bluuebunny/crossref_metadata_2025_split huggingface dataset:
Research and Development: Utilization of Local Additive in the Cementation of HPHT Wells in Nigeria
Authors: Joel Ogbonna F. , Iseghohi Prince Theo 
Published: December 2009

Abstract
Cementing of high temperature wells poses a big challenge and requires special considerations in slurry design applications. Among others, the problem of strength retrogression encountered during the life of the well if special additives are not added to the slurry design is critical.
Silica sand is one of such additives that is used to provide strength stability while maintaining good permeability characteristics when static temperature in the zone exceeds 230°F.
It is obvious that almost all of the additives used in Nigeria for oil well operations, including silica sand are imported. However, it is imperative to note that this material is in commercial quantity at Ibi in Taraba State. Moreover, test results indicated that results obtained from lab experimentation as well as field applications with the local silica sand compares favourably with the imported one.
For about four years, this local product has been deployed in Nigeria for high temperature, high pressure wells with huge success. This has resulted in cost savings by oil companies; break through in home based technology in line with local capacity and capability development, a step towards realizing the Nigerian vision 2020.
This paper is aimed at highlighting a local content initiative effort in research and development to source silica sand locally to be used as a suitable alternative for imported silica sand, the success story in field application as well as the challenges for effective implementation.
Vertical Flow Barrier Characterisation in Amenam R4 Reservoir (Nigeria) and Impact on Field Development and Reservoir Management
Authors: Mathieu Xavier , Onyema Uche , Sabatier Lionel , Blanchais Sébastien , Eme Uche 
Published: December 2009

Abstract
In the Amenam–Kpono Field, six of the hydrocarbon bearing reservoirs encountered are currently developed. The Main Reservoir (R4) is characterized by vertically stacked sand bodies with intercalated shale layers, laterally well extended.
In the initial reservoir study, a low vertical reservoir permeability (Kv/Kh=0.01) and maps of vertical transmissibility within these shale layers were implemented in the dynamic model.
In fall 2007, Amenam East well confirmed an excellent lateral communication with Amenam Main Field through the aquifer and highlighted the presence of multi disconnected hydrocarbon bearing flow units within R4 reservoir of the Amenam-East structure.
It was assumed in the initial Field Development Plan that these shale layers would play a crucial role in fluid dynamics and hydrocarbons recovery. The initial dynamic model was used to optimise well location and perforation strategy.
With 35 development wells drilled and almost five years of production (1 st oil in July 2003), the significant impact of vertical shale barriers was confirmed and 4 main dynamic units were identified in the R4 reservoir. Data acquisition during the development phase and early production life of the field with pressure data, interference tests and gas tracers yielded very significant results, essential to optimise the development strategy and to establish a proper reservoir management scheme of the Amenam-Kpono field.
A limited number of corrective actions were implemented, mainly with 4 additional wells in 2007-2008, drilled to sustain pressure and/or to enhance recovery in the under developed R4 bottom unit.
Achieving World Class Condensate Recovery Using Integrated Reservoir Management Practices - Oso 1-Y1 Case Study
Authors: Saborogha I. A. , Mkpasi E. E. , Ogunnusi H. , Leininger S. , Gunther M. , Wanorue E. P. , Ogunlowo R. F. 
Published: December 2009

