bluuebunny/crossref_metadata_2025 huggingface dataset:
Social Capital. Viewing Nordic Paths of Management
Authors: Veggeland Noralv
Published: May 2017

How do Nordic states conduct policies in order to bring people closer to the socio-economic realm, in the sense that they, being social capital, tend to be integrated as active and participatory citizens? How do the interventionist and expensive Nordic welfare states survive in the global age, with demanding and ever changing claims to international competitiveness? This paper addresses these questions. Social capital and partnership building are introduced as terms and policy concepts in order to find answers in the framework of intended or unintended strategic endeavours. As a critical approach claims a contextual conceptualisation, we shall here view different European social models and administrative traditions in relation to comparative basic contexts in order to arrive at analytical answers. Leaning especially on the Anglo-Saxon model, the traditional Scandinavian universal welfare state model of the post-war Keynesian order has gradually been transformed into the contemporary Nordic model (Veggeland 2007). Contextual regulatory innovations and path-dependent processes have generated the survival of universal welfare state arrangements and collective action but with the mixed use of Market-Type Mechanisms (MTM) in the public sector of Anglo-Saxon origin. In summary, this blending of policies has resulted in the advantageous social capital of what is called flexicurity, social security combined with a flexible participatory labour market. We shall discuss both flexicurity policy and participatory subsidiarity defined downwards as contribution to an explanation of why the expensive welfare states of the Nordic type have not only so far been doing well but have also sustained both democratic and output-side legitimacy.
Exports as a Determinant of Inflation in Kenya: Disaggregated Econommetric Analysis
Authors: Kiganda Evans Ovamba , Adhiambo Scholastica , Obange Nelson
Published: May 2017

The purpose of this study was to examine exports as a determinant of inflation in Kenya: A disaggregated econometric analysis with specific objectives of establishing the relationship between domestic exports and inflation in Kenya and determining the relationship between re - exports and inflation in Kenya. This was occasioned by inconclusive and incomprehensive analysis on the relationship between exports and inflation given mixed results and failure by scholars to disaggregate total exports into domestic exports and re-exports. Correlation research design was employed using monthly time series obtained from Central Bank of Kenya (CBK) data spanning 132 months from January 2005 to December 2015.Vector Autoregressive (VAR) techniques of cointegration, Granger causality and impulse response analysis were employed. Results indicated a significant positive and negative long run relationship between domestic exports and re- exports with inflation in Kenya respectively that were supported by the impulse response analysis. A unidirectional causality running from domestic exports to inflation and re-exports to inflation was also established. The study concluded that domestic exports and re-exports determine inflation in Kenya with domestic exports having greater influence and therefore recommended that the government of Kenya needs to advocate for a trade policy that aims at reducing exports of domestically produced products and increase re-exports. This will ensure that only surplus is exported to reduce shortage of domestically produced commodities hence a reduction in price for the products.
Climate Change and Rural Livelihoods in the Lawra District of Ghana. A Qualitative Based Study
Authors: Abdulai Abdul-Rahim , Ziemah Marshal K. , Akaabre Paul Boniface
Published: May 2017

Climate change is a growing threat to the world's poorest and most vulnerable living in rural areas. The impacts of climate change challenge efforts to reducing poverty and hence, will require new approaches to focus development programming on the changing realities of the world. Understanding how the impacts of climate change affect the people, and their knowledge and experience in coping with it will assist in identifying appropriate strategies for adaptation to it. This paper thus examined the impacts of climate change on livelihoods of rural communities in the Upper West region of Ghana and the challenges posed to efforts at reducing poverty in the area. Discussions on vulnerability to climate variability and adaptation issues in this paper focused on evidence observed by 10 communities in the Lawra District. Adopting a qualitative approach, ten focused group discussions were organized to gather data. Specific issues discussed surrounded evidence of climate change in the communities, its impacts, underlying causes of vulnerability to climate and coping strategies employed by community members. Based on the discussions, the paper recommends the need to develop and intensify effective institutional mechanisms to facilitate community adaptation measures, awareness raising (creation) on anti-environments practices in communities, institution of bye and customary laws to regulate human anti-environmental activities, and the implementation of adaptation projects to aid communities cope with the major impacts of climate change in the district and world at large.
O Fundo Nacional de Desenvolvimento Científico e Tecnológico - FNDCT e a Financiadora de Estudos e Projetos - FINEP
Authors: Ferrari Amílcar Figueira
Published: May 2017

