bluuebunny/crossref_metadata_2025_split huggingface dataset:
Occupational Health Conditions Improvement Replace Carcinogenic Oxygen Scavenger with an Alternate Safer Product
Authors: Hassan M. A. , Vasagam Manicka , Pandav Prafull S. 
Published: December 2007

Abstract
LNG production units located in Das Island have four (Boiler Nos. 1 to 4) high pressure/high capacity Boilers for steam generation (which supplies steam to LNG Trains 1&2). Each of the four massive Boilers have separate De-aeration unit, where the major portion of dissolved gases (mainly oxygen and carbon dioxide) present in the feed water are removed by scrubbing with steam. Followed by De-aeration, to get rid of the remaining oxygen present in the feed water, an oxygen scavenger is injected downstream of De-aerator. This product chemically scavenges the remaining dissolved oxygen by reaction. The oxygen present in the feed water is the chief culprit for boiler steam system corrosion and would cause accelerated oxygen pitting, especially at elevated temperatures. The oxygen scavenger quietly does its job and keeps up the boiler life; hence the use of this product is very vital in any boiler operation.
During all these years of operation, "hydrazine" was employed as the oxygen scavenger and found to be meeting the operational requirement. But continuing this product became an important issue, because it has been widely claimed as a carcinogen and toxic.
The issue started gaining importance as it directly concerned with "Health Effect". The necessity to evaluate a safer alternative turned out as a challenging task for ADGAS, because on one hand the proven product needed replacement due to the health hazard and on the other hand the Boiler performance/integrity had to be ensured.
The task was handled successfully; a better alternative oxygen scavenger was chosen (DEHA, Diethyl Hydroxyl amine) after detailed evaluation and is in satisfactory service since July 2002 in Boiler 1 to 4. Based on the experience from Boilers 1 to 4, ADGAS have very recently switched over to use of this safer alternative (DEHA) also in the remaining Boilers 5&6 also, which supply steam to Train-3.
The successful approach has helped ADGAS to contribute for the Occupational Health improvement to the working environment and thereby enhance its HSE STANDARDS. Through this paper ADGAS shares their experience in this regard.
Combination of Dual-Energy Gamma Ray/Venturi Multiphase Flowmeter and Phase Splitter for Application in Very High Gas Volume Fraction Environment
Authors: Delvaux E. , Germond B. , Jha N. K. 
Published: December 2007

Abstract
In mature fields, operators are confronted with wells producing high water cut at low pressure with consequently very high gas volume fraction (GVF). Under these conditions, the net oil flow rate is low and therefore, permanent or periodic testing becomes critical to determine profitability and manage the field production.
To optimize and monitor the oil production under these conditions, operators are looking to utilize multiphase flowmetering technologies. Accuracies achievable by inline multiphase flowmeters have greatly improved in recent years, but liquid and water-cut measurement accuracies decrease when the GVF is very high.
At low pressure to reduce the GVF, it is necessary to separate a large portion of the gas upstream of the multiphase flowmeter, thus enabling optimum measurement of the liquid and water cut under lower-GVF conditions.
Market drivers generally dictated by operator requirements have resulted in the formation of an project team with specific Middle East focus to deliver an operational prototype for a production well testing campaign on a fast track basis. The package comprises a partial separation unit and a dual-energy gamma ray/Venturi meter.
The selection of a partial separation design was based on a review of the commercially available solutions capable of handling the large operating range required for use in periodic well testing applications in terms of flow rates and pressure rating. The design comprises gas liquid cylindrical cyclone with tangential inlet. The capacity of each device to ensure a dry gas phase with minimum pressure loss over the complete required operating range was critical in the selection process.
This paper presents test results validating that a gas liquid cylindrical cyclone located upstream of a dual-energy gamma ray/Venturi meter is an effective partial separation system. With an inlet GVF of 99% and 90% of the inlet gas extracted by the partial separation system, the GVF at the multiphase flowmeter condition is below 90%, and accurate measurement of the 3 phases is achieved.
Salvage of Casing Leak Wells on Artificial Lift in a Mature Oil Field
Authors: Sivakumar V. C. Babu , Janahi Isa Ali 
Published: December 2007

