bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of Viscosity and Stability of Polyacrylamide Aqueous Solution Using Carbon Black as a Nano-Additive
Authors: Silva Glaura Goulart , Oliveira A.L. De , Caliman Vinicius , Viana Marcelo Machado , Soares Meiriane Cristina Faria 
Published: June 2014

Abstract
Carbon black was oxidized (OCB) and added in the concentrations from 0.05 to 0.50 wt% to various aqueous solutions containing Poly(acrylamide-co-acrylic acid 1 wt%) in concentration of 3.0 g L−1. The nanofluids' viscosity were measured during 150 days and showed that small amount of the OCB nanoparticles improved the viscosity and the stability of aqueous and saline solutions. Therefore, the use of OCB onto polyacrylamide dispersions shows potential application in oil recovery.

Introduction
Polyacrylamide (PAM) is a water-soluble polymer that shows high viscosity, low toxicity and low cost [1]. This polymer has been used as a mobility control agent as well as an agent for permeability profile correction in improved oil recovery [2]. Partially hydrolyzed polyacrylamide (HPAM) (Figure 01) has also been used in oil recovery since its negative carboxyl groups in aqueous solution causes extension of its chain leading to viscosity increase of the solution [3]. However, its use is limited due to the low stability under several harsh conditions, e.g. temperature, shear stress and salinity [4].
Previously work using polyacrylamide nanofluid prepared with carbon nanotubes as a nanofillers showed significant improvement in maintaining viscosity [5]. The carbon black (CB) is also a versatile carbonaceous nanomaterial which has highly developed porous structure and low cost [6]. The CB has been widely used as an adsorbent, catalyst and catalyst support. Surface modification of CB allows the direct modulation of its physicochemical properties to improve its suitability in various applications. Oxygen-containing functional groups can provide active sites and can change the hydrophobicity of the carbon surface. These functionalizations increase the dispersion of the carbon nanomaterials in water [7]. To improve the stability with time and saline solution of PAM solutions we have used oxidized carbon black (OCB) as a nano-additive.
Advances in Autonomous Deepwater Inspection
Authors: Mcleod D. , Jacobson J. 
Published: June 2014

Abstract
Advances in autonomous inspection of deepwater subsea facilities are examined to illustrate the favorable enhancement of safety, reliability, reduction in risks, economic benefits and superior data products compared to conventional means. These benefits provide operators with significant improvements over general visual inspection by the addition of sensors that produce 3D models of the structure being inspected. Examples are provided illustrating test data from operations conducted from 2011–2013.
Additional benefits include rapid response when a loss of well containment requires large standoff distances between the host vessel and the sensing platform. Three dimensional georegistered models of the entire scene can be rapidly collected within hours of the incident providing responders with a clear vision of the underwater scene along with in-situ status of critical components.
Introduction of new sensors support even more advanced capabilities leading to autonomous metrology, hydrocarbon detection tracking and fingerprinting, non-contact corrosion potential measurement, thermal measurements and three dimensional underwater scanning lasers.
Application to deepwater life of field inspection will be presented with evidence gained from offshore trials in 2011 and 2012. This emergent technology supports Subsea Facility Inspection Repair and Maintenance, Integrity Management Inspections of Marine Risers, Moorings and anchors, Subsea Pipelines, Flowlines, Umbilicals, and supporting subsea infrastructure.

Introduction
Frequent risk based assessment of the condition and integrity of subsea equipment is vital to predicting the life of the equipment and prevention of uncontrolled release of hydrocarbons into the environment. Oil and Gas operators must know the state of the equipment that is often thousands of meters below the ocean surface shrouded in the veil of darkness. " Protection of health, safety, and the environment is a critical component of the processes and procedures used to monitor the conditions of offshore surface and subsea facilities and structures" (1). Traditional means of inspecting this equipment employs visual sensors such as video or still cameras mounted on Remotely Operated Vehicles (ROVs) that are hardwired to the operators controlling the vehicle from a ship above the inspection site. Such General Visual Inspection (GVI) requires significant topside support equipment and numerous skilled operators on site to control observe and maintain the ROV and interpret the images along with a large vessel support crew (MTS Journal Article). While the quality of images has improved with the advent of digital High-Definition or HD sensors the images are often degraded by movement of the cameras and the turbidity of the water, reducing the effectiveness of the inspection. In addition, the data provided to clients is often hours upon hours of recorded video that must be archived and revisited by humans for detailed examination.
Wettability Alteration in Carbonates By Surfactants: The Effects of Interfacial Tension on this Process and Reflex in Porous Media Behavior
Authors: Pinto Michel Ferreira 
Published: June 2014