Mesmo considerando as ações sendo desenvolvidas pelo Conselho Nacional de Pesquisas – CNPq, cujo titular, à época, do ponto de vista formal, respondia diretamente ao Presidente da República, pela Coordenação de Aperfeiçoamento do Pessoal de Nível Superior – CAPES do Ministério da Educação e Cultura – MEC e pelo Fundo de Desenvolvimento Técnico-Científico – FUNTEC, do então Banco Nacional do Desenvolvimento Econômico – BNDE, vinculado ao Ministério do Planejamento e Coordenação Geral – MPCG e por outras agências federais, ou talvez até pelo contrário, como conseqüência dessas ações, percebia-se, no final da década de 1960, a carência de apoio a: “um sistema de pesquisas científicas e tecnológicas que refletisse as necessidades efetivas e potenciais da economia brasileira e que passasse a * Este texto é, com poucos ajustes, uma transcrição do capítulo homônimo de José Pelúcio Ferreira e a Pós-Graduação no Brasil/Amílcar Figueira Ferrari Brasília Paralelo 15, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, 2001. 152 Revista Brasileira de Inovação conduzir o processo de expansão de seu aparelho produtivo sincronizado com a revolução científica e tecnológica”.
Causal Pathways for Temperature Predictability from Snow Depth
Authors: Kolstad Erik W.
Published: May 2017

Subseasonal-to-seasonal (S2S) weather forecasting has improved in recent years, thanks partly to better representation of physical variables in models. For instance, realistic initializations of snow and soil moisture in models yield enhanced predictability on S2S time scales. Snow depth and soil moisture also mediate month-to-month persistence of near-surface air temperature. Here the role of snow depth as predictor of temperature one month ahead in the Northern Hemisphere is probed via two causal pathways. Through the first pathway, snow depth anomalies in month 1 cause snow depth anomalies in month 2, which then cause temperature anomalies in month 2. This pathway represents the snow–albedo feedback, as well as cooling due to insulation, emissivity and heat loss. It is active from fall to summer, and its effect peaks in March/April in the midlatitudes and in May/June at high latitudes. A complementary second pathway, where snow depth anomalies in month 1 cause soil moisture anomalies in month 2, which then cause temperature anomalies in month 2 through soil moisture–temperature feedbacks, is only active in spring and summer. Its effect peaks later in the warm season than the effect of the first pathway. Geographically, snow depth mediates north of, and soil moisture south of, the areas with the highest temperature predictability from snow depth. These results indicate that the two pathways describe complementary physical mechanisms. The first pathway embodies month-to-month persistence of snow depth, and the second pathway represents melting of snow from one month to the next.
Problemas recurrentes de la traducción literaria
Authors: BENSOUSSAN Albert
Published: May 2017

Se aborda en este trabajo el concepto de fidelidad en la traducción literaria y su significado en la actualidad. El papel del traductor puede cifrarse en el de descubridor de un texto incógnito y misterioso. Al traducir se tiende a escribir de forma estéticamente bella sin considerar, según Milán Kundera, la transgresión frecuente en el lenguaje: registros coloquiales y vulgares, por ejemplo. Realizo varias reflexiones sobre mis traduciones de Vargas Llosa, para así tratar del deber de fidelidad al traducir lo escabroso, lo truculento y lo escatológico.
Panorámica de la Poesía "Canadiense-Française" Contemporánea
Authors: GARCÍA PEINADO Miguel A.
Published: May 2017

Breve panorámica de la poesía contemporánea del Canadá francés, que se inicia en la práctica con la figura de Nelligan, sigue con la generación denominada de los “grands arnés”, configurándose posteriormente en cuatro grandes bloques: la poesía de estética surrealista, la influencia de la casa editorial "El Hexágono” y los poetas nacionalistas, la poesía femenina y el lirismo urbano de la poesía del actual Quebec.
Effect of Heterogeneity on SAGD Start-Up and Optimization of Steam Circulation for a Deep Massive Reservoir: A Case Study
Authors: Wang Ziji , Han Bing , Zou Zhaoyu
Published: May 2017

Liaohe field is one of the largest heavy-oil fields in China. Its D-N Block is a deep massive ultra-heavy oil reservoir undertaking SAGD development, which will serve as a case study in this paper. Part of the dual horizontal wells had used cycle steam stimulation to start up the SAGD process but it generated severely uneven distributions of temperature, pressure, and saturation around wells due to the high reservoir heterogeneity. An improved steam circulation start-up methods instead of cycle steam stimulation is needed to overcome the problems.

We developed an optimization method by coupling the wellbore-reservoir simulation for steam circulation using a specialized thermal wellbore simulator and a commercial thermal reservoir simulation, and carefully considering the structure of the wellbore, fluid flow in the wellbore and reservoir characteristics. We found out several dominating factors on the heat loss and efficiency of steam circulation by considering the properties of tubing, annulus, liner, fluid components and formations on a conceptual model. Using an advanced criterion by monitoring the temperature distributions near the wellbore, wellbore operations including the injection rate and circulation period, the tubing strings layouts and other critical operation parameters are designed according to the features of downhole conditions to ensure a more homogeneous development of the steam chamber.

The simulation workflow and optimum circulation start-up stratergy was applied to a pilot dual-horizontal well group in the D-N Block. Steam circulating start-up process both in the wellbore and the reservoir was successfully simulated and compared with the conceptual model case. After optimization, reservoir simulation results showed a much better behavior in the start-up and the subsequent SAGD stage, mitigating the risk of steam fingering, resulting in a steady transition to SAGD stage. Monitoring data from downhole temperature sensors also suggested a favorable process. For example, temperature data in a series of time showed that the temperature between the horizontal wells kept increasing uniformly, which indicated that the steam chamber connects the two wells in a favorable manner. Comparing with the cyclic steam stimulation start-up and the steam circulation without optimization, the optimized steam circulation achieved much better recovery efficiency in SAGD process.

