bluuebunny/crossref_metadata_2025 huggingface dataset:
Using NMR T2 to Predict the Drainage Capillary Curves Pc-Sw in Carbonates Reservoirs
Authors: Raheem Oriyomi Nurudeen , Fernandes Martin Olivier , Thomas Nithin Chacko , Hashem Mohamed Hossni , Alfazazi Umar , Sulemana Nuhu Turosung
Published: May 2017

This research work predicts capillary pressure curves at primary drainage from the transverse T2 relaxation times of the NMR pore size distributions with ninety percent accuracy, which could do the trick in reservoir applications. The capillary pressure-water saturation curves are important instructions to reservoir simulators for predicting the dynamic properties of the reservoir as well the fluid saturations at different depths. This study originated from the challenges in forecasting the initial saturations from an NMR logged well. The procedure is a simple and non-damaging construction of capillary pressure curves from plug samples measurements.

Dynamic rock typing was used to assign the capillary pressure data to different layers in the reservoir. Laboratory Nuclear Magnetic Resonance (NMR) equipment has been proven to produce information on pore size distribution and varieties of methods was found in the literature to predict capillary pressure curves from borehole NMR logs. The proposed idea of integrating drainage capillary pressure from centrifuge to T2 distributions from NMR enables rapid synthesis of capillary pressure from plugs and interpretation of logs.

A scaling factor k, is adopted in the T2-Pc conversion. The optimum scaling factors for most research work is built upon the results. Water saturation at certain pressures, is often estimated from capillary pressure curves. It can therefore be argued that the perfect procedure of estimating the best scale factors is to recreate the saturations by the capillary pressure curves developed from NMR. In this research work, the range of pressures and T2 relaxation time was 0 – 500 psi and 1 – 10000 ms respectively. Due to different geological facies usually described by the capillary pressure curves of different formations, the capillary pressure curves of the completely cored reservoir were reconstructed to get the average scaling constant, k of 4 psi.s with a low standard deviation of 0.02. The capillary pressure versus T2 curve tend to fit a power regression with a coefficient of determination of R2= 1, signifying that the regression line analysis fits perfectly with the data for the 18 core samples.

With the T2-Pc conversion established, the capillary pressure data can be predicted continuously in the whole section of the reservoir. The procedure is more accurate compared to others since it takes cognizance of the pore structure from NMR distribution, and it is applicable to T2 distributions estimated at various water saturations. Previous methods are applicable to 100% brine saturated plugs, which nullifies their predicted capillary pressure curves.
Adaptive Approach For Heavy Oil Reservoir Description And Simulation
Authors: Ursegov Stanislav , Zakharian Armen , Taraskin Evgenii
Published: May 2017

The main goal of the reservoir modeling including heavy oil ones by means of any deterministic model is to predict their further development results. A similar problem is solved by decline curves. We propose a new system that combines both approaches. The developed model was called adaptive. The main advantage of the adaptive approach is the possibility to modify the mathematical apparatus of the model, depending on the uncertainty of geological and production data.

The volume of initial information to construct the adaptive model is comparable to the volume of initial information to construct any deterministic model. The structure of the adaptive model also suggests the presence of deterministic geological and hydrodynamic components. However, they are based on different principles than the deterministic models. The mathematical apparatus of adaptive modeling is based on the use of such approaches as a non-parametric statistics, fuzzy logic, numerical solution of differential equations, and intelligent algorithms.

On the basis of the developed approach, the adaptive geological and hydrodynamic models of the Permian - Carboniferous reservoir of the Usinsk field, which is the largest one according to its value of remaining recoverable reserves of heavy oil in the Timan-Pechora region of Russia were created. The main objective of reservoir simulation using the adaptive model is to determine which cells of the model obtained the produced oil and water, and where they remained less, and where the injected water or steam went. For the adaptive hydrodynamic models, the absolute values of reservoir parameters are not important; their diversity between neighboring cells is more significant.

A new approach to the construction of geological and hydrodynamic models of heavy oil reservoirs based on the principle of fully discrete simulation which can be used to solve the most of the known problems associated with the reservoir development and increase of oil recovery on such complex objects including the forecast of efficiency of work-over techniques measures (drilling of new wells, cycle steam stimulation, water shut-off works, etc.).
A New Approach for the Simulation of Fractured Vuggy Carbonate Reservoir with an Application to Upscaling
Authors: Gao Sunhua , Killough John E. , He Jie , Fadlelmula Mohamed M. , Wang F. Yuhe , Fraim Michael L.
Published: May 2017

Numerical modeling of naturally fractured vuggy reservoirs presents many challenges due to the coexistence of three very different kinds of media and their complex interaction on multiple scales. With current computing capabilities, conventional fine-scale single-porosity models are not practical for large-scale reservoir simulation. A multi-continuum reservoir model is presented as an effective approach to modeling fractured vuggy reservoirs on the coarse scale. This model consists of four different porosity systems, i.e. the matrix, fractures, isolated vugs and connected vugs. This study investigates mass exchange between different porosity systems with the final objective of developing new transfer functions that can be used as an application to upscaling fractured vuggy reservoir models.

