bluuebunny/crossref_metadata_2025 huggingface dataset:
Comprehensive behavioral analysis of ENU-induced Disc1-Q31L and -L100P mutant mice
Authors: Shoji Hirotaka , Toyama Keiko , Takamiya Yoshihiro , Wakana Shigeharu , Gondo Yoichi , Miyakawa Tsuyoshi
Published: February 2012

Background

Disrupted-in-Schizophrenia 1 (DISC1) is considered to be a candidate susceptibility gene for psychiatric disorders, including schizophrenia, bipolar disorder, and major depression. A recent study reported that N-ethyl-N-nitrosourea (ENU)-induced mutations in exon 2 of the mouse Disc1 gene, which resulted in the amino acid exchange of Q31L and L100P, caused an increase in depression-like behavior in 31 L mutant mice and schizophrenia-like behavior in 100P mutant mice; thus, these are potential animal models of psychiatric disorders. However, remaining heterozygous mutations that possibly occur in flanking genes other than Disc1 itself might induce behavioral abnormalities in the mutant mice. Here, to confirm the effects of Disc1-Q31L and Disc1-L100P mutations on behavioral phenotypes and to investigate the behaviors of the mutant mice in more detail, the mutant lines were backcrossed to C57BL/6JJcl through an additional two generations and the behaviors were analyzed using a comprehensive behavioral test battery.

Results

Contrary to expectations, 31 L mutant mice showed no significant behavioral differences when compared with wild-type control mice in any of the behavioral tests, including the Porsolt forced swim and tail suspension tests, commonly used tests for depression-like behavior. Also, 100P mutant mice exhibited no differences in almost all of the behavioral tests, including the prepulse inhibition test for measuring sensorimotor gating, which is known to be impaired in schizophrenia patients; however, 100P mutant mice showed higher locomotor activity compared with wild-type control mice in the light/dark transition test.

Conclusions

Although these results are partially consistent with the previous study in that there was hyperactivity in 100P mutant mice, the vast majority of the results are inconsistent with those of the previous study; this discrepancy may be explained by differences in the genetic background of the mice, the laboratory environment, experimental protocols, and more. Further behavioral studies under various experimental conditions are necessary to determine whether these Disc1 mutant mouse lines are suitable animal models of schizophrenia and major depression.
Are Ascaris lumbricoides and Ascaris suum a single species?
Authors: Leles Daniela , Gardner Scott L , Reinhard Karl , Iñiguez Alena , Araujo Adauto
Published: February 2012

Since the original description and naming ofAscaris lumbricoidesfrom humans by Linnaeus in 1758 and later ofAscaris suumfrom pigs by Goeze 1782, these species have been considered to be valid. Four hypotheses relative to the conspecificity or lack thereof (and thus origin of these species) are possible: 1)Ascaris lumbricoides(usually infecting humans) andAscaris suum(recorded mostly from pigs) are both valid species, with the two species originating via a speciation event from a common ancestor sometime before the domestication of pigs by humans, or 2)Ascaris lumbricoidesin humans is derived directly from the speciesA. suumfound in pigs withA. suumthen existing as a persistent ancestor after formation ofA. lumbricoides, or 3)Ascaris suumis derived directly fromA. lumbricoideswith the persistent ancestor beingA. lumbricoidesandA. suumbeing the newly derived species, and finally, 4)Ascaris lumbricoidesandA. suumare the same species, this hypothesis being supported by studies showing both low morphological and low genetic divergence at several genes. We present and discuss paleoparasitological and genetic evidence that complement new data to evaluate the origin and evolution ofAscarisspp. in humans and pigs, and the uniqueness of the species in both hosts. Finally, we conclude thatAscaris lumbricoidesandA. suumare a single species and that the nameA. lumbricoidesLinnaeus 1758 has taxonomic priority; thereforeA. suumGoeze 1782 should be considered a synonym ofA. lumbricoides.
Article Series: Communications from the division "Environmental Chemistry and Ecotoxicology" of the German Chemical Society (GDCh) -Statements and reports of the working groups "Environmental Monitoring" and "Soil Chemistry and Soil Ecology"
Authors: Rüdel Heinz , Hennecke Dieter , Kördel Werner , Fischer Klaus
Published: February 2012

A continuous task of the working group "Environmental Monitoring" is the development of methods and guidelines for a systematic and long-term analytical control of the chemical burden of environmental compartments and biota A new recommendation regarding the substance-related environmental monitoring is published in "Environmental Science and Pollution Research" (Rüdel et al., 2009). The "Chemical and Biological Monitoring Series", published in the same journal, originates from the working group or from its individual members also. Some central points of these articles are picked up and updated in this report. Current topics of major concern are the transformation of pharmaceuticals and its consequences for environmental monitoring and the monitoring of biocides and nanoparticles.