Abstract
Oso 1-Y1 is a large, mature condensate field located in OML 70, about 45 km from shoreline in the southeastern part of Nigeria. Several geoscience studies for this complex deltaic have assessed Original-Condensate-In-Place (OCIP). Over 63% of the OCIP has been recovered, primarily through miscible crestal gas injection combined with sound reservoir management practices.
In 1987, MPN carried out a pre-production simulation study of the Oso field with the primary objectives of determining the condensate recovery factor, the optimal placement of wells and to obtain an insight into the reservoir behaviour under gas injection. The results indicated that the highest recovery factor (70%) would best be obtained by miscible gas injection. Additional simulation results post-production also estimated recovery efficiency of 72%. Actual production performance indicates a 74% recovery versus 55% average usually obtainable for gas-condensate reservoirs.
Although crestal miscible gas injection is the main recovery mechanism, different tools that use real-time production performance have also been concurrently utilized to continually optimize and update the depletion plan as required/necessary. These tools include adequate pressure monitoring to determine pressure trends and track efficiency of gas injection while monitoring miscible gas front movement and ensuring optimum contact closure. In addition, Integrated Production Model (IPM) updates are done periodically to confirm condensate remaining-in-place and recoverable volumes, assess infill opportunities and optimize production. The main objective of these tools is to reduce unswept condensate, condensate lost due to retrograde condensation and hence improve recovery.
This paper will focus on how the application of various reservoir management practices have been integrated to develop an ever-green depletion plan in order to optimize production and achieve world class recovery from a structurally and stratigraphically complex condensate field.
Comparative Evaluation of Models for Joint Venture Agreement and Production Sharing Contract Fiscal Systems in Nigeria
Authors: Mmakwe I. , Ajienka J. A. 
Published: December 2009

Abstract
Joint venture agreement and Production sharing contract are the two most common fiscal systems for petroleum operations in Nigeria. In this study, models were developed and compared for Joint venture agreement (JVA) and Production sharing contract (PSC) for the Nigeria fiscal systems. The results showed that the government has more take and a higher NPV under the JVA than the PSC. Sensitivities were carried out for the NPV and the results showed that NPV was most sensitive to oil price.
An approach was also developed, based on the percentage loss in NPV of the contractor and community take, that serves as a guide for the contracting firms and JVA partners to determine how much should be given to the host community in such a manner that will not significantly affect their NPV and yet achieve their social responsibility.
Estimation of Developed Reserves in Gas Lifted Wells
Authors: Daniel A. , Isehunwa S. O. 
Published: December 2009

Abstract
Reliable estimates of petroleum reserves are invaluable in reservoir management decisions and economic evaluation. Classical decline curve analysis techniques have been routinely used and are generally accepted in the industry to reliably estimate developed reserves up to a predetermined economic limit qec in oil wells. However Decline curve analysis techniques are based on the assumption that past production trends and their controlling factors will continue in the future and therefore can be extrapolated for predictions.
During gas lifting, production trends could be distorted hence there is need to modify the classical decline curve analysis equation. In this study, the principle of superposition has been applied to the entire duration of production (t) of wells producing under gas lift. This resulted in the so called Double Semi log equation for well decline analysis. Model validation with two fields in the Niger Delta area show excellent results and the economic advantage of gas lifting. The Models showed excellent correlation coefficients with available field data.
It is concluded that gas lift could increase the reserves in some wells. Furthermore the Double Semi log technique provides a better and more reliable theoretical foundation, easier and more reliable technique for decline analysis in gas lifted wells.
New Bubblepoint Pressure Empirical PVT Correlation
Authors: Ikiensikimama Sunday Sunday , Ogboja Olu 
Published: December 2009

Abstract
Knowledge of bubblepoint pressure is one of the important factors in the primary and subsequent developments of an oil field. Bubblepoint pressure is required for material balance calculations, analysis of well performance, reservoir simulation, and production engineering calculations. New bubblepoint pressure correlation based on data from the Niger Delta crude oils has been developed. Both quantitative and qualitative assessments were employed to evaluate this correlation which is compared to the best existing bubblepoint pressure correlation for the Niger Delta crude. The new correlation outperformed the best existing correlation by the statistical parameters used with a rank of 7.3 and better performance plot.
Obagi – Present and Future Challenges of a Mature Oil Field
Authors: Guillonneau N. , Fontaine G. , Gory J. Y. , Iwuoha S. , Ahmed H. , Ekpenyong D. 
Published: December 2009