A well-designed procedure is proposed to obtain the novel transfer functions in multi-continuum fractured vuggy reservoir models. Different realizations of the vug-filled matrix blocks are generated to show the effect of vug fraction, distribution and connectivity on multi-phase fluid flow. For interporosity flow between vugs and the other two media, new formulations of the shape factors that incorporate the effect of vug spatial variation are developed respectively. The dominant mechanisms of multiphase fluid exchange between each two porosity systems (matrix-isolated vugs, fractures-connected vugs) are discussed separately. New transfer functions for multiphase flow in the multi-continuum fractured vuggy model to capture the complex flow mechanisms and emulate the results of the fine-grid model are provided. In addition, a transmissibility multiplier table is introduced as another connection term for the transfer functions to improve the accuracy of upscaling solution. Finally, a new upscaling approach by incorporating the proposed transfer functions into multi-continuum models is presented.

This paper provides a new insight to the complex fluid exchange among three different media in fractured vuggy reservoirs. Results show that the new upscaling methodology helps to reduce the size of simulation model and improve the computational speed significantly, while providing an accurate representation of the fine-scale results.
An Injection Optimization Decision-Making Tool Using Streamline Based Fuzzy Logic Workflow
Authors: BuKhamseen Nader Y. , Al-Najem Abdullah A. , Saffar Ali H. , Ganis Santiago A.
Published: May 2017

Streamlines provide detailed information about dynamic fluid paths and connectivity between injectors and producers. Fuzzy logic can simulate human thinking and handle different categories of information including linguistic, imprecise, approximate, and overlapping to name a few. This paper presents a genuine approach for field injection optimization using a streamline-based fuzzy logic system.

In a previous paper, we presented an adaptive streamline based fuzzy logic system that uses three input parameters namely injection efficiency (IE), water cut (WC), and injection loss to aquifer to assign an injector ranking index (IRI) according to injector performance. In this paper, we enhanced the streamline based fuzzy logic workflow to smartly redistribute water injection by accounting for operational constraints and number of supported producers in a pattern in addition to the IRI. The new workflow examines the low performers (i.e., low and medium IRI categories) and assigns different injection reduction factors for each injector in these categories. Then, the total amount of reduced injection is assigned to high performers (i.e., high IRI) while ensuring no operational constraint is violated, such as BHP and capacity of pumps.

This approach has been tested on a large-scale DPDP simulation model. The area of interest in this field has two rows of injectors: downdip and updip. The updip injectors are the focus of the study. The results of this case study show noticeable improvements in injection efficiency for most wells in the area of interest ensuring better sweep, good pressure support, and improving cumulative oil production.

We believe combining both technologies, namely streamlines and fuzzy logic, can provide reservoir engineers with a robust decision-making tool to attain a more successful field-wide water injection strategy.
Evaluation of Enhanced Oil Recovery Technologies for the Sabriyah Lower Burgan Reservoir Kuwait
Authors: Al-Murayri M. T. , Al-Mayyan H. E. , Faraj A. A. , AlAbdullah M. B. , Pitts M. , Wyatt K.
Published: May 2017

This paper presents the results of a methodical screening and evaluation study on various enhanced oil recovery technologies for potential deployment at the Sabriya Lower Burgan (SALB) reservoir in Kuwait. The EOR technologies that were considered in this study included alkaline-surfactant-polymer, surfactant-polymer, polymer, CO2, N2 and Low Salinity flooding. Initial parametric screening of different EOR technologies was conducted based on reservoir characteristics, and this was followed by laboratory studies to determine the extent to which the initial screening conclusions were valid. Sector model simulations were also used to evaluate and confirm the suitability of the Sabriya Lower Burgan reservoir for the above-mentioned EOR technologies.

Screening and sector model simulations of the Sabriyah Lower Burgan formation indicated that Section A has potential for enhanced oil recovery technologies while the B zone does not, primarily due to the strong water drive in Section B. Chemical flooding, specifically alkaline-surfactant-polymer and surfactant-polymer flooding, low sal flooding, miscible N2 flooding, and CO2 flooding were considered to have potential while polymer flooding, thermal technologies, and immiscible gas flooding were not considered to be viable technologies.

