bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat Pump Dryer Design Optimization Algorithm
Authors: Andrade Bernardo , Amorim Ighor , Silva Michel , Savosh Larysa , Frölén Ribeiro Luís
Published: September 2019

Drying food involves complex physical atmospheric mechanisms with non-linear relations from the air-food interactions and those relations are strongly dependent on the moisture contents and the type of food. Such dependence makes it complex to design suitable dryers dedicated to a single drying process. To streamline the design of a novel compact food-drying machine, a heat pump dryer component design optimization algorithm was developed as a subprogram of a Computer Aided Engineering tool. The algorithm requires inputting food and air properties, the volume of the drying container and the technical specifications of the heat-pump off-the shelf components. The heat required to dehumidify the food supplied by the heat exchange process from condenser to evaporator, and the compressor’s requirements (refrigerant mass flow rate and operating pressures) are then calculated. Compressors can then be selected based in the volume and type of food to be dried. The algorithm is shown via a flow chart to guide the user through 3 different stages: Changes in drying air properties, Heat flow within dryer and Product moisture content. Example results of how different compressors are selected for different type of produces and quantities (Agaricus Blazei mushroom with 3 different moisture contents or fish from Thunnini tribe) conclude this article.
The ZIKA Virus Delays Cell Death through the Anti-Apoptotic Bcl-2 Family Proteins
Authors: Turpin Jonathan , Frumence Etienne , Desprès Philippe , Viranaïcken Wildriss , Krejbich-Trotot Pascale
Published: September 2019

Zika virus (ZIKV) is an emerging human mosquito-transmitted pathogen of global concern, known to be associated with complications such as congenital defects and neurological disorders in adults. ZIKV infection is associated with induction of cell death. However, previous studies suggest that the virally-induced apoptosis occurs at a slower rate compared to the course of viral production. In this present study, we investigated the capacity of ZIKV to delay host cell apoptosis. We provide evidence that ZIKV has the ability to interfere with apoptosis whether it is intrinsically or extrinsically induced. In cells expressing viral replicon-type constructions, we show that this control is achieved through replication. Finally, our work highlights an important role for anti-apoptotic Bcl-2 family protein in the ability of ZIKV to control apoptotic pathways, avoiding premature cell death and thereby promoting virus replication in the host-cell.
How Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS) Progresses: A Framework for Research and the Prevention, Treatment, and Rehabilitation in ME/CFS
Authors: Nacul Luis , O'Boyle Shennae , Nacul Flavio E. , Mudie Kathleen , Kingdon Caroline C. , Cliff Jacqueline M. , Clark Taane G. , Dockrell Hazel M. , Lacerda Eliana M.
Published: September 2019

We propose a framework for the understanding of the pathophysiology and management of Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS) that considers wider determinants of health and long-term temporal variation in pathophysiological features and disease phenotype throughout the natural history of the disease. As in other chronic diseases, ME/CFS evolves through different stages, from asymptomatic predisposition, progressing to a prodromal stage, and then to symptomatic disease. Disease incidence depends on genetic makeup and environment factors, the exposure to an insult, or repeated insults, and the nature of the host response. In people who develop ME/CFS, normal homeostatic processes in response to adverse insults may be replaced by aberrant responses leading to dysfunctional states. Thus, the predominantly neuro-immune and autonomic manifestations, underlined by a hyper-metabolic state, that characterise early disease, may be followed by various processes leading to multi-systemic related symptoms. This abnormal metabolic state and the effects of a range of mediators such as products of oxidative and nitrosamine stress, may lead to progressive cell and metabolic dysfunction culminating in a hypometabolic state with low energy production. These processes do not seem to happen uniformly; although a spiralling of progressive inter-related and self-sustaining abnormalities may ensue, reversion to states of milder abnormalities is possible if the host is able to restate responses to improve homeostatic equilibrium. Disease management and research efforts should seek to identify and apply strategies targeted at the different pathophysiological dysfunctions that characterise different disease stages. As disease presentation varies over time, no single case description, set of diagnostic criteria, or molecular feature is currently diagnostic for all patients at all times. While acknowledging its limitations due to the incomplete research evidence, we suggest the proposed framework may improve research design and health care interventions for people with ME/CFS.
The Quantum Regime Operation of Beam Splitters and Interference Filters
Authors: Vatarescu Andre
Published: September 2019

The quantum Rayleigh spontaneous emission replaces entangled photons with independent ones in homogeneous dielectric media where single photons cannot propagate in a straight line. Single and independent groups of photons, described by the original bare states of Jaynes-Cummings model, deliver the correct expectation values for the number of photons carried by a photonic wavefront, its complex optical field, and phase quadratures. The intrinsic longitudinal field profile associated with a photonic wavefront is derived for any instantaneous number of photons. These photonic properties enable a step-by-step analysis of various beam splitters and interferometric filters. As a result, generalized expressions are derived for the correlation functions characterizing counting of coincident numbers of photons for fourth-order interference, whether classical or quantum optical, without entangled photons.
Perbanyakan Jabon Merah (Anthocephallus macrophyllus (Roxb.) Havil) Secara Vegetatif dengan Stek Pucuk Muda dan Stek Pucuk Tua (tunas wiwilan) dengan Zat Pengatur Tumbuh
Authors: Agustin Ely Kristiati
Published: September 2019