Besides other objectives the working group "Soil Chemistry and Soil Ecology" focuses on the development and standardisation of methods for the chemical, physical, and biological characterisation of soil pollution by specific contaminants as well as on the elaboration of methods for the assessment of potential harmful effects on soil, soil ecology, and on other potentially targeted environmental media. Recently the working group has summarized its main outcomes and conclusions in the position paper "Target Orientated Exposition Estimation in Soil Assessment" which is part of this report. Furthermore several other initiatives and activities of the working group are presented.
Clinical risk management of obstetric anal sphincter injury
Authors: Burke N , Corcoran S , Ryan H , Barrett N , Geary M
Published: February 2012

Perineal injury sustained during childbirth, and more particularly third and fourth degree tears, can have substantial effects on future continence, sexual function and the choice of method of childbirth in the future. The aim of our audit was to see if the use of clinical risk management methods could help improve documentation and clincial outcomes for women who sustained an obstetric anal sphincter injury. A proforma for the management of obstetric anal sphincter injury was introduced to the labour ward. We found that after the introduction of the proforma documentation improved significantly for classification of the type of injury ( P < .01), counts of swabs, instuments and sharps ( P < .01) and future pregnancy information ( P < .05). This audit demonstrates how simple clinical risk managment strategies can help ensure the best standards of care are implemented.
Risk management for the future of clinical negligence claims
Authors: Evans William , Pipkin David
Published: February 2012

Risk management for clinical negligence claims: an underwriter's view.
Pitfalls in the management of acute upper gastrointestinal bleeding
Authors: Palmer Kel
Published: February 2012

Acute upper gastrointestinal bleeding is a common life-threatening medical emergency. Whilst the evidence base for optimum management is well defined in published guidelines, a large UK audit revealed deficiencies and inequalities in service provision that almost certainly contribute to a crude hospital mortality that has not improved in more than sixty years. Attention to critical areas in the diagnostic and therapeutic pathway could improve outcome for patients and reduce the risk of litigation for hospitals and individual practitioners.
Reconciliation of Core and Log Data Analysis in Very Thin Reservoirs of Krishna Godavari Basin, India
Authors: Yadav Lalaji , Dutta Tanmoy , Sinha Neeraj
Published: February 2012

Deep water Tertiary reservoirs of Krishna Godavari basin are generally very complex and heterogeneous, ranging from massive thick sands to highly laminated very thin sand/shale sequences beyond the vertical resolution of imaging tools. Verification of log-derived quantities in very thin reservoirs is frequently difficult because of bias and scatter introduced by non-uniform or incomplete plugging of the available over 750 meters of conventional cores. As laminar shale does not occupy or alter the intergranular sand porosity, the conventional way of validation of log derived porosity and water saturation with core data showing excellent correlation does not ensure the correctness of petrophysical evaluations.

In this paper, it has been demonstrated that there are potential problems associated with the integration of petrophysical evaluation and core data. Sources of errors are mainly due to the use of different parametric systems viz. using of the terms shale volume and clay volume interchangeably and validating log derived shaliness with clay abundance from XRD core data. Shaliness derived from logs cannot be directly correlated with such core data because neither de-averaging of lithology on log analysis nor averaging of core data is possible for the effective core-log integration.

Average hydrocarbon pore volume in laminated reservoirs is linearly related to the average cumulative net sand fraction or shaliness of the formation. Laminar sand porosity and water saturations are independent of shaliness or net sand. Excellent correlation of log derived deconvolved data sets like porosity and water saturation with core measurements does not validate the correctness of hydrocarbon pore volume estimation, which is linearly related to net sand. Accurate estimation of hydrocarbon pore volume requires an accurate calibration of laminar sand/shale volumes, which can be precisely validated only with lamcount data.
FEA Modelled MSE/UCS Values Optimise PDC Design for Entire Hole Section
Authors: Hammoutene Cherif , Bits Smith
Published: February 2012

The value of the mechanical specific energy (MSE) concept to analyze drilling efficiency and bit performance is well established. Recent operator-driven research has concentrated on predicting and maximizing rate of penetration (ROP). The specific energy ROP model has been successfully implemented in numerous high-cost/high-profile environments. To further advance the mechanical specific energy (MSE) concept, an engineering team is developing a methodology to optimize polycrystalline diamond compact (PDC) bit design for the entire hole section based on modeled MSE and unconfined compressive strength (UCS) values.