Laboratory studies indicated that alkaline-surfactant-polymer, surfactant-polymer, polymer, and CO2 flooding show potential to recover incremental oil. Alkaline-surfactant-polymer, surfactant-polymer, and polymer flooding technologies recovered up to 35% OOIP incremental oil in dead oil and live oil corefloods. CO2 was miscible at reservoir pressure while N2 was not. In the laboratory, polymer flooding showed incremental oil and Low Salinity flooding did not. These results were not consistent with the original screening observations, thereby emphasizing the importance of laboratory studies.
Improving Reservoir Exploitation Using Fast Geomechanical Modelling Coupled With Surface Displacement Data Assimilation
Authors: Candela T. , Osinga S. , Veer E. F. , Heege J. H. , Fokker P. A.
Published: May 2017

One way to improve our understanding of the reservoir behavior at depth is to analyze the ground surface response during reservoir exploitation. During reservoir exploitation, pressure changes can lead to compaction/dilation at depth resulting in ground surface displacements. Disentangling the information encrypted in the surface displacement data should therefore provide information about the reservoir behavior at depth. In the last decade we developed a workflow imbricating fast geomechanical forward models and a surface displacement data assimilation scheme to improve our (i) understanding of the subsurface processes and (ii) improve predictions of reservoir behavior in terms of reservoir management. Here we present two case studies to illustrate the versatility and robustness of the workflow. The first case study identified undepleted gas compartments in a strongly faulted and compartmentalized reservoir in a Dutch gas field through inversion of combined surface levelling and InSAR data. The second case study constrained spatial variation in aquifer activity around another Dutch gas field by directly employing ascending and descending PS-InSAR line-of-sight data. We also show the benefit of using multiple data assimilation for constraining parameters in forward models that contain non-linearity. Additionally, we present a novel approach for an inversion workflow that includes uncertainties in every step of the inversion process in a single integrated inversion procedure.
Adaptive Time Stepping with the Modified Local Error Method for Coupled Flow-Geomechanics Modeling
Authors: An Cheng , Zhou Peng , Yan Bicheng , Wang Yuhe , Killough John
Published: May 2017

The coupled flow-geomechanics model is required to investigate the stress change, rock-compaction behavior, and stress-dependent properties in many reservoir scenarios. However, the coupled model for large-scale or three-dimensional simulation problems usually encounters large matrix system and high computation expenses, where the time stepping is a crucial factor for numerical stability and computational efficiency. In this paper, an adaptive time stepping with the modified local error method was presented to reduce iteration time and improve the computation efficiency for the coupled flow-geomechanics modeling. Firstly, the iterative coupling approach with the fixed-stress method was introduced, where the flow and geomechanics equations are sequentially solved at each time step. Secondly, due to updating geomechanics module consumes the major computing time for the coupled problems, the modified local error method was mainly used for geomechanics module, where fewer geomechanics time steps are needed after implementation. Specifically, the geomechanics module will be updated until a given local error of displacement is reached, and the time step size will be automatically adapted based on the change of displacement, which is more efficient than the constant time step method. Finally, a synthetic two-dimensional coupled production problem is established to apply the proposed adaptive time stepping approach, where the numerical results including the computing efficiency are compared with the results from regular sequential method and the fully coupled model. The sensitivity about the local error tolerance was also investigated.

The geomechanical responses regarding mechanical loading is validated by comparing with the analytical solution of Terzaghi's consolidation problem. The numerical results about the pressure and displacement change on the two-dimensional coupled model are compared with the results from the regular sequential method and the fully-coupled method. The modified local error method, which adjusts time step size for both flow and geomechanics module, not only yields a higher-order solution for better accuracy, but also significantly reduces the iteration number and computation time, especially for the cases with low truncation error requirement. The error tolerance of displacement is critical on when the step size will be adapted. Small error tolerance can maintain the accuracy while it needs more iteration computing. The strategy about how to modify step size plays an important role in the stability and computing efficiency for the modified local error method. A large increase or cut on one-step size could bring the oscillation results. Overall, the adaptive time stepping approach can both effectively reduce total computation time and simultaneously maintain the accuracy for the coupled flow-geomechanics problems. It is useful for large-scale or three-dimensional coupled problems, where the high computational efficiency is required.
The Impact of Dolomitization on Reservoir Quality Evolution of the Fractured Carbonate Reservoir Upper Cretaceous, Onshore Abu Dhabi Oilfield, U.A.E
Authors: Farooq Umer , Caetano Hugo , Radwan EL Sayed
Published: May 2017

Dolomitization, as part of diagenesis of carbonate rocks, may or may not significantly enhance reservoir quality of the altered sediments. In this context, a diagenesis study was performed on Upper Cretaceous reservoir of an onshore oil field, Abu Dhabi, U.A.E. The paper elaborates facies related dolomitization and its selective influence on the reservoir quality enhancements. The framework of the study is based on detailed petrographic examination and description of 850 thin sections, isotopic compositions (C, O, Sr) of selected samples; and fluid inclusion microthermometry of dolomite formed in upper and middle reservoir units.