Jabon merah(Anthocephallus macrophylus) merupakan salah satu anggota keluarga kopi-kopian (Rubiaceae). Tumbuhan ini tergolong jenis tanaman hutan yang cepat tumbuh (fast growing species). Pada umumnya pengembangan kayu jabon diperuntukan sebagai bahan baku pulp dan kertas, kayu lapis, mebeler, bahan bangunan dan konstruksi ringan. Beberapa tahun belakangan ini laju perkembangan industri perkayuan terhambat terkait dengan berbagai masalah yang dihadapi saat ini, salah satu permasalahan utamanya adalah pasokan kayu. Mengingat lajunya kebutuhan kayu ini kiranya diperlukan salah satu materi genetik perbanyakan vegetatif. Perbanyakan vegetatif mempunyai beberapa keunggulan, diantaranya adalah tidak bergantung pada musim buah, efektif dalam perbanyakan secara masal dan mempunyai keturunan yang sifat genetiknya sama dengan induknya. Rancangan percobaan yang digunakan adalah Rancangan Acak Kelompok (RAK) dengan 2 faktor. Faktor pertama yaitu pengaruh pemberian Rootone-f. Faktor kedua adalah asal bahan stek. Teknik perbanyakan vegetatif merupakan salah satu alternatif untuk memperbanyak jenis tanaman ini. Penelitian ini bertujuan untuk mengetahui pengaruh pemberian zat pengatur tumbuh dan asal sumber stek juvenil muda dan tunas wiwilan jabon merah. Hasil penelitian menunjukkan bahwa Rootone-f memberikan pengaruh signifikan terhadap persen berakar tunas muda (98,67%) dan stek pucuk tua (74,67%). Demikian pula tumbuh akar paling cepat yaitu pada hari ke-4 setelah tanam. Persentase stek hidup adalah  91,58 %.
Efektivitas Metode Discovery dan Media Youtube Terhadap Siswa Kelas V SD N Tlahap Dalam Materi Fotosintesis
Authors: Bargi
Published: September 2019

Pembelajaran di Sekolah Dasar akan lebih efektif, menarik, dan menyenangkan apabila guru dalam menjelaskan materi pelajaran memanfaatkan berbagai media dan metode secara bervariasi. Penggunaan metode yang tidak bervariasi, menjadikan hasil belajar sangat rendah seperti yang terjadi pada siswa kelas V SDN Tlahap tahun pelajaran 2018/2019. Untuk memecahkan masalah tersebut, peneliti  melakukan tindakan dengan mengubah  metode dan media pembelajaran, yang semula menggunakan mengunakan metode konvensional diganti  metode discovery dan media youtube. Tujuan dari penelitian ini adalah untuk meningkatkan minat dan motivasi belajar pada siswa kelas V SDN Tlahap tahun pelajaran 2018/2019 pada materi fotosintesis yang nilainya masih rendah. Dalam menggunakan metode discovery dan media youtube siswa diajak untuk mengamati dari video yang diambil dari youtube kemudian diarahkan untuk berdiskusi dalam kelompok. Hasil diskusi disampaikan di depan kelas dan ditanggapi oleh kelompok lain, yang kemudian akan disimpulkan bersama guru. Sumber data diambil dari pretest sebelum dilakukan tindakan untuk mengetahui kemampuan awal, dan postest pada akhir siklus kedua. Dalam tiap siklus, penggunaan metode discovery dan media youtube akan meningkatkan hasil belajar karena lebih menarik, menyenangkan, dan pengetahuannya pun diperoleh dari pengalaman belajar sendiri bersama teman-temannya. Hasil belajar terbukti lebih baik ada peningkatan sebesar 60,87%
Model Problem Based Learning dengan Mind Mapping dalam Pembelajaran IPA Abad 21
Authors: Tri Pudji Astuti
Published: September 2019

Pembelajaran IPA abad 21 menuntut guru untuk mengimplementasikan pembelajaran yang mencerminkan empat keterampilan hidup yang disebut dengan 4C yaitu critical thinking, communication, collaboration dan creativity. Model pembelajaran yang mampu mengakomodir hal tersebut adalah model problem based learning. PBL berakar dari persoalan-persoalan kontekstual dan diasumsikan dapat meningkatkan siswa dalam berpikir kritis, keterampilan memecahkan masalah dan memperoleh pengetahuan. Mind mapping adalah salah satu teknik pembelajaran yang memanfaatkan citra visual dan bentuk grafis untuk membangun kesan. Tujuan utama mind mapping adalah untuk memfasilitasi siswa dengan gaya belajar yang beragam. Efektivitas pencapaian tujuan pembelajaran melalui aktivitas pemecahan masalah secara berkelompok yang terarah dapat terwujud melalui integrasi mind mapping dalam sintak PBL. Mind mapping memudahkan guru untuk memberikan masukan dengan cepat dari hasil pemecahan masalah di masing-masing kelompok
Applying Decision Trees to Improve Decision Quality in Unconventional Resource Development
Authors: Miller Patrick , Gouveia James
Published: September 2019