Abstract
Most rocks of carbonate reservoirs is preferably lipophilic, this feature of rock-fluid interaction, also known as wettability and is closely linked at low oil recovery rates. The application of surface modifying agents is a way to changing the wettability of carbonates, making them preferentially hydrophilic and thereby favoring the reduction of residual oil saturation (Ros).
Actually reservoirs with heterogeneous permeability, which have regions of low permeability and presence of fractures and high permeability channels, there is a tendency that the injection water to flow preferentially through these channels with high permeability. This type of reservoir, the oil recovery process is improved by capillary forces, spontaneous process known as imbibition, where water tends to soak the smaller pores, expelling the oil to the larger pores. This phenomenon retard " breakthrough" and reducing the residual oil saturation (Ros). However, spontaneous imbibition only occurs appreciably in water wet reservoir. In the oil wet formations, the water has less affinity for the wall of the pores and the capillary forces are small and in many cases could be negative.
The paper presents results of Enhanced Oil Recovery (EOR) Group from Cenpes/ Petrobras, evaluating two anionics and one cationic surfactants, with different interfacial tension (IFT) and their ability to increase hydrophilicity of carbonates. The results showed that the anionic surfactant with higher IFT values was responsible for increased to make the carbonate preferably hydrophilic, keeping in high values the capillary pressure.
The results were demonstrated by the core flow tests, which showed higher oil relative permeability and Ros reduction; spontaneous imbibition test, presents higher oil recovery and contact angle evaluated, which showed lower adhesion of the oil phase on the surface of carbonate.
The agent wettability modifying can be applied as a chemical method of EOR, as well as around the producing well. In this last one, could be created convergence zones for oil and be increased the effective oil permeability near the oil production well.
The Multi-Column Floater: A Dry-Tree Semisubmersible for Deepwater Offshore Brazil
Authors: Williams Neil , Tahar Arcandra , Finn Lyle 
Published: June 2014

Abstract
This paper presents the Multi-Column Floater (MCF), a dry-tree semisubmersible (DTS) platform concept appropriate for deepwater applications worldwide. The hull geometry is based on cell spar technology where each column consists of several individual vertical sub-columns (or cells). The use of multiple cells to provide column buoyancy results in a design flexible enough to be built anywhere in the world, and can be used to satisfy local content requirements. Hydrocarbons are produced from dry completion wells connected individually to well slots arranged in a rectangular pattern in a central wellbay. The key differentiator between the MCF and other proposed DTS solutions is that in the MCF design the drilling and production risers are supported from a vertically restrained well deck in the center of the MCF, termed the Multi-Riser Buoyancy Can (MRBC). The efficiency of the MCF design is demonstrated by configuring and analyzing the system for a hybrid development consisting of a wellhead DTS and an FPSO in 1,525 m water depth in the Campos Basin offshore Brazil.

Background
Selection of the optimal floating production system (FPS) for a given application depends on several factors, including reservoir characteristics, well-access requirements, payload, water depth and metocean conditions. In water depths greater than 1,500m (beyond the range of conventional TLP technology) a dry-tree semisubmersible (DTS) offers an attractive FPS solution. A semisubmersible hull can be configured for quayside/inshore hull-topsides integration, hook-up and commissioning, thereby eliminating the project risk associated with an offshore lift. Furthermore, dry-trees allow easier well management, reduced OPEX and superior recovery rates than a wet-tree solution. Also, compared to Spars, semisubmersibles provide safer, more efficient wellbay and topsides layouts, while offering similar mooring characteristics.
The development of the dry-tree semisubmersible concept has attracted significant attention from all the major engineering contractors, primarily those based in Houston [1 - 6]. The proposed concepts all support the drilling and production risers using long-stroke riser tensioners, and both hanging and ram style tensioners have been proposed. The design of a semisubmersible hull to support dry trees requires careful consideration of the allowable hull motions so that existing riser tensioner technology may be utilized, and requires integrating the design of the riser system into that of the hull and topsides. Acceptable motions are obtained by a combination of heave natural period control and a large operating draft. A review of current industry efforts and the design challenges associated with the development of a DTS concept may be found in [7].
Relative Permeability Effects on the Miscible CO2 WAG Injection Schemes Trough Compositional Simulations of Brazilian Small Scale Water-Wet Synthetic Pre-Salt Reservoir
Authors: Laboissiere Philipe , Mello Samuel Ferreira , Trevisan Osvair Vidal , Schiozer Denis Jose 
Published: June 2014