The study concluded that dolomitization of shoal grainstones and packstones resulted in coarse crystalline dolomite, which caused significant increase in reservoir porosity and permeability in the middle resercoir unit. Conversly, dolomitization of pretidal mudstones and wackestones resulted in microcrystalline dolomite, which has caused limted increase in the micro-porosity with little impact on permeability in the upper reservoir unit. Dolomite was formed during eo- and mesodiagenesis (Th = ca 65-90° C; salinity = 15-21 wt. % NaCl). Dolomitization of pretidal mudstones is suggested to have occurred in an evaporative setting, whereas dolomitization developed in packstones and grainstones of bioclastic shoal and subtidal sediments may have been driven by deepage reflux mechanisms. Consequently, dolomitization trend maps were produced for both middle and upper reservoir units. These dolomitization trend maps were than used as constrain to build the facies model to honor the diagenetic overprint. Blind test on integrated facies model revealed high predictiability in terms over reservoir quality distribution and production behavior in both upper and middle reservoir units. This in turn has added value to optimize field development stratergies with proper well placement into the reservoir.
Metamodeling via Hybridized Particle Swarm with Polynomial and Splines Regression for Optimization of CO2-EOR in Unconventional Oil Reservoirs
Authors: Al-Mudhafar Watheq J. , Dalton Christian A. , Al Musabeh Muzher I.
Published: May 2017

Various studies have been conducted to optimize oil production in unconventional reservoirs using gas injection processes. Some studies determined the optimal design of hydraulic fractures through horizontal wells while others optimized the placement of horizontal wells to maximize oil recovery. In this study, an integrated optimization workflow combining Particle Swarm and Non-parametric Proxy Metamodels was adopted to optimize oil production using CO2-EOR in shale oil reservoirs.

A pseudo-component black oil reservoir model was considered to simulate CO2 flooding in shale oil reservoirs and to predict future reservoir performance over a 30-year prediction period. The cyclic CO2 flooding optimization procedure consisted of 3 cyclic operational decision factors and 5 well constraints for 5 pairs of horizontal injector and producer wells with 8 fractures each. The cyclic injection factors included injection, soaking, and production durations over the prediction period. Minimum bottom hole pressure, maximum oil production rate, and water cut were optimized for the production wells, and maximum bottom hole injection pressure and maximum gas injection rate were optimized for the injection wells. An integrated optimization approach conducted using Particle Swarm Optimization (PSO) and Proxy Metamodeling was integrated to find the optimal level for each of the 8 factors. PSO was adopted to create a search-space swarm of candidate solutions (particles) considering the range of each operational factor. These particles were then evaluated by the reservoir simulator to calculate the cumulative oil production by the end of the prediction period. To reach the optimal solution, 100 candidate solutions were created as training experiments with 4 successive iterations of approximately 20 experiments each. The optimal solution increased oil production by 322,675 surface barrels. Next, a 2nd order polynomial regression proxy model was constructed to metamodel the large reservoir simulator. The performance of the polynomial proxy model was validated via a comparison to non-parametric algorithms of Multivariate Adaptive Regression Splines. A cross-validation was considered prior to building the proxy models by sampling and subdividing the entire dataset into two subsets: 70% training for modeling and 30% testing for prediction. The testing subset and the entire dataset were compared to the three proxy models by computing the Root Mean Square Prediction Error and the Adjusted R-square for each. It was concluded that polynomial regression is the best metamodel, followed by the MARS algorithm, to produce a simplified alternative metamodel for the reservoir simulator to evaluate the cyclic CO2 flooding in shale oil reservoirs. The most influential operational factors were also identified for their effects on the CO2-EOR process performance in shale reservoirs.
Modeling the Depletion of Fractured Vuggy Carbonate Reservoir by Coupling Geomechanics with Reservoir Flow
Authors: Zhang Fengshou , An Mengke , Yan Bicheng , Wang Yuhe
Published: May 2017

In this paper, geomechanics is coupled with reservoir flow for modeling the depletion and deformation in fractured vuggy carbonate reservoir. Different from the dual- and triple-porosity models or the coupled approaches in which the vugs are considered as a continuous porosity, the vugs are treated as virtual volumes in this study. For each vug, the fluid exchange at the vug-matrix interface is dynamically calculated with time evolution and the pore pressure in the vugs is updated through considering both the fluid material balance and the volume change due to the mechanical deformation of vug. The fluid-mechanical interaction in the rock matrix and natural fractures is calculated based on the framework of Biot's poroelstic theory. The mechanical and hydraulic interactions between vugs and matrix are preserved and the stress evolution due to the depletion can be dynamically updated. The results in this study show that, the depletion process is mainly controlled by the fluid storage of the vugs. Fluid modulus is thus a more sensitive parameter than the rock/fracture modulus in terms of the depletion. However, the rock/fracture modulus can also affect the deformation of the system and thus affect the volume and pressure changes of the vugs.
Investigation of the Impact of Diagenesis on Reservoir Quality in Carbonate Reservoir: A Case Study
Authors: Sabeai Jawaher Al , Lavenu Arthur P.
Published: May 2017

Diagenesis can enhance, preserve or degrade the reservoir quality by changing its fabric partially or completely as it will affect directly the porosity and permeability. It is anticipated that by understanding the impact of diagenesis and integrating it with the depositional settings and sequence stratigraphy will represent a powerful tool for predicting a spatial distribution of reservoir quality in carbonate reservoir located offshore Abu Dhabi, United Arab Emirates.

The study is based on sedimentological core descriptions and petrographical analysis of thin-sections for selected cored wells at field-scale. It will enable a semi- deterministic approach for the prediction of the key facies across the field. It will then be integrated with the different diagenetic processes that have been defined with respect to different relative time events.

