bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Well Integrity – Surface Casing Corrosion Management Strategy North Sea Experience
Authors: Benjamin Ajaraogu , Taylor Ian , Bakker Eelco
Published: July 2016

Structural Well Integrity is an emerging area in Well Integrity Management in the oil and gas Industry. A key component that ensures the structural integrity for wells is the surface casing.

However, over the years little or nothing has been done to address corrosion problems of the surface casing. Though a number of reports have been completed that analysed the casing failures with recommendations for monitoring and maintenance of affected wells, surface casing corrosion has remained an issue with many operators globally.

The loss of casing wall thickness due to corrosion (Microbial, Oxygen and acid) can lead to collapse of affected wells with attendant loss of production, environment concerns from resulting spills, loss of lives, significant remediation cost and reputational damage. With recent failures of the surface casing due to corrosion and the need to extend the end of field life, a campaign was embarked on to develop an industry-acceptable management strategy.

This paper discusses the integrated approach employed to understand the problem and develop management strategy. The objective of the strategy developed is to implement a management system that ensures that structural integrity of the surface casings of the operators' well portfolio is maintained in line with the well life extension requirements. Effort was made to trace the history of surface casing corrosion within North Sea; review results from surveys of the surface casing; review the calculated risks associated with structural integrity of surface casings for all sample wells; develop workflow for corrosion management; and document monitoring and mitigating measures.
Lessons Learned from Drilling a High Pressure Well in the Niger Delta
Authors: Akinfolarin Ayodele , Erinle Adeyemi , Awe Sunday , Amah Obinna , Ibrahim Timothy , Roes Vincent , Obanya Phillip , Akhideno Mathias , Ugwu Celestine
Published: July 2016

The objective hole section of a High Pressure (HP) well in the Niger Delta was designed to be drilled with Managed Pressure Drilling (MPD) technology. While drilling the well, a significant well-control incident occurred; subsequently the well was redesigned to be drilled conventionally. This paper presents the drilling of the well before the well-control incident; the redesign of the well after the well-control incident; and the eventual drilling of the well to secure the primary objective. The overall intent of the paper is to share the learnings acquired during this sequence of activities. The redesign after the well-control incident involved splitting the objective section in two intervals. This enabled the well to be drilled without compromising the primary objectives, which were data acquisition and an eventual completion on one of the objective sands. The paper also contains the strategies used in the management of the narrow margin between pore pressure and the fracture pressure of the well, without MPD assistance.
Oil Rim De-Risking and Appraisal Value of Information in a Gas Reservoir
Authors: David Olayinka , Laoye Abiodun , Odegbesan Seyi , Isimbabi Onoze , Obeahon Percy
Published: July 2016

Millions of dollars are spent across the oil and gas industry on data gathering activities with a view to reducing subsurface uncertainties towards optimizing reservoir development and management. However, suboptimal attention is often paid to assessing the value of the information (VoI) during data acquisition requirement planning and before requesting for such information. The capital intensiveness of the industry and emerging low oil price regime has necessitated scrutiny on every dollar spent on data gathering in the current business terrain.

The application of the VoI concept in the oil & gas industry provides a predictive, analytic and quantitative framework for decisions and justifications for data gathering activities including but not limited to log data acquisition; downhole fluid sampling; subsurface diagnostic tests; core data acquisition; appraisal drilling and seismic acquisitions. Value of Information in simple terms is described as the amount a decision maker should be willing to pay for a piece of information. It is evaluated as the difference between the future value of a project given the availability of particular information versus its value without it.

This paper demonstrates the methodology and application of VoI analysis to support a key decision on whether or not to drill an appraisal leg of a well to test for fluid contact and possible presence of an oil rim in a reservoir prior to initial gas development. The major uncertainty in this study is the evaluation of the hydrocarbon extent in a gas reservoir with a gas-down-to (GDT). To evaluate the options, a VoI analysis was carried out by integrating results of different data sources; well log data; formation pressures; seismic data and analogue information. Integration of the different data was used to arrive at different subsurface realizations which fed into 3D static and dynamic simulation models. The modeling result for the different scenarios was used as input for economics in the VoI analysis.

Using the multiscenario analysis, the range of oil rim thickness proved to be non-commercial and the VoI analysis showed that drilling an appraisal will result in a negative value of appraisal giving the estimated VoI and cost of drilling an appraisal well. The analysis has led to significant cost saving of about $8million which is the appraisal cost of an earlier planned appraisal/development well. The analysis also helped to challenge the pre-existing appraisal paradigm and provided a robust basis for a commercial decision without compromising on regulator standards and industry best practices.
Predicting the Fluid Above Shallowest Known Oil SKO: Integration of PVT, Well Logs and Seismic - Limited Data
Authors: Awasthi Amit , Ikwueze Obinna , Itua Osazua J. , Tendo Fidelis , Osayande Francesca
Published: July 2016

For reservoirs that are not fully appraised, fluid type and resource volumes above Shallowest Known Oil (SKO) or Deepest Known Oil (DKO) are often unknown. This paper discusses the workflow adapted to predict the fluid type above the SKO with reasonable certainty. This enables to book SPE compliant resource volume (SCRV) above SKO to be proposed for booking and up dip wells to be justified.