Decision trees have been used for many years in conventional oil and gas plays to help managers better understand risk and expected value for a project. Although industry has rapidly shifted over the past decade to developing unconventional resources, application of decision trees to these plays has lagged behind. When building decision trees for unconventional plays, it is often unclear to evaluators how to build the tree, namely, how to estimate the probability of meeting a given commercial threshold, as well as the production profiles and costs to use for each branch of the tree. This paper presents a workflow that can be used to build a decision tree for an unconventional play in the appraisal phase of development, given ranges of uncertainty in production profiles and drilling and completion costs. In applying this workflow, managers will better understand both the drivers of uncertainty in expected value and how they can influence it via appraisal program design and setting commercial thresholds. An example from a North American unconventional play is used as an example to illustrate the steps of the workflow.
Field Trial Results of Ball-Activated Outflow Control Devices for SAGD
Authors: Webb Patrick David , Gauthier Joshua , Skeates Craig
Published: September 2019

A field-trialed ball-activated Outflow Control Device (OCD) is presented that eliminates coiled tubing intervention in SAGD injection wells when converting from steam circulation to SAGD. This paper builds on a previously presented paper by the same authors where the design and tool qualification of the ball-activated OCD was presented (Webb et al, 2017). In this paper, the results of the field trial are shared and compared with analogous wells where coiled tubing shiftable OCDs were used.

The field trial of the ball-activated OCD is compared to coiled tubing shiftable OCDs on three main criteria: job efficiency, confirmation of shift, and environmental, health, and safety (EHS) considerations. Acoustic-based monitoring equipment and pressure signatures were used to confirm successful ball-activation of the ball-activated OCD. A tension response from the coiled tubing was used to confirm shifting of the coiled tubing shiftable OCDs. Steam modelling and observed tubing pressure drop data is also shared for all trials as another indication of successful shift.

In five of six ball-activated OCD shifts, the tools functioned as intended with clear pressure and acoustic signatures confirming a successful shift of the sliding sleeve. One of six was intentionally left closed. In addition, the jobs were completed more efficiently and with less EHS risk than the coiled tubing shiftable OCDs. The coiled tubing shifting tension data indicated that two out of six coiled tubing shiftable OCDs were successfully shifted, with inconclusive shifts occurring on three OCDs, and one left intentionally closed. The observed pressure drop data presented, indicates that shifting was successful in all ball-activated trial wells, and two of three coiled tubing shiftable trial wells.

The ball-activated OCD is a novel tool for use in SAGD injector wells to improve efficiency by reducing operational time and personnel required in shifting OCDs. In addition, the shift confirmation pressure signature and optional acoustic monitoring provides greater confidence of sleeve shift.
Ears On Wells: Reservoir Delineation and Monitoring Using True 3D Imaging Approaches
Authors: Ghazali Ahmad Riza , Abdul Rahim M. Faizal , Mad Zahir M. Hafizal , Muhammad M. Daniel , Mohammad M. Afzan , A. Aziz Khairul Mustaqim
Published: September 2019

The key objectives were to achieve better seismic resolution and spatial delineation in very heterogeneous reservoirs. We decided to supplement simultaneously the surface 3D multi component seismic acquisition by placing additional fiber optic live receivers in the subsurface via a "True-3D" experiment without shutting down the oil production. The most cost-effective method to snapshot this wavefield propagation downhole is by utilizing fiber optic Distributed Acoustic Sensing (DAS). The borehole 3D VSP data were acquired by sharing the surface OBN nodal survey airgun sources. This is an important experiment for the field in the future so that the need to halt insitu field production for 4D time lapse monitoring will not be required if the S/N is acceptable by using this method. This permanent installation of fiber optic cables has become our ears on wells, not only for 3D DAS VSP but for proactive monitoring of the field, ensuring optimum production performance throughout the life of the field.
The Effect of Changes in Hydraulic Fracking Fluid Chemistries on the Dissolution Rate of Dissolvable Magnesium Frack Plug Components
Authors: Murphy Matthew , Turski Mark , Warfield William , Lyon Paul
Published: September 2019

Objectives/Scope: The use of dissolvable metal technologies for use in downhole tools for the hydraulic fracking industry has expanded rapidly over the last few years. The dissolution rate of these alloys is known to be sensitive to the chemistry of the fracking fluids used. Recently, there has been a drive to increase the use of recycled fracking fluid, resulting in unintended changes to the fluid chemistry. This work will review the effect of such changes in frac fluid chemistries on the dissolution rate of commercially available magnesium based dissolvable alloys. These results are compared to the published dissolution rate for the same alloys.