Traditionally, PDC design engineers adjust cutter density/size, back rake, blade count and nozzle placement to optimize the bit for a specific application. The goal is to maximize ROP and total footage capabilities by minimizing damaging vibrations (axial, lateral, torsional) in a predetermined series of formations. Generally, the selected design has the least potential for vibration across all lithology types. PDC bits can generally drill a homogeneous formation without issues, but when transitioning zones or penetrating interbedded/unexpected formations vibrations can lead to performance degradation and cutter damage.

The industry requires a method to unify bit efficiency throughout the entire section on a meter-by-meter basis. To calculate a bit efficiency factor (Em), engineers are utilizing a sophisticated, integrated, dynamic engineering modeling system. They start with a meter-by-meter correlation between actual borehole lithology and a digitized rock library (UCS). MSE is then calculated using the modeled drilling parameters, torque, and ROP. The resulting two curves are then standardized by calculating the mean value of MSE/UCS fraction to derive a hard value bit efficiency factor. By overlapping the two curves, design and field engineers can identify lithologies that have the optimum correlation then compute the mean efficiency factor for the interval and use it as baseline for the entire hole section.

In the test case study a 38m thick shale section offered the best match, yielding a median efficiency factor. Using the fixed median efficiency factor, engineers designed and optimized a PDC bit for the entire 16-in. hole section instead of each specific formation. The resulting ROP was significantly improved, as is documented in a case study that will be presented.
Geomechanics Helped Improving Cementing Quality in South Iraq Fields
Authors: Soroush Hamed , Zaki Said , Shaheed Bilal Sami , Kalathingal Paul , Qutob Hani , Khdier Basem
Published: February 2012

Cementing is a major factor affecting the integrity of a well for its entire life. Proper cement bonding to the casing and formation is a key measure of well integrity. Unlike most drilling related activities, the cement placed into wells must remain competent for the entire life of the well and beyond to ensure no fluid leakage even after the well has been abandoned.

Cementing operations in the giant southern field of Rumaila were conducted using single 15.80 ppg cement slurry. The slurry was tested in laboratory for its thickening time, free water and compressive strength. However, reviewing and interpretation of the cement bond logs indicated poor cement quality with no cement in some intervals.

Review of daily drilling reports showed a significant amount of mud losses during drilling through some of the carbonate formations, mainly the Dammam, Tayarat, Shiranish and Hartha. A geomechanical study was performed in order to define the safe operating mud weight window. This study revealed that the formation fracture gradient was significantly lower that the utilized cement weight. This implied that cementing with this high cement weight could reopen the natural fractures and even create new fractures which could consequently open conduits for cement slurry losses.

As a result, it was recommended to use quality light weight cement instead of the current filler cement and perform cementing in more than two stages in order to improve the quality of cementing operation and to avoid fracturing the formation. Furthermore, additives such as fiber and sodium silicate were recommended to be added to combat losses through open fractures and vugs.

Considering some of these recommendations, the quality of the cement job was significantly improved in subsequent wells.
Joint Stimulation-Water Shut-off Technology Leads to Extra Oil from Mature Fields
Authors: Kosztin B.. , Ferdiansyah E.. , Zadjali F.. , Al-Sharji H.. , Al-Ma'amari K.. , Al-Salmani S..
Published: February 2012

There are number of challenges encountered in oil production of mature, depleted fields like naturally fractured complex carbonate reservoirs found in Oman and the Middle East Region. These include production under high water cut ranging from 90 to 99%, the presence of conductive natural fractures connected to the aquifer in the producing zones, multi-zone production and reservoir heterogeneities encountered in each zone.

Conventional acid stimulation at such reservoir conditions is rather questionable, showing no economic value and exhibits very high risk of losing the remaining oil production with unwanted, further increased water production. However, acid stimulation combined with water control gives good opportunity for recovering extra oil using hydrophobic chains containing associative polymer.

The polymer adsorption has double roles during and after the treatments acting as an acid diverter and water control agent as relative permeability modifier. In naturally fractured producing zones, this combined method shows lower risk and better potential than in those zones where matrix flow exists only.