As part of SCRV estimation for Field-X to book hydrocarbon volumes above the SKO, the oil properties, reservoir pressure data and seismic information were integrated utilizing the limitations and uncertainties around each data for the candidate reservoirs. The fluid properties (specifically bubble point pressure) are the most essential element in this analysis, which sometimes are not available or not of sufficient quality. This article will discuss the methodology and workflow adopted to use the existing limited information with their corresponding uncertainties to circumvent these limitations.

This methodology was demonstrated as a reliable technology supporting SCRV for Field X, resulting in the increase of ~ 25-30 % of the oil SCRV. Furthermore it has potential to be applied to other fields with similar circumstances.
Technical Assessment of In-Country Capabilities in the Oil and Gas Operations in Nigeria
Authors: Oriaku T. O. , Udo N. A. , Ifeduba E. A.
Published: July 2016

Building local capacity among indigenous oil and gas players is a non-negotiable mandate for the Nigerian Oil and Gas Industry. A technical evaluation was conducted to assess the capabilities of 33 indigenous companies rendering services ranging from Tubing Inspection Handling and Management Services, Slickline Operations and, Surface Well Testing Operations within the Warri and Port-Harcourt areas of the Niger Delta. The table top and facility inspection evaluations showed that, for the Tubing Inspection Services, 44% out of the 18 companies sampled scored the mandatory 60% minimum required to qualify technically. Surface well testing services showed 63% of the 8 companies scoring above 70% while Slickline services revealed 88% pass for the 8 companies sampled. Criteria used in the technical assessment of these companies include; equipment and materials availability, service delivery time, job experience, HSE standards, personnel, staff training and project management. This paper attempts to evaluate the technical capabilities of indigenous companies as well as highlight some of the challenges facing the local content initiative.
Integrated Surveillance in the Management of Decline on a North Sea Mature Field
Authors: Ogedengbe Allen
Published: July 2016

The purpose of this paper is to describe how integration of different well and reservoir surveillance methods on a mature field in the North Sea is used to deliver value. The surveillance plans for a mature North Sea field named Field X here broadly serves two purposes: Short term day-to day-data gathering for well operations, well work planning, voidage management and optimization.Use of longer term tools like seismic to identify bypassed pools of oil reserves in different parts of the field for optimization, well intervention and infill drilling.

A good surveillance strategy is a well thought out integrated plan which is fit for purpose for particular fields. This plan allows the field development plan to be delivered in an efficient and timely manner. The value of surveillance needs to be clearly articulated for all stake holders to allow a buy in for quality surveillance data. Future production delivery is tied to the quality of information obtained during data gathering.

Surveillance planning on Field X has been standardized to allow ease of use. The objectives of the surveillance planning to obtain data that will ensure safe well operations, enhanced well stock value. This process is kept simple, and allows for speed and flexibility during well work execution. The whole surveillance/intervention cycle integrates knowledge from a multi-discipline team from when ideas are generated, evaluated, approved, executed and stored.
Comparative Study of Rena and Mycoremediation Techniques in Reduction of Heavy Metals in Crude Oil Impacted Soil
Authors: Maduekwe C. , Nwachukwu E. O. , Joel O. F.
Published: July 2016

The comparative study of RENA, Mycoremediation and combination of the two techniques were carried out to determine their ability in the degradation of selected heavy metals (Cadmium, Chromium, Nickel, lead, Zinc, Manganese and Iron) in a Crude oil impacted soil. Three different plots for each technique and control were each spiked with 7.5 Litres of Bonny Light crude Soil Samples were taken at 0-15cm and 15-30cm depths for each of the techniques and control at 0, 4, 8, 12, 16 and 20 weekly intervals for heavy metal analyses. Results indicated that in the plots treated with RENA, Mycoremediation and combination of the two techniques, Lead (Pb) concentration was degraded by 55.9%,65.8%,85.1% respectively compared with control plots that gave 23.7% reduction of Pb. The percentage degradation of Manganese by RENA, Mycoremediation and Myco/RENA was 57.3, 64.3, 83.1 respectively while control plots recorded 26.1% Mn degradation. Concentration of Ni was reduced by 57.8% by RENA, 64.2%, by Mycoremediation and 85.6% by the combination of the two techniques (Myco/RENA) while in the control plots Ni was reduced by 27.89%. Concentration of Cd was reduced by 56.7% 65.6%, 88.7% by RENA, Mycoremediation and Myco/RENA respectively. The control plots recorded 26.1% Cd degradation. This was similar trend observed for other heavy metals studied. Thus the combination of the two techniques (Myco/RENA technique) gave a promising result in the degradation of all the heavy metals studied in Crude Oil Impacted soil.
Predicting Tubing Movement and Stress on Tubulars During Scale Remediation Jobs Using Computer Simulations
Authors: Ighalo Samuel , Romaine Keith , Andriessen Blake
Published: July 2016

Scale-squeeze remediation has been used extensively for removing scale from production strings in offshore and deepwater environments. During scale remediation treatments, the affected tubulars undergo displacement and stress that can affect the effective seal length and integrity of the completion system. Numerous laboratory simulations can be performed to help determine the effectiveness of the treatment fluids, injection volume, scale-inhibitor retention time, fluid composition, and shut-in time; however, sufficient research has not been conducted regarding the effects of these important parameters on the structural integrity of completion systems during an actual scale-inhibition squeeze treatment.

