bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of Well Placement in Waterfloods With Optimal Control Theory Under Geological Uncertainty
Authors: Temizel Cenk , Zhiyenkulov Murat , Ussenova Kamshat , Kazhym Tilek , Canbaz Celal Hakan , Saputelli Luigi Alfonso 
Published: October 2018

Abstract
Optimum well placement in intelligent fields, using previously developed optimal control methods to maximize net present value (NPV), is becoming practical with recent advances in technologies as well as their applications to the petroleum industry. To efficiently use these methods in an intelligent field, an assessment of its economic aspects and its performance, especially in reservoirs with high degree of heterogeneity (uncertainty), must be made. By using such integrated workflows, mature and new field can be developed better. The workflow could be used as a reliable tool for improving the decision-making process.
There are multiple optimization techniques used in the industry for optimizing well placement (e.g. direct and gradient optimization). With the use of reservoir simulation case study, this paper aims to provide a comparative performance analysis of multiple optimization techniques. To make the evaluation stronger and more application to a real-world problem, the model selected for this study has a high degree of geological uncertainty and constraints for computation time, infrastructure and complexity to decide on optimal well placements.
Having a better understanding on the uncertainties in geology lead to more robust decisions in reservoir management. Right strategy especially helps in optimizing larger scale, million-cell model simulations enabling practical implementation of reservoir simulation coupled with optimization.
Optimum well placement in complex reservoirs requires a complete grasp of optimization methods, key factors and constraints but most importantly the effect of geological uncertainty. A lack of awareness of optimization algorithms and their applications by engineers is a drawback in this process. In addition, complete evaluation of geological uncertainty is another challenge. This study provides an understanding and clarification to serve as a guideline on optimization practices by outlining the significant components in the process.
A Novel Approach to Barrier Integrity Testing in Well
Authors: Stein Arild 
Published: October 2018

Abstract
Verification and testing of a newly installed wellbore barrier, in older assets has proven to be challenging. Even more so when the well has structural issues, indemnities or weak spots in the barrier envelope, or weakend well construction that limits the possibility to acheive a positive pressure verification of the barrier with an applied surface pressure versus the reservoir pressure.
A suitable location with necessary support and strength should be located in the well. If installing a mechanical barrier in means of a bridge plug as the primary barrier, we will monitor the installation forces in the anchoring and sealing sequence. This individual signature will be verified towards a nominal base line signature of a ISO approved test and a library of thousands of collected installation profiles. Any abnormality can trigger a release and relocating of the barrier. A second verification barrier will then be installed close above the primary barrier and installation sequence will be verified the same way as the primary barrier. When both installation signatures are accounted for we can pressure test the installed barriers. This can be done with a pressure manipulation tool, where we introduce a calculated predetermined pressure drop between the installed primary barrier and the verification barrier above. By monitoring this pressure alteration vs. the pressure above the verification barrier, we can determine if we have a verified primary and verification barrier.
The Primary Barrier is verified in the direction of flow (negative pressure test). And verification barrier as the secondary barrier is verified with a positive pressure test. If a dual barrier is requested you can leave the verification barrier as secondary barrier or pull to re-use.
The Complex Approach to Seismic Researches at Studying of a Nonconventional Reservoir
Authors: Konushenko Alexander , Kovalenko Maxim , Shkrabov Andrey 
Published: October 2018

Abstract
Development of methodical techniques for performing seismic studies in complex geological environments and the sequence of their application for the study of an unconventional reservoir. Evaluation of seismic prospecting capabilities for detailed study of the structure of a specific area and subsequent justification for 3D seismic survey.
The Viability of Gas Injection EOR in Eagle Ford Shale Reservoirs
Authors: Atan Safian , Ajayi Arashi , Honarpour Matt , Turek Edward , Dillenbeck Eric , Mock Cheryl , Ahmadi Mahmood , Pereira Carlos 
Published: October 2018