In summary, this paper will cover the theory behind the above-mentioned method, stimulation challenges, candidate selection, treatment design and the results of the campaign started since 2006 in one of matured fields in North Oman. The campaign focused on oil producing wells having more than 97 % water cut. These trials were the last chance for achieving acceptable oil production before abandonment. The main achievement of the campaign resulted in more than 207% incremental oil (net) added to the stock tank in parallel with 1.5% average water cut reduction. The technology will be applied in a bigger scale as part of production optimization.
Drilling Intervention - Milling and Fishing of High Strength Aluminum Drill Pipe
Authors: Nicolescu Adrian , Fisher Jerry , Haq Mohammed A. , Bailey Tom , Lazarev Alexander
Published: February 2012

Superior dependability of the drill string plays an important role in drilling deep and especially ultra-deep, highly inclined and long departure horizontal wells, where it is often exposed to extreme loading conditions in a high pressure and high temperature environment. This need has resulted in the technological development of high strength Aluminum Drill Pipe (ADP) for use in deep and ultra-deep wells, where its' properties and the advantages that it offers can make a significant contribution to reaching the most challenging of drilling targets. Drilling intervention operations such as milling and fishing are also a major challenge in such extreme environments and have led to the development of new tools and techniques to address them.

This paper will review the use of ADP in comparison to steel drill pipe and discuss the milling scenarios of cemented and un-cemented drill pipe as well as fishing operations using external and internal engagements. The intent of this paper is to disseminate technical knowledge in this new area of drilling technology.
WAX Deposition Forecast
Authors: Semenov Andrey
Published: February 2012

In case of altering PVT-properties change of the aggregate state of oil is one of the main issues in the oil processing. When oil lifts to the surface the most advantageous energy state of high weight components becomes the state in which a part of the molecules becomes solid. Phase behavior diagrams could actually be plotted using typical compositional simulator. But even if one knows the phase behavior, he still won't be able to understand the WAX deposition in the tubing or pipeline and will not forecast this process performance.

As some authors mentioned, the resins and asphaltenes concentration in the oil affects the WAX deposition velocity. Due to the high complexity of a crystallization mechanism the high weight molecules are not taken into consideration in a phase behavior simulator. Thus for the opportunity of qualitative characterization of the oil tendency to the aggregation the oil from different reservoirs has been compared.

Due to the temperature gradient between rock (permafrost) and oil the probability of WAX deposition in the tubing appears. Deposition growing model presupposes different diffusion assumptions. Equilibrium model and film mass transfer model (as well as solidification and separation) have been applied. Using these models the WAX growing velocity and tubing drift diameter have been forecasted.

Due to the harsh north environment there is a serious risk of oil solidification in the surface pipeline in a case of pump stopping. Based on the laboratory measurements, with the help of stepwise approximation the oil viscosity dependence on temperature has been derived. By solving heat transfer equation (between oil in the pipeline and environment) and using nodal analysis the maximum safety time in a case of accident in the pipeline has been determined.
Kuwait Oil Company Conceptualized & Implemented HSE Traffic Lights for HSE Demonstration & Site Verification
Authors: Al Mansouri Fares , Aftab Alam Mohammad , De La Roche Alberto
Published: February 2012

The increase in business activities during last decade brought forward several challenges in upstream hydrocarbon industry like KOC which has 40 operational facilities, 65 rigs and around 600 Contractors' worksites. However 5 fatalities within a quarter during 2009-10 was a serious concern that demanded immediate gap analysis focusing most relevant regulatory, procedural & contractual HSE issues compared to actual situation at site. Based on gaps, a unique tool of HSE demonstration & site verification was devised and implemented conceptualizing HSE traffic lights.

Accordingly Site Verification Visits (SVV) process with 5 crucial elements & 25 sub-elements which directly impact worksites' safety & integrity was developed on concept of green, yellow & red traffic lights corresponding to As Required, Need Improvement & Unacceptable Condition at site. The process is supported and explained through specific procedure, online reporting system, verification checklists, brochures, posters and audio-visual film. The system is decentralised at each directorate level for efficient management but progress is monitored at corporate level for effectiveness and improvement scope.

The SVV conducted across facilities & contractors worksites by KOC senior and middle management resulted in significant HSE improvement during 2010-11 comparing the past performance. Taking into account the positive impact, the SVV process has been extended with appropriate modification and support to KOC supervisory levels & Contractors' Managers responsible for the safety & integrity of their worksites.