Abstract
The Bahrain oilfield, discovered in 1932, is one of the most mature fields still under active exploitation in the Arabian Gulf. Around 750 wells have been drilled in the field and it is worth mentioning that even today the discovery well in the field is also under active service as a gas injector after several salvages.
Over the years starting from the discovery year the well design has evolved from the initial 6 casing string completions to the present simplified 2 casing string completions for the 12 vertically stacked Bahrain Zones from the Mishrifs occurring at 1600 ft. to the Kharaib zone occurring at depths of around 3200 ft. The prevalence of a very highly permeable shallow aquifer has made it very difficult to obtain effective isolation by cementing of the surface casing to surface. In addition, the high salinity and corrosivity of the water in this aquifer has lead to casing leaks is several earlier generation wells. This has in a few cases lead to underground blow outs from the high pressure producing zones into the aquifer and in some instance even surface gas seepages.
In this paper, we shall be presenting an update of the history of casing leak occurrences in the field and the various innovative methods adopted to abandon self flowing high pressure zones and then salvage these wells in low pressure non-self flowing zones. The low pressure zones are completed on artificial lift either on pump or gas lift after isolating the leak zone with a concentric string and packers as necessary. In a way, it can also be said that, these salvaged wells have enabled us to test, evaluate and produce the otherwise economically unviable low pressure, low productivity zones.
To summarize the paper will dwell on the reasons for casing leak occurrence, evolution of the well design to minimize casing leak and optimize well costs, abandonment of high pressure self flowing zones in the casing leak wells and finally the re completion of these wells on artificial lift in non self flowing low pressure zones.
High Resolution Probes Provide Real Time Data for Corrosion Inhibitor Field Trial Test Evaluation
Authors: Elkordi Ali 
Published: December 2007

ABSTRACT
The conventional ER (electrical resistance) probes have a suitable response time in systems with high or severe corrosion rates as defined by NACE Recommended Practice (&gt; 5 mpy).
In low-corrosion environments (&lt; 1 mpy), their response time may become incompatible with the day-to-day management of corrosion. For inhibited systems, where it is now common to expect the residual corrosion rate to be in the low range (for oil and gas lines) or in the medium range (for water injection lines), alternative techniques are required for the surveillance of the critical lines and for the optimization of inhibitor dosage.
A new generation of high-resolution (HR) corrosion monitoring has been introduced in the last 5 years, aimed at improving the response time of the on-line corrosion monitors.
A program was initiated in order to determine the real-time response of the HR probes against changes of inhibitor concentrations at different predetermined time intervals. The trial was performed on 24" transmission line carrying stabilized crude with 0.01% water cut.
This paper presents the real time response of the various probes at different inhibitor concentrations and analyzes the suitability of the techniques in terms of sensitivity, noise and repeatability, in order to be utilized for the forthcoming corrosion inhibitor (CI) field trial test. It also discusses the preliminary results of the actual field trial tests in terms of the aforementioned probes characteristics.
An Analytical Model of Temperature and Stress Fields During Cold Water Injection into an Oil Reservoir
Authors: Kocabas I. 
Published: December 2007

Abstract
A new transient analytical model has been developed to study the temperature and stress distribution induced by a non-isothermal fluid injection, particularly conventional waterflooding. In the model, the transient pressure, temperature and stress fields are computed consecutively. The pressure field has been computed by using the exponential integral solution. The transient temperature field has been computed by using a model that can account for both the overburden heat losses and transversal heat dispersion within the reservoir. The stress distribution has been calculated by a method presented for a plane strain in a hollow cylinder
The results implied that the thermoelastic changes in the cooled zone could affect the surrounding stress fields in a profound manner. For instance for a porous medium with stiff material such as carbonate reservoirs owing to cooling by the injected cold water large scale tensile stresses arise and may induce new fractures or propagates existing ones far into the reservoir. In addition, a major tangential stress concentration develops just in front of the cooled zone and hence shear yield is highly likely to occur ahead of the thermal front.
The two dimensional treatment of the temperature field makes the new method superior to the previous analytical models where only one dimensional field has been employed.
Near Wellbore Stimulation by Acoustic Waves
Authors: van der Bas Fred , de Rouffignac Eric , Zuiderwijk Pedro , van Batenburg Diederik 
Published: December 2007

AbstractNear-wellbore formation damage reduces the productivity in most of the existing oil and gas wells. The formation damage is caused by the invasion of fluids during the drilling and completion process and in a later stage by the deposition of particles (fines, scale, asphalthenes, etc) due to production. The conventional technique to remove these types of damage is injection of fluids to dissolve the damage. The treatments typically involve pumping of chemicals (acid, corrosion inhibitor etc.) under matrix conditions. Controlled placement of the treatment fluids in the zones that need to be treated is difficult and sometimes impossible in particular in long, horizontal intervals.A promising new technique to remove the near-wellbore damage is high-frequency acoustic stimulation; a specially designed acoustic tool is utilized on wireline or coiled tubing to selectively treat the required reservoir intervals. The preferred application of this tool is at underbalance pressure condition: damage particles mobilized by the acoustic waves are removed from the reservoir interval by the production flow. The paper reports on the ongoing acoustic stimulation research.Laboratory work showing the potential of acoustic cleaning has been previously reported; it was performed on sandstone cores saturated with brine in a laboratory set-up using linear acoustic waves. Recent acoustic cleaning experiments examined the effect of various other conditions i.e. oil saturated rock and gravel pack completion. Results from these experiments are presented here.
Improvements in Downhole Equipment for Fluid Injection and Hydraulic Fracturing Monitoring using Associated Induced Seismicity
Authors: Deflandre J.-P. , Vidal-Gilbert S. , Wittrisch C. 
Published: December 2007