A diagenetic sequence made of 14 different processes, which are either enhancing or degrading reservoir quality, has been defined. In parallel, 3rd and 4th order sequence stratigraphy are defined using lithofacies association and allow determining a depositional framework at field scale. Combining depositional settings with diagenetic evolution enables to define how the rock properties evolved and where are located the better quality rock in the reservoir.

The reservoir quality is controlled by the depositional environment, which controls the subsequent diagenetic processes. Hence, it is important to understand the lateral and vertical facies distribution as well as the different type of diagenetic alterations in order to have a clearer image of the spatial variation of the reservoir quality. With the help of this acquired knowledge the geologist will be aware of the reservoir limitations and could predict its behavior with time.
Seismic TI Anisotropy Estimation in Nahr Umr Shale from Walkaway VSP
Authors: Waqas Muhammad , Willemsen Pierre , Rufino Rogelio , Suliman Israa
Published: May 2017

Seismic anisotropy parametrization has a vital role in seismic imaging as well as in geomechanical applications. The most common form of seismic anisotropy is Transversely Isotropic (TI) caused by fine geological layering such as in shales. TI, if not incorporated can lead to geological miss-positioning of the seismic image. Walkaway VSP data was used to estimate TI parameters for the Nahr Umr shale, which is a highly anisotropic formation and is a regional cap rock.

Walkaway VSP was recorded using 16 level 3 Component (3C) downhole receiver array positioned across Nahr Umr formation with 402 surface shot points in an offshore field Abu Dhabi. Walkaway VSP provides direct information of upgoing and downgoing primary and shear waves. 3C data was oriented followed by 3C wavefield separation in order to obtain slowness and polarization of the upgoing and downgoing primary and shear waves. Slowness and polarization information gives insight to in situ wavefield propagation.

Slowness and polarization data was inverted to obtain TI anisotropy parameters along receiver array. The inversion of slowness and polarization data does not rely on overburden structural complexities hence providing robust local anisotropy estimates. Strong primary to shear wave mode conversion in the vicinity of Nahr Umr formation helped to obtain good results. The estimated TI anisotropy parameters helped to guide anisotropy parameters in Nahr Umr shale for a nearby field pre-stack depth imaging project (Waqas et al., 2016). The overburden anisotropy needs to be as accurate as possible in order to obtain better seismic imaging and characterization for underlying reservoir. The parameters can also be used in geomechanical applications.

This paper provides TI anisotropy parameters estimation for the regional highly anisotropic shale formation. The unique method was proposed for quite some time in the literature however has not been applied or reported to estimate anisotropy for the Nahr Umr shale.
Multiscale Coupling of Triple-Continuum Model and Discrete Fracture Network for Carbonate Reservoir Simulation
Authors: Zhang Na , Sun Qian , Wang Yuhe , Efendiev Yalchin
Published: May 2017

Multiphase flow in carbonate reservoirs has been a hard problem of scientific research for many years. Accurate flow simulation is essential for the efficient exploitation. In this paper, a coupled triple-continuum and discrete fracture network approach is developed for modeling multiphase flow through fractured vuggy porous media. Multiple levels of fractures can be not only modeled as different superimposed continua but also embodied as discrete fracture network based on their geometrical characteristics. We develop a systematic coupling using Multiscale Finite Element Method (MsFEM) as a framework for coarsening and refinement. MsFEM is used to capture subgrid scale heterogeneities and interactions through multiscale basis functions calculated based on the triple-continuum background. Unstructured mesh is applied to model discrete fractures in arbitrary. This paper presents a significant advancement in terms of elevating the limitations of the triple-continuum models in handling complex fractures and extending the model reduction capability of MsFEM. Several numerical examples are carried out to demonstrate the capability of the proposed coupling method.
A New Permeability Anisotropy Characterization Approach for Heterogeneous Reservoir
Authors: Huang J. , Wang B. , Chen H. , Liu S.
Published: May 2017