SVV process is a unique and innovative tool of verifying HSE commitment & demonstration of regulatory, procedural and contractual requirement through HSE oriented critical factors which indicates actual situation at site based on traffic lights concept of green (go), yellow (alert) and red (stop) as relevant action. The paper shall demonstrate a typical but realistic solution for worksite safety & integrity through a comprehensive verification system.
Improve Oil Production Using Blocking and TSO Fracturing in Ultra Low Permeability Reservoir, China
Authors: Dingwei Weng , Qun Lei , Yunhong Ding , Yongjun Lu , Zhenzhou Yang , Biansheng Li , Oilfield Jilin
Published: February 2012

In China, about 70% of new discovered oil reserves and 80% of new discovered natural gas reserves are in the low permeability reservoirs, and the lower limit of reservoir permeability is becoming lower and lower in new oilfields. The blocking and tip-screen-out (TSO) fracturing are introduced to create more complex fractures and increase the stimulating reservoir volume, comparing to the 2-wing symmetrical planar fractures, and so develop these ultra low permeability oilfields.

A model was set up to describe when the complex fractures form, and the key point is when fracturing elevating fracture net pressure to exceed the sum of tensile strength and the difference of maximum and minimum principal stress. And then two cases are detailed to illustrate how the blocking and TSO fracturing are designed and executed. The blocking fracturing is pumping some wax balls or larger size proppant to temporarily block the fracture and so increase the net pressure. And the TSO fracturing is similar to that used in the high permeability reservoir, but the aim is also increasing the net pressure not creating a wide and short fracture. The net pressure and the oil production are only matched when considering multiple fractures, so the blocking and TSO fracturing actually make more fractures spread, and increase the stimulating reservoir volume.

The two fracturing methods have been applied in several ultra low permeability oilfields in China, and average oil production is much more than that of neighbor wells. So the fracturing makes these ultra low permeability oilfields can be developed economically.
Wellbore Alteration - It's Implications on Measurement of Formation Properties
Authors: Abangwu Prince , Dutta Dhruba J. , Baig Mirza Hassan , Miranda Pereira
Published: February 2012

Deep-water offshore exploration has revealed increasing discovery of unconsolidated and under-compacted reservoirs characterized by high porosity and permeability. Formation evaluation becomes challenging since conventional drilling practices adapted for this environment often results in near-wellbore alteration which can reach deeper into the formation due to relatively low competency of the rock. This characteristic is observed for almost all the deep-water Miocene-Oligocene turbiditic sands across the globe.

The concept of near-wellbore damage is a well-known topic, however, its implication in deep-water exploration and production is being studied now in great detail. Measurements of properties like mobility and formation-fluid attributes have been jeopardized by fines migration, damage and alteration. The effect of near wellbore deformation causes development of skin and stiffness change that has a strong impact on formation fluid sampling and pressure acquisition. Multi-pole multi-array sonic acquisition has shown that damage causes variation of sonic-velocity in the radial direction that could be identified and quantified with the current technology. Innovations in Nuclear Magnetic Resonance (NMR) with greater depth-of-investigation (DOI) and radial-imaging and interpretation techniques indicates that the concept of fines migration causes considerable effect on formation permeability and porosity estimation and has a critical impact on reserve estimation.

The current work focuses mainly on two aspects of wellbore alteration on measured logs. First, effect of alteration has been identified by using multi-DOI NMR and sonic measurements in an integrated manner. Secondly, and subsequently, quantification of the damage was measured along with its impact on other measurements like formation-tester. This integrated technique can significantly and efficiently reduce formation sampling duration by locating damaged-zones and effectively reduces acquisition cost in a complex deepwater operation. The implication of identifying the damaged zone has a great value in designing optimum completion and sand management and exclusion technique at the subsequent stages of development.
Development of Unconventional Resources in North Africa: Evaluation Approach
Authors: Melo Ricardo C. , Lakani Ramin
Published: February 2012

The "Shale Gas Revolution" in North America has created both an opportunity and a challenge for the North Africa region for finding such unconventional resources. Approaches to finding them must be based on technology and planning to avoid unwanted expenses and error. Unconventional resources, for the purpose of this paper, are defined as tight and/or shale gas resources, although in North Africa, many of the challenges and potential solutions are equally applicable to oil rich resources. Key challenges specific to the North Africa region include the following:

The availability of gas in North America has shifted LNG shipments to Europe (which is North Africa's biggest export market). The potential spread of this "revolution" to Europe could further erode the region's market share. The region faces a lack of infrastructure and a higher cost base for developing unconventional resources.