Methods, Procedures, Process: The published rate of dissolution is based on tightly controlled temperatures, utilising KCl solutions typically up to 3 % KCl. In this work, the dissolution rate was measured for a range of simulated frac fluid chemistries. Tests were carried out in tightly controlled laboratory conditions at ambient pressures and at temperatures up to 200 F. A range of brine solutions were investigated, applying systematic changes to the compositions of each solution. This approach provided reproducible conditions, allowing the effect of specific species typically found in downhole frac fluids to be isolated and evaluated.

Results, Observations, Conclusions: The results show clear trends on the dissolution rate of dissolvable magnesium alloys with changes in frac fluid chemistry. In particular, the presence of certain salts have shown to significantly reduce the material dissolution rate.

Novel/Additive Information: While the general trend for increased dissolution rate with increasing brine concentration is well understood it was surprising to find a decrease in corrosion rate where certain salts are present. These results are invaluable in providing the operator a greater understanding on the expected dissolution rate of dissolvable magnesium technologies within the field for a given chemistry of frac fluid. These results are of particular importance given the trend towards reuse of frac fluids in the field.
Image Processing and Machine Learning Applied to Lithology Identification, Classification and Quantification of Thin Section Cutting Samples
Authors: Caja Miguel Ángel , Peña Andrea Carolina , Campos José Rafael , García Diego Laura , Tritlla Jordi , Bover-Arnal Telm , Martín-Martín Juan Diego
Published: September 2019

Cuttings provide the opportunity to precisely look at the rock that has been drilled. A preliminary drill cuttings description is commontly performed by mudloggers and wellsite geologists using conventional binocular microscope at the drilling rig. After this preliminary description, often the bags of cuttings are stored in a warehouse and samples are seldom examined back again. Cuttings give the geologist information about the formation lithology needed for geologic correlation, understanding about reservoir quality, seals and source rocks, and can also be an input for the petrophysicist.

In this study, we are testing a methodology to identify, classify and quantify lithologies present in cutting samples using thin section images. The method includes sample preparation (washing, drying and thin section cuttings preparation), image acquisition (to obtain whole thin section gigapixel high resolution microscopy images), virtual microscopy (to identify lithologies) and automatic image analysis (to perform supervised machine learning lithology clasiffication).

Virtual microscopy allowed the identification of four main lithologies in all the studied thin sections: quartzites (including loose quartz grains), siltstones, claystones and carbonates. Image analysis allowed the classification and quantification of the identified lithologies in 16 drill cutting samples from two tight gas reservoirs.

This innovative methodology allowed the fast identification of lithologies using virtual microscopy and their classification and quantification by image analysis and supervised machine learning. This approach is widely accessible as open source software was used for virtual microscopy and image analysis. Algorithm training and model generation was relativelly fast, and its performance or accuracy was qualititavely evaluated by virtual microscopy with good classification results.
A Hybrid Data and Physics Modeling Approach Towards Unconventional Well Performance Analysis
Authors: Molinari Diego , Sankaran Sathish , Symmons Dave , Perrotte Michael
Published: September 2019

As unconventional reservoirs have become more challenging to develop and predict, understanding well performance has proven to be essential for driving value. Though there have been continuous advancements in well performance analysis and production forecasting for unconventional reservoirs that exhibit prolonged transient flow conditions, there is a still a gaping need for robust and scalable methods which are usable from a practical standpoint, considering data availability and other uncertainties.

Traditional forecasting methods (decline curve analysis and its variants) are often not fully representative and impacted by surface operations such as constrained flow, choke changes etc. or subsurface events such as well interference, frac hits, depletion below saturation pressure, etc. Analytical and numerical modeling methods address this issue by applying first principles and simplified physics for integrating flow diagnostics and time-rate-pressure analysis. However, this is often quite interpretive through manual analyses that are not scalable, requiring additional reservoir inputs that are often not collected or known for all wells. Consequently, these methods are not suitable for large scale, repetitive forecasting purposes.

We desire a reliable, consistent and scalable well performance analysis method that can work with routinely measured data for most unconventional wells (i.e. surface pressures, flow rates and fluid data).

A novel continuous drainage volume estimation method based on the concept of diffusive time of flight is used in conjunction with material balance calculation to estimate pressure depletion and well deliverability from daily flow rates and bottomhole pressure. A data-driven procedure for estimating PVT properties for all wells is also developed and applied to convert surface pressures to bottomhole pressures. A predicted rate profile can be obtained from the productivity and depletion trends. Finally, based on the "learned" well response, a new stochastic method is used for a reliable uncertainty quantification in production forecasting.

The proposed workflow has been applied to more than a thousand wells in a major unconventional field successfully through an automated platform, after applying necessary data processing and cleansing procedures. We present value-driven case studies demonstrating tangible ways in which this method can be successfully implemented, providing additional insights compared to traditional forecasting techniques.

