historically have been done and analytical models have been developed for various reservoir boundary conditions including constant pressure boundary. Bourdarot (1988) and Kuchuk (1996) stated that the effect of an aquifer can be modeled with a constant pressure boundary model. This model assumes that the pressure at the boundary of the reservoir consistently remains at the initial reservoir pressure during the drawdown and build up phases of the well test. Hence, it suggests that the pressure support from gas cap is very strong due to expansion and that the multi-phase flow effects can be neglected. These assumptions work well for gas cap depletion systems since mobility change from oil reservoir to gas reservoir makes sense (i.e. gas reservoir mobility is generally much higher than oil reservoir mobility). This assumption is not valid for gas-water drive system since gas reservoir mobility is much higher than water reservoir mobility. Kehinde (2013) demonstrated this phenomenon by utilizing a numerical simulation for gas reservoir. This paper states the false response of constant pressure boundary model for gas reservoir pressure transient analysis (PTA), explores an alternative solution for this phenomenon and demonstrates the value of new method. In this study, Analytical model of constant pressure boundary model was reviewed and discussed. Then, two gas reservoir PTA's were interpreted analytically where constant pressure boundary model was required to able to get a match. However, those reservoirs do not have a connected aquifer. The possible explanation of constant pressure boundary response is likely pressure support from neighboring block, which is geologically supported. Study were extended to make a comprehensive numerical well test models where various combination of cross flow models (i.e. partial compartmentalization) were tested and It was confirmed the pressure support from neighboring block is most likely explanation for that PTA's behavior. This document provides a summary of the constant pressure boundary interpretation models for gas reservoir and discuss the application of analytical models into practical cases. The result of this investigation indicates pitfalls of direct application of analytical models. It was demonstrated that revealing of false response of constant pressure boundary model for gas reservoir pressure transient analysis enabled in increased and realistic in place estimation. Results shown that conventional analytical constant pressure boundary models are underestimating in-place volumes, resulted in โผ2-15 times less than what It should be since it does not model the pressure support properly. Study results concluded that cross flow from neighboring blocks will give the similar response of constant pressure boundary effect in PTA. However, consequence of 2 scenario (cross flow versus constant pressure) will be totally different in terms of in place volume that is crucially affects the field development opportunities.
Prediction of ESPs Failure Using ML at Western Siberia Oilfields with Large Number of Wells
Khabibullin, Rinat Alfredovich (Gubkin Oil and Gas University Moscow) | Shabonas, Arturas Rimo (Gubkin Oil and Gas University Moscow) | Gurbatov, Nikolay Sergeevich (Deeplight) | Timonov, Alexey Vasilievich (Expert)
Abstract The development of a technology forecasting ESP failures is one of the key tasks of the oil industry today. Simple statistical methods do not allow to predict the equipment's failure and its cause, which would allow to select and conduct the planned preventive measure in time. This paper describes the methodology of ESP failure prediction developed based on field data. The main stage of the methodology is the creation of an ensemble model of machine training, the application of which allows for the taking into account of many factors and extensive experience in operating ESPs contained in field data, so considerable time has been devoted to working with them. The uniqueness of the presented work is the use of field information on well operation in Western Siberia, accumulated for the last 5-7 years from the discrete measurements of one day, in which there was a significant amount of information omission. To improve the quality of forecasting, it required multilevel pre-processing of initial data and formation of additional analytical features, which allowed improvement of the quality of predictions. The study of the developed model for the prediction of the ESP failures at different prediction horizons was carried out and it was determined that the quality of prediction increases when the interval of prediction decreases. The developed model shows the best results when predicting the ESP failure 1-3 days before its actual stop. The groups of parameters, on which the duration of failure-free operation of pumping equipment in a well depends to a great extent, have been determined this is information about the well operation mode, information about ESP operation parameters, dynamic information about complicating factors of the ESP operation and additional analytical parameters describing the processes occurring in the system "Wellbore โ ESP โ Tubing". The ESP failure prediction model, the development of which is described in this work, can become the basis of the decision support system, its implementation in production will allow to identify in advance the cases of possible downhole pumping equipment failure and to take timely measures based on this information. Based on the obtained results and high relevance of the problem under consideration, the main directions for further improvement of the developed methodology have been defined.