This paper studies the effects of these important parameters on completion system integrity by (1) performing wellbore thermal simulations of the treatment operations, (2) investigating how much tubing movement has occurred during these operations, (3) analyzing stress on the tubulars during different operations, (4) investigating the effects of scale-inhibition application methods on tubing movement, and (5) recommending a fit-for-purpose tubing movement workflow for the scale remediation process based on laboratory and field data.

This paper investigates six cases using data from a Gulf of Mexico deepwater well. The parameters studied include injection rate, injection pressure, shut-in "soak period" time, and volume of injected treatment fluids. The results show that shut-in time, injection pressure, and injection rate are sensitive parameters that can significantly affect tubing movement and wellbore stress on tubulars.

The method of application by means of squeeze treatment or continuous pumping is proven to be an important requirement for these types of operations and should be seriously considered when designing scale-squeeze treatments. These findings also provide the necessary information for optimizing the design treatment, developing good completion spaceout and design, as well as improving operational procedures for scale-remediation applications.
Predicting the Cricondenbar of Lean Natural Gas
Authors: Aimikhe V. J , Joel O. F , Ikiensikimama S. S , Iyuke S
Published: July 2016

This work focuses on predicting lean sweet natural gas cricondenbar. This is an important parameter used in predicting the phase envelope, which determines whether the transported gas is in a single gas phase or a two phase (gas and liquid) and in compressor horsepower sizing and selection. Equations of state are the best methods for predicting natural gas cricondenbar, but they are usually very tedious and rigorous. For instance the use of an equation of state requires the knowledge of the gas critical properties, Acentric factors, Molecular Weight and Binary interaction parameters some of which are not so easy to get. In this study, a FORTRAN compiler was used to generate natural gas composition data in the range of lean and processed natural gas with a specific gravity of 0.58 to 0.69. From the data generated, a correlation was found to exist between the specific gravity of the gas and the cricondenbar. A relationship between natural gas cricondenbar and apparent molecular weight of natural gas was developed. This model was then tested with the calculated cricondenbar of fourteen (14) different natural gases obtained from the field and literature using the SRK equation of state phase envelope utility tool of ASPEN HYSIS software. The results gave a percentage average relative deviation and average absolute deviation of 1.85 and 5.3 respectively.
Predicting Water Content of Sweet Natural Gas – Hydrate Systems
Authors: Aimikhe V. J , Joel O. F , Ikiensikimama S. S , Iyuke S
Published: July 2016

Water content measurement and prediction can be very challenging at conditions of low temperatures and high pressures (hydrate conditions). As a result, many correlations for natural gas water content determination either cannot predict water content of natural gas at these conditions or, have a low accuracy of prediction when they do. In this study, nomographic data generated with the Cubic Plus Association (CPA) equation of state with pressure range of 50 to 500 Bar and temperature range of -20 to 20 °C was used in developing a simple, easy to use correlation with a single predictor (Temperature) variable. This correlation was validated with experimental data obtained from a high pressure variable volume hydrate cell with an analyser based on the Tuneable Diode Laser Absorption Spectroscopy (TDLAS) technology and compared with six (6) other correlations for predicting water content at these conditions. The average absolute deviation (AAD) for the correlations showed that the model in this study had the least AAD of 21 and 5 at 50 and 75 bar respectively. The Behr's correlation had the least AAD of 5 and 10 at 150 and 200 bar respectively, closely followed by the model in this study with AAD's of 9 and 13 respectively. While the Moshfeghian and Sloan correlations gave fairly accurate predictions with maximum AAD's of 36 and 32 respectively, the Kazim and Ning correlations performed poorly with AAD's of 50 and 44 respectively.
Experimental Study of Balanced Activity of Shale During Interaction With Oil Based Mud
Authors: Ndubuisi Elizabeth , O Joel
Published: July 2016