Our proposed method overcomes common practical challenges of traditional production analysis and forecasting methods (decline curve, analytical and numerical models) to provide a consistent and reliable measure to compare well performance at large scale.
Analyzing Fractures Using Time-Lapse Electric Potential Data
Authors: Hu Jason , Horne Roland
Published: September 2019

Characterizing the fractures is an important task to improve the understanding and utilization of hydraulic fracturing. As an approach to augment and improve on the existing methods, time-lapse electric potential measurements could be used to characterize subsurface features. In this study we investigated the characterization of fracture length and fracture density by using time-lapse electric potential data. A new borehole ERT (electric resistivity tomography) method designed specifically for hydraulic fracture characterization is proposed to better capture reservoir dynamics during hydraulic fracturing. This method uses high resolution electric potential data by implementing electrodes in or near boreholes and monitor electric potential distribution near the horizontal fracture zone. The time-lapse electric potential data generated by this tool were simulated and subsequently used to analyze fracture characteristics. Inverse analysis was then performed on the electric potential data to estimate fracture length and fracture density. Last, we performed sensitivity analysis to examine the robustness of the estimates in nonideal environments. The results of this work show that time-lapse electric potential data are capable of capturing flow dynamics during the fracturing process. Using the proposed borehole ERT method we successfully estimated the true fracture length and true fracture density of a constructed fracture model. We were able to determine the best locations in the constructed reservoir to place the electrodes, and through sensitivity analysis we found the maximum noise level of the electric potential data that can still allow the proposed method to make robust fracture length and fracture density estimates.

Our proposed method offers a new approach to make robust estimates of fracture length and fracture density. Electric potential data have been used mostly for well logging in the past. This study demonstrates a novel way of using electric potential data in unconventional development and opens possibilities for more applications such as production monitoring.
Artificial Intelligence Applied in Sucker Rod Pumping Wells: Intelligent Dynamometer Card Generation, Diagnosis, and Failure Detection Using Deep Neural Networks
Authors: Peng Yi
Published: September 2019

For most of the mature fields, the oil well operation and maintenance expenditures continue to put financial pressure on the operators in the low oil price period. Digital oilfields and artificial intelligent technology are the major areas invested to fight for declining oil production and increasing cost. This paper provides a novel artificial intelligent method to monitoring and diagnose the sucker-rod pumping wells using deep learning algorithms.

Traditional method using load and displacement sensors to measure the dynamometer card needs large investment on the equipment installation and maintenance. We build a general model that generates the dynamometer card from electrical parameter using state-of-art deep learning algorithms. The deep learning algorithms can analyze the relationships between the electrical data and corresponding dynamometer card in different conditions, which is very hard for human being to detect. In addition, we build another automated diagnosis deep learning model from thousands of dynamometer cards labeled with different classifications.

We have already tested these newly developed artificial intelligent models on hundreds of sucker rod pumped wells in different oilfields in PetroChina. The field test results show that the dynamometer cards generated from electrical data have above 90% similarity compared to the real dynamometer, which meet the requirement for well diagnosis. The card generation model is stable and prevents the disturbance of hostile environment change and sensor failures. The automated diagnosis model also proved to be a good substitute to the conventional software, with above 95% prediction accuracy. The automated diagnosis model reduces the liability and uncertainty of traditional diagnosis software and can integrated with the former dynamometer card generation model to fulfill well monitoring and diagnosis automatically without any physical model based calculations.

These models developed with artificial intelligent technology will be important components in the "Intelligent Fields". They can also be embedded in the IIoT edge computing machines for automatic diagnosis and control. For ultra-low production wells and the newly producing wells utilized this method, operator can save expenditure and human resources tremendously.
Enhancing Scale Prediction in Pre-Salt Wells Using Numerical Simulation
Authors: Simões Maciel Rodrigo , Ressel Pereira Fábio de , Fieni Fejoli Rômulo , Leibsohn Martins André , Duarte Ferreira Marcus Vinicius
Published: September 2019

Petrobras has faced several challenges concerning inorganic scaling in the Pre-salt cluster. Scale prediction plays an important role on well completion selection and supporting to define better alternatives for chemical injection location. However, predicting scale in wellbores is traditionally performed based on thermodynamical equilibrium of the formation water under static conditions. This strategy leads to conservative results since it neglects hydrodynamics and kinetics of the scaling process. This paper proposes a new approach to predict scaling in downhole conditions. The study seeks to contribute on the comprehension of the effect of fluid flow and equipment geometry variation in the crystal deposition process in intelligent well completion equipment.

Such completion devices act in managing the fluid flow influx from different reservoirs or multiple zones of the same reservoir. Despite the positive aspects of this technology, some authors have been pointing out some problems associated with specific applications of these tools. The most common issues are related to the considerable pressure differential and the occurrence of calcium carbonate (CaCO3) scale. The pressure drop in this tool induces the flash liberation of CO2 from the aqueous solution. Consequently, the chemical equilibrium is displaced towards the direction of precipitation of CaCO3 in the flow stream. This paper proposes a new approach to predict scaling in downhole conditions and aims to quantitatively evaluate the calcium carbonate precipitation on the smart completion element internal surfaces. Computational Fluid Dynamics (CFD) along with discrete phase modeling (DPM) is employed to simulate the transport and adhesion of the calcium carbonate crystals on the device. The valves geometries consider the main features observed on the field according to different suppliers, accounting the different possibilities of completion geometries for Brazilian Pre-Salt environment.