- Europe > Russia (0.29)
- Asia (0.29)
- North America > United States (0.28)
Analysis and Prediction of Well Performance in Heterogeneous Reservoirs Based on Field Theory Methods
Yudin, Evgeniy (Gazpromneft Science & Technology Centre) | Poroshin, Ilya (Research and Education Center Gazpromneft Polytech) | Korikov, Dmitriy (Research and Education Center Gazpromneft Polytech) | Morozova, Anna (Research and Education Center Gazpromneft Polytech) | Kolyuk, Olesya (Gazpromneft Science & Technology Centre)
Abstract As a rule, the basis for engineering calculations for monitoring the productivity of wells is the model of stationary and unsteady inflow in homogeneous formations or formations with a given type of zonal heterogeneity. This is due to the presence of analytical models for these cases with a high calculation speed. The approaches proposed in the article on the use of field theory methods, on the one hand, being analytical, have a high calculation speed, and, on the other hand, allow one to take into account an arbitrarily distributed inhomogeneity in filtration-capacitive properties. This advantage can become the basis for the development of new engineering tools in assessing the flow in heterogeneous reservoirs. The main goal of this work is to develop a methodology for calculating well productivity and rapid assessment of pressure distribution in heterogeneous reservoirs. In contrast to the traditional approach to modeling filtration in inhomogeneous media using numerical finite-difference and finite-element methods, the article investigates the applicability of computational algorithms based on the use of the mathematical apparatus of perturbation methods and composite asymptotics.
- Reservoir Description and Dynamics > Formation Evaluation & Management > Drillstem/well testing (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (0.72)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Well performance, inflow performance (0.71)
Abstract Completion designs in horizontal, multi-stage wellbores is a complex problem and has many potential scenarios depending on the desired well performance. Up until recently the industry has been focused on improving early-time productivity; 90-day cumulative production, 24-hour initial potential (IP) or achieving a target daily rate. Many operators are now refocusing on a desired economic outcome; achieving free cash flow, improving return on investment and increased net present value. Our paper will discuss the effects that different completion design changes have on these desired results and present examples of past well performance and new well performance utilizing these changes. Our methodology will include the analysis of producing well histories to determine average reservoir permeability and completion effectiveness as described by the number of created, producing transverse fractures and the average effective length of those fractures. From this characterization of the reservoir and past completions we will forward model completion design scenarios to determine the effect changes in design have on the performance parameters we wish to achieve. The process used includes hundreds of completion design scenarios which are compared to each other to find the design which maximizes the desired economic result. Multiple examples of this will be presented. Increasing early-time production performance has resulted in increasing capital expenditure. Several completion design parameters lead to increases in this performance parameter (IP); increasing lateral length, increasing stage volume and decreasing stage spacing. However, all of these changes increase the capital spent on the completion. To achieve improved economic performance parameters, balancing the total capital expenditure against the revenue generated becomes the primary focus. What may have worked in the past to meet past goals does not work to meet new, economic focused goals. The most important parameter we must know when designing the completion is the reservoir permeability. This value determines the reservoirs ability to deliver hydrocarbons to the well and how effective the reservoir can be to creating the revenue necessary to pay for the capital spent. Identifying the balance between capital spent and revenue generated leads to completion designs that reduce well cost while maximizing economic parameters versus maximizing early-time production alone. The results and conclusions from this paper will run contrary to the industry's past trends in completion design. However, the focus on economic improvement can be a pathway to our industry to achieve better economic results. Our industry has provided increased energy independence for our nation, but far too many companies are suffering financially while doing so. Billions of barrels of oil have been produced, yet many are going broke.
Tuned liquid column damper (TLCD) has been widely used in ship industry to damp the roll motion. Utilizing this technology for floating offshore wind turbines (FOWTs) has been recently studied. Research shows that the overall FOWT system benefits from the extra damping introduced by the TLCD. Nevertheless, the challenge of adapting the special configuration of the conventional TLCD for ships to the state-ofart floaters for wind turbines is highlighted. In addition, because of the existence of the yaw system of the turbine, a three dimensional damper is required, which is difficult to achieve by conventional TLCD. The concept of tuned liquid multiple column damper (TLMCD) solves this problem ideally. Analytical model describing the dynamics of such concept has been presented. To verify the model, CFD transient simulations are carried out in this study. Pressure inlet and outlet are used to describe the free surface boundary condition and the flow inside the fluid tanks is dominated by the gravity and pressure. The aim is to verify the natural frequency of the analytical model, and discuss the damping coefficient related to different geometries. The validity of the analytical model is identified and the behavior of natural frequencies and damping coefficient of the TLMCD are discussed. INTRODUCTION Compared to bottom fixed wind turbines, floating offshore wind turbines (FOWTs) confront more challenges due to the complex environmental conditions. On one hand, the wave load, which is one of the dominant load sources, yields extra responses, e.g. at the tower base (Fleming, Pineda, Rossetti, Wright, & Arora, 2014). On the other hand, the soft support structure can lead to instability due to a coupling with the wind turbine controller. Wind and wave feedforward controllers show the potential to improve the system dynamics and loads numerically, however increased sensors lead to a less robust system (Yu et al., 2018), (Lemmer (nรฉ Sandner), Yu, Schlipf, & Cheng, 2019).