In this paper, a systematic workflow has been described which couples the simulation of the reservoir characteristics and wellbore conditions. Optimized operation guideline was implemented into the SAGD wells and overcame the uneven start-up of dual-horizontal wells. This achievement can be applied to other SAGD wells in Liaohe, and probably extended to other fields.
Full Pore Petrophysical Analysis to Model A Large Multimodal Carbonate Oil Reservoir
Authors: Al-Awdah Mohammed S. , Clerke E. A. , Badawi Ahmed F. , Mubarak Yasir
Published: May 2017

A major reservoir has been analyzed using the now established Saudi Aramco Full Pore System petrophysical modelling workflow. This workflow acquires a complete mercury injection capillary pressure (MICP – analyzed using the Thomeer method) database to cover the universe of petrophysical possibilities. Detailed MICP data gathering processes, sample selection and quality control procedures are deployed by this petrophysical workflow. The Thomeer database created is used by internally designed software, to apply these parameters for the geocellular saturation-height model for the multiltimodal pore systems in this reservoir.

As a part of this process, detailed core to log integration, permeability prediction modelling, and well log quality control steps are utilized. Database retrievals of Thomeer parameters and petrophysical rock types using well log data are compared to those from core data. The reservoir saturation analysis indicates that this reservoir of interest has an anomalous resistivity leg below the Free Water Level, which is indicative of a residual relic oil accumulation. This residual relic oil has been modelled separately using a Drainage – Imbibition – Drainage cycle and is essential to reconcile the well log data and the saturation – height model.
Upscaled Permeability and Rock Types in a Heterogeneous Carbonate Core from the Middle East
Authors: Dernaika Moustafa R. , Mansour Bashar , Gonzalez David , Koronfol Safouh , Mahgoub Faris , Al Jallad Osama , Contreras Mauricio
Published: May 2017

Determination of Reservoir Rock Types (RRT) is one of the main parameters in the process of reservoir modelling and simulation. In carbonate reservoirs, the rock typing process is challenging due to multiscale heterogeneity with varying pore types and complex microstructures. The objective in this paper is to select representative samples from a heterogeneous core (350 feet) and establish unique reservoir rock types as well as model permeability along the entire core length based on textural analysis, geological interpretations and petrophysical measurements.

Representative core plugs were selected in a full-diameter heterogeneous core from a carbonate reservoir in the Middle East. The sample selection was based on statistical distribution of porosity and CT-textures in the core. The porosity and textural variations were determined along the core length at 0.5 mm resolution using advanced dual energy X-ray CT imaging. Plug-scale rock types were established based on micro-textures and pore types using thin-section photomicrographs, mercury injection analysis and poroperm measurements. The micro-texture analysis (grainy, muddy, mixed) and pore types were linked to the poroperm data. The micro-texture information was then upscaled to the entire core length using CT-textural analysis.

The porosity and permeability data were fitted into unique trends that were derived from the detailed textural analysis. This process provided the link between the poroperm trends and the different textures in the core enabling permeability and rock types to be upscaled to the entire whole core intervals. Variation of reservoir rock types was studied for each poro-perm trend. The different trends were mainly controlled by the different rock micro-textures whereas the extent of the trend was due to different diagenesis processes (i.e. dissolution, cementation & compaction).

This paper describes a novel approach of combining textures with porosity to model permeability and rock types at the plug scale and core level. A unique dual energy CT technique was used to ensure that all the core property variations were well represented in the plug-scale core analysis measurements.
Development of a Coupled Discrete Dual Continuum and Discrete Fracture Model for the Simulation of Naturally Fractured Reservoirs
Authors: Zhu Langtao , Liao Xinwei , Chen Zhiming , Mu Lingyu
Published: May 2017

Accurate and efficient numerical simulation of naturally fractured reservoirs is challenging. One of the main challenges is to model the flow behavior in a complex fracture network of multi-scale natural fractures. Though conventional dual porosity and dual permeability(DP/DK) models are accurate and efficient in simulating the ideal fractured reservoirs, the DP/DK models are not adequate for modeling these complex networks of multi-scale fractures. Therefore, it is critical important to develop a new approach to model the complex fracture network with a wide range of fracture-length scales and fracture topologies.

In this paper, we develop a coupled discrete fracture and discrete dual continuum model to simulate the fluid flow in fractured systems. Large-scale fractures(LF) are modeled explicitly using a discrete fracture model, called UDFM, and the local-grid refinement is used to accurately handle the transient-flow regime around LFs. Sparse small-scale fractures(SF) are modeled using a discrete dual continuum approach, called EDFM, which is different from the conventional DP/DK models. This coupled model includes three domains: matrix, discrete LFs, and discrete SFs domains. Moreover, an upscaling technique, applying EDFM on the detailed realization of discrete SFs to generate an appropriate discrete dual-permeability model, is also developed. The upscaling technique is suitable for cases where a detailed prior model for the complete fracture network is available.