ABSTRACT
OBAGI is an onshore oil field located on OML58, 85 km north-west of Port-Harcourt, Nigeria. It is composed of 26 stacked reservoir levels with an estimated total OOIP of 1.2 Gbbls. It was discovered in 1964 and has been producing since 1966 through 123 wells and 257 completions. 21 layers have been developed.
With a global recovery to-date of 50% and an average producing water-cut of 75%, OBAGI can be considered as a mature oil field. Current activities are driven by two main objectives: to sustain short term production level, andto identify potential remaining resources for additional developments
Appropriate monitoring and global static/dynamic review are the key factors to achieve these objectives.
The short term objective is to maintain production by optimizing the injection capacity. Difficulties to model reservoir performance have resulted in implementation of an intensive monitoring program. This is to limit water production and to maintain/increase water injection capacity.
For the long term, it is believed that potential resources not accessible with current wells could effectively double the remaining reserves. For this purpose, complementary developments have to be proposed to target clearly identified attic oil or bypassed regions. A pragmatic approach was adopted based on 2G model review, material balance study and fluid contact updates (with regular saturation survey campaigns) to identify additional reserves potential.
The progress of the study is presented for one of the layers of the field.
A System Approach to Enhance Offshore Drilling and Production
Authors: Polito Sergio , Brambilla Mauro , Dall’Aglio Dario 
Published: December 2009

ABSTRACT
The main design criteria of an innovative semisubmersible drilling rig are presented. Among other distinctive features, the "functional availability" is illustrated as the most effective fault tolerance systemic approach of the state of the art. The basic tool to implement functional availability is the "Fault isolation through distribution" with ensuing beneficial effects bot technical and economical on the major onboard systems.
Consistent, reliable performance quality-level and overall operational safety enhancement are the direct result of such an approach, alongside with a substantial increase of operational flexibility.
This applies as well to the easy and quick conversion of the rig into an early production unit (and back) in P modes:
Production & Drilling Mode, keeping drilling equipment onboard with a 40 - 60,000 BBPD oil production capacity
Production Only Mode, removing main drilling equipment, with a resulting oil production capacity of 80 - 110,000 BBPD, without considering possible associated gas.
The unit has been designed to fully comply with the stringent Norwegian Petroleum Directorate rules for floating production units, including all extra requirements for fire protection (also structural).
A modular approach to production and drilling equipment and facilities enhances easy, safe, quick installation & removal.
Finally a concise description of the technical nature of the maiden assignement of the rig is supplemented, with a variety of operational duties on the Snorre Field off Norway, which could extended, from 1990, untill 1998.
Delivering BP North Sea's Longest OHGP Completion in the Harsh Environment Deepwater West of Shetlands
Authors: White D. , Wilson A. , Roy A. , Stewart S. , Woudwijk R. , Nadeem A. 
Published: December 2009

Abstract
The BP Operated Foinaven, Schiehallion and Loyal fields, located West of Shetland (WoS) in the UKCS, are a highly challenging environment to work in. The three deepwater fields are drilled and completed utilising 4th generation semi-submersible rigs and the harsh marine environment can severely impact operations.
Although standalone screen completions have been used successfully in the majority of the wells, premature sanding problems have been experienced, potentially jeopardizing project economics due to prohibitively high cost of remediation. To improve this situation, alternative means of sand control completions have therefore been sought. There are now four Open Hole Gavel Pack (OHGP) completions in the fields, all of which are performing well with high productivities and no sand production.
In this paper, we present a case history on the application of the circulating water pack in the Foinaven field. The P11 sidetrack is the third gravel pack completion in this deepwater environment, and the first to be completed with a water pack. The subject well is the longest OHGP in BP's North Sea portfolio with a 3,345 ft open hole, penetrating through two sand bodies and multiple shale and mudstone packages.
The well was designed with a long horizontal open hole section to cost-effectively access multiple sand bodies and maximise productivity while minimising drawdown across the sandface. Baker Oil Tools BetaBreaker technology was utilised for the completion to maintain the treatment pressure below the reservoir fracture gradient during the gravel pack. The well was completed with a +110% packing efficiency, has an early time mechanical skin of +2 based on pressure buildup testing and was delivered safely 5 days ahead of target at P(10) production expectations.
The use of ultrasonic treatment for improvement of metrological performance of sorption atomic absorption determination of lead(II) and cadmium(II) traces
Authors: Alemasova Antonina , Belova Elena 
Published: December 2009