Shales are considered to be the most challenging formation to drill. Over 90% of the formations drilled worldwide are classified as shale formations and about 75% of drilling operation problems are related to shales. There are many factors affecting shale stability, which can be classified into three. The first factors are in relation to geological mechanics, the second type is the chemical factors of the mud which is the main focus of the work and the third type is the engineering factors, which includes the time when the wellbore is opened, the parameters of the depth of the well, inclination and azimuth angles, pressure excitation and drawing. All these factors and parameters governing the shale stability react upon and affect each other, making the problem of wellbore instability extremely complicated. The osmotic effect which is the principal driving mechanism causes water to enter either in the shale or drilling fluid depending on the strength each other. The shale acts like a membrane, but a very poor membrane, so water with improper salt concentration could increase the rate of imbibitions of water into the shale or the reverse may be the case. Therefore, there is need to strike a balance in the design of water activities of the mud and shale in order to achieve wellbore stability. The focus of this research therefore is to design balanced activity drilling mud with the shales from Niger Delta that will prevent wellbore instability. Experimental results for four shale samples collected from the Niger Delta was able to establish the balance activities points for; shale A is 0.86, Shale B is 0.73, shale C is 0.72and shale D is 0.79 respectively. It is recommended that the activities of the shale and oil based mud must strike a balance in order to achieve wellbore stability chemically.
Calculation of Connected Hydrocarbon Initially In-Place Volumes for R5000 Reservoir Using Buckley Leverett & Decline Curve Analysis
Authors: Onu Chukwuemeka , Orekoya Adedoyin , Ori-Jesu Efeoghene , Onita Caroline
Published: July 2016

The use of dynamic method to determine hydrocarbon in-place volumes in R5000 reservoir in Urad field became necessary when it was discovered that the in-place volumes estimated in previous studies for this reservoir cannot be validated by current production data. A combination of Buckley Leverett and Decline Curve Analysis has been used to significantly reduce the wide range of uncertainty reflected in previous in place volumes estimation.

R5000 reservoir in Urad field has two producing wells, one closed-in well and two planned wells; from production data review, it was discovered that estimated in-place volumes was less than optimum. The challenge of re-evaluation to obtain result that both structural interpretation and production performance data will support arose. This paper therefore has deployed Buckley Leverett method with assumption of moderate water drive and gravity drainage to approximate a water flood and as such predict recovery efficiency using the interaction between fluid mobilities, fractional flow and water saturation. Decline curve analysis performed on the producing wells in R5000 reservoir was used to derive technical Ultimate Recovery and a reverse calculation has been done to estimate hydrocarbon initially in-place that supports structure and production data.

The recovery factors of three reservoirs in Urad field, namely P1000, H2000 and K3000 have been previously estimated in an earlier study on this field using Buckley Leverett method and result obtained in this work was validated by repeating the BL evaluation for these three reservoirs to reproduce the recovery factor results obtained in earlier study.

This work provides a solution to the challenge of estimating hydrocarbon initially in-place volumes in reservoirs where available rock and fluid data as well as fluid contacts information are not reliable.
Multivariate Analysis of Air Quality in Selected Oil Operating Areas in the Niger Delta Region of Nigeria
Authors: Ramson Enotoriuwa , Oluchi Nwachukwu Eunice , John Ugbebor
Published: July 2016

This study assessed air quality in selected oil operating areas in Rivers State of Nigeria with consideration to land use type such as oil and gas facilities, major bus stops, schools, Markets, hospitals, residential areas, vegetation and commercial centers. Air quality and meteorological parameters across 25 locations were monitored during the wet season (April to October) 2015 to ascertain major air pollutant sources. The parameters monitored were, Nitrogen dioxide (NO2), Sulphur dioxide (SO2), Carbon ii oxide (CO), Volatile organic compounds (VOCs), particulate matter (PM) 1, PM2.5, PM4, PM7, PM10, TSP, wind speed, humidity and temperature. Descriptive statistics, agglomerative hierarchical cluster analysis (AHCA), Principal component analysis (PCA), Multiple linear regression (MLR) and Principal component regression (PCR) were used in the data analysis and modeling of Air quality index. Results showed that SO2 values ranged from 0.04 ppm to 0.15 ppm, NO2 values ranged from 0.025 ppm to 0.162 ppm, CO concentration ranged from 0.24 ppm to 6.36 ppm, VOC values ranged from 0.18 ppm to 2.19 ppm across all study locations. Particulate matter also varied across the study locations. Three clusters were obtained from AHCA. The dendogram plot from AHCA showed that the observed variation can be attributed to the land use pattern in the study area. Three principal components were extracted from the PCA based on eigenvalue of >1 and from the biplot after varimax rotation revealed that the major sources of air pollution in the area based on land use type are markets, major bus stops, residential and commercial centers. Vehicular emissions, biomass burning and dusty roads are the major sources of air pollution in the study area. MLR performed better than PCR with MLR and PCR having an R2 of 0.967 and 0.930 respectively. PCA, AHCA, MLR and PCR proved to be useful tools in air quality analysis for source apportionment and prediction as this can aid in air pollution abatement planning. There is need to improve existing policies in other to proactively mitigate the impacts of air pollution from oil and non-oil operation sources.
Collaborative Solutions in Well Integrity: Investigating and Restoring Failure of Well Safety Critical Components
Authors: Weaver Sophia
Published: July 2016