Abstract
In the last 10 years the use of passive seismic monitoring has been improved with the development of downhole equipment such as permanent downhole 3C-geophones and downhole telemetry. Simultaneously, surface equipment were improved, 20 and 24-bits system occurred with advanced integrated acquisition software. In these conditions, the ratio of the relevant information (microseisms) to the total amount of recorded files increase from less than 5% to more than 90%. Consequently, processing time decreased significantly and real-time interpretation became possible. These improvements directly benefit to both long term and short term applications of microseismic monitoring.
The paper refers on the principle of passive seismic monitoring, describes the new development possibilities and the way this domain is evolving. Feedback on field experiences are given to optimise data acquisition and interpretation.
Vertical Miscible Displacement of Oil from Fractured Reservoir
Authors: Jamshidnezhad Mohammad 
Published: December 2007

Abstract
This paper discusses the problem of the displacement of oil, saturating the fractured reservoir, by another fluid miscible with it in all ratios, in a gravity field. The equations are derived with allowance for all three mechanisms of mass transfer between fracture and matrix. Utilizing the method of characteristics provides the analytical solutions of the resulting system of equations. The results have been compared with experimental results. There is a very good agreement between the results and experiments.
Determination of Recovery and Relative Permeability for Gas Condensate Reservoirs
Authors: Al-Honi Mohamed , Zekri Abdulrazag Y. 
Published: December 2007

Abstract
Coreflood experiments on gas condensate flow behavior were conducted for a Libyan gas condensate reservoir. The objectives were to investigate the effects of rock and fluid characteristics on critical condensate saturation (CCS), gas and condensate relative permeability's, hydrocarbon recovery and trapping by water injection, and incremental recovery by subsequent blowdown and vaporization by dry gas injection.
The water/gas relative permeability data were generated using implicit historical matching simulator which uses a reverse history matching technique to generate a full suite of relative permeability curves over the range of interest. The results of the tests on the reduction in gas permeability due to retrograde condensate accumulation demonstrated that, in general, the effective permeability to gas decreased significantly at pressures below the dew point pressure due to the condensate trapping effect for all the stacks investigated in this study. Permeability continues to drop at very low pressures even though theoretically condensate should be re-vaporizing. The recoveries of the liquid condensate during the vaporization by dry gas injection at pressures below the dew point pressure were generally high. The recovery ranged from 66% to 70% for the high permeability core stack and 86% to 98% for the lower permeability core stack. In theory, it is possible for all of the condensate to be revaporized into the methane gas stream. However, in practice, the recovery is usually less than 100% due to macroscopic sweep efficiency limitations and mass transfer limitations within the rock matrix.
Poor mobility ratio and viscous fingering during the methane injection characterize the re-vaporization of gas condensate by methane gas. This results in early breakthrough of the methane gas and very high gas/liquid ratios during the test. The volume of methane gas injection required to recover a significant amount of the condensate liquid in the core is a function of temperature, pressure, composition of the gas, heterogeneity and especially the permeability of the core sample.
Laboratory Investigation of CO2 Flooding
Authors: Yongmao Hao , Zenggui Wu , Binshan Ju , Yueming Chen , Xiangjie Luo , Petro Xinjiang 
Published: December 2007

Abstract
Carbon dioxide(CO2) flooding is an efficacious method of EOR and it is a very complicated process, involving phase behavior. To master the performance of CO2 flooding and provide accurate data for designing oil development, a comprehensive investigation of CO2 flooding phase behavior and mechanism based on laboratory study was conducted. In order to get representative fluid samples of a reservoir, it was necessary that the right operation of mixing the separator oil and gas samples to match the bubble point pressure be carried out. The result from PVT experiments shows that for a certain reservoir, through a slight manipulation of the measured PVT properties including bubble point pressure, volume factor, swelling factor, solubility of CO2 and viscosity, it is possible to obtain regression curves, which can be used to estimated the PVT behavior for any hydrocarbon fluid-CO2 mixture of this reservoir. The result of slim tubule tests indicates that it is more appropriate to determine the minimum miscibility pressure of the reservoir fluid-CO2 mixture by the position of inflexion on the curve of oil recovery with flooding pressure than by reaching a special oil recovery point.
Thin Sand Development Made Possible through Enhanced Geosteering and Reservoir Planning with While-drilling Resistivity and NMR Logs: Example from Niger Delta
Authors: Oguntona J. A. , Kelsch K. , Osman K. , Ingebrigtsen E. , Butt P. , Saha S. 
Published: December 2007