The simulation studies of model verification demonstrate the applicability, and robustness of the coupled model for fractured oil reservoirs. We examine naturally fractured reservoirs with multiple configurations in the presence of numerous pre-existing fractures. The simulations of depletion development show that LFs have a noticeable impact on the pressure profile. However, the effect of discrete SFs is weak but can't be ignored. In addition, the LFs and SFs both have a remarkable effect on the water saturation field during the water flooding process.

This study further improves the accuracy and efficiency of modeling irregular and no-ideal fracture geometries.
Using Cross-Well Electromagnetics EM to Monitor the Impact and Efficiency of CO2 Injection
Authors: Zhang Ping , Ramadhan Moemen
Published: May 2017

Applying water alternating gas (WAG) process as an enhanced oil recovery method became a well-known strategy in the industry. In a typical WAG process, either water or gas initially is injected for a designed injection cycle followed by another injection cycle for the other phase. Both cycles are repeated sequentially aiming to optimize the overall sweep efficiency. In this paper, we will explore the benefits of using cross-well EM to monitor the water and CO2 injection in WAG applications and address particularly the following two issues: 1) does cross-well EM has the required sensitivity to evaluate the performance of water and CO2 injection? 2) Cancross-well EM monitor the different cycles of a typical WAG application?

Cross-well EM involves applying inductive physics and 2D/3D inversion to define the inter-well conductivity distribution. Due to its unique spatial configuration, both transmitters and receivers are close to the intended survey targets, the cross-well EM is a proper tool for EOR and time lapse studies. CO2 normally has very low conductivity, which is not a good target for induction method. In a WAG project, both water and CO2 are injected into a reservoir, each has its own cycle (typically three to six months). The water used in WAG normally has much higher conductivity than that of CO2, therefore, by alternating the injection cycle the resulting conductivity change could be large enough to be a good target for cross-well EM.

The model used for simulation consists of injection, production and monitor wells. CO2 and water are injected sequentially, each with three-month cycle. The formation porosity and permeability are selected based on real field results. The water and CO2 floods are simulated using dynamic reservoir simulation software. The water and CO2 injection cycles were continued for 5 years to provide opportunity for time-lapse surveys. The formation resistivity variations due to water and CO2 were calculated using Archie's law. The cross-well EM fields were calculated between injection and monitor wells before and after water/CO2 injection cycles to study the sensitivity. Data inversions were performed to understand how well we could reconstruct the water and CO2 fronts.

The preliminary studies suggested that the cross-well EM is an appropriate tool for tracking CO2 and water flood for the models tested and the technique has an excellent ability to define the reservoir volume being affected by the injected fluid. The modeling results positively answer the sensitivity and efficiency questions for the use of cross-well EM as a surveillance tool for a WAG application.
Dynamic Characterization of Different Reservoir Stacked Patterns for a Giant Carbonate Reservoir in Middle East
Authors: Yong Li , Qi Zhang , Chenji Wei , Benbiao Song
Published: May 2017

Understanding reservoir stacked styles is critical for a successful water injection in a carbonate reservoir. Especially for the giant carbonate reservoirs, different regions with different reservoir architecture stacked patterns developed may be applied to different development options. So reservoir stacked pattern characterization are especially important for the giant carbonate reservoir. This paper propose a systematic method of dynamic characterization on different reservoir stacked pattern, which applied to a giant carbonate reservoir in Middle East.

This paper focuses on a giant carbonate reservoir, which is a Cretaceous carbonate reservoir in Middle East, with conducting waterflooding pilots currently. Thief zones are developed in this reservoir. Four patterns of reservoir architecture stacked style are classified based on geological study. Then the proposed systematic dynamic characterization method are applied, which mainly based on the dynamic data analysis (production data, formation test pressure, production logging test data etc.) and reservoir engineering methods (material balance analysis, well test analysis). Finally, distribution of the four patterns are mapped combined geological and dynamic understanding.

The four patterns have distinctive geological features and dynamic characteristics. For example, pattern A are mostly composed by good quality reservoirs with high production rate for most intervals. Pressure gradient has almost no change from top to bottom, and well test log-log curve shows typical homogeneous reservoir characteristics. And OOIP of pattern A well is large with drainage radius mostly larger than 900m. While from pattern A to pattern D, poor reservoir and barriers increase, which change from massive reservoir to multi-layered reservoir. For pattern D, pressure gradient are separated as zigzag curve, and boundary response is clearly shown in well test log-log curve. Well OOIP and well drainage radius become smaller. After systematic dynamic characterization, reservoir architectures of all wells are calibrated and validated with geological results, and lateral distribution of architecture patterns are mapped.