Abstract
The present study aims to deepen the investigations of a previous study, in order to rank which variables are more critical to CO2-WAG process Enhanced Oil Recovery and which injection schemes and parameters are more effective when capillary pressure and relative permeability are adapted to Brazilian pre-salt scenario. The methods compared were Water Alternating Gas (WAG) and Hybrid Water Alternating Gas, considering saturation dependent hysteresis modeled through Larsen-Skauge model.
A detailed and reliable Equation of State for oil with high pressure, and unusual natural carbon dioxide content (8.4%) was developed based in published data to match rheology and swelling measurements. The model was a small scale water-wet carbonate/stromatolite reservoir model with the same set of relative permeability and capillary pressure with hysteresis and entrapment data were modeled as basis for pre-salt Brazilian reservoir data. The optimization were analized including hysteresis and entrapment data from the literature.
The reservoir model well constraints for each strategy were meant to be as realistic as possible, the recovery was optimized using an optimization tool, and the cases were analyzed comparatively. The most important effects were ranked and the best injection scheme and parameters were determined for the studied case in order to clear conclusions about the importance of fluid and petrophysical mechanisms for miscible final oil recovery.
Among a series of petrophysical phenomena needing further investigations on their influence on oil recovery, relative permeability is of critical importance. Nonetheless, its representation in reservoir simulation is quite a complicated task. It may incorporate hysteresis effects (at least three different models that can be used), and it may present three-phase behavior (extrapolated from two phase relative permeability experimental data). Just like relative permeability hysteresis, there are at least four different models available to represent three phase relative permeability. In the present work, only Larsen and Skauge model was addressed.
As a consequence of all complexities involved, for some subtle changes in the injection scheme, such as the injector operating restraints, make recoveries sensitive to hysteresis and passive of improvement. Simulations indicated that an incremental oil recovery of about 11%, in both WAG and HWAG schemes when hysteresis was considered compared to no-hysteresis case.
Optimization of well operating conditions and constraints (bottom-hole pressure of producers and injectors, gas and water rate limits) has a significant effect on oil recovery and production rates.
Severe Slugging in Catenary Risers - Simplified Modeling
Authors: Jian Su , Oliveira Junior Jose Vilani , Vaz Murilo Augusto 
Published: June 2014

Abstract
The objectives of this research are: to analyze the effects of the catenary shape during the occurrence of severe slugging and to develop a simplified but accurate mathematical model to calculate the main parameters of severe slugging in a flowline - catenary riser system.
Offshore exploration is achieving new records of ultra deep water petroleum production in subsea oil fields with multiple production wells at different flow rates, multiphase flow, high pressure gradients, and a wide range of flowlines and risers systems spread over the irregular seabed topography, which can lead to the occurrence of severe slugging. Severe slugging is an undesirable phenomenon.
Catenary riser is the most used geometry in the Brazilian offshore deepwater production scenario, and the catenary shape influence over the severe slugging is unknown.
The proposed model, which is based on Taitel´s model (1986), has been modified in order to take into consideration the geometric configuration of the riser in catenary. Therefore, new formulations for the residual liquid fallback have also been proposed and incorporated in the original models for the vertical riser. The developed model has been validated with experimental data of three test cases: being the first one of a vertical riser with 38.1m of length (case 1), the second one of a group of nine combinations of superficial speed of gas and liquid obtained from a catenary riser system with 9.886m height (case 2), and finally the third one being a real offshore system in production of a flowline-riser in catenary, operating in a water depth of 1,250m (case 3).
The obtained conclusion is that the catenary riser geometry has direct influence over the severe slugging cycle, the slug formation pressure, the liquid level inside the system, and the liquid fallback. It was also possible to verify the severe slugging cycle model sensibility to the top side riser angle, separator pressure, riser height, and liquid and gas superficial velocities.
Based on the comparison between the simulation results and the experimental data, it could be concluded that the proposed modified model for the flowline-riser system in catenary may be applied on the simulation of severe slugging with rather accurate precision.
Optimization of Corrosion Resistance and Weldability: A Challenge for Superduplex Filler Metals
Authors: Zinke D. , Hoberg Bernd , Gross Volker 
Published: June 2014

Abstract
The SDSS have been increasingly used in the offshore industry due to their excellent mechanical properties and corrosion resistance properties to the media they are exposed to. The SDSS are mainly used in subsea components such as Christmas Trees, Manifolds, BOP and also for Topside Modules in Platforms. A well balanced chemical composition guarantees the outstanding corrosion and mechanical properties of SDSS material. Ferrite forming elements such as Cr, Mo ensure a high resistance to chloride containing media as well as a high strength. Austenite forming elements Ni and Ni balance the microstructure to 50%. However, the thermal instability increases with the amount of elements and restricts the weldability compared to usual stainless weld metal of the 3xx series.
In particular the GMA-, and SA welding process asks for a specific approach to minimize the tendency to pore formation. This report describes the influence of a fine tuned chemical composition and welding parameters to achieve a sound weld metal along with an optimum in corrosion resistance.

