bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Filter Cake Generated by Water-Based Drilling Fluids Using CT Scan
Authors: Elkatatny S.M.. M. , Mahmoud M.A.. A. , Nasr-El-Din H.A.. A. 
Published: November 2012

Summary
Filter-cake characterization is very important in drilling and completion operations. The homogeneity of the filter cake affects the properties of the filtration process such as the volume of filtrate, the thickness of the filter cake, and the best method to remove it. Various models were used to determine the thickness and permeability of the filter cake. Most of these models assumed that the filter cake was homogeneous. The present study shows that the filter cake is not homogeneous, and consists of two layers of different properties.
The objective of this study is to measure the filter-cake thickness and permeability of water-based drilling fluids by a new approach and compare the results with previous models. A high-pressure/high-temperature (HP/HT) filter press was used to perform the filtration process under static conditions (225°F and 300 psi). A computed-tomography (CT) scan was used to measure the thickness and porosity of the filter cake. Scanning electron microscopy (SEM) was used to provide the morphology of the filter cake.
The results obtained from the CT scan showed that the filter cake was heterogeneous and contained two layers with different properties under static and dynamic conditions. Under static conditions, the layer close to the rock surface had a 0.06-in. thickness, 10- to 20-vol% porosity, and 0.087-pd permeability, while under dynamic conditions, this layer had a 0.04-in. thickness, 15-vol% porosity, and 0.068-pd permeability. The layer close to the drilling fluid had a 0.1-in. and 0.07-in. thickness under static and dynamic conditions, respectively, and it had zero porosity and permeability after 30 minutes under static and dynamic conditions. SEM results showed that the two layers contained large and small particles, but there was extremely poor sorting in the layer, that was close to the drilling fluid, which led to zero porosity in this layer. Previous models underestimated the thickness of the filter cake by almost 50%. A new method was developed to measure the thickness of the filter cake, and various models were screened to identify the best model that can predict our permeability measurements.
Mechanically Induced Fracture-Face Skin—Insights From Laboratory Testing and Modeling Approaches
Authors: Reinicke Andreas , Blöcher Guido , Zimmermann Günter , Huenges Ernst , Dresen Georg , Stanchits Sergei , Legarth Björn , Makurat Axel 
Published: November 2012

Summary
In the context of this work, a new formation-damage mechanism is proposed—the mechanically induced fracture-face skin (FFS). This new mechanism results from mechanical interactions between the proppants and the reservoir rock caused by the increasing stress on the rock/proppant system during production. Proppant embedment into the fracture face and proppant crushing lead to fines production and may impair the fracture performance. To achieve sustainable, long-term productivity from a reservoir, it is indispensable to understand the hydraulic and mechanical interactions in rock/proppant systems. In this study, permeability measurements on sandstones with propped fractures under stress using various flow cells were performed, allowing localization and quantification of the mechanical damage at the fracture face. The laboratory experiments identified a permeability reduction at the fracture face of up to 90%. The mechanical damage at the rock/proppant interface began immediately with loading of the rock/proppant system and for fracture-closure stresses less than 35 MPa; the damage was localized at the fracture face. Microstructure analysis identified quartz-grain crushing, fines production, and pore-space blocking at the fracture face, causing the observed mechanically induced FFS. At higher stresses, damage and embedment of the ceramic proppants reduce the fracture permeability further. Numerical modeling of the rock/proppant system identified highly inhomogeneous stress distributions in the granular system of grains and proppants. High tensile-stress concentrations beneath the area of contact between quartz grains and proppants were observed, even at small differential stress applied to the rock/proppant system. These high-stress concentrations were responsible for the early onset of damage at the fracture face. Therefore, even low differential stresses, which are expected under in-situ conditions, may affect the productivity of a hydraulically fractured well.
Field-Scale Modeling of Tracer Injection in Naturally Fractured Reservoirs Using the Random-Walk Particle-Tracking Simulation
Authors: Stalgorova E.. , Babadagli T.. 
Published: November 2012