- Health, Safety, Environment & Sustainability > Environment (1.00)
- Health, Safety, Environment & Sustainability > Sustainability/Social Responsibility > Sustainable development (0.91)
- Facilities Design, Construction and Operation > Facilities and Construction Project Management > Offshore projects planning and execution (0.55)
ABSTRACT Based on the analytical model of maneuvering response, the ship's heading objective function is directly constructed, and the genetic algorithm based on Gray code is used to optimize the maneuverability KT index. Based on actual ship test data, a series of identification experiments are carried out by reducing the number of identified samples, which shows that the identification method proposed in this paper can achieve extremely high recognition accuracy with only a small amount of data, and greatly improve the identification accuracy. The identification method proposed in this paper solves the problem of accurately calculating the ship's maneuverability KT index when the test data is insufficient, and improves the identification accuracy and efficiency of the KT index. And the data error of the actual ship test is analyzed. Through the actual investigation of the performance parameters of the actual ship equipment, using the uncertainty calculation principle, the uncertainty analysis of the identified KT index is carried out, and the influence of the error on the result is quantitatively measured. INTRODUCTION Since Nomoto proposed the method of using the Z-shaped test to obtain the KT index of the steering response, the KT equation has been widely used in ship steering modeling. With the development of computers, the identification of the KT index has gradually evolved from the most primitive mapping methods to today's system identification. Xin (1983) established a continuous model of first- and second-order KT nonlinearity through the least square method of the natural regression discrete model; The parameters of the equation were identified. Zou (1985) used a two-step identification method to identify the parameters of one and two order non-linear K-T equation to overcome the cancellation effect among the parameters. Serge and Guedes (2014, 2015) used classic genetic algorithm combined with self-propelled model test to identify the hydrodynamic derivative of the ship's motion model. Yin (2015) used the partial least square method to identify the hydrodynamic derivative of the mathematical model of integral ship maneuvering motion. Xie (2017, 2018) and others used the innovation least square method and Kalman filter to identify the parameters of the KT equation.
Application of Analytical Model for Tidal Residual Sediment Transport in Estuaries
Xu, Yi (College of Harbor Coastal and offshore Engineering, Hohai University) | Chu, Ao (College of Harbor Coastal and offshore Engineering, Hohai University / Civil Engineering and Geoscience, Delft University of Technology / Jiangsu Key Laboratory of Coast Ocean Resources Development and Environment Security, Hohai University) | Chen, Yongping (College of Harbor Coastal and offshore Engineering, Hohai University)
ABSTRACT In coastal seas and estuaries, the presence of periodic forces, e.g. tides, results in the fluctuation of sediment transports. Therefore, the study of residual sediment transport in a tidal environment is more practical rather than sediment transport itself. Based on the assumption that sediment transport is proportional to an exponential power of current velocity (u), a simplified analytical expression is derived for residual total load sediment transport in a tidal environment. The tidal current is represented by tidal current constituent series of M0, M2, S2, N2, M4, MS4, MN4, M6, K1 and O1. The expression can be adapted to quantify the sediment transport in areas with significant residual current and diurnal tidal regimes. INTRODUCTION In coastal seas and estuaries, sediment transport, which is closely related to morphological changes, is greatly influenced by runoff, tidal currents, waves and human activities. In such areas, the presence of periodic forces, e.g. tides, results in the fluctuation of sediment transports. However, the morphological changes are principally determined by the residual sediment transport without the influence of periodic factors (Postma, 1961; van der Wegen and Roelvink, 2008). Previous studies have shown that tide wave is distorted as it propagates into estuaries and coastal seas influenced by water depth, run off and landform (Prandle, 1985; Friedrichs and Aubrey, 1994). Tidal current asymmetry and tidal pumping effects play major roles in residual sediment transport (Dronkers, 1986; van de Kreeke and Robaczewska, 1993; Friedrichs and Aubrey, 1988; Wang et al., 1999). A flooddominant tidal asymmetry leads to a landward residual sediment transport, and an ebb-dominant tidal asymmetry causes a sea ward residual sediment transport (Boon and Byrne, 1981; Speer and Aubrey, 1985). Assuming the transport of sediment to be proportional to the power of the depth-averaged local current speed (Bagnold, 1966; Engelund and Hansen, 1967), van de Kreeke and Robacczewska (1993) analyzed the influence of residual current M0 and tidal current constituent series of M2, M4, M6, S2 to residual sediment transport. They derived an analytical expression for residual transport of coarse sediment in terms of the amplitudes and phases of the tidal current constituents. van de Kreeke and Robacczewska (1993)further adopted the tidal current constituents of M0, M2, M4, M6 and the full tidal current constituent series to drive the model of the Ems Estuary with the comparable model results of residual sediment transport. The results are regarded as the theoretical basis for the reduction of tidal signals from the full constituents series to the simplified series of M0, M2, M4 and M6in coastal morphodynamics modelling applications (van de Wegen, 2005; Guo, 2014).