A number of SCSSV failures led to deferred production, loss of integrity and additional costs resulting from interventions to restore integrity. An investigation team initially focused on hardware components, until a new multidisciplinary team applied systems thinking to expand the investigation to include operations, subsea controls and fluid components, where analysis on system fluids revealed the root cause – through a series of tests – to be fluid and material incompatibility in the subsea tree hydraulic circuit. Further analysis provided the development of a failure mechanism and understanding of how the problem was exasperated. By executing an integrated investigation, the team gained valuable insight on the fluid and material interactions of the system and was able to make vital recommendations to restore production as well as implement mitigating factors in the approach to completions and well integrity. This paper highlights the collaborative approach to resolving well and subsea integrity between the production, wells and subsea disciplines.
Sustainable Management of Natural Gas Resources: A Case Study of Nigeria
Authors: Okafor Emeka , Carim Akintunde , Onyekonwu Mike
Published: July 2016

There are continued challenges associated with natural gas usage in Nigeria even in the face of both domestic and global increase in its demand. In order to meet those challenges, there is a need for proper management of natural gas resources and its applicable technologies in- Country. In this paper, we highlight the future demand, production and utilization of natural gas based on economic and technological constraints and opportunities in Nigeria with special consideration of its sustainable management. We propose appropriate measures and strategies to meet the challenges associated with natural gas production and usage. We further present results obtained from qualitative evaluation of Nigeria's future gas demand, pricing, and applicable technologies. Overall, the paper provides useful information to decision makers responsible for managing gas resources in a developing Country like Nigeria with commercial quantities of proven gas reserves.
Uncertainty Management in the Development of MOT Reservoir, X Field, Niger Delta
Authors: Makinde Oluwasegun , Aderibigbe Olatubosun , Smart Osarenogowu , Sonde Adenike , Nwabudike Udoka
Published: July 2016

MOT reservoir has a unique case of uncertainties as a result of data paucity being in a field where no production has occurred, and there is need to reduce the uncertainties associated with the key evaluation parameters required for making investment decisions. This paper presents how a multidisciplinary team resource was leveraged on in managing the identified uncertainties to deliver a robust development plan for the reservoir of interest.

The approach deployed emphasize on integration and collaborative interpretations from the constituting disciplines in the study team. Early focus was placed on uncertainty identification, quantification and management. Iterative efforts were necessary to achieve consistency of results and preservation of physical meaning as the study moves from one domain to another. A consistent framework for quantifying the respective impacts of the identified uncertainties was developed, and realizations were constrained by the most impacting parameters to generate a probable representation of the subsurface. Subsurface development concepts were tested and suitably selected to optimize recovery using the base case realization as a control, and preliminary economic evaluations were also performed to determine the project robustness to risk and the magnitude of the investment.

The experience from this work provides a reliable approach to handling the development of a green field reservoir with limited data availability. An approach to overcoming several limitations on how to predict a fit-for-purpose PVT-table, developing a representative SHM were also presented, and the success obtained further emphasize the advantage of integration in a multidisciplinary team. The results showed that the high impacting uncertainties were structure, fluid contacts, and relative permeability, and the identified uncertainties were managed by building realizations to adequately capture the possible outcomes, and the preliminary project economic evaluations suggests that the project would be viable even for the Low-Case outcomes, hence adding value to the company portfolio.
Analysis of Pressure Response to Variable Rate Imputs
Authors: Adewale Adeniji
Published: July 2016

Mathematical models are used to relate pressure response (output) to flow rate history (input). The solution may not be unique due to the fact that different models can give same response to different input function. However, this drawback can be minimized by careful well test design in such a way that the measured responses are superposition of series of impulses. This research work presents an investigation on an approach to pressure transient response to variable rate change of production.

It is hinged on the view that a diffusion process is a process of equalization than differentiation. The objective is with installation of bottom hole pressure gauges, and belief that rapidly acquired data critical for future reservoir management are available for interference testing during field start-up. Vital concerns over reservoir continuity were answered immediately, allowing the operators to implement fast-track plans for pressure maintenance to optimize oil recovery.

Consequently, with the increasing number of permanent gauge installations, interference testing becomes more cost efficient than conventional methods, and inverse problem is solved with unique solution. Further, there is improved measure of knowledge on reservoir continuity, drive mechanism and recoverable reserved
A Generalized Functional Model for Predicting Hydrocarbon Shrinkage Factors
Authors: Ogwo Obike Umeha , Mbeledogu Ikechukwu Uduezue
Published: July 2016