Summary
Modeling complex transport processes in naturally fractured reservoirs (NFRs) using classical continuum models may not be practically possible because the algorithms used in this type of modeling approach for the detailed structure of fracture/matrix systems require unreasonable computational time. Also, fractured reservoirs are highly irregular, and finite-difference calculations for such models often cause convergence problems. In addition, an exact representation of a complex fracture network in classical continuum modeling algorithms is highly difficult. An alternative is to use a nonclassical technique known as the random-walk particle-tracking (RWPT) algorithm.
We showed earlier (Stalgorova and Babadagli 2012) that the random-walk (RW) technique can be adapted to model miscible flooding in a fractured porous medium at the laboratory scale. The unknown parameters used to match the model results were only the diffusion coefficients for oil and solvent, as the diffusive/dispersive transport (effective in fracture and matrix) was coupled with viscous (effective in fracture) and gravity (effective in fracture and matrix) displacement. Advantages of this method over classical simulation include a shorter computational time, which allows avoidance of simplifications; the ability to model the matrix/fracture diffusion process without any transfer function; and the representation of a complex and irregular fracture network system.
In this paper, we modified this laboratory-scale RW model for field-scale applications. A series of tracer-test results from the Midale field in Canada was used to test the model. A fracture-network model was constructed on the basis of geological data, and then we used the RWPT model to calibrate the fracture network against tracer-test results. The results were compared to those obtained using continuum (dual-porosity) models, and it was observed that the connectivity and breakthrough times can be captured more correctly with the RWPT model.
We performed a sensitivity analysis to identify the importance of different parameters for the simulation results. The new model and observations can be used to validate and calibrate stochastically generated fracture-network models and to estimate the enhanced-oil-recovery (EOR) performance of NFRs.
History Matching and Production Forecast With Logs as Effective Completion and Reservoir-Managing Tools in Horizontal and Vertical Wells
Authors: Haro Carlos F. 
Published: November 2012

SummarySimulation history matching is a daunting, time-consuming task with numerous unknowns and several plausible answers. Scale differences in the data frequently obscure results, limiting its application in completion strategies. Good history matching does not guarantee accurate production forecasts, however. Reliable predictions, required for well planning, depend on the ability of the user to reduce the uncertainties to find consistent and timely solutions. Logs can provide appropriate conditioning data for history matching to enable its use for reservoir management.Electrofacies, capillary pressure, and absolute and relative permeability, imprinted on logs, can be mathematically linked with irreducible water saturation (Swi). Unlike reservoir simulators, well logs are at the right scale for completion designs. Logs facilitate upscaling, honoring rock and fluid properties and the physics of flow (Haro 2006). Logs are snapshot measurements that are amenable for conversion into dynamic forecasting tools by use of flow and pressure equations. This concept permits creation of synthetic production logs (SPLTs) over time, from which production decline can be calculated.This method consists of integrating material balance, flow/ pressure algorithms, fluid data, cores, and log data. Thus, the corresponding analytical expressions are required. In this approach, every well represents a finite, gridded tank, capable of producing a measurable volume of fluids, limited by its petrophysical constraints. Superposition, in terms of pressure and flow, combines the various components within and among wells. The quality of the results is ensured because material balance must be honored at every depth at all times under different production scenarios and the prevailing drive mechanism.This log-handling technique helps when making strategic economic decisions to maximize reserves and optimize the reservoir-development plan. This strategy is used to obtain oil in place (OIP), drainage radii, lateral connectivity, fluid-bank arrival times, productivity indices (PIs), inflow performance relationship (IPR), production allocation, and recovery per zone per well. Current log analyses or simulators generally do not provide these parameters at this detail. This refined use of logs streamlines completion designs and improves conformance, enabling us to comply with an important part of daily reservoir management.
A New Method for the Design and Selection of Premium/Woven Sand Screens
Authors: Mondal Somnath , M. Sharma Mukul , M. Hodge Richard , A. Chanpura Rajesh , Parlar Mehmet , A. Ayoub Joseph 
Published: November 2012

Summary
Woven-metal-mesh sand screens, commonly known as premium screens, have been used extensively by the industry. Sand-retention testing is often executed to evaluate the performance of these screens and to establish empirical guidelines for screen-size selection. These tests are tedious, however, and the results are prone to artifacts and have been used, at best, to correlate trends in sandretention performance with select sand-size-distribution parameters. A new method incorporating results from numerical modeling, in addition to experimental data, is presented to estimate the mass and size distribution of the produced solids in prepack sandretention tests (SRTs) through premium screens. This method provides a fast, reliable correlation to estimate sand production through premium mesh screens when the size distribution of the formation sand is known.
This paper presents results from a wide range of pre-pack sand-retention experiments. In these tests, which represent complete hole collapse, the mass of sand produced and its size distribution over time are measured. Results of 3D, discrete- element computer simulations of woven-screen geometry placed in contact with granular sandpacks of approximately 100,000 particles are also presented. On the basis of both the simulations and the experiments, a new method for screen selection is presented. This method is based on a correlation that allows one to use the entire sand-size distribution of the formation sand and to estimate the mass and size distribution of the produced sand. The method is validated by comparisons with experimental data.
A new method and new correlations for estimating the mass and size distribution of produced solids in prepack tests through premium screens are presented. Key differences in sand-retention mechanisms between premium screens and wire-wrapped screens (WWSs) have been identified. The method uses the entire-formation sand-size distribution (as opposed to a single design point), and has been validated with laboratory tests. The method also helps in screening anomalous test results.
A Modern Method for Using Databases To Obtain Accurate Solutions to Complex Reservoir-Characterization Problems
Authors: Freedman R.. , Anand V.. , Zhou T.. , Rose D.. , Beekman S.. 
Published: November 2012