Abstract
The optimal parameters for ultrasonic treatment (frequency 200–300 kHz, intensity 2–4 W cm−2) were obtained to intensify Pb(II) and Cd(II) sorption concentration by carbon sorbent from apricot pit. The combined action of ultrasonic frequency of 18 kHz and 1 MHz on concentrate slurry increases its sedimentation stability from 3 to 180 minutes and decreases Sr value up to 7% at Pb(II), Cd(II) hybrid sorption atomic absorption determination in natural waters, brines, common salt.
Synthesis and biological screening of octasubstituted-triphenodioxazines and its sulphur analogues with some novel intermediates
Authors: Heda Lalchand , Pareek Chandresh , Pareek Dushyant , Mosalpuri Sonraj 
Published: December 2009

Abstract
Attempts have been made to prepare for the first time the octasubstituted-triphenodioxazines and triphenodithiazines heterocycles by cyclisation of 3,6-dichloro-2,5-bis(2′,4′,5′-trichloroanilino)-1,4-benzoquinone and condensation. This wasfollowed by cyclisation of substituted 2-aminobenzenethiol respectively with chloranil and bromanil in ethanolic solution of fused sodium acetate in the presence of benzoyl chloride in nitrobenzene. Their structures were confirmed on the basis of their chemical and spectral analyses. Moreover, the biological activity of these compounds was evaluated against the test organisms viz — E.coli, S. aureus, B. subtilis, M.luteus and C. albicans. These compounds synthesized from 2,4,5-trichloroaniline appeared to possess significant antimicrobial activities and an explicit correlation between structure and biological activity was also observed.
The difference in stability between 5′R and 5′S diastereomers of 5′,8-cyclopurine-2′-deoxynucleosides. DFT study in gaseous and aqueous phase
Authors: Karwowski Boleslaw 
Published: December 2009

Abstract
Oxidatively generated damage to DNA frequently appears in the human genome as an effect of aerobic metabolism or as the result of exposure to exogenous oxidizing agents. Due to these facts it has been decided to calculate the stability of 5′,8-cyclo-2′-deoxyadenosine/guanosine (cdA, cdG) in their 5′R and 5′S diastereomeric forms. For all points of quantum mechanics studies presented, the density functional theory (DFT) with B3LYP parameters on 6-311++G** basis set level was used. The calculations showed a significant negative enthalpy for glycosidic bond cleavage reaction for cationic forms and slightly negative for neutral ones. The preliminary study of the discussed process has shown the nature of stepwise nucleophilic substitution DN*AD type mechanism. Surprisingly, the different values in free energy, between short-lived oxacarbenium ion intermediates, have been found to lie over a relatively small range, around 1 and 2.8 kcal mol−1. For anions, the decomposition enthalpies were found as positive in aqueous phases. These theoretical results are supported by the formic acid hydrolysis experiments of both diastereomers of cdA, for the first time. (5′S)cdA exhibited higher stability than (5′R)cdA.
Formation of amyloid-like aggregates through the attachment of protein molecules to a Congo red scaffolding framework ordered under the influence of an electric field
Authors: Stopa Barbara , Piekarska Barbara , Konieczny Leszek , Król Marcin , Rybarska Janina , Jagusiak Anna , Spólnik Paweł , Roterman Irena , Urbanowicz Barbara , Piwowar Piotr , Lewiński Krzysztof 
Published: December 2009