Hydrocarbon shrinkage factor is one of the essential parameters required in the inventory of produced hydrocarbons at operating conditions of temperature and pressure different from standard conditions. When shrinkage factor is ignored, the well would be overproduced with the attendant consequence of water coning and/ or gas cusping. Laboratory determination of shrinkage factors is rigorous, expensive and time consuming. Since hydrocarbon inventory is a daily affair, it is usually desired that shrinkage factors be obtained analytically based on system operating conditions instead of from laboratory experiments. This work has investigated the dependence of shrinkage factors on operating conditions that are readily measured in the industry. Available data has confirmed that hydrocarbon shrinkage factor is a function of fluid gravity, operating pressure and temperature. This paper presents the experimental data and the functional model generated therefrom, the model of which would be employed in determining hydrocarbon shrinkage factors without recourse to extensive laboratory analysis.
Evaluation of Flow Enhanced Preferential Weld Corrosion of X65 Pipeline Steel Using a Novel Submerged Impingement Jet
Authors: Adegbite Michael A. , Robinson Michael J. , Impey Sue A.
Published: July 2016

Preferential weld corrosion (PWC) remains a major operational challenge that jeopardizes the integrity of oil and gas carbon steel pipelines. Corrosion inhibition is conventionally used to mitigate this problem however several indications suggest that some corrosion inhibitors may increase PWC. This work therefore, seeks to assess the suitability of a novel submerged jet impingement technique for the study of flow enhanced preferential weld corrosion and inhibitor evaluation in a typical offshore production system.

A novel jet-impingement target was constructed from samples of parent material, heat affected zone and weld metal, and subjected to flowing brine at velocities up to 10 ms-1, to give a range of hydrodynamic conditions from stagnation to high turbulence. The submerged jet-impingement flow loop was used to investigate corrosion control of X65 steel weldment in flowing brine, saturated with carbon dioxide at 1 bar, and containing a typical oilfield corrosion inhibitor. Galvanic currents between the electrodes in each hydrodynamic zone were recorded using zero-resistance ammeters and their self-corrosion rates were measured using the linear polarisation technique. At low flow rates, the galvanic currents were small and in some cases the weld metal and heat affected zone were partially protected by the sacrificial corrosion of the parent material. However, at higher flow rates the galvanic currents increased but some current reversals were observed, leading to accelerated corrosion of the weld region. The results are explained in terms of the selective removal of the inhibitor film from different regions of the weldment at high flow rates and the corrosion mechanism in the presence of oxygen is discussed.
Qualitative Analysis of Drill String Torsional Vibration Preventive Measures: Present Status and Future Possible Solution
Authors: Asgharzadeh Arash , Bello Opeyemi , Perozo Baptista Nelson Rafael , Paz Carvajal Carlos Andres , Berdasco Javier Holzmann , Oppelt Joachim
Published: July 2016

The integrity of drill string while drilling especially under dynamic conditions plays a very crucial role in efficiency; reaching the target (pay zone) and even economical aspects. Considering the dynamics of drill string one would immediately think of vibrations; particularly torsional vibrations, posed on drill string. In worst cases the phenomenon of stick/slip occurs, in which the bit comes to a full stop and then accelerates uncontrollably. The non-uniform acceleration and deceleration of RPM continues to exist during drilling operation with possible catastrophic consequences. Bringing the bit off the bottom and adjusting the RPM are the conventional approaches which are performed on the surface.

This paper reviews and analyzes the present solution approach as related to drill string torsional prevention measures. Furthermore, a proactive solution would be proposed in contrary to the existing methods to prevent the occurrence of torsional vibration in both vertical and directional wells drilled with top-drive system, which will be performed downhole.

By rotating the drill string at top, it stores energy along itself. At a particular point in time drill string accelerates and rotates in an uncontrollable manner due to act of friction and spiral spring behavior of the drill string. During this process the stored potential energy in drill string is converted to kinetic energy.

The proposed approach entails the use of hydraulic power to prevent storing the potential energy along the drill string. That is, if there is an acceptable maximum level of stored potential energy, conversion into kinetic energy will not happen. By this means, the torsional vibrations are highly mitigated if not eliminated completely.

The proactive solution seeks prevention of a phenomenon (torsional vibrations) which can lead to calamities if not contained. However, efficient drilling and ROP are chief goals of drilling engineers. Also this proactive solution will be done down the hole not on the surface. Hence, more efficient drilling is sought by preventing one of most disastrous incidents.
Torsional and Lateral Vibrations of Polycrystalline Diamond Compact PDC Bits in Directional Drilling
Authors: Emudiaga Odesa David , Dosunmu Adewale , Victor Ossia C.
Published: July 2016

Drillstring vibration has adverse effect on rate of penetration, causes equipment failure and increase in non productive time (NPT). In carrying out this research work on torsional and lateral vibrations of Polycrystalline Diamond Compact (PDC) bits in directional drilling, harmonic and modal finite element analyses were adopted for the obvious advantage that it is able to approximate the real structure with a finite number of degrees of freedom. The effect of weight on bit on rate of penetration, resonance, damping effect of drilling mud and friction between drillstring and the wellbore were analyzed. In the cause of the analysis, different critical load, critical speed for the finite element of the drillstring and the BHA and saturation points were developed for the different components of the drillstring from the Euler model to determine the crippling loads that will cause each component to buckle and propagate lateral and torsional vibration. The effect of angle inclination was also considered in the design of the vibration analysis model for directional wells application. A new concept, managing WOB while drilling was also advanced to avoid reaching the founder's point in real time drilling operation. The deductions and findings resulted in the development of a computer model, vibraCOM which detects, analyses and mitigates torsional and lateral drillstring vibrations realtime for practical applications. The results shows that it is better to drill below the critical speed of the finite elements of the drillstring and BHA to avoid resonance and to ensure the axial forces acting on the BHA is below the critical load.
El Conocimiento como una Actividad Colectiva
Authors: Eraña Ángeles , Barceló Aspeitia Axel Arturo
Published: July 2016