Effects of Wave-Induced Two-Dimensional Seepage Flow on Sediment Incipient Motion
Zhai, Hualing (School of Civil Engineering, Southwest Jiaotong University) | Jeng, Dong-Sheng (School of Engineering & Built Environment, Gri?th University Gold Coast Campus) | Liu, Junwei (School of Civil Engineering, Qingdao University of Technology)
ABSTRACT Sediment incipient motion is the first stage of the whole process of local scour around a marine infrastructure. Most previous investigations ignored seepage flow on the mobility of bed particles except a recent study including the effects of vertical seepage flow in the prediction of sediment motion. In this paper, a new model further combing the vertical and horizontal seepage force is proposed. The modified Shields parameter by considering two-dimensional seepage is derived. Then, the effects of wave and soil parameters on sediment incipient motion are analyzed. It was found that lower water depth and saturation, higher wave height, shear modulus and permeability, will remarkably increase both modified Shields parameters and the gaps of the results considering vertical and two-dimensional seepage forces. Therefore, the horizontal seepage can not be ignored. INTRODUCTION As the first step of sediment incipient motion in the process of local scour, the critical Shields number is an important threshold condition for the sediment moving from a static condition. Numerous studies (Shields, 1936; Bagnold, 1960; Yalin, 1977) proposed various criteria. In most criteria, the Shields parameter has been commonly used to determine the threshold condition of sediment incipient motion. Initially, the Shields parameter was used for the unidirectional flows in a flat or near-flate bed. Later, several modifications to the conventional Shields diagram have been proposed for different sediments based on laboratory tests. For example, Madsen and Grant (1976) modified the Shields Criterion obtained for an oscillatory flow. They concluded that the Shields parameter is essential to consider the influence of the sediment incipient motion under the action of wave in the prediction of the local scour. Le Roux (2001) proposed a simple method to predict the threshold of particle transport under oscillatory waves, which was valid for grains of varying size and density in a laminar or turbulent flow. Whitehouse et al. (1988) and Chiew et al. (1994) modified the Shields diagram for a sloping bed with an inclination angle.
- Research Report > New Finding (0.68)
- Research Report > Experimental Study (0.46)
ABSTRACT This paper proposes a reliable and stable numerical method for homogenized axial elastic modulus prediction of RTPs using finite element models subjected to tension. Compared with the homogenization method, the differences were even less than 1%, which demonstrated that the homogenization method could be applied to prompt and accurate predictions of elastic responses of RTPs subjected to tension. The investigation on the effect of winding angles demonstrated the thickness and area ratios of each layer also play significant roles in the determination of homogenized axial elastic moduli. The effects of thickness-radius and stacking sequences are also discussed. INTRODUCTION In recent years, RTPs have been found an increasingly extensive utilization in ocean oil and gas industry in terms of its excellent performance such as corrosion resistance, high-pressure resistance, high strength, and low weight, etc (Bai et al.,2014; Bai et al., 2016; Toh et al., 2018; Liu and Wang, 2019a). As shown in Fig.1, liner and coating made of isotropic materials such as HDPE are the innermost and outermost layers of RTPs to protect the laminates from corroding due to the transported fluid and the external environment (Yu et al., 2015; Liu and Wang, 2019b). The middle laminates composed of HDPE matrix and carbon fibers (or glass fibers) wound at different angles are the principle load-bearing structures when RTPs are subjected to various loads. Adjacent layers should be bonded with good adhesion and no delamination for a quality RTP. As the exploration of oil and gas moves into deep water, understanding the mechanical responses of RTPs under tension are essential to ensure the secure and reliable operation of offshore engineering constructions. However, due to the complicated material components, it's hard to predict the axial elastic characteristics of RTPs with high accuracy. Many pieces of research has been carried out in the past decades to push forward the utilization and promotion of RTPs. Based on the classical laminated-plate theory, Xia et al. (2002) proposed a displacement-based approach to analyze the stress-strain and deformation of pipes under pure bending. The results coincided with the results from the general method (Pagano,1972). By assuming RTPs as homogenous cylindrically orthotropic pipes, Sun et al. (2014a; 2014b) proposed the homogenization method based on stress approach to predict the homogenized elastic constants. Compared with other analytical