The results showed the tendency of scale deposition pointing out hot spots in several different completion accessories at downhole conditions. A better understanding of the scale potential has influenced the decision-making process on the completion design and workover alternatives in the Pre-salt wellbores.
A New Approach To Clastic Rocks Pore-Scale Topology Reconstruction Based On Automatic Thin-Section Images and Ct Scans Analysis
Authors: Krutko Vladislav , Belozerov Boris , Budennyy Semyon , Sadikhov Emin , Kuzmina Olga , Orlov Denis , Muravleva Ekaterina , Koroteev Dmitri
Published: September 2019

A framework for porous media topology reconstruction from petrographic thin sections for clastic rocks is proposed. The framework is based on two sequential stages: segmentation of thin sections imagesinto grains, porous media, cement (with further mineralogical classification of segmented elements) and reconstructing a three-dimensional voxel model of rock at pore scale.

The framework exploits machine learning algorithms in order to segment2D thin section images, perform structural and mineralogical classification of grains, cement, pore space, and reconstruct 3D models of porous media. Segmentation of petrographic thin section images and mineral classification of the segmented objects are performed by the means of combination of image processing methods and Convolutional Neural Networks (CNNs). The 3D porous media reconstruction is done by means of the Generative Adversarial Networks (GANs) are applied to the segmented and classified 2D images of thin sections.

As the criteria of the reconstruction quality, the following metrics were numerically calculated and compared for original and reconstructed synthetic 3D models of porous rocks: Minkowski functionals (porosity, surface area, mean breadth, Euler characteristic) and absolute permeability. Absolute permeability was calculated using pore network model. The 3D reconstruction framework was tested on a set of thin sections and CT tomograms of the clastic samples from the Achimovskiy formation (Western Siberia). The results showed the validity of the goodness-of-fit metrics based on Minkowski functionals for reconstruction the topology of porous media. The combined usage of CNN and GAN allowed to create a robust 3D topology reconstruction framework. The calculated poroperm characteristics are correlated with laboratory measurements of porosity and permeability.

The developed algorithms of automatic feature extraction from petrographic thin sections and 3D reconstruction based on these features allow to achieve the following goals. First is the reduction of the amount of the routine work done by an expert during petrographic analysis. Second leads to the reduction of the number of expensive and time-consuming CT scannings required for each physical sample in order to perform further absolute and relative permeability calculations. The proposed method can bring the petrographic thin section and CT data analysis to a new level and significantly change traditional core experiments workflow in terms of speed, data integration and rock sample preparation.
Third Generation Production Logging Technologies Enhance Inflow Profiling in Deepwater Gulf of Mexico Reservoirs
Authors: Donovan Glenn , Kamath Sagar , Tanis Elizabeth , Abbassi Linda , Gysen Alain
Published: September 2019

This paper discusses the effectiveness of the third-generation (Gen3) Production Logging Tool (PLT) technology which incorporates the use of co-located digital sensors for simultaneous acquisition of flow data. Case studies are provided which demonstrate that this technology is a step-change in the application of digitalization to a down-hole sensor platform which provides the most accurate characterization of the flow condition at each depth surveyed. The resulting data allows for much improved processing which is also described. The probabilistic interpretive model used in the processing has been updated to incorporate this and future developments in PLT architecture.

Planning, execution, and analysis of data for the wells is described in detail. Due to the significantly shorter configuration of Gen3 tools, safety at the wellsite is enhanced by allowing for a much-simplified surface rig-up. One well was logged in surface readout (SRO) mode while data in the other two were recorded in the downhole tool's memory for retrieval at the surface at the end of operations. This flexibility in logging modes optimizes operations by addressing the needs of the operation teams.

Three Deepwater Gulf of Mexico producers logged with the Gen3 PLT are described. In each case, a clear path forward is provided for optimal management of the reservoirs through effective production management.

The first generation (Gen1) of PLT provided a single discrete measurement for each sensor along the tool assembly's length, resulting in long tool assemblies and measurements taken at different points along the flow path. This approach had several drawbacks: long toolstrings, point sensors only provided a measurement at a single point in the cross-section of the flow, and measurements were not acquired simultaneously at each depth logged. The second generation (Gen2) of PLT was an improvement as sensors were arranged as an array enabling multiple measurements to be made at a single depth but were still long and not all were optimally arranged to capture data in the path of flow. The Gen3 PLT is one-tenth the length of the Gen1 versions and roughly one-third of the shortest Gen2 tools. Digitization allows for direct measurement of flow conditions and rapid interpretation of results. In multi-phase flow and deviated wells, the co-location of sensors in a spatial geometry provides the optimal information with which to create a fully accurate picture of the downhole flow.
Engineers’ Dilemma: When to Use Soft String and Stiff String Torque and Drag Models
Authors: Zhang Yuan , Samuel Robello
Published: September 2019

The soft string and stiff string models are different string methods that have been used by the oil industry to calculate torque and drag for years. Opinions have often varied as to which model is better. This paper discusses the intrinsic difference between these two models and proposes a criterion for determining which method would deliver the most accurate results.