A new absolute permeability upscaling method based on geological hierarchical models that affect different scales reservoir heterogeneities is presented. Reservoir anisotropy is evaluated via horizontal permeability (Kh) and vertical permeability (Kv). The new approach based on the geologic viewpoint that various geologic hierarchical-elements set result in relevant permeability display of different reservoir scales. For reservoirs, from micro-scale to macro-scale, influencing factors of permeability become abstruse. In conventional scenario, the calculation method based on single-phase numerical simulation test, core analysis and data statistics integrates all these factors as much as possible to upscale permeability. Considering reservoir anisotropy, horizontal permeability (Kh) and vertical permeability (Kv) are studied to show how anisotropy changes according to different reservoir heterogeneities. In the case study of Mackay River Oil Sand Block, Alberta, Canada, database includes regional depositional setting, core, and logging data for more than 20 wells. Generally, reservoir sedimentary setting poses a direct effect on permeability. Local rock bedding affects permeability anisotropy greatly, as well. There is no obvious linear parity between horizontal permeability (Kh) and vertical permeability (Kv) in core-plug. Vertical and lateral grain size variance also alters permeability. The mm-cm scale mud drapes have a worse effect on vertical permeability (Kv) than on horizontal permeability (Kh). Besides, bioturbations in the transitional facies could be favor of permeability. The three factors have non-linear relationship on effecting permeability. The new upscaling model synthesizes all these factors to upscale the permeability for nearly all scales of reservoirs, from the scale of core to lithofacies or even to the entire reservoir. Comparisons study is also conducted between this model and current upscaling algorithms such as arithmetic average, harmonic average, etc. The results showed that the upscaling model of this paper is more reasonable. Meanwhile, reservoir characterization hierarchical models can also be applied to explicate heterogeneity effect on the attribute of reservoir fluid qualitatively. The novelty of this approach lies in solving reservoir fluids' attributes quantitatively through exact heterogeneities analysis.
Implicit Fracture Modelling for Permeability Enhancement in Carbonate Reservoirs: A Novel Approach to Bridge Data Gaps for Honoring Dynamic Observations
Authors: Lavenu Arthur P. , Howell Katharine , Kane Peter
Published: May 2017

In a giant carbonate reservoir, located offshore Abu Dhabi, permeability and production data are hard to reconciliate. Recent investigations on this reservoir have shown that it is affected by natural fractures. Borehole images, cores and thin-sections allowed characterizing two main fracture sets. However, the scarcity of data, with regards to the size of the reservoir, did not allow building a discrete fracture network. To overcome this gap, modelling fractures in an implicit way appears the best and simplest solution to enhance permeability and match the production data.

Implicit means that fractures are not considered as a discrete object. Instead, at the cell scale, fracture impact on permeability has been translated into multipliers in the x, y, and z directions, superimposed on the matrix permeability. The process of implicit fracture modelling is not straightforward. Building a fracture conceptual model (seismic faults, fault-related fractures, subseismic faults, and background fractures) is the starting point, to understand the big picture. The second step is defining the layer/fracture relationships, and quantifying the interaction between matrix and fractures (transmissibility). The third step is modelling and implementing the permeability modifiers in the 3D geological grid.

The distribution and occurrence of the different features remains difficult to constrain using one single deterministic model. Using multi-realization is powerful tool to get the closest match to PTA.

Deterministic scenarios have been created combining joints and faults, assigning different properties to each of the feature: size, frequency, degree of baffling, degree of permeability anisotropy, vertical transmissibility, mechanical stratigraphy, position to the structure of the reservoir…The permeability field resulting from each scenario has then be compared to PTA to determine which case best matches the dynamic data. The created permeability array is then added to the matrix permeability of the reservoir, enhancing it up to 6 times.

Implicitly modelling fractures through multi-realizations enable to get a solution that match as much as possible the PTA. In the particular case of large reservoir with scarce data, it allows geologists to have an estimate of the fracturing state of the reservoir and how these fractures are contributing to the overall field flow behavior. It is also a way of mimicking the fracture pattern in the case of few data availability, and which ultimately will enhance the quality of the history match
Uncertainties Associated with the Interpretation and Estimation of Relative Permeabilities Using In-Situ Formation Tester Measurements
Authors: Yznaga Reinaldo Jose , Quintero Luis Fernando , Negm Ehab , Arevalo Francisco , Soleiman Wael
Published: May 2017

Relative permeability is an essential parameter for reservoir description, engineering, and management. Relative permeabilities are typically obtained in the laboratory through evaluation of the dynamic behavior in cores using fluids that are assumed to be representative of those in the reservoir. In-situ measurements of effective permeability can provide valuable information about fluids, rock, pressure, temperature, and their interactions in the evaluated formation at original reservoir conditions. Recent technological advances allow data obtained from formation testers to be analyzed and interpreted for estimating relative permeabilities.

Formation testers are typically run when wells are drilled; therefore, using acquired data for estimating effective permeability can be cost-effective and less time-intensive compared to existing effective permeability estimation methodologies. However, the measurement process, the meaning of the acquired data, the interpretation of the data, and the resulting relative permeability values are affected by the uncertain environment associated with the entire process, which also affects the confidence of the estimated relative permeabilities and their use as an input for reservoir description, engineering, and management.

Although the use of formation testers as a tool to estimate relative permeabilities is promising, it is crucial to understand the environment in which the dynamic events occur and the impact of the uncertainties related to the physical phenomena and interactions associated with the measurement and interpretation processes. Conversion of the acquired information at the oil/gas well into inputs to properly interpret the acquired data, the models available to interpret the phenomena, and the formation tester tool capabilities all require understanding of the uncertainties associated with the entire process. These uncertainties, when properly qualified and quantified, can serve as the decision criteria to estimate the value of information (VOI) of relative permeability determination using in-situ formation tester data.