Abstract
Gas Injection, Huff-and-Puff Enhanced Oil Recovery (EOR) technique have the potential to improve liquid hydrocarbon recovery in ultra-tight, unconventional reservoirs. This paper studies the technical and economic viability of this EOR technique in Eagle Ford shale reservoirs using natural gas injection – generally after some period of primary depletion, typically through long horizontal reach wells that were hydraulically fractured.
To achieve this, three primary steps were undertaken: First, a series of multi-well, compositional simulation models were constructed, calibrated with lab data, and history matched for an extended production period. This effort characterizes a set of equiprobable combinations of fracture and matrix properties, as well as the parametric description of the stimulated reservoir volume. Second, these history matched models were then used to numerically simulate the Gas Injection Huff-and-Puff EOR process to determine a set of optimized operational variables (operating pressures, injection pressure, cycle durations, the corresponding injection rate, and slug size). The results were also sensitized to the effect of geomechanics, containment, as well as the effect of diffusion. The primary source of information that feeds the sensitivity analysis was derived from laboratory work investigating the EOR processes at the core scale. The third and last step, economic analysis was performed using calibrated rate profiles to assess the impact of initial yield and the amount of depletion on value. Resulting analysis provided insight to the economic viability of the EOR deployment at field-scale.
Results show that the recovery factor uplift, all things being equal, is a function of the original yield, the amount of depletion, and the minimum operating pressure during the production cycles. In reality, however, equally as critical to the success of an EOR project is the formulation of the deployment strategy - the timing of the development start (forecasted price environment), pad selection, compressor scheduling, injection-soak-production durations, surveillance plans, and mitigation strategies (for poor containment and inefficient compressor utilization).
The workflow utilized in this paper both characterizes the uncertainties in an EOR project in the Eagle Ford and provides insight into operating conditions and surveillance recommendations. This is the key for a successful demonstration pilot which can then lead to a field-scale EOR deployment.
Arctic Zone of the Siberian Platform - Resource Base and Development Potential
Authors: Dmitrievsky Anatoly , Eremin Nikolai , Shabalin Nikolai 
Published: October 2018

Abstract
The interest of oil and gas companies in the Arctic region of the Earth, despite the difficulties in the geological exploration, the development and the exploitation of discovered fields, in access to markets for the produced hydrocarbons is quite high. According to the US Geological survey, the subsoil of the Arctic zones of five coastal States – the United States, Canada, Russia, Denmark and Norway – contains at least 525 billion BBOE (barrels of oil equivalent) or 75 billion tons, including the subsoil of the Arctic zone of Russia – 315.4 billion BBOE (26). The Arctic zone of the Eastern Siberia is characterized by a harsh climate (in winter the temperature drops below −60 °C on land and to −40 °C at sea), the presence of the permafrost, the lack or remoteness of the infrastructure for the delivery of the necessary equipment and materials, the transportation of produced hydrocarbons, short periods of the field work from November to April on land, from July to September at sea (6, 7, 25). The basic concepts of the geological and tectonic structure and the oil and gas content of the land and the adjacent shelf of the Arctic zone of the Siberian platform are based on the seismic data, tied to the existing deep parametric and exploratory wells. To date, five regional seismostratigraphic complexes have been identified and described: the Mesozoic-Cenozoic, the Permian-Lower Triassic, the Upper-Middle Paleozoic, the Upper Proterozoic-Cambrian and the surface of the basement. The evaluation of the potential hydrocarbon resources was carried out in the Yenisei-Khatanga, the Anabaro-Khatanga, the Anabar-Lena and part on the Laptev Sea oil and gas regions.
Subsea Well Integrity - Permanent Monitoring Solution to Verify Critical Well Barriers, Simplify and Reduce Cost of Periodic Testing
Authors: Grimstad Sverre 
Published: October 2018

Abstract
This paper will focus on well integrity standards and give practical examples on how they are applied for wells in the Norwegian Sea.
Further the paper will review how the standards are used for testing and verifying barriers in a well, and how well integrity on subsea and TLP (tension leg platforms) benefit with the introduction of annulus B monitoring.
Examples will present how barriers can be moved and testing time reduced, while still complying to standards and local regulations as well as making the well design more robust.
Data from a well using the annulus B monitoring system will be presented and explained to give an understanding how this can benefit subsea wells throughout life of well.
Minimization of Risks in Reservoir Prediction Based on Seismic Data
Authors: Vasilyev Mikhail , Butorin Aleksandr 
Published: October 2018

Abstract
The article reviews a fast-track high-quality evaluation approach to the net pay reservoir thickness in a well-to-well space. The review is based on rocks the upper-Jurassic (J1-1) Vasyugan suite exemplified by two areas in Western Siberia.
The presence of certain geological prerequisites for reservoir formation supported by the use of historical data analysis made it possible to cluster the area in question interest according to the level of confidence in the availability of net pay thicknesses.
The approach described in the article has been instrumental in optimizing the drilling program by mitigating cost risks. New wells delivered corroborating evidence of data reviewed.
Application of Formation Pressure While Drilling FPWD Technology in Challenging Low Mobility Environment – Case Study from Western Kazakhstan
Authors: Ramatullayev Samat , Makhmotov Akikat , Zhabagenov Muratbek , Ospanov Dastan , Markelov Yura , Navrotsky Alexander , Gabdyzhamalov Yerlan , Nurgaliyev Ruslan , Maletti Giorgio , Assanova Tatyana 
Published: October 2018