As a result, little margin for error exists, nor can you afford to "learn by the drill bit." Therefore, you need to apply technology to reduce costs and increase well productivity and you need to develop a methodology that ensures minimal iterations. The latter requires a fully integrated approach to project evaluation, planning, and execution. As the highest portion of costs associated with developing shale/tight gas resources is for hydraulic stimulation (fracturing), this paper will focus on the best way to integrate:

Reservoir characteristics (rock and fluid properties) Geomechanics Fracturing techniques

A synergy of reservoir consultancy and pumping services has developed a close rapport and integrated approach that could be used by resource holders. This methodology can be modified to fit the requirements of NOCs or IOCs.

This paper aims to highlight these and also offer a potential approach and methodology to evaluate these unconventional resources and secondly to apply technology to unlock their potential. Case studies will be used to demonstrate the pitfalls and challenges faced by projects in North America.
Ultra-Lightweight Proppants: Best Practices for Long Horizontal Gravel Packs Offshore Brazil
Authors: Jardim A. T. , Prata F. G. , Gomez J. R. , Pedroso C. A. , Martins M. O. , Silva D. N.
Published: February 2012

Operators developing reservoirs and producing them from deep and ultra-deepwater wells are pushing the technical limits regarding horizontal extension. Deepwater wells completed in uncosilidated formations usually have low fracture gradients, severe leak-off zones and/or significant wash outs. Long horizontal open holes, therefore, may become technically difficult or economically unfeasible to gravel pack using conventional fluids and gravels.

Typical completions offshore Brazil start from a 9 5/8-in. or 10 3/4-in. casing, where a 5 1/2-in. premium screen and tubular string is hung along an open hole drilled with 8 1/2-in. or 9 1/2-in. bit. Horizontal extensions range from 980 to 4,000 ft.

Ultra-lightweight proppants have enabled gravel packing in these longer horizontal open holes. The reduced gravel density allows a significant reduction in pumping rate, which avoids fracturing the formation, minimizes fluid losses and eliminates the risk of premature screen out due to excessive gravel settling.

This paper summarizes the procedures and results of almost 60 wells that have been gravel packed using ultra-lightweight proppants technology pumped for a local operator.
Tight Reservoir Permeability Prediction by Integrated Petrophysical Evaluation, Core Date, and Micro-frac Wireline Formation Tester Analysis
Authors: Elarouci Fethi , Mihail Nicolae , Adnan Iguer , Benaissa Hicham , Nabil Mokrani , Fouzi Bouillouta
Published: February 2012

Most gas reserves in Algeria are located in unconventional tight reservoirs that typically contain multiple rock types from different depositional systems. Identifying and evaluating these reservoirs is difficult. Permeability predictions are very challenging because of results reliability from different downhole tools, and also by its direct relationship on production and economic impact.

This paper presents a case study that used an integrated formation evaluation approach of tight reservoir during an appraisal stage in an Algerian gas field. The workflow includes:

– Petrophysical model using stochastic analysis to get shale volume, effective porosity and water saturation calculation. – Hydraulic flow unit zonation using flow zone indicator (FZI) and global hydraulic element (GHE) methods identified from core data. – Pressure transient analysis from wireline formation tester. – Mathematical phi-k relationship from core data under confining pressure. – Synthetic permeability log using previous relationships

In addition to determining reservoir geomechanical properties from the micro frac operation, Synthetic permeability curve were generated in areas of the reservoir that were not core sampled. These predictions were constraint by core data analysis as well as permeability from wireline formation tester.