1 Superduplex Stainless Steels
Superduplex Stainless Steels are materials characterized by a microstructure of austenite and ferrite, figure 1. Driven mainly by the offshore industry to increase the corrosion resistance and the mechanical properties enhancement of the conventional Duplex Steels has led to the so called Superduplex Stainless Steels. Main (Super) Duplex Steels are UNS 35750 and 35760. An overview of the chemical composition of usual Duplex steels is given in table 1. These steels are featured, compared to the conventional Duplex grades, by increased contents in Cr (22–25%), Mo (2–4%) and N (0,2 -0,35%), with possible additions of Cu and W. These increased contents lead to a higher corrosion equivalent (Pitting-Index PREN =% Cr + 3,3 % Mo + (0,5 % W) + 16 % N). This does not only improve the pitting (crevice) corrosion resistance in the as welded condition but is beneficial for a higher strength level as well.
Superduplex Stainless Steels show a PREn &gt; 40. The heat affected zone (HAZ) was already experienced as the weakest part in conventional Duplex joints. A sufficient high N-content (&gt; 0,20%) is badly required, to control embrittlement by grain grow and increased ferrite contents in the heat affected zone, even more for Superduplex Stainless steels.
Deepwater Floating Production Systems in Harsh Environment - a Look at a Field Development Offshore Norway and Need for Technology Qualification
Authors: Meling Trond Stokka 
Published: June 2014

Abstract
Deepwater field developments are regarded as standard technology in several areas of the world such as offshore Angola, Brazil and in Gulf of Mexico, but in very harsh environments no deepwater fields are put in production yet. When moving into harsher environment the extreme design loads becomes more challenging, but the increased fatigue loading may be just as important when selecting concept for field development. Especially riser and mooring solutions are vulnerable to the loading conditions in harsh environment. In the present paper key challenges for developing deepwater fields in harsh environment will be addressed. Development solutions that are working very well in more benign environments may not work as required in the deepwater harsh environments offshore Norway and Shetland. Careful reviews must be carried out to assess current technology status and applicability of selected technology in new environment settings. The Aasta Hansteen deepwater field development offshore Norway will be used to illustrate the drivers for the concept selection. Necessary steps to qualify the concept for sanctioning will also be highlighted.
Workflow For Wellbore Integrity Analysis During Reservoir Development
Authors: Fontoura Sergio , Lautenschlager Carlos Emmanuel Ribeiro , Righetto Guilherme Lima , Inoue Nelson , Albuquerque Rafael Augusto do Couto , Goncalves Clemente Jose , Alcure Marcos 
Published: June 2014

Abstract
Oil wells are engineering structures that should last safe and sound for decades. Its integrity should be guaranteed not only during drilling but also throughout the life of the reservoir. Reservoir production generates stress changes within the reservoir as well as throughout the surrounding rocks. These stress changes cause displacements and strains around existing wells that may lead to undesired casing deformation and eventually to its failure. The aim of this paper is to describe the geomechanical workflow to deal with wellbore integrity during the life of the reservoir. The stress and displacement fields developed during reservoir production are evaluated through the use of a coupled stress-flow analysis. Since the stresses are defined within large volumes of rocks, a special workflow has to be followed in order to define the stress field at the scale of the wellbore. It is presented an application example of a real reservoir considering a blackoil model containing producer and injector wells. It was made a submodel analysis around the producer well, considering the results of two global models simulated using one and two-way partial coupling. The results showed the workflow applicability and the importance of employing a rigorous fluid mechanical methodology in well integrity analysis.

Introduction
Current challenges in the extraction of hydrocarbons include the exploration of deep reservoirs, which are often part of highly complex geological scenarios, as well as the drilling and completion of wells, in broad spectrum of directions, in such formations. From the geomechanical point of view, the problematic of wells and reservoirs is often distinctly addressed, mainly because of the scale difference between such entities. Although the system behaves in an integrated way, the association of the phenomena involved in the analysis of wells and reservoirs is frequently neglected. The wells are linear constructions whose geomechanical behavior is closely related to the stress state of the rock which is going through, to the fluid employed during drilling, to the drilling direction and to the casing type. By the activities performed through the well, the reservoir undergoes significant changes in its equilibrium configuration, once the production (or injection) of fluid in the porous medium causes significant variations in their pore pressure and therefore in its stress state. Nevertheless, the reactions of the reservoir to the effects of development are not concentrated only within its borders, but they spread through the adjacent rocks, many of which are crossed by wells that propel the geomechanical changes. Clearly, there is what may be called well-reservoir system, since the behaviors of entities involved are not independent of each other, mainly due to the aforementioned stress state morphology.