Abstract
Historically, pressure measurements have been performed with wireline formation tester (WFT) tools. In highly deviated and horizontal wells, wireline tools are drill-pipe conveyed and this operation can be complex and adds significant expenses and operational risks. On the other hand, formation pressure while drilling (FPWD) technology minimizes operational risks at reduced overall cost and results in increased operational efficiency. This is particularly true for highly deviated and horizontal wells.
FPWD technology has its own application envelope. Low permeability reservoirs are traditionally considered to be "no-go zone" for FPWD. Reason being nearly all FPWD tools on the market are equipped with a single probe that has a modest flow area. Whenever formation exhibits extremely low mobility, in the order of 0.1 mD/cP or lower, operators prefer to opt for configurations that increase the flow area such as dual packer conveyed on wireline, despite the added cost and conveyance risk. However, proper job planning and real-time data transmission allows to acquire critical reservoir dynamic data with FPWD tool in challenging low-permeability environment in horizontal wells with reduced operational risks.
The following paper discusses the first successful application of FPWD technology in horizontal wells drilled in low permeability giant carbonate reservoir located in Western Kazakhstan. It focuses on the approaches taken during job planning and execution, dwells upon the acquired results and offers a methodology on how to optimize the acquisition. It is worth noting that fluid mobility in some stations was below 0.1 mD/cP, making it an extremely challenging environment. Nevertheless, the results acquired in eight wells has proven that FPWD can perform effectively and provide crucial reservoir dynamic data in separate clinoforms and gain insights about reservoir depletion mechanism, which was previously inaccessible due to operational risks related to formation tester tools conveyance in horizontal wells.
Best Practices of Assisted History Matching Using Design of Experiments
Authors: Li Boxiao , Bhark Eric W. , Gross Stephen J. , Billiter Travis C. , Dehghani Kaveh 
Published: October 2018

Abstract
Assisted history matching (AHM) using Design of Experiments (DoE) is one of the most commonly applied history matching techniques in the oil and gas industry. When applied properly, this stochastic method finds a representative ensemble of history-matched reservoir models for probabilistic uncertainty analysis of production forecast. Although DoE-based AHM is straightforward in concept, it can be misused in practice because the workflow involves many statistical and modeling principles that should be followed rigorously.
In this paper, the entire DoE-based AHM workflow is demonstrated in a coherent and comprehensive case study that is divided in seven key stages: problem framing, sensitivity analysis, proxy building, Monte-Carlo simulation, history-match filtering, production forecast, and representative model selection. Best practices of each stage are summarized to help reservoir management (RM) engineers understand and apply this powerful workflow for reliable history matching and probabilistic production forecasting.
One major difficulty in any history matching method is to define the history-match tolerance, which reflects the engineer's comfort level of calling a reservoir model "history-matched" even though the difference between simulated and observed production data is not zero. It is a compromise to the intrinsic and unavoidable imperfectness of reservoir model construction, data measurement, and proxy creation. A practical procedure is provided to help engineers define the history-match tolerance considering the model, data-measurement, and proxy errors.
Refracturing of Multistage Horizontal Wells in PJSC Gazprom Neft
Authors: Ogorodov Alexey , Ostashuk Anatoly , Barkalov Stanislav 
Published: October 2018

Abstract
Since 2011 most newly commissioned wells at Gazprom Neft fields are horizontal (Hz), subjected to multi-stage hydraulic fracturing (multi-stage frac). To date, about 1,300 horizontal wells with multi-stage frac, equipped with packer-port liner assemblies (non-cemented), ball- activated, including about 800 wells equipped with single-action fracturing collars, have been drilled at the Company's fields.
Retrospective Analysis of Hydrofracturing with the Dimensionless Parameters: Comparing Design and Transient Tests
Authors: Shel Egor , Paderin Grigory , Kabanova Polina 
Published: October 2018

Abstract
Due to the frequent application of hydraulic fracturing technology (HF) on oil and gas fields, there is a large amount of statistical information about the operations carried out. It is possible to make a conclusion about the efficiency of the hydraulic fracturing, consider the design changes and make recommendations on the basis of results of data processing. However this task becomes complicated because conduction of pressure transient analysis on fracking wells reveals that the values of the fracture parameters, in particular the half-length, significantly differ from those planned for design.
This paper is devoted to the investigation of the possible reasons of this discrepancy by using dimensionless variables, which allows analyzing of information about the performed fracturing operations. The nondimensionalization of the basic equations using for the hydraulic fracture modeling made it possible to obtain the dependence of the dimensionless half-length of the fracture on the dimensionless volume of the injected liquid, and also to obtain an empirical formula for estimating the half-length of the fracture. Also, the analysis provides a possibility to exclude the influence of different factors that could make a significant contribution to the existing discrepancy.
As a result of the analysis, limitation of PTA models, related, for example, to the non-uniform fracture conductivity and the lack of interflow between layers with different properties, as well as the fracture design errors associated with incorrect closing ratios are identified among the most probable causes of the fracture length difference.
A Comprehensive Approach to Improve the Efficiency of MSF is Implemented in PAO Gazprom Neft
Authors: Kazakov Evgeny , Sayfutdinov Elnar , Bukharov Dinar , Fayzullin Ildar 
Published: October 2018