Summary
Many problems in reservoir characterization require the formulation and solution of an inverse problem. The definition of the inverse problem is the prediction of reservoir properties from measurements made on the reservoir. The most familiar example of an inverse problem is well-log interpretation. Well logging involves the acquisition of various kinds of data for the purpose of predicting reservoir properties of the earth formations near the borehole.
Conventional inverse methods used in the industry today typically involve the constrained minimization of a weighted sum of the squared deviations between a set of measurements and a forward-model equation or equations. The forward-model equations are either empirically or theoretically derived equations. These equations relate the reservoir property to be predicted (e.g., saturation, permeability) to measurements (e.g., resistivity, T2 distributions, porosity). Adjustable parameters in the forward-model equations are determined using a "calibration database" of laboratory measurements made on a suite of representative samples. This traditional methodology suffers from fundamental limitations that stem from the fact that reservoir rocks and fluids are too complex to be described accurately by the simple idealized equations that are used today as forward models. Additionally, the forward models contain adjustable parameters that can vary over a wide range, thereby leading to additional inaccuracies in reservoir properties.
Our paper discusses a new model-independent inversion method that overcomes the limitations and inaccuracies of the conventional method. The new inversion method predicts reservoir properties without the need to use idealized model equations or to solve minimization problems. The new method divides the calibration database into input measurements (i.e., used for the predictions) and output measurements (i.e., the reservoir properties to be predicted). The outputs are mapped to the inputs using model-independent mapping functions constructed from Gaussian radial-basis functions (RBFs). The RBF mapping functions are accurate representations of the functional relationship between the database inputs and outputs. The coefficients of the mapping function can be determined uniquely using the database. Once the coefficients are determined, there are no adjustable parameters.
The new method is applicable to a wide variety of reservoir-characterization problems. The construction of the mapping functions is presented in detail. We apply the method to a challenging problem in nuclear well logging: accurate predictions of formation thermal neutron-capture cross sections (sigma) from welllogging data. Logs of formation Σ predicted using the conventional regression method and using the new method are compared and discussed.
Simple Engineering Applications Recycled as Effective Training Aids
Authors: Sawaryn S.J.. J. 
Published: November 2012

Summary
Technical advances have led to both expansion and increased specialization in the engineering skills employed in our industry. In many cases, these specializations involve the use of complex engineering calculations involving a bewildering number of inputs and outputs to match real-world situations. Another problem with high-end applications is that they are costly and their logic is often presented as a "black box"—disclosure may be hampered by intellectual-property concerns. Although such high-fidelity applications may be essential for operations, simpler models with few inputs are better for scoping exercises or training.
The rapid and effective transfer of knowledge and experience to new hires with diverse backgrounds remains a key challenge. Though information technology and richer media have helped standardize delivery methods, accessing appropriate engineering applications for training purposes remains a challenge.
The important requirements are to communicate the fundamentals and build on knowledge gained at university. At the same time, the teaching methods and modules should instill curiosity and encourage critical assessment of the models and methods used. Therefore, the models should not be too far from reality.
Technical progress and refinement of a broad range of topics are inherent in the content and structure of the SPE paper library. The application to training is illustrated using examples including the simple 2D bottomhole-assembly (BHA) algorithm presented by Walker (1973). This paper shows how key refinements have been included by use of simple geometrical constructs and how the model has been used effectively in spreadsheet form to develop an understanding of BHA behavior and directional-survey-sag correction, and to identify and correct programmatic errors.
It is suggested that greater use can be made of the SPE library as a ready source of cost-effective training material and that the descriptions of the simpler engineering applications it contains can be recycled as valuable training aids.
Fracture-Stimulation Diagnostics in Horizontal Wells Through Use of Distributed-Temperature-Sensing Technology
Authors: Tabatabaei M.. , Zhu D.. 
Published: November 2012