methods for composite plates and shells (Sun and Li, 1988; Enie and Rizzo, 1970), the homogenization method can predict similar results and carry out the stress analysis quickly. On the other hand, the finite element method is an alternative method to analyze the composite cylindrical structures under different loading cases. Yoo et al. (2017) proposed a practical and stable method using 8-layer and 5-layer finite element models to conduct the ultimate-tension assessment and elastic response of unbonded flexible risers. He et al. (2014) predicted the collapse behavior of thick-wall pipes taking account in the effects of initial ovality, yield stress and anisotropy by Abaqus. Bai et al. (2016) simulated the collapse behavior of steel strip reinforced thermoplastic pipes subjected to external pressure using the arc-length method. Ren et al. (2013) studied the behavior of unbonded flexible risers subjected to axial tension based on Abaqus/Explicit. The above numerical methods can provide reliable predictions of ultimate strength and elastic responses, but it requires building a specific model in each case. Meanwhile, due to the geometric nonlinearity and material anisotropy, the numerical models of composite pipes generally occupy massive computation resources.
A Pore-Scale Investigation of Solvent-Assisted Thermal Processes for Heavy Oil and Bitumen Recovery - Mass Transfer and Condensation Mixing
Bayestehparvin, Bita (VMG, A Schlumberger Technology) | S.M., Farouq Ali (University of Houston) | Kariznovi, Mohammad (Univeristy of Calgary) | Mohammadzadeh, Omid (Schlumberger - Doll Research)
Abstract Dispersion of a solvent into heavy oil and bitumen in porous media has special significance in the context of solvent-based as well as solvent-aided versions of SAGD and CSS recovery processes. While solvent is injected with steam, the mixture condensation temperature changes based on solvent partial pressure. In addition, water condensate creates a film which acts as a barrier and impacts solvent dissolution in oil. The solvent, which is not soluble or has very low solubility in water, may not be able to diffuse in the oleic phase due to the presence of the water film. The objective of the present study is to investigate the pore-scale solvent diffusion in oil for solvent-based and hybrid (steam + solvent) processes through the following steps: Developing a pore-scale simulator, capable of handling steam and solvent condensation as well as mass transfer in porous media. Investigating solvent dissolution in the oleic phase at the pore-level considering the asynchronous condensation of solvent and steam. Investigating the dissolution of solvent, either in gaseous phase or in the form of liquified thin bulk films of condensed solvent and water condensate, in the oleic phase. A pore-scale simulator was developed with the capability of modelling solvent mass transfer and condensation of both solvent and steam, along with a Navier-Stokes type solution for the velocity field. In addition, conjugate heat transfer was included in the model that takes into account the heat transfer from solvent and steam to the solid grains by considering the two media (i.e. solid and fluid) for the solution. A realistic description of a 2-dimensional porous medium is used for direct numerical simulation (DNS). The properties of a typical heavy oil and solvent were implemented in the model with diffusion coefficient as functions of both temperature and solvent concentration. After model setup, the newly added features of mass transfer and conjugate heat transfer were validated by comparison with analytical models. For mass transfer validation, the numerical results were in agreement with analytical solution for a capillary whereas the model performance for conjugate heat transfer were inline with the analytical solution proposed for heat flow over a slab. The pore-scale simulator was then used to model two-dimensional pore-scale experiments of solvent co-injection with steam. To reproduce the experimental results, the interface advancement velocity was calculated as an evidence of the chamber growth. The 2D numerical simulation results were in agreement with the experimental data. The condensation of solvent vapor and steam also changes fluid flow and flow pathways of solvent at the pore-scale which results in some complex fluid flow and behavior such as excessive unexpected channeling. The present study is the first of its kind which considers condensation of steam and solvent vapor at the pore scale. The model is used to investigate solvent vapor condensation in competition with steam at the pore-scale and to study the impact of solvent type and operating conditions such as pressure. The outcome of the present study improves our understanding of mass transfer in porous media for solvent- based and solvent-aided thermal recovery processes.
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Thermal methods (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Steam-solvent combination methods (1.00)