This paper offers a case study of systematic dynamic characterization of reservoir architectures for carbonate reservoirs. And understanding of reservoir architectures is much valuable for the next development options decision, which means different waterflooding well pattern, well type etc. are applied to different reservoir architectures. It also provides a methodology and reference case for engineers and geologists to investigate on other similar fields.
Digital Rock Analysis of the Transition Zone in the Minagish Formation, Kuwait
Authors: Hayat L. , Al-Rushaid M. A. , Idowu N. , Fogden A. , Sommacal S. , Golab A. , Zalzale M.
Published: May 2017

We present the results of a comprehensive multiscale imaging and simulation projecton core plugs from the Minagish formation in South East Kuwait. The objective of the study was to calculate petrophysical and two-phase flow properties of core plugs representative of well BG-0836. The well contains multiple rock types ranging from packstone to coarse grainstone and includes an oil-water transition zone.

Nine plugs were selected to represent the different rock types and wettability conditions encountered in the well. A digital rock analysis (DRA) program was established to characterize the plugs by combining experiments, imaging, modeling, and simulations. The plugs were imaged at multiple scales by X-ray micro Computed Tomography (microCT), Scanning Electron Microscopy (SEM) and SEM-Energy Dispersive X-ray Spectroscopy (SEM-EDS) to allow a detailed characterization of the pore space and the construction of representative rock models.

The rock models were used to calculate the petrophysical properties of the core plugs including porosity, permeability, formation factor and the cementation exponent (m). The simulation of two-phase flow properties requires plausible pore-scale wettability distribution input. This is particularly important in the transition zone where the samples can range from oil-wet to water-wet. Consequently, to increase the reliability of the results, the DRA workflow was complemented by an advanced 3D pore-scale imaging workflow in which the fluid distributions in the samples were imaged by micro CT after experimental water saturation, primary drainage, spontaneous and forced imbibitions. The 3D images obtained at different saturation states were used to quantify the wettability and guide the two-phase flow simulations. Oil/water capillary pressure and relative permeability curves for primary drainage and water imbibition as well as the saturation end-points were generated.
Developing Infill and EOR Opportunities While Managing Subsurface Uncertainties in a Mature Complex Field Using Probabilistic Dynamic Modeling
Authors: Karim R. Abd , Tewari R. D.
Published: May 2017

This paper discusses about a systematic approach of probabilistic dynamic modeling which was used to assess subsurface uncertainties, and to forecast range of ultimate recovery (P90, P50, and P10) for infill and EOR opportunity (immiscible Water-Alternating-Gas, iWAG) in a mature offshore oilfield.

The field is very complex, with multi-layered and highly compartmentalized reservoirs and has been on production under natural depletion since the last 47 years. It is in "mid-life crisis", facing problems of high watercut and GOR, with bypassed oil areas and pressure depletion, and therefore in need for redevelopment to increase its recovery factor. However, despite the long production history, subsurface uncertainties remain high due to its reservoirs complexity and limited reservoir data.

To assess the subsurface uncertainties and their impact on field redevelopment plan, a fine-scaled sector model was built for a focused area of the field with substantial remaining opportunity. Multiple static realizations were used to represent different reservoir connectivity that can be highly influential on the ultimate recovery, especially for iWAG injection. Along with these multi-static realizations, key dynamic uncertainties such as fault transmissibility, kv/kh, aquifer properties, etc. were also incorporated. It is very important to note that uncertainty parameters may vary between history matching and forecast period, especially when there is a change in drive mechanisms. Therefore, additional uncertainty parameters such as residual oil saturation (Sorw, Sorg), in the case for iWAG scenario, have also been included from the very beginning to ensure seamless transition from history matching up to forecasting.

Another big challenge to conduct probabilistic dynamic modeling in a mature field is, to generate multiple equally probable history matched realizations for subsequent proxy modeling and probabilistic forecasting. The uncertainty and optimization (U&O) modeling tools, including experimental designs, have made this possible and proven to be the most efficient way to speed up the modeling process. It has helped to generate the physical P90, P50, and P10 dynamic models that could be used to assess the robustness of various development options, hence able to deliver the optimum strategies while managing subsurface uncertainties.

All these proved to be a comprehensive probabilistic workflow to firm up several sizeable infill and injection portfolios in this complex mature field, with potential to increase recovery factor by 8% to 13%. Most importantly, decision makers were given a range of outcomes instead of a deterministic forecast, allowing proper risks mitigation plans to be devised to deliver a robust project definition and superior performance.
Coupled Geomechanics And Flow Simulation For Water Injection Induced Fracture Propagation in Tight Reservoirs During Waterflood Process
Authors: Lei Zhengdong , Li Junchao , Tang Huiying
Published: May 2017

During waterflooding process, the characteristics of injection water induced fracture propagation and resulting percolated fracture network remain unclear and are of great importance for the optimization of waterflood performance. In this paper, a coupled geomechanics and flow model based on discrete fracture model is developed to model the fracture propagation induced by injected water. A displacement discontinuity method is applied to simulate the stress redistribution and newly formed fractures. The fracture geometry is updated and re-gridding procedures are carried out according to the situation at the certain time step. A validate case and a real field case are studied and results demonstrate the effectivity of the proposed method.
Estimation of Three-Phase Relative Permeabilities for A WAG Process Using An Improved Ensemble Randomized Maximum Likelihood Algorithm
Authors: Fan Zhaoqi , Zhang Yin , Yang Daoyong
Published: May 2017