Although both the soft string and stiff string models are used for torque and drag calculation, the soft string model is calculated like a soft rope, without considering the influence of the hole size and radial clearance. On the other hand, the stiff string model considers the effect of stiffness, thereby accounting for the extra side contact force. In theory, the stiff string model is more accurate because more variables are considered. However, the field data is more inclined to match the soft string model as opposed to the stiff string model. In fact, many factors, including the stiffness of the string, the shape of the wellbore, and clearance, can influence the status of the string and the value of the contact side force on the string. The present stiff string model does not consider these factors, making it difficult to predict accurate results. This paper analyzes the physics statuses of the string under different scenarios in order to determine which model to apply.

Results demonstrate that borehole tortuosity and the shape of the wellbore can significantly change the status of the string. All factors are relative. A string with a large-size section can be very soft in a straight wellbore, which is fit for a soft string model. Likewise, a string with small-size section can be very stiff in a wellbore with severe tortuosity, which is a better fit for a stiff string model. To accurately estimate the drag force, the stiffness, as well as the wellbore shape and its clearance, should be considered. Extensive simulations have been performed and are reviewed in this paper. Results confirm that the soft string model is a better choice when the string is slimmer, the wellbore is in a lower curvature shape, and the clearance is larger. On the contrary, the stiff string model is more useful when the string is stronger, the wellbore is in a high curvature shape, and the clearance is lower. When to use the models depends on the bending shape of the string in the wellbore. Since neither model is equipped to handle all scenarios, combining the two methods provides better results.
A New Strategy for Developing Horizontal Well Inner Potential Based on Fiber Optic Distributed Acoustic Sensing Monitoring
Authors: Li Li , Luo Qiyuan , Xiong Qi
Published: September 2019

An optical fiber has been utilized to continuously acquire liquid production profiles in horizontal well in X oilfield. The results obtained from the dynamical monitoring system confirm the time-varying law of the physical property under the condition of high-water flooding, which can serve as the guidelines to explore the potential of remaining oil in high water-cut/high recovery factor oilfield.

Usually, the sound wave shows different propagation speeds in different medium, which is the basic principle of this test. Firstly, optical cable is used for sound wave detection and signal demodulation.Meanwhile, a series of other processes are applied to calculate the sound velocity of mixed medium; Then the volume velocity and holdup of mixed medium for each phase are determined.The measure of liquid-producing profile along the whole horizontal well has been realized in real time. Finally, numerical simulation model considering the time-varying physical properties is established based on the core flooding laboratory experiment. This result will provide guidelines for the exploration of remaining oil in the well.

The results obtained from optical fiber monitoring system during last two years show that 80% of the fluid produced from the 502-meter horizontal well is mainly contributed to the first 90-meter horizontal section. Experimental results of core flooding under excessive water flooding (2000 pore volume) indicate that the permeability is 1.4 times of the original. The results of numerical simulations considering the time-varying physical properties illustrate that there is still internal remaining oil along the horizontal well section. So, the strategy of exploiting potential oil is proposed using an accurate directional water plugging, which will decrease 10% water cut and obtain more recoverable reserves.

Based on the dynamical monitoring results of optical fiber, this paper innovatively provides the strategy of exploiting potential remaining oil in the horizontal wells, which can provide a valuable suggestion for offshore oilfield with high productivity at high water-cut stage.
Dual-Polymer Fracturing Fluids Provide Major Advantages Over Traditional Fluids
Authors: Almubarak Tariq
Published: September 2019

As exploration for oil and gas continues, it becomes necessary to produce from deeper formations, have low permeability, and higher temperature. Unconventional shale formations utilize slickwater fracturing fluids due to the shale’s unique geomechanical properties. On the other hand, conventional formations require crosslinked fracturing fluids to properly enhance productivity.

Guar and its derivatives have a history of success in crosslinked hydraulic fracturing fluids. However, they require higher polymer loading to withstand higher temperature environments. This leads to an increase in mixing time and additive requirements. Most importantly, due to the high polymer loading, they do not break completely and generate residual polymer fragments that can plug the formation and reduce fracture conductivity significantly.

In this work, a new hybrid dual polymer hydraulic fracturing fluid is developed. The fluid consists of a guar derivative and a polyacrylamide-based synthetic polymer. Compared to conventional fracturing fluids, this new system is easily hydrated, requires fewer additives, can be mixed on the fly, and is capable of maintaining excellent rheological performance at low polymer loadings.