Abstract
The horizontal well placement within a thin sand with structural dip and economically produce these reserves are a challenge for the oil industry. New Reservoir Management and Formation Evaluation techniques are making these very thin hydrocarbon sands accessible and economic for development. Upfront planning by multi functional team to define well placement, uncertainty management and tool selection are key. Next execution of landing and lateral require maximum flexibility and accuracy from tools and team.
In this paper, two case studies are presented where Logging-While-Drilling (LWD) resistivity and Nuclear Magnetic Resonance (NMR) were utilized to geosteer a horizontal section through a thin sand and to geo-stop the horizontal well after drilling an optimal drain hole length.
Resistivity and NMR-LWD provides critical formation evaluation information such as resistivity at bit, up and down resistivities, structural dip, formation porosity, bound-fluid volume, free-fluid volume and permeability. Obtaining this information while drilling has a significant impact on drilling and completion decisions in Niger Delta.
In the first case study, based on the information of NMR LWD from a pilot hole, a horizontal sidetrack was optimised in the high permeable section of the thin reservoir. In addition, NMR logs demonstrate the horizontal section was placed generally within the sweet spot of high free fluid section.
Drawing experience from the first case study, a more difficult situation of drilling a horizontal well with a six feet window was addressed. The objective was to place the well within the sand and drill an optimal length that will meet hydrocarbon deliverability. First, resistivity at bit was used to restrict the well within the target sand. Within this heterogeneous sand, the while-drilling resistivity image and up and down deep Resistivity measurements allowed the geosteering team to stay in the "sweet spot" of the reservoir. Concurrently, permeability was estimated from the NMR log. Based on this permeability, hydrocarbon producibility was computed and decision was reached to drill the optimal length. This novel approach combining geosteering techniques using flexibly LWD tools are key to future development of thin hydrocarbon reservoirs.
A Statistical Approach to Reservoir Zonation
Authors: Agunwoke Godwin O. , Egbele Emmanuel , Onyekonwu Michael 
Published: December 2007

Abstract
Reservoir flow zones reflects group of rocks that have similar geologic, physical properties and depositional environment that affect fluid flow. Variations in rock properties result from depositional, diagenetic and post-depositional changes. Aside from a geologic approach, statistical analyses are required to verify the existence of these flow zones.
A statistical zonation technique developed by Testerman1 to identify and describe naturally occurring zones in a reservoir and to correlate these zones from well to well was used here. The flow performance is a strong function of the average permeability, and therefore of the statistical flow unit definition method used.
Five reservoir flow zones were established based on the geologic litho-stratigraphic correlation using gamma ray and resistivity logs. This is against the two flow zones estimated from statistical correlation. Where this happens, the simulator may lump together several geologic layers. Lumping involve adding layers that have similar physical properties. The number of zones depends on the computing limitation and any other constraints of the simulator. Reconciling these two differences provides a better input into numerical flow simulation.
Congenital Reservoir Rock Characterization of Weak Hydraulic Properties
Authors: Chike Ikechukwu , Egbele Emmanuel , Onyekonwu Mike 
Published: December 2007

Abstract
Weak hydraulic units occur frequently in many Niger Delta fields. This makes the characterization of reservoirs in such fields quite challenging.
In this work the interpretation procedure, adopted model and algorithm were chosen such that each unit is treated separately to make the evaluation process as detailed as possible. Also, a conscious effort was made to incorporate functions in our adopted model that take care of the factors responsible for the weak hydraulic units in the reservoir.
The application of cut-offs was done in a manner that blocked properties and predictive algorithm only relate to intervals that will contribute to production. This approach is necessary to improve the precision and predictive algorithm of porosity, permeability and water saturation that form part of the reservoir evaluation process. Usually the inclusion of units with weak hydraulic properties in the evaluation of hydraulic storage at the onset will decrease and weaken the precision of the evaluation process if cut-off were not applied. Also, the approach resulted to a construction of the simplest dynamic model that is compatible with the static model which is the objective of every reservoir characterization.
The prime aim of this approach is a more precise reservoir characterization as against a mere approximate.