Summary
Horizontal wells with hydraulic-fracture treatments have proved to be an effective method for developing unconventional oil and gas reservoirs. During the past several years, fracturing methods have evolved and improved rapidly; however, there still exist many uncertainties in fracture design. Several fracture-diagnostic techniques have been developed to improve the understanding of the fracturing process. In this study, after reviewing the application and limitations of the current fracture-diagnostic techniques, we describe the application of distributed-temperature-sensing (DTS) technology as a complementary tool for real-time fracture diagnostics. DTS technology has enabled us to observe the dynamic-temperature profile along the wellbore during the treatment. However, quantitative interpretation of dynamic-temperature data is very challenging and requires in-depth mathematical modeling of heat and mass transfer during the treatment.
We have developed a thermal model to simulate the temperature behavior along the wellbore during the treatment, as well as during the shut-in period. This model takes into account the effect of all significant thermal processes involved, including conduction and convection.
Examples are presented to illustrate how this model can be applied for fracture-stimulation diagnostics. Estimation of the fracture-initiation points, number of created fractures, and distribution of stimulation fluid along each isolated zone are the problems for which DTS technology can help obtain answers. The effectiveness of isolation can also be diagnosed by DTS technology because the heat-transfer mechanism changes when convection caused by leaking in isolation occurs. This information can be used for more-accurate fracture modeling and better estimation of fracture conductivity and fracture geometry and, therefore, to optimize future treatments and also to evaluate the well performance.
Wax-Deposition Forecast
Authors: Semenov Andrey 
Published: November 2012

Summary
In the case of altering the pressure/volume/temperature properties of oil, change of the aggregate state of oil is one of the main issues in oil processing. When oil lifts to the surface, the most advantageous energy state of high-weight components becomes the state in which a portion of the molecules becomes solid. Phase-behavior diagrams could be plotted using a typical compositional simulator, but even if one knows the phase behavior, one still will not be able to understand the wax deposition in the tubing or pipeline and will not forecast this process performance.
As some authors have mentioned, the resin and asphaltene concentrations in the oil affect the wax-deposition velocity. Because of the high complexity of the crystallization mechanism, the high-weight molecules are not taken into consideration in a phase-behavior simulator. Thus, with the intent of qualitatively characterizing the oil tendency to the aggregate, the oil from different reservoirs has been compared.
Because of the temperature gradient between rock (permafrost) and oil, there is a probability of wax deposition in the tubing. The deposition-growth model makes different diffusion assumptions. The equilibrium model and the film-mass-transfer model (as well as solidification and separation) have been applied. Using these models, the wax-growth velocity and tubing-drift diameter have been forecast.
As a result of the harsh northern environment, there is a serious risk of oil solidification in the surface pipeline in the case of a pump stopping. On the basis of the laboratory measurements and with the help of a stepwise approximation, the oil-viscosity dependence on temperature has been derived. By solving the heat-transfer equation (between oil in the pipeline and the environment) and using nodal analysis, the maximum safety time in case of an accident in the pipeline has been determined.
Contemporary Approach Coupled With Traditional Techniques Tackles Extreme Wellbore Environment in Schoonebeek Heavy Oil Field
Authors: Foster Andrew , Pollema Auke , Petitt Ian , Heathman James , Johnson Carl , Schlepers Rudy 
Published: November 2012

Summary
The Schoonebeek heavy-oil field was first developed by Nederlandse Aardolie Maatschappij B.V. (NAM) in the late 1940s. Because of economics, it was abandoned in 1996. In 2008, the Schoonebeek Redevelopment Project, using a gravity-assisted-steamflood (GASF) design concept, was initiated with 73 wells (44 producers, 25 injectors, and 4 observation wells).
Steam injection and cool-down cycles subject a cement sheath to some of the most severe load conditions in the industry. Wellbore thermal modeling predicted that surface and production sections would experience temperatures in excess of 285°C (545°F) and considerable stress across weak formations. A key design requirement was long-term integrity of the cement sheath over an expected 25- to 30-year field life span. Complicating this requirement was the need for lightweight cementing systems, because lost-circulation issues were expected in both hole sections, particularly in the mechanically weak Bentheim sandstone.
The long-term integrity challenge was divided into chemical and mechanical elements. Prior research on high-temperature cement performance by the operator provided necessary guidance for this project. Laboratory mechanical and analytical tests were conducted to confirm the high-temperature stability of the chosen design.
In addition to using lightweight components, foaming the slurry allowed the density, mechanical, and economic targets to be met. A standardized logistical plan was put in place to allow use of the same base blend for the entire well, adjusted as needed, using liquid additives, and applying the foaming process when necessary. This single-blend approach greatly simplified bulk-handling logistics, allowing use of dedicated bulk-handling equipment.
The first well was constructed in January 2009; all 73 wells have been successfully cemented to surface. The steaming process, initiated in May 2011, has progressed with no well integrity issues to date.