This methodology was applied in an Ordovician tight sandstone reservoir in the South east Algerian Sahara gas field.
Guidelines for Selecting Appropriate PVT Correlations for Black Oils
Authors: Al-Zahaby Ahmed , El-Banbi Ahmed , Sayyouh Mohamed H.
Published: February 2012

Accurate determination of the crude oil PVT properties is essential for solving many reservoir engineering, production engineering, and surface production and operational problems. A large number of PVT correlations for oil exist in the petroleum literature and numerous studies are also present for with data favoring one correlation over the other. In the absence of PVT data from laboratory experiments, it is often difficult to choose which correlation to use to calculate different PVT properties. We approached this problem in two ways. First, we developed an expert system that checks the input parameters (e.g. reservoir parameters) against the valid ranges of input data for different correlations, and then recommends which correlations to use for specific input parameters. Second, we tested all available PVT correlations for black oil on a database of selected 35 Egyptian crudes to develop guidelines on which correlations to use for each PVT property for the specific range of input data. These specific crudes were selected to allow testing of those guidelines on a wide range of reservoir input data for black oils. Our database included oils with oAPI ranging from 17 to 51, gas-oil-ratios of 8 to 7,800 scf/STB, formation volume factor at bubble point of 1.04 to 4.47 bbl/STB, bubble point pressures of 60 to 4,739 psia, and reservoir temperatures of 40 to 270 °F.

The present work included 13 bubble points, 6 solution-gas-oil ratio, 14 formation volume factors, 13 oil compressibilities, 14 dead oil viscosities, 9 saturated oil viscosities, 10 under saturated oil viscosities, 12 under-saturated densities, 2 total formation volume factors and 2 saturated density correlations.

Based on this study, guidelines for selecting an appropriate correlation for PVT oil properties are introduced. These guidelines are recommended in programming of PVT correlations regardless of their geographic origin.
Foam Assisted WAG, Snorre Revisit with New Foam Screening Model
Authors: Spirov Pavel , Rudyk Svetlana N. , Khan Arif. A.
Published: February 2012

This study deals with simulation model of Foam Assisted Water Alternating Gas (FAWAG) method that had been implemented to two Norwegian Reservoirs. Being studied on number of pilot projects, the method proved successful, but Field Scale simulation was never understood properly. New phenomenological foam model was tested with sensitivity analysis on foam properties to provide a guideline for the history matching process (GOR alteration) of FAWAG Pilot of Snorre Field (Statoil).

The aim was to check the authenticity of presented new foam model in commercial software whether it is implementable on a complex geological model for quick feasibility studies, either for onward practical pilot or as justification for more detailed technical study.

The simulation showed that Foam model is applicable. The mismatch between history and actual GOR in some periods of injection is due to the complexity of the fluid flows control inside reservoir. The way; how specific properties control the time of gas arrival and values of GOR are described. The analyses of the improvements in the injection schedule are shown.

With increasing number of CO2 and FAWAG methods in preparation worldwide, the use of the simulation contributes to more precise planning of the schedule of water and gas injection, prediction of the injection results and evaluation of the method efficiency. The testing of the surfactant properties allows making grounded choice of surfactant to use. The analysis of the history match gives insight in the physics of in-situ processes.

Detailed Qualitative analysis is presented for foam modeling against the FAWAG historical data that provides sharp idea of the behavior of Foam model for different foam factors, which in turn provides reasons for the unpredictable foam behavior in WFB Project and also serve as quick reference for future general foam pilot simulations at field scale.
Cased Hole Formation Resistivity Evaluation Results in Successful Identification and Isolation of Watered out Zones in Nubia Formation
Authors: Ghadiry Sherif , Ismail Abdallah
Published: February 2012

Water production is one of the main challenges facing oil and gas producers. It is necessary to carefully manage water production in order to enhance oil production. In order to identify watered out zones, a time lapse cased hole resistivity survey was carried out to evaluate hydrocarbon saturation.

In static conditions, the value of cased hole resistivity over other time lapse techniques resides in its deep depth of investigation, which results in increased immunity to borehole fluid reinvasion.

This technique was applied on three wells, where the water cut was ranging from 65 % to 90 %. The cased hole formation resistivity clearly identified the watered out zones. A water shutoff operation followed. The objective of the cased hole resistivity acquisition was met as the water cut dropped down to 1 to 40 % after isolation of the watered out zones.
An Optimization Model to Determine Horizontal Well Location and Parameters for Strong Bottom Water Reservoir in Sudan
Authors: Xianghong Wu , Liangyu Rao , Xianbing Li , Xiangling Li
Published: February 2012

The purpose of this study is to develop a horizontal well closed-looped optimization model for enhancing ultimate recovery of strong bottom water reservoir in Sudan.