In this paper, a modified ensemble randomized maximum likelihood (EnRML) algorithm has been developed to estimate three-phase relative permeabilities with consideration of hysteresis effect by reproducing the actualproduction data. Ensemble-based history matching uses an ensemble of realizations to construct Monte Carlo approximations of the mean and covariance of the model variables, which can acquire the gradient information from the correlation provided by the ensemble. A power-law model is firstly utilized to represent the three-phase relative permeabilities whose coefficients can be automatically adjusteduntil production history is matched. A damping factor is introduced as an adjustment to the step length since a reduced step length is commonly required if an inverse problem is sufficiently nonlinear. Arecursive approach for determining the damping factor has been developed to reduce the number of iterations and the computational loadof the EnRML algorithm. The restart of reservoir simulations for reducing the cost of reservoir simulations is of significant importance for the EnRML algorithm where iterations are inevitable. By comparing a direct-restart methodand an indirect-restart method for numerical simulations, we optimize the restart method used for a specific problem. Subsequently, we validate the proposed methodologyby using a synthetic water-alternating-gas (WAG) displacement experiment and then extend it to match laboratory experiments. The proposed technique has proved toefficientlydetermine the three-phase relative permeabilities for the WAG processes with consideration of the hysteresis effect, while history matching results are gradually improved as more production data are taken into account. The synthetic scenarios demonstrate that the recursive approach saves 33.7% of the computational expense compared to the trial-and-error method when the maximum iteration is 14. Also, the consistency between the production data and model variables has been well maintained during the updating processes by using the direct-restart method, whereas the indirect-restart method fails to minimize the uncertainties associated with the model variables representing three-phase relative permeabilities.
Innovative Testing for Potential Compaction of Heterogeneous Carbonate Reservoir in A Giant Field, Abu Dhabi, UAE
Authors: Noufal A. , Ateeq B. , Al Amari K. , Masoud R. , Al Gohary M. , Sirat M. , Bois A.-P. , Dadouche H. , Kpatta D. , Mohajerani M.
Published: May 2017

A carbonate reservoir has an average thickness of 90 feet and an average porosity of 24% (with localized porosity stringers up to 32%). After 25 years production, it experienced a reduction in pore pressure from 4,300 psi to 2,000 psi. Subsequent modeling indicated that continued production would reduce the reservoir's pore pressure to 600 psi. This led to concerns related to increase in effective stresses, which could result in reservoir compaction and subsequent surface subsidence.

To assess this risk, ADCO performed a geomechanical testing campaign using carbonate plugs with high porosity (25-30%). Because of the heterogeneous nature of the reservoir, it was not possible to use conventional testing methods, which would require a set of five to ten "identical" plugs. Moreover, conventional multi-stage triaxial tests could not be used to evaluate cohesion and friction angle parameters of high-porosity plugs because the yield cap was reached before the critical state line. Consequently, a dedicated multi-stage triaxial testing method was developed, which consisted of performing a series of loading/unloading cycles starting from an isotropic cycle, followed by deviatoric-stress cycles with confining pressures decreasing from one cycle to the next one, until the critical state line is reached.

These innovative tests were used to evaluate the parameters of a capped constitutive law by back-analyzing the stress-strain curves of all cycles in one operation, which gave very good matches between measured and back-analyzed curves, with high-confidence estimation of the constitutive law parameters. This allowed developing trends of Young's modulus, cohesion, and friction angle versus porosity. However, the point characterizing the in situ stress was sometimes located outside the envelope, meaning that some plugs were damaged before testing.
Numerical Simulation of Electrical-Heating Assisted SAGD in Heterogeneous Heavy Oil Reservoirs
Authors: Yongbin Wu , Xingmin Li , Wanjun He , Fang Zhao , Yueyue Fang , Weinan Ai , Youwei Jiang , Xiaoxiong Liu
Published: May 2017

In order to massively enhance the performance of heterogeneous SAGD projects, the targeted Electrical-Heating in poor steam chamber segment assisted SAGD (EH-SAGD) was proposed, the simulation method was established coupling geo-mechanics of both payzone and interbeds, and delivery of energy by electrical heating into the subsurface. The screening criteria of EH-SAGD was formed and the typical SAGD wellpair performance was predicted and compared.

As the EH-SAGD is quite complex in its mechanisms, the precise simulation must reflect the impact of these mechanisms. Therefore, systematic experiments were carried out firstly to provide the key parameters of the rock and fluid to the simulation model. The geo-mechanic characteristics of barriers with different rock types was obtained by tri-axial compression tests, and the mineral composition change and reaction at elevated temperatures were obtained by means of X ray diffraction and interpretation.