This work provides a detailed description of the uncertainties related to relative permeability estimation based on in-situ measurements of formation testers and its impact on the interpretation outputs.
Temperature Effects on Cotton Seedling Emergence, Growth, and Development
Authors: Reddy K. Raja , Brand David , Wijewardana Chathurika , Gao Wei
Published: May 2017

Little insight of temperature effects on cotton root morphology and seed germination.

Cotton cultivars vary in their response to different temperatures.

Growth and developmental responses developed will be useful in cotton crop models.

Establishing vigorous cotton (Gossypium hirsutum L.) seedling stand for an early planted crop will help to develop healthy root and canopy development. Cotton planted early in the season will be subjected to low, but variable temperatures and soil moisture conditions. There has been little exploration of temperature effects on the cotton root system architecture. The objective of this study was to study the effects of a wide range of temperatures during seed germination and early seedling growth stages on above‐ and belowground growth and developmental parameters of four cotton cultivars. A molecular standard, Texas Marker (TM)‐1 and three modern cotton cultivars (DP1522B2XF, PHY496W3R, and ST4747GLB2) were sown at five day/night temperature regimes of 20/12, 25/17, 30/22, 35/27, and 40/32 °C (day/night). Shoot and root growth parameters were measured 20 days after planting (DAP). The small differences observed between the obsolete molecular standard, TM‐1, and the three modern cultivars in response to temperature indicate that successive breeding efforts did not change the rate or behavior of these traits to temperature. Seedling emergence was best described by both linear (TM‐1 and PHY496W3R) and quadratic (DP1522 B2XF, and ST4747 GLB2) functions. Node numbers and root tips increased linearly with increase in temperature, and no cultivar differences were observed for this trait. The functional relationships between temperature and cotton seed emergence and pre‐squaring above‐ and belowground growth and developmental responses will be useful in assisting management and in improving functionality of many cotton models for on‐farm and research and policy decisions.
Delineating Soybean Maturity Groups across the United States
Authors: Mourtzinis Spyridon , Conley Shawn P.
Published: May 2017

Core Ideas

Seven maturity group zones were identified across the United States.

The width of maturity group zones 4 and 5 cover the largest geographic region.

Maturity group zones were defined by a downward deflection of the maturity group lines.

Maturity group adaptation zones need to be continuously monitored and adjusted.

Photoperiod and in‐season temperature are the primary factors that dictate the region where a soybean [Glycine max (L.) Merr.] variety is adapted. The first study that defined hypothetical maturity groups (MGs) zones across the US was 45 yr ago, and the most recent used data up to 2003. Although, photoperiod remains constant, climatic conditions, management practices, and soybean genetics have changed during the past decades. Therefore, the objective of this study was to re‐delineate soybean MGs across the US using recent genetics. Soybean MG‐specific yield data from variety trials conducted in 2005–2015 were aggregated from 312 locations across the United States. Seven MG zones were identified starting from MG = 0 in North Dakota to MG = 6 in southern Georgia and South Carolina. The width of MG = 4 and 5 zones cover the largest geographic region extending from north of latitude 28°N to 39°N. Additionally, in contrast to previous studies, the MG zones were defined by a downward deflection of the MG lines moving from East to West rather than convex parallel lines. Due to the strong effect of planting date on MG selection, a multi‐location‐year experiment should be conducted across the United States using multiple MGs evaluated in several planting dates. Such study could provide further insight on location‐specific optimum MG. Overall results, update current knowledge by providing valuable information for decision making and regional modeling. This work highlights the need to continuously monitor and adjust the MG zones due to the constantly changing climate, management, and genetics.
Wind Erosion and PM10 Emissions from No‐Tillage Cropping Systems in the Pacific Northwest
Authors: Sharratt Brenton , Young Frank , Feng Gary
Published: May 2017

Core Ideas

Erosion of agricultural lands affect air quality in the Inland Pacific Northwest.

Alternatives to tillage‐based cropping systems are needed to reduce wind erosion.

No‐tillage cereal cropping systems reduce wind erosion and particulates ≤10 µm in diameter emissions.

Economically viable strategies are sought for no‐tillage cropping systems.

Wind erosion is a concern in the Inland Pacific Northwest (PNW) of the United States where the emission of particulates ≤10 µm in diameter (PM10) from winter wheat (Triticum aestivum L.)/summer fallow (WW/SF) dryland cropping systems during high winds degrades air quality. There is a potential to reduce the risk of wind erosion using no‐tillage or chemical fallow cropping systems, but wind erosion observations are lacking from these systems. We measured sediment and PM10 flux from reduced‐tillage WW/SF, no‐tillage wheat/chemical fallow (NTW/CF), and no‐tillage spring barley (Hordeum vulgare L.)/spring wheat (NTSB/SW) using a portable wind tunnel near Ralston, WA. Horizontal sediment flux, wind speed, and PM10 concentration were measured over two consecutive 10 min sampling periods inside the tunnel after sowing wheat in spring or late summer on four replications of the rotations. Sediment flux was measured with a modified Bagnold type sampler while wind speed and PM10 concentration were respectively measured with pitot tubes and aerosol monitors positioned at six heights above the soil surface inside the tunnel. Sediment and PM10 fluxes were an order of magnitude greater in late summer than spring. After sowing wheat in spring, sediment and PM10 fluxes were greater for the NTSB/SW than NTW/CF rotation while, after sowing winter wheat in late summer, sediment and PM10 fluxes were greater for the WW/SF than the NTSB/SW rotation. Our results suggest that wind erosion and PM10 emissions can be significantly reduced using no tillage cropping systems in the PNW.
Assessing the Utility of Primed Acclimation for Improving Water Savings in Cotton using a Sensor‐Based Irrigation Scheduling System
Authors: Meeks Calvin D. , Snider John L. , Porter Wesley M. , Vellidis George , Hawkins Gary , Rowland Diane
Published: May 2017