En este ensayo exploramos una perspectiva epistemológica en la que el elemento social y colectivo del conocimiento juega un papel fundamental en la explicación de su producción y transmisión. Primero presentamos y criticamos una posición individualista que ha sido dominante en la epistemología contemporánea y cuyas raíces pueden trazarse, al menos, hasta Descartes. Posteriormente introducimos y defendemos nuestra propia mirada, una en la que el conocimiento es un proceso constituido por un conjunto de actividades y prácticas que tiene un carácter material y objetivo.
Dieterlen, Paulette: Justicia distributiva y salud. México: FCE, 2015, 201 pp.
Authors: Vela Valeria López
Published: July 2016

Justicia distributiva y salud analiza las teorías de la distribución de la salud que siguen, rechazan o reinterpretan la Teoría de la Justicia (1971) de John Rawls con el fin de repensar las condiciones, limitantes y posibilidades del sistema de salud mexicano.
Incorporating large-scale atmospheric variables in long-term seasonal rainfall forecasting using artificial neural networks: an application to the Ping Basin in Thailand
Authors: Babel M. S. , Sirisena T. A. J. G. , Singhrattna N.
Published: July 2016

Understanding long-term seasonal or annual or inter-annual rainfall variability and its relationship with large-scale atmospheric variables (LSAVs) is important for water resource planning and management. In this study, rainfall forecasting models using the artificial neural network technique were developed to forecast seasonal rainfall in May–June–July (MJJ), August–September–October (ASO), November–December–January (NDJ), and February–March–April (FMA) and to determine the effects of climate change on seasonal rainfall. LSAVs, temperature, pressure, wind, precipitable water, and relative humidity at different lead times were identified as the significant predictors. To determine the impacts of climate change the predictors obtained from two general circulation models, CSIRO Mk3.6 and MPI-ESM-MR, were used with quantile mapping bias correction. Our results show that the models with the best performance for FMA and MJJ seasons are able to forecast rainfall one month in advance for these seasons and the best models for ASO and NDJ seasons are able do so two months in advance. Under the RCP4.5 scenario, a decreasing trend of MJJ rainfall and an increasing trend of ASO rainfall can be observed from 2011 to 2040. For the dry season, while NDJ rainfall decreases, FMA rainfall increases for the same period of time.
Operational strategy, economic and environmental performance of sludge treatment reed bed systems – based on 28 years of experience
Authors: Nielsen S. , Larsen J. D.
Published: July 2016

Sludge treatment reed bed (STRB) systems have been used for dewatering and mineralisation of sludge in Europe since 1988. STRB systems provide substantial environmental, economic, and operational benefits compared to mechanical sludge dewatering solutions such as belt presses and centrifuges. They require less energy, no chemicals, reduce the sludge volume and produce bio solids with dry solid contents up to 20–40% under Danish climate conditions, depending on the sludge quality. Experience has shown that sludge treated in STRBs represents a high quality product with a low content of pathogens and hazardous organic compounds, qualities that make it suitable for recycling on agricultural land. The upfront capital cost for STRBs are often higher compared to mechanical dewatering devices. However, the operational expenses (OPEX) (including energy, chemicals, bio solid handling) are significantly lower compared to conventional mechanical dewatering devices, delivering an economic break-even of about 3–5 years. This paper provides an overview of the operation and maintenance costs and environmental benefits of a typical STRB based on the experiences gained from the operation of a large number of STRBs with yearly treatment capacities between 100 and 3,000 tonnes of dry solid up to approximately 250,000 PE in Denmark and Europe.
Concussion knowledge among amateur motocross riders
Authors: Miller Kristina O , Langdon Jody L , Burdette Glenn P , Buckley Thomas A
Published: July 2016

Aim: There has been considerable increase in concussion awareness and risks; however, extreme sports such as motocross have received scant attention. The purpose of this study was to assess concussion knowledge among motocross riders and determine differences based on demographic factors. Methodology & results: 782 motocross riders responded to an Internet-based questionnaire, and participant's knowledge score was 14.3 ± 2.7 out of 20 and symptom recognition was 6.8 ± 1.4 out of 8. Riders who had performed baseline concussion testing or received formal concussion education demonstrated higher knowledge scores. Rider's demographics did not predict outcome measures. Conclusions: Considerable misconceptions and lack of symptom knowledge persist among motocross riders and these results can be used for future interventions to improve concussion reporting.
Oral health status in children with inherited dystrophic epidermolysis bullosa
Authors: Colovic Aleksandra , Jovicic Olivera , Stevanovic Radoje , Ivanovic Mirjana
Published: July 2016