The numerical simulation model of EH-SAGD was established based on the experimental results. The geo-mechanic model were added into the simulation based on the experimental results illustrating the Young's modulus, Poisson's ratio, compression strength, yield stress and the corresponding changes of the porosity and permeability.

From numerical simulation, the screening criteria for reservoirs that feasible for EH-SAGD was optimized by multi-parameters. The SAGD wellpairs with barriers in between the horizontal segments were the applicable targets for electrical heating. The combination heating of downhole heaters in both injector and producer was recommended for rapid breakthrough of the barriers. The heat power of the heaters with time was also optimized which required the highest power of 2500W/m for each heater. Following which a typical SAGD wellpair was selected to make the comparison. It is simulated that by targeted electrical heating, the oil drainage route can be established, the steam chamber along the whole horizontal segment can be developed, and the oil rate can be enhanced by 45% from conventional SAGD. It is forecasted that the oil recovery factor of EH-SAGD is 12.1% higher than SAGD.

The results indicate that the EH-SAGD has encouraging effect to enhance the oil rate, steam chamber uniformity, and the final oil recovery factor, which is a practical and novel EOR approach for heterogeneous SAGD reservoirs.
Proposing Low Temperature CO2 for Enhancing Miscibility in High Temperature Reservoirs
Authors: Hamdi Zakaria , Awang Mariyamni , Bataee Mahmood , Vatanparast Maryam
Published: May 2017

For several decades, CO2 injection has been used as a successful recovery method in enhanced oil recovery. The main impact of CO2 is on lowering minimum miscibility pressure (MMP). Reaching the miscibility pressure is often limited by the reservoir pressure and temperature. Based on the earlier studies, lowering the temperature of the medium by the injection fluid may help in a decrease of MMP, resulting in miscible flooding. However, the proposed method should be determined by experimental procedures and numerical calculation. For the evaluation of MMP reduction and the limitations involved, the slimtube displacement experiments were used along with simulation runs. Then the results were compared with empirical correlations. The results showed that injection of low temperature CO2 (LCO2) has a direct impact on the MMP of a high temperature system. However, it limited when the injection temperature is below the critical temperature of CO2. A modification equation was presented to be applied on available empirical correlations. In terms of MMP, LCO2 injection is more beneficial than CO2 when it enters the reservoir at lower temperatures with respect to injection limitations.
Coupled Fluid Flow to Geomechanics in Fractued Reservoir: Governing Equation, Geomechanics Parameters and Numerical Method
Authors: Wang Yarlong
Published: May 2017

The effectiveness of a hydraulic fracturing technology has been primarily attributed to a creation of the geometry in the primary fracture. This concept however has been challenged particularly in low-permeability formations in which the size of a Stimulating Reservoir Volume (SRV) becomes the most important issue. Unlike the primary fracture, the area in the SRV is controlled by the fundamental geomechanics behaviors of the formation and a secondary fracture network propagation with possible different modes, and more importantly by the formation permeability change which is controlled by the induced stresses near the primary fracture. In this paper, the induced stresses near a hydraulic fracture in a pure elastic, poroelastic, dual-porosity media are analyzed and compared in order to characterize the low-permeability, sandstone and fractured formations, respectively. The general formulation for a fractured reservoir by a dual porosity model is developed and pore pressures and stresses near a wellbore and a hydraulic fracture are highlighted for production enhancement as the permeability change near a wellbore or a hydraulic fracture may contribute to such an enhancement significantly. Those key parameters controlling the pressure and stresses change and numerical method used are analyzed and presented.
Aquifer Influx and Reservoir Connectivity Evaluation through Surveillance Data Analysis for a Large Sandstone Multi-Layered Reservoir
Authors: Yong Li , Baozhu Li , Jiasheng Zhou
Published: May 2017

M1 reservoir is a large multi-layered sandstone reservoir in Middle East, which is under primary depletion and edge aquifer drive. There are lots of sources of water production data in M1, and water production data are one of the most important and invaluable surveillance data to understand reservoir connectivity. This paper proposes a method to show how to integrate all sources of aquifer influx surveillance data to evaluate reservoir connectivity of M1.

There are four types of aquifer influx identification data in M1 reservoir, and different type of surveillance data are analyzed in detail. Through aquifer influx analysis, it can be confirmed if wells are aquifer flooded in some zones. Then, combined geological understanding with well aquifer breakthrough time and well water cut change characteristic analysis, the possible aquifer influx zone is determined. Finally, aquifer support and sand body connectivity around water flooded wells are better understood, which is helpful and useful for next waterflooding development.

M1 reservoir is a large multi-layered sandstone reservoir of deltaic environment with oil bearing area around 500Km2 in Middle East. And M1 is influenced by fluvial, tide and wave, which results in great variations of sand bodies' distribution, reservoir quality and connectivity. Furthermore, M1 reservoir is still under primary depletion with reservoir pressure close to saturation pressure, so waterflooding should be applied urgently. Four types of data were analyzed to study the aquifer influx, which including measured water cut data, flowtest data, saturation logging data and SGS data. Through data analysis, the confirmed aquifer-influx wells and possible aquifer -influx wells are determined, and water breakthrough time and water cut change characteristic are also determined. And based on the characteristic, four areas with different characteristic are classified. Combined with the geological understanding, it is found that the connectivity within each area are similar, but there are barriers among different areas which results in poor communication among different areas. Also the water breakthrough zone of each area are different, and it is useful to understanding aquifer support and reservoir lateral heterogeneity of different zones. Furthermore, aquifer influx has preferred direction, which mainly moves along with the channels axis. This phenomenon should be considered in well pattern decision making during the following waterflooding study.