This study addressed the potential of reduced prebloom irrigation, referred to as primed acclimation (PA), to increase agricultural water‐use efficiency (WUE) using a soil‐moisture‐based irrigation scheduling system in cotton (Gossypium hirsutum L.). To address this, a study was conducted near Camilla, GA, under a variable‐rate, center‐pivot irrigation system using a Watermark‐based automated soil moisture sensing approach to measure soil water potential (SWP) and impose varying irrigation scheduling treatments during the prebloom stage of development. Early season thresholds were −20 (Treatment 1), −40 (Treatment 2), −70 (Treatment 3), to −100 kPa (Treatment 4) prior to flowering. Reductions in prebloom irrigation of up to 17% were noted in this study for the driest thresholds (−100 kPa) with no reduction in lint yield relative to the −20 and −40 kPa thresholds. In some cases, prebloom irrigation was eliminated completely in the drier prebloom threshold treatments with no appreciable yield reductions. In rainfed treatments, episodic drought during flowering (2014) limited plant growth and node production, hastened cutout, decreased boll numbers per plant, produced a more compact boll distribution on the plant, and decreased yield and WUE relative to irrigated treatments. In contrast, season‐long rainfed treatments exhibited the highest WUE in 2015 (a wet season). The results of this study conclude that prebloom irrigation thresholds between −70 and −100 kPa appear to be viable for use in a sensor‐based PA irrigation scheduling system, whereas episodic drought coinciding with flowering represents a major threat to yield stability and WUE for cotton production in the southeastern United States.
DIALEKTIKA PLURALISME HUKUM: Upaya Penyelesaian Masalah Ancaman Keberagaman dan Keberagamaan di Indonesia
Authors: Masyithoh Novita Dewi
Published: May 2017

Conflict resolution on SARA requires pluralistic approaches. Hence, the presence of legal pluralism becomes a new approach to resolve the problem. This study is a qualitative research that convey three dimensions of legal pluralism, namely natural law, state law and society law. The study used secondary data, with primary and secondary legal materials obtained by documentation resources. Data were analyzed inductively, used the contemporary theories to produce more conceptual and general propositions for conclusions and recommendations. The result shows that there have been 8 cases on SARA conflict in Indonesia during the last three years. To solve these problems, religious leaders can use natural law approach to re-internalize religious values and tolerance. In addition, the government also should understand that those conflicts were a form of society law owing to discreditable law society and religious diversity. Therefore, non penal policy with persuasive appeals is needed to reduce the problems. However, penal policy through law enforcement should also be implemented as a form of state positivism law. In other words, state positivism law should go hand in hand with natural law and society law in order to reach the best decision based on moral and religious ethics as well as social values.

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Penyelesaian konflik SARA membutuhkan pendekatan-pendekatan yang plural. Oleh karena itu pluralisme hukum hadir sebagai pendekatan baru untuk menyelesaikan tersebut Penelitian ini adalah penelitian hukum dengan tradisi kualitatif yang berusaha mendialektikakan 3 dimensi dari legal pluralism, yaitu natural law, state law dan law society. Penelitian menggunakan data sekunder, dengan bahan hukum primer dan sekunder yang diperoleh dengan teknik dokumentasi. Data dianalisis secara induktif dengan menggunakan teori-teori yang ada untuk mem­produksi suatu proposisi yang umum, sehingga menghasilkan kesimpulan dan rekomendasi. Hasil penelitian menunjukkan bahwa telah terjadi 8 konflik SARA di Indonesia dalam 3 tahun terakhir. Untuk memecahkan masalah tersebut, para pemuka agama menggunakan pendekatan natural law untuk reinternaliasasi nilai-nilai keluhuran atas agama dan toleransi. Pemerintah seharusnya me­mahami bahwa konflik tersebut adalah bentuk society law karena tercederainya keragaman dan keberagamaan. Perlu kebijakan non penal dengan seruan-seruan persuasif agar persoalan serupa tidak lagi terjadi. Di sisi lain, kebijakan penal melalui penegakan hukum juga harus dilakukan, sebagai bentuk state positivism law. State positivism law harus mampu menggandeng natural law dan law society, agar diperoleh putusan terbaik yang berlandaskan nilai-nilai moral ethic religion dan nilai-nilai sosial kemasyarakatan.