Background/Aim. Epidermolysis bullosa is a group of rare, genetic connective tissue diseases that cause blisters in the skin and mucosal membranes. The aim of this study was to evaluate the oral health status of patients with epidermolysis bullosa dystrophica and level of knowledge and opinion of parents about the implementation of preventive measaures and quality of dental care of affected children. Methods. This study included a group of 17 patients from Serbia suffering from dystrophic epidermolysis bullosa and matched control group. Dental caries status was assessed using the Klein-Palmer index. Oral hygiene status was verified with oral hygiene indices, simplified plaque index, and calculus index as described by Green and Vermillion. The gingiva was assessed as healthy or inflamed (gingivitis) on the basis of any changes in color, shape, size and surface texture. The condition of oral mucosa has been registered on the basis of inspection of the lips, tongue, a floor of the mouth, mouth vestibule and palate. The level of knowledge and the impressions of parents about the application of preventive measures were investigated through two questionnaires specifically designed for this study. Results. In both dentitions, there was the highest percentage of caries teeth. In primary dentition average value of the modified plaque index was 1.4 ? 1.14 and modified calculus was 0.7 ? 1. On permanent teeth average plaque index was 2 ? 0.4, and average calculus 1.6 ? 0.6. Statistically, significant higher values were found in permanent dentition in percentage distribution of decayed, missing, filled teeth and also for plaque and calculus indices between affected children and the control group. Most common findings on mucosa were microstomia (76.5%) and ankyloglossia (88.2%). Conclusion. The absence of protocol between the treating physician and the dentist and not sufficiently informed parents are leading to inadequate dental care. The implementation of preventive measures is of most importance to decrease the risk of severe complications that are difficult to be managed.
Evaluation of physical fitness of elderly women, residents of houses of social services
Authors: Kaczorowska Antonina , Ignasiak Zofia , Katan Aleksandra
Published: July 2016

Aim of the study: The aim of the paper is evaluation of chosen parameters of physical fitness of elderly women residing in houses of social services with different standards of living.

Material and methods: The research was conducted on 124 women, residents of houses of social services, aged 60-89. Women included in the survey were divided into two groups according to their age: a younger group, 60-74 years old, and an older group, 75-89. Among houses of social services two kinds were distinguished: the first one - model houses with higher standard in which there is motor rehabilitation and occupational therapy, stimulating their residents, and the second kind - average houses in which rehabilitation and occupational therapy is given to a lesser degree and among lower number of residents. To evaluate physical fitness the Senior Test - Fullerton Functional Fitness Test was used. This test is designed to evaluate functional efficiency of elderly people.

Results: As a result of the survey it has been stated that residents of model houses, leading an active life, have better results in the fitness test than women from average houses.

Conclusions: Physical activity has a positive influence on a level of physical fitness and increases self-reliance of residents in performing everyday activities.
Application of the NDT-Bobath approach in pediatric rehabilitation
Authors: Wysoczańska Emilia , Skrzek Anna , Pyzio-Kowalik Magdalena
Published: July 2016

The aim of this paper was to present a range of possible applications of the NDT-Bobath approach in pediatric rehabilitation. A group of children undergoing a therapeutic procedures in the “Promyk Słońca” Foundation in Wrocław, Poland were selected. The study was based on the analysis of the data abstracted from the patient medical records. The parameters which were analyzed included: a diagnosed underlying disease, functional disorders, date and mode of delivery, the occurrence of perinatal complications or fetal development, the Apgar score, and birth weight. The study found that the NDT-Bobath approach constitutes a comprehensive therapeutic method that may be applied regardless of the child’s age (both infants and older children) and the underlying disease. Moreover, concomitant diseases and symptoms as well as the risk group affiliation (eventful perinatal medical history) have been recognized as common clinical indications for the application of the NDT-Bobath approach.
Rehabilitation of people with haemophilia. Part II – Surgical treatment and rehabilitation procedure guidelines
Authors: Jaszczur-Janus Izabela , Janus Andrzej , Wrzosek Zdzisława , Kuliszkiewicz-Janus Małgorzata
Published: July 2016

In the first article of the series about the rehabilitation of haemophilic patients, the issues related to the aetiology of the disease, its clinical picture, changes in locomotor system, and substitution therapy have been discussed. In this paper the authors present the orthopaedic treatment methods and the guidelines for rehabilitation procedures after intraarticular and intramuscular haemorrhages. They also describe the physical examination and medical interview of a patient with plasmatic diathesis. Also, they point out the specificities of therapeutic procedure which has to take into account not only the changes in locomotor system but also haemostatic abnormalities and substitution therapy. The authors have divided the rehabilitation process into three phases, depending on the patient’s clinical status.