This paper offers a case study of reservoir connectivity analysis based on different types of aquifer influx surveillance data analysis. And the understanding is also much valuable and useful for depositional facies mapping and the next waterflooding well pattern selection and decision. It also provide a reference for the related study on other similar field.
Multiscale Adapted Time-Splitting Technique for Nonisothermal Two-Phase Flow and Nanoparticles Transport in Heterogenous Porous Media
Authors: El-Amin Mohamed F. , Kou Jisheng , Sun Shuyu
Published: May 2017

This paper is devoted to study the problem of nonisothermal two-phase flow with nanoparticles transport in heterogenous porous media, numerically. For this purpose, we introduce a multiscale adapted time-splitting technique to simulate the problem under consideration. The mathematical model consists of equations of pressure, saturation, heat, nanoparticles concentration in the water–phase, deposited nanoparticles concentration on the pore–walls, and entrapped nanoparticles concentration in the pore–throats. We propose a multiscale time splitting IMplicit Pressure Explicit Saturation–IMplicit Temperature Concentration (IMPES-IMTC) scheme to solve the system of governing equations. The time step-size adaptation is achieved by satisfying the stability Courant–Friedrichs–Lewy (CFL<1) condition. Moreover, numerical test of a highly heterogeneous porous medium is provided and the water saturation, the temperature, the nanoparticles concentration, the deposited nanoparticles concentration, and the permeability are presented in graphs.
History to Forecast Transition Challenges in Reservoir Simulation of Giant Oilfields
Authors: Mohmed Farzeen , Patacchini Leonardo
Published: May 2017

While history matching of a reservoir simulation model principally aims at reproducing past shut-in pressure and fractional flow observations, transition from history to forecast further requires honoring the productivities (or injectivities) of wells, and implementing the current field operational strategy to avoid unwanted reallocation of rates.

Well-level matching is particularly lengthy for giant oilfields with several hundreds to thousands of completions, hence sometimes not refined enough to warrant using observed flowing pressures as forecast constraints. Furthermore, breakthrough times are not necessarily replicated in all wells; this strongly increases discrepancies between measured and simulated flowing pressures, and can cause spurious shutting of wells infringing on reservoir management guidelines.

Short-term forecast confidence can be improved by compensating well-level mismatches observed at the end of history for production and injection control purposes only, without solving the inherent model problems. The purpose of this paper is to describe a workflow followable with most commercial reservoir simulators to achieve such objective, forcing production and injection continuity at the onset of forecast while keeping the choked margin of wells producing below capacity.

A successful application of the workflow is illustrated using the model of a giant Middle Eastern carbonate oilfield with more than 150 active production strings, using an eight-year (2015–2023) drilling schedule followed by no further activity. In this example, confidence in long-term field-level forecasts does not deteriorate after applying the proposed well-level compensations.
Prediction of Polymer Injectivity in Damaged Wellbore by Using Rheological Dependent Skin
Authors: Behr Aron , Rafiee Mohsen
Published: May 2017

In polymer flooding, the polymer solution injectivity is a key element to estimate the success of EOR measure, which is highly related to the polymer viscosity. Because of the high shear rate near the injector wells, the polymer viscosity changes considerably due to the non-Newtonian rheological behaviour. The existing well inflow/outflow models implemented in numerical reservoir simulators are not flexible enough to consider strong shear thinning effect without building extremely fine grids. Therefore, the predicted pressure difference in the vicinity of the wells is usually overestimated.

In this paper, the way to improve the quality of the polymer injectivity calculation within the reservoir model with a coarse Cartesian grid is suggested. The idea of introducing a negative skin factor into the inflow model is extended and applied for damaged wells (in which positive skin is available in the existing model) or wells with a reduced contact surface with the formation layers due to perforation. To cover a non-uniform and high speed flow in the vicinity of discrete distributed perforation openings, special approximations for a predefined transition zone are considered. In all derivations of the analytical solutions, the power law rheology of the polymer is assumed.

The method was adapted to the commercial reservoir simulators Eclipse 100 and CMG STARS with different viscosity representative radii in the polymer inflow model. The impact of the improvements on the numerically reproduced injection of non-Newtonian fluid is tested on a synthetic box model as well as on a real field model by injection of the biopolymer Schizophyllan which exhibits a remarkable shear thinning behaviour.

Depending on the grid size resolution, the results show significant improvement in polymer injectivity prediction. Advantage of the approach becomes more distinct, as the size of the well grid block increases, which allows to significantly reduce the CPU run time.