Abstract
This study describes a technique which makes it possible to introduce the amyloid-like order to protein aggregates by using the scaffolding framework built from supramolecular, fibrillar Congo red structures arranged in an electric field. The electric field was used not only to obtain a uniform orientation of the charged dye fibrils, but also to make the fibrils long, compact and rigid due to the delocalization of pi electrons, which favors ring stacking and, as a consequence, results in an increased tendency to self-assemble. The protein molecules (immunoglobulin L chain lambda, ferritin) attached to this easily adsorbing dye framework assume its ordered structure. The complex precipitating as plate-like fragments shows birefringence in polarized light. The parallel organization of fibrils can be observed with an electron microscope. The dye framework may be removed via reduction with sodium dithionite, leaving the aggregated protein molecules in the ordered state, as confirmed by X-ray diffraction studies.
Spatio-temporal visual properties in the ascending tectofugal system
Authors: Rokszin Alice , Márkus Zita , Braunitzer Gábor , Berényi Antal , Wypych Marek , Waleszczyk Wioletta , Benedek György , Nagy Attila 
Published: December 2009

AbstractOur study compares the spatio-temporal visual receptive field properties of different subcortical stages of the ascending tectofugal visual system. Extracellular single-cell recordings were performed in the superficial (SCs) and intermediate (SCi) layers of the superior colliculus (SC), the suprageniculate nucleus (Sg) of the posterior thalamus and the caudate nucleus (CN) of halothane-anesthetized cats. Neuronal responses to drifting gratings of various spatial and temporal frequencies were recorded. The neurons of each structure responded optimally to low spatial and high temporal frequencies and displayed narrow spatial and temporal frequency tuning. The detailed statistical analysis revealed that according to its stimulus preferences the SCs has markedly different spatio-temporal properties from the homogeneous group formed by the SCi, Sg and CN. The SCs neurons preferred higher spatial and lower temporal frequencies and had broader spatial tuning than the other structures. In contrast to the SCs the visually active SCi, as well as the Sg and the CN neurons possessed consequently similar spatio-temporal preferences. These data support our hypothesis that the visually active SCi, Sg and CN neurons form a homogeneous neuronal population given a similar spatio-temporal frequency preference and a common function in processing of dynamic visual information.
Synchrotron microanalytical methods in the study of trace and minor elements in apatite
Authors: Rakovan John , Luo Yun , Borkiewicz Olaf 
Published: December 2009

Synchrotron microanalytical methods in the study of trace and minor elements in apatiteSynchrotron X-ray facilities have the capability for numerous microanalytical methods with spatial resolutions in the micron to submicron range and sensitivities as low as ppm to ppb. These capabilities are the result of a high X-ray brilliance (many orders of magnitude greater than standard tube and rotating anode sources); a continuous, or white, spectrum through the hard X-ray region; high degrees of X-ray columniation and polarization; and new developments in X-ray focusing methods. The high photon flux and pulsed nature of the source also allow for rapid data collection and high temporal resolution in certain experiments. Of particular interest to geoscientists are X-ray fluorescence microprobes which allow for numerous analytical techniques including X-ray fluorescence (XRF) analysis of trace element concentrations and distributions; X-ray absorption spectroscopy (XAS) for chemical speciation, structural and oxidation state information; X-ray diffraction (XRD) for phase identification; and fluorescence microtomography (CMT) for mapping the internal structure of porous or composite materials as well as elemental distributions (Newville et al. 1999; Sutton et al. 2002; Sutton et al. 2004).We have employed several synchrotron based microanalytical methods including XRF, microEXAFS (Extended X-ray Absorption Fine Structure), microXANES (X-ray Absorption Near Edge Structure) and CMT for the study of minor and trace elements in apatite (and other minerals). We have also been conducting time resolved X-ray diffraction to study nucleation of and phase transformations among precursor phases in the formation of apatite from solution at earth surface conditions. Summaries of these studies are given to exemplify the capabilities of synchrotron microanalytical techniques.