Abstract
A rather challenging situation in the oil and gas industry requires to improve the efficiency of field development models and reservoir stimulation methods (EOR). An important factor that determines an effective model is an increased oil recovery factor at the Gazprom Neft fields and additional oil production with a commensurate increase in costs. To improve the oil recovery factor, the first step was to drill new horizontal wells and sidetracks with a horizontal ending which allowed increasing the contact area of the well and the reservoir and involved new reservoir zones into the development, increasing its oil recovery. However, drilling of new horizontal wells and sidetracking alone, without the introduction of advanced completion technologies, does not allow to achieve the desired result and maintain the production rates.
Currently, many service companies have their own research centers and offer a huge amount of technologies, but in fact such technologies have not been tested at reservoir conditions of Russia's oil and gas fields. The main challenge is the development and implementation of new technological solutions within modern business strategies for completing wells with multi-stage frac assemblies.
The Company's teams have studied the world experience and the offers of service companies in the field of horizontal and multi-stag frac completion technologies, as well have analyzed all the proposed solutions and model history matching applied worldwide with regard to the Russian reservoir conditions. In many practical cases, the application of successful foreign technologies provided by the service companies at the conditions of Russian fields turns out to be "raw". To achieve success, an additional comprehensive development of technologies is required at the planning stage with regard to the field conditions and the Standards requirements. New organizational forms have been introduced to work out the entire range of activities, from drilling to pre-production of each specific well, which allowed, jointly with the Contractor, to run a virtual simulation and to implement the scheduled operations at the preparation stage, taking into account the existing experience of all subsidiaries: the scheduled well interventions, the analysis of possible risks at the preparation and implementation stages. Such comprehensive approach, as well as new organizational forms, virtual modeling and implementation of scheduled operations resulted in the following: accident-free execution of scheduled operations, strict schedule compliance, reduced time costs, new technical and technological solutions.
A New Productivity Prediction Hybrid Model for Multi-Fractured Horizontal Wells in Tight Oil Reservoirs
Authors: Tao Liang , Guo Jianchun , Zhou Xiaofeng , Kitaeva Alena , Zeng Jie 
Published: October 2018

Abstract
Productivity analysis relates to the quantitative evaluation of factors for individual members as well as to their comprehensive influence. It is difficult to describe the nonlinear relationship of various factors. A novel and original combination of grey relation analysis (GRA) and fuzzy logic productivity prediction hybrid model is proposed in this study to solve the problem. First, based on the parameters of the constructed wells, several elements were chosen as appraisal factors. The multi-level appraisal system was established to describe the nonlinear relationship of various factors. Then, GRA was used to calculate the weight factor and determine the main factors that influence the result of multi-fractured horizontal wells (MFHWs). Finally, coupling GRA with fuzzy logic to calculate the comprehensive evaluation score (CES), which is used to predict productivity and determine the classification value of the reservoir to evaluate the reservoir quality. The hybrid prediction model has been successfully applied to 18 wells of the tight oil field in Northeast China. Practical application results demonstrated a good agreement between the measured initial production and the output of the hybrid model. The new model can be used to predict production for MFHWs quickly and economically.
Technological Development of Hydraulic Fracturing in TATNEFT's Carbonate Reservoirs. Experience in Engineering Design, Monitoring and Management of Fracture's Geometrical Parameters
Authors: Khusainov Ruslan , Kochetkov Aleksandr , Garifullin Rustem , Sirazdinov Vagiz , Ganiev Bulat , Lutfullin Azat 
Published: October 2018

Abstract
Nowaday, more than half of the residual oil reserves in PJSC Tatneft are concentrated in carbonate reservoirs, while the share of their production is lower than in terrigenous sediments (Figure 1).
This determines the set of challenges facing PJSC Tatneft in the field of stimulation of oil production from carbonate reservoirs. The work is devoted to the search for the best solutions for the selection, design and implementation of various types of fracturing (acid, propane, hybrid) in carbonate reservoirs. A qualitative and comprehensive assessment of the applied technical solutions and tools for monitoring the implementation of hydraulic fracturing is given.