An optimization model for horizontal well using the statistical properties of geology and development data, numerical simulation and fuzzy mathematics, is presented. The study was carried out as follows: 1) a mechanism model was established based on physical and fluid properties of the oilfields in Block 1/2/4, Sudan. The factors affecting the development performance of horizontal well, such as reservoir and fluid properties, inter-beds distribution, parameters of horizontal segment and production rate were discussed. 2) Development performance of typical massive bottom water reservoir in Sudan was analyzed. 3) The weight of each factor was determined using fuzzy mathematics method based on the mechanism study and on site practice of horizontal wells. 4) Determine the optimized location and production parameters of horizontal well by combining numerical simulation and integrated evaluation model.

The optimization model was used in H oilfield of Block 1/2/4, Sudan, the result of numerical simulation show that this model can efficiently determine the location of horizontal well and can lead to increase oil production in bottom water reservoir. It can also give a reference for numerical simulation, and have a great improve place.
Improved Determination of Well Rate From Temperature and Pressure Distributions Along the Well
Authors: Barrett E.. , Abbasy I.. , Wu C.-R.. -R. , You Z.. , Bedrikovetsky P..
Published: February 2012

The gas flow profile along the wellbore that includes contribution of all productive layers is an important piece of information for reservoir characterization and well management. It provides flow contribution from each producing interval along the wellbore, which is critical for optimizing well performance and maximizing gas recovery. The present work discussed determination of the rate profile from the pressure and temperature profiles in gas wells, which is significantly cheaper and more precise than the direct flow metering. An effective and robust algorithm for calculation of the rate and thermal conductivity profiles from the depth pressure and temperature distributions have been developed by tuning the mathematical model of non-isothermal gas flow in vertical well. The detailed sensitivity analysis shows that the inverse problem is well-posed. The initial values of rate and thermal conductivity for iterative minimization algorithm were obtained by averaging the values directly calculated from the measured pressure and temperature profiles. The initial values are shown to provide the final solution with good accuracy. It allows recommending the initial values for the estimates of the rate profile. Application of the algorithm to field cases shows good agreement between the directly measured and calculated rate profiles; the results are also consistent with flowmeter (PLT) data. It validates the proposed method.
Strategies to Unlock the Unexploited Oil Production Potential in Ashrafi Field, Gulf of Suez, Egypt
Authors: Sabaa Ahmed , Crema Giordano , Salvini Giovanni , Konga Felix I. , Abdelnabi Tamer , Bekheit A.. , El Farahaty M..
Published: February 2012

Mature fields have the potential to contribute significantly to future reserves provided that the recovery can be optimized. The main objective of this paper is to discuss the application of some techniques and technologies to optimize the production in Ashrafi Field offshore, Gulf of Suez (GOS), Egypt.

Ashrafi Field, located in south-western part of the Gulf of Suez was discovered in 1987 and put in production in 1992 from its Main Area. In 1997, the South-West Area, discovered one year before, started contributing significantly to the overall field production. The field consists of sedimentary reservoir units partially overlying a tilted block of fractured Basement reservoir. The field reached its peak production of 25,800 BOPD in June 2000 from 12 naturally flowing wells and then the production declined drastically. The only artificial lift type that was suitable for the field was the gas lift system and it was implemented starting 2004 in 80% of the wells.

The strategy to unlock the unexploited potential in the field was to search for the bypassed oil through cutting edge technologies, using special techniques for stimulation of fracture Basement reservoir, combating scale and paraffin depositions in an efficient and economical manner.

The final result for the use of such techniques and technologies was the increase of the oil production to more than 225 % of its levels before the intervention campaign, the increase of the gas production needed for gas lift system feeding and the decrease of the amount of produced water.
Use of Water Cut to Optimize Conventional and Smart Wells
Authors: Barreto C. E. , Munerato F. P. , Ravagnani A. T. , Schiozer D. J.
Published: February 2012

Water-cut prediction by reservoir simulation can be used as the main parameter to determine well shutdown time. In general, analytical formulations are used to determine the maximum water cut that a well can reach and this value is used as a monitoring parameter in reservoir simulation. Moreover, water-cut value can be a good indicator to evaluate field performance and it can be used as a variable in optimization process. This paper presents a methodology to optimize production strategy using water cut as a parameter to shut down wells and smart completions as a variable of the optimization process and as an economic indicator to evaluate strategy efficiency. A discussion on the use of water cut in a reservoir simulation is made, regarding the benefits and limitations of the use. The results show that using only analytical formulation to determine the water cut to shut down wells and completions is not a good approach to maximize production strategy Net Present Value (NPV). On the other hand, the optimization of well and valve operation using water cut significantly improves the NPV. Water cut is successfully used to