The polymer mixture solutions were prepared at a total polymer concentration of 20 to 40 lb/1,000 gal and at a volume ratio of 2:1, 1:1, and 1:2. The fluids were crosslinked with a metallic crosslinker and broken with an oxidizer at 300°F. Testing focused on crosslinker to polymer ratio analysis to effectively lower loading while maintaining sufficient performance to carry proppant at this temperature. HP/HT rheometer was used to measure viscosity, storage modulus, and fluid breaking performance. HP/HT aging cell and HP/HT see-through cell were utilized for proppant settling. FTIR, Cryo-SEM and HP/HT rheometer were also utilized to understand the interaction.

Results indicate that the dual polymer fracturing fluid is able to generate stable viscosity at 300°F and 100 s-1. Results show that the dual polymer fracturing fluid can generate higher viscosity compared to the individual polymer fracturing fluid. Also, properly understanding and tuning the crosslinker to polymer ratio generates excellent performance at 20 lb/1,000 gal. The two polymers form an improved crosslinking network that enhances proppant carrying properties. It also demonstrates a clean and controlled break performance with an oxidizer.

Extensive experiments were pursued to evaluate the new dual polymer system for the first time. This system exhibits a positive interaction between polysaccharide and polyacrylamide families and generates excellent rheological properties. The major benefit of using a mixed polymer system is to reduce polymer loading. Lower loading is highly desirable because it reduces material cost, eases field operation and potentially lowers damage to the fracture face, proppant pack, and formation.
The Effectiveness of Thermal Gas Treatment on Bazenov Formation Using Numerical Simulation
Authors: Shakhmaev Artur
Published: September 2019

This paper presents a description of the technology for numerical simulation of thermal gas treatment on Bazhenov formation, taking into account features of Bazhenov formation and thermal gas treatment and assumptions of the simulator.

First of all it is required to determine the following parameters: voidness (porosity), permeability, fracturing, free oil (initial oil saturation), TOC (Total Organic Carbon). And also it is important to establish dependence of the parameters on temperature and pressure. Then, the process of thermal gas treatment can be conditionally divided into several stages: Effective production of light oil from drainable (permeable) zones (miscible displacement in front of the combustion front)Involvement of zones of reservoir containing kerogen during to heat treatment (pyrolysis reaction) and liberation of light oil and gaseous hydrocarbons from "locked" zones of reservoir.Involvement of the initially non-drainable (impermeable) zones of reservoir, named matrix (doesn’t mean the same as in dual porosity/permeability system). Especially these zones are the greatest interest among reservoir engineers because it can contain huge reserves of hydrocarbons.

As a result of the steps described above, a 2D model was created, a numerical realization of the key processes taking place during thermal gas treatment on Bazhenov formation was carried out. Further, the main zones characterizing the process were identified and a physical justification for the individual indicators was given. Calculations of variants involving the matrix in the drainage process were carried out.

The calculated technological effect over a 50-year period of thermal gas treatment on the model (involving the production from matrix) was about 50% of the additional oil production, relative to the thermal gas treatment variant without involvement of matrix.

According to the results of the work, an evaluation of the efficiency of wet combustion was carried out during thermal gas treatment. The results of the calculations clearly demonstrate the advantage of using wet combustion. It is as stimulation of production of reservoir oil, as of additional synthetic oil as a result of kerogen pyrolysis reaction.
Capillary Condensation in Shale: A Narrative Review
Authors: Barsotti Elizabeth
Published: September 2019

Shale reservoirs are estimated to account for approximately 10-30% of oil and gas worldwide, yet operators rarely produce more than 10% of the original hydrocarbons in place from them. These poor production numbers are a result of the assumption that the same pressure-volume-temperature (PVT) analysis procedures that are employed in conventional reservoirs are also applicable to shale and tight reservoirs. However, traditional PVT analysis does not account for the nanoporosity of the shale and, therefore, neglects the ability of nanopores to significantly alter the phase behavior of reservoir fluids. To quantify the effects of shale nanoporosity on the phase behavior of reservoir fluids, a novel gravimetric apparatus was developed. Unlike other gravimetric apparatuses in the literature, ours is compatible with both simple and complex experimental fluids and up to several hundred grams of unconsolidated or consolidated porous media at temperatures and pressures up to 232ᵒC and 5,000 psi, respectively. Furthermore, our apparatus does not require a buoyant force correction, which is one of the major shortcomings of most commercially available gravimetric apparatuses. These unique features allow us to study fluid phase behavior in shale and tight cores with high accuracy and efficiency. In the course of an exhaustive three-year research program, we have used this apparatus to measure the first capillary condensation isotherm for a fluid mixture with more than two components and discovered new phenomena of capillary condensed and supercritical fluids in the nanopores of shale rock and synthetic porous media. By reviewing the works produced over the course of this research, we are now able to answer longstanding questions as to when and how nanoconfinement-induced phase behavior occur in shale reservoirs and the implications that different types of phase behavior, including capillary condensation and nanoconfined supercriticality, have for oil and gas production.