bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Casing Fatigue Failure During Multistage Fracturing Operations
Authors: Liu Zhengchun , Samuel Robello , Gonzales Adolfo , Kang Yongfeng 
Published: November 2018

Abstract
Tubular fatigue failures have been commonly reported in geothermal and heavy oil wells with cyclic steam injection operations. Recently, possible fatigue failures in casing connections during multistage fracturing operations have also been reported in the literature. These occurrences raised the question of whether casing fatigue is a real problem, even for shale plays. This paper describes fatigue modeling and analysis of the casing connections during fracturing operations to provide additional information about this issue.
The varying casing temperature and temperature-dependent casing loads were obtained using numerical simulations of cyclic hydraulic fracturing operations, such as end of cementing → shut-in → plug and perforation → stimulation (stage 1) → shut-in → plug and perforation → stimulation (stage 2) etc. These simulations were accomplished using commercial software, including a thermal flow simulator and stress analyzer. The previously simulated casing loads were then used to calculate localized stress amplitude, strain amplitude, and maximum stress. Finally, the localized strain and stress values were used as input parameters of fatigue models to estimate the lifetime (cycles) of selected casing sections.
The fatigue model was implemented in a computer program and integrated with the thermal flow and stress analysis commercial software, and a field case (shale oil/gas well) was studied with the integrated fatigue simulation. The predicted casing connection fatigue behavior closely correlates with failure field data, and the casing failure location was analyzed and explained in terms of environmental and cyclic stress/strain conditions. The corrosion fatigue appears important for the acidic environment during hydraulic fracturing. The field case study indicates that the fatigue analysis, coupled with numerical thermal-flow analysis and multistring stress analysis, can provide more insight into the failure of casing connections during fracturing operations. Consequently, it is valuable to include fatigue analysis during the wellbore tubular design when multistage fracturing and/or refracturing operations are involved.
Successful Well Test Operations in Complex Reservoir Fluids: Lessons Learned and Best Practices Over 40 Years of Worldwide Operations
Authors: Shumakov Yakov , Hollaender Florian , Theuveny Bertrand 
Published: November 2018

Abstract
Today many exploration, appraisal and development welltest operations are performed in new frontiers. These include extreme environmental conditions and reservoirs bearing complex reservoir fluids, such as heavy oil, or fluids with a high concentration of H2S, CO2, high wax and asphaltenes content, which have rarely been tested in the past. Many failures and operational issues have hindered the interpretability of data, significantly increased the total costs of such well tests or led to severe HSE incidents.
Currently, such operations are often designed and executed on a case-by-case basis, and there are no practical recommendations available that would summarise the well testing experience in such environments to guide the operating companies through the process of efficiently planning welltest operations. Consequently, operations are often planned on a "copy-paste" basis, with potentially disastrous consequences.
This paper describes in detail the challenges associated with safety, flow assurance, safe handling and disposal of produced fluids, and data quality during current welltest operations with complex reservoir fluids or challenging environmental conditions. Complex reservoir fluids, including highly corrosive fluids, introduce unique challenges that need to be addressed at the design stage of the test, each requiring an appropriate design of surface well test spread and DST string, as well as the overall job operation and equipment planning to incorporate "what-if" scenarios. To address these issues, we summarize the best well-testing practices, and for each of the cases outlined illustrate proven welltesting techniques. Examples show that it is nearly impossible to perform the well test and handle complex reservoir fluids at surface using a traditional approach and standard well test equipment. Novel well testing equipment such as new generation welltest separators equipped with Coriolis mass flow meters, new generation burners and others, in combination with recently developed well testing techniques, allowed us to overcome these challenges.
The paper provides practical recommendations, supported by case studies, highlighting the results and lessons learned from successful operations around the worlds in the following well test areas: –Heavy oil testing–Well test operations in high H2S and CO2 environment–Well test operations in reservoir fluids with high wax or Asphaltene content–Deepwater welltest operations with a high risk of hydrate formation–Well test operations with production of foamy oil–Heat management–Viscous fluid management–Contingency planning
Recipes for success are provided to ensure that safe operation can be performed in the challenging environment while keeping the cost in line with the AFEs.
The Impact of Digital Transformation on Cutting Drilling Costs - A Case Study from Oman
Authors: Al-Aufi Yousuf , Malik Al Sulti Al Salt , Arnaout Arghad , Bakhti Sara , Thonhauser Gerhard 
Published: November 2018

Abstract
Digital transformation is a process of applying all digital technologies on current workflows to be able to deliver high quality information at the right time. Improving well delivery time is one of the goals for applying digital transformation inside the company. The drilling performance should be reported on daily basis and all the drifting from predefined targets should be spotted and reported directly. Hence, the drilling crews require more detailed information of their performance, to proactively develop best practices and improve efficiency. Drilling process digitalization is one of the tools that has significant impact to achieve this goal.
This was initially started inside the operating company to implement advanced digitalization technologies to monitoring and improvement drilling operations and to follow up drilling contractors through their digital footprints on the operational performance. The advances in digital technologies and tools provide enable measuring rig activities through real-time rig sensor data and merge it with other information sources. Therefore, a setup of a real-time digitalization tool based on automated rig activities detection technology is established and a measurement and monitoring process was started.
The results of the digitalization process, after an initial evaluation period of approximately 1 month, exposed the savings potential by identifying Invisible Lost Time (ILT). As an example, the result of applying this agile and collaborative process, an improvement of "Weight to Weight" times between 45% and respectively 25% was achieved for two rigs, which reflects an actual saving up to 7% of the total well delivery time. The drilling team achieved measurable savings equal to one average total well duration in the one year of operation.
The Barriers to Smooth Implementation of Diversity as a Workforce Strategy by the Worldwide Oil and Gas Industry
Authors: Emmanuel Joseph Itodo , Emmanuel Gloria Ileigo , Shaapere Timothy Terver , Okomgboeso Samuel Mohammed 
Published: November 2018

Abstract
Advances in technology, business mix, globalization, sluggish oil price and high staff turnover combined with the benefits of diverse workforce has provided the solid basis for the worldwide oil and gas industry to recruit and retain a multicultural workforce made up of the best and most qualified talents to remain competitive and increase their overall effectiveness irrespective of the size of their organizations.
To achieve their bottom line, oil and gas industry need to embrace diversity as a workforce strategy and promote social inclusion and equal opportunities amongst all their workers. Organizations that adopt diversity as a workforce strategy are committed to fair treatment of all regardless of their ethnic origin, race, marital status, disability, colour, social class, trade union membership, nationality, sexual identity, religious beliefs, age and any other discriminatory factors.
In spite of the direct effect of workforce diversity on company performance based on plethora of research, there is a gap in knowledge on the barriers to smooth implementation of diversity as a workforce strategy by the worldwide Oil and Gas Industry.
It is also worrisome that only limited research exist that have evaluated the barriers to effective implementation of diversity as a workforce strategy by the worldwide Oil and Gas Industry. The need to do this constitutes the focus of this study and the findings of this research work will be useful to all stakeholders in the worldwide oil and gas Industry.
This give rise to the purpose of this research work which is to examine the barriers to smooth Implementation of diversity as a workforce strategy by the worldwide oil and gas Industry.
This paper presents the findings on the barriers to smooth implementation of diversity as a workforce strategy by the worldwide oil and gas Industry. This study will be underpinned by relevant literatures and views of some practitioners in the Industry.
New Developement of Cationic Surfactant Formulations for Foam Assisted CO2-EOR in Carbonates Formations
Authors: Gland Nicolas , Chevallier Eloïse , Cuenca Amandine , Batot Guillaume 
Published: November 2018

Abstract
While the global oil demand is set to increase, reducing CO2 emissions is one of the great challenges to be tackled in the coming decades. CO2-EOR has a lot of potential within a CCUS strategy, but the low gas viscosity induces limited sweep efficiency, resulting in poor storage capacity, especially in heterogeneous carbonates formations. CO2-Foams are used to alleviate such drawbacks but special care must be taken with carbonates due to water/surfactants-rock interactions.
A new cationic surfactant formulation is designed through a high throughput screening procedure accounting for solubility at high temperature (80°C), high salinity (160g/L TDS) and high hardness (R+=0.3), increased foam half-life time (at 120bar), reduced adsorption on carbonate powder and finally Ottawa sandpack flood tests (non-reactive transport). Core flooding experiments are performed on Indiana Limestone cores at 130bar and 40°C, prior targeting higher temperature. Dense supercritical CO2 is co-injected along with the surfactant formulation at the core inlet to ensure foam generation inside the rock and apparent CO2 viscosity is measured to assess the foam performance of each formulation.
In this work several surfactant families are tested, among which: (1) anionic surfactants formulation optimized for their performances in sandstones, (2) switchable cationic surfactant (tertiary amine ethoxylate), (3) cationic surfactant, and (4) optimized cationic surfactant formulation. Solubility of the optimized formulation is found to be excellent in all considered brine (up to high salinity and hardness) and at high temperature; low static is obtained on the carbonate minerals (99% calcite) and bulk foam half-life time with supercritical CO2 (40°C/120bar) exceeds 24h. As a first demonstration step, foaming performance of each surfactant formulation is assessed through coreflood tests using intermediate salinity level water. The foam shear-thinning rheological behavior is obtained for velocities representative of near wellbore to in-depth reservoir conditions (from 5ft/day up to 50ft/day). Apparent viscosities are found to be very good, about dozens of centipoises for the lowest velocities. A technical challenges with carbonates lies in fluid/rock reactivity. The increase of divalent ions concentration in brine generally impairs both solubility and foaming ability of surfactant formulations. Here the use of the selected cationic surfactants less sensitive to divalent cations and allows both low adsorption on carbonate rocks and good foaming performance.
A highly promising foaming cationic formulation, compliant with dense CO2 and carbonates, has been designed and thoroughly tested. Results obtained bring new opportunities for the CO2-foam process applied to carbonate formations within an EOR+/CCUS strategy.
Complex Geological Modeling and Quality Assurance Using Unstructured Grids
Authors: Harris Simon , Santoshini Samita , Kashem Sheleem , Viard Thomas , Levannier Arnaud , Benabbou Azeddine 
Published: November 2018

Abstract
Conceptual limitations of existing gridding technologies often lead to undesirable simplifications to the modeling of structurally complex areas, and consequently poor predictions. We present a structural modeling and gridding workflow that limits these modeling compromises.
A volume-based 3D structural model based on fault and horizon surfaces is constructed from input data that has undergone basic quality checking using a variety of techniques. The critical step in the grid creation is the definition of a flattened (‘depositional’) space that deforms the structural model mesh under mechanical constraints. A 3D ‘unstructured’ grid is created in the depositional space, based on ‘cutting’ a property-populated, regular cuboidal grid by the geological discontinuities. The tectonic consistency and better preservation of geodetic distance make the flattened space ideal for a range of property modeling approaches. The forward-deformation of the grid into true geological space tends to preserve the layer-orthogonality of the grid columns and makes the grid more suited to numerical simulation approximations. The final grid is unstructured, high quality and an accurate representation of the input structural model.
The 3D structural model, depositional space transform and grid geometries all provide valuable information on the structural quality of the input data. The stretching and deforming of the orthogonal local axes in the transformation from depositional space to geological space are used to focus further effort on structural model quality assurance (QA). The key step in generating accurate property population and simulation models is the application of QA metrics on the grid geometry; the transformation from depositional space to geological space is used to generate a set of grid properties that highlight potential structural inconsistencies or data quality issues back in the structural model. We present several examples based on a range of structurally complex models, and demonstrate the downstream impact of applying this QA workflow throughout the stages of input data validation, structural model creation and grid creation.
Nanoparticle Stabilized Foam in Harsh Conditions for CO2 EOR
Authors: Eide Øyvind , Føyen Tore , Skjelsvik Eldri , Rognmo Arthur , Fernø Martin 
Published: November 2018

Abstract
This paper investigates CO2-foam stabilized with nanoparticles (NP) as an enhanced oil recovery (EOR) agent in carbonate reservoirs with high temperature and salt content. Under these conditions surfactants, widely used to stabilize foams, becomes unstable and will not generate strong foam. Our objective is to use NP as a stabilizing agent for surfactant based foam through an integrated process where the surfactants generate foam and the NP stabilizes the foam. Aqueous NP solutions (1500 ppm) were injected through porous media at high temperature (120 °C) to evaluate solution stability for a range of brine salinities, pH and resident times. Stable solutions were subsequently co-injected with supercritical CO2 to create foam and increase the apparent viscosity of CO2.
High temperature and salinity are challenging for most surfactants; however it is a common reservoir condition in many carbonate fields. The nanoparticles had a high degree of stability with little precipitation or gelation in the presence of salt content as high as 23 wt.% NaCl as long as the pH was sufficiently low. The stability of the nanoparticles decreased with increased temperature, leading to gelation and injectivity problems in limestone core samples when the injection water had native pH. The problem was less pronounced in sandstone core samples. Nanoparticle stability increased with decreasing pH, and it was possible to achieve steady-state conditions at 120 °C for longer periods of time. CO2 was shown to be a viable stabilizing agent by decreasing the pH of the injection brine and had the added benefit of creating stable foam for enhanced oil recovery. This is particularly important in limestones and carbonates where the pH of the injection water tends to increase as it interacts with the rock. The nanoparticles can be used alone or in combination with surfactants to increase the stability the surfactant generated foam. Surfactant based foam is generally more effective at generating foam, but is less stable at harsh conditions than nanoparticles.
A Novel Multi-Density Dynamic Well Killing Method for Ultra-Deep Wells and the Simulation System
Authors: Zhou Haobo , Sun Mingguang , Niu Xinming , Zhang Jinshuang , Huang Qingfeng 
Published: November 2018

Abstract
Tremendous amounts of oil and gas reservoir are located in ultra-deep formations, such as Shunbei and Shuntuo block in Tarim basin of China, some reservoirs buried deeper than 8000m and which are major exploration areas of SINOPEC. The reservoirs in these areas are full of fractures and cavities which resulting in a series of drilling problems, especially well control safety problems. Therefore, the novel well killing method for ultra-deep wells is very important.
Firstly, in order to reduce the well head pressure (WHP) and balance the formation pressure of ultra-deep well quickly in the killing well process, a novel multi-density dynamic well killing method was established, through which we can use two different killing fluids to kill well and one of them is high density fluid. A comprehensive multi-density killing fluids design method was proposed based on the theoretical analysis, through which the optimal density and volume of different fluids can be obtained easily. And based on the optimal killing fluid parameters, we can not only balance formation pressure quickly but also avoid fracturing formation. Secondly, according to the density contrast of operating fluids, a vacuum (U-Tube effect) will appear at the inlet in the well killing process without dynamic controlling of killing parameters, an integrated U-Tube effect analytical model was established based on the Euler equation. For preventing result into a vacuum phenomenon, a real-time calculation model for killing parameters dynamic adjusting was proposed, in which the multiphase flow model was take into account. Based on this model the real-time stand pipe pressure (SPP), WHP and pump flow rate in different stages of well killing can be obtained easily. Moreover, a series of system software for parameters calculating and simulating of multi-density dynamic killing well was developed, through which we can accurate calculating dynamic parameters and hydraulics.
The proposed model has been applied in ultra-deep well kick control in SINOPEC Northwest oil filed, the simulating result show that the proposed method and software system can give precisely killing parameters design and simulation. Based on the proposed killing well method, we can quickly reduce operating risk and improve the success rate of killing well.
This paper established a novel multi-density dynamic well killing method and the corresponding software, which has been verified with field data and applied in ultra-deep well killing simulating. Through the application, the results show that it can provide technical support to reduce operating risk, and the novel method can improve the success rate of killing well and reduce the drilling cost.
Interpretation Guided Seismic Data Processing of a Large 3D OBC Survey With Simultaneous Shooting: A Case Study from Offshore Abu Dhabi
Authors: Paul Subhrankar , Barajas Carlos Manuel , Gawron Konrad Piotr , Khakimov Oleg , Chatterjee Shraddha , Van Kleef Franciscus , Lecoq Thierry Francis 
Published: November 2018

Abstract
The 3D ocean bottom cable technique allows for acquiring long offset and wide azimuth seismic data. The use of simultaneous sources reduces the acquisition turn-around and HSE exposure. In shallow water environments, simultaneous source data are highly contaminated by surface waves and interference noise. Poor signal to noise ratio (S/N) affects velocity estimation, wavelet stability and overall image quality. This paper demonstrates the successful implementation of different processing and interpretation tools to deal with these challenges.
The initial velocity model was built by extrapolating checkshot corrected sonic velocities along the interpreted key horizons and was subsequently updated to achieve final PSTM velocity. Several passes of noise attenuation were applied. Volumetric curvature analysis was used to monitor and protect fault planes from smearing during the denoising process. Seismic to well ties were continuously monitored to quantify the improvement after each key process was applied and to QC the seismic wavelet through different processing steps.
A key factor to achieve a stable wavelet, at the end of the processing in the shallow water environment offshore Abu Dhabi, was the well driven horizon consistent velocity modeling. High seismic to well synthetic cross-correlation was observed on the final processed data due to the high S/N achieved by several passes of denoising, plus attenuation of strong multiple energy by velocity discrimination. High S/N, pickable geological events, and high resolution fault images are some of the key features of the final stacked image. In pre-stack data, long offset information is available to facilitate AVO and AVAz studies.
Incorporating geological knowledge in the interpretation of horizons and faults and using well data during the course of seismic processing proved to be effective in obtaining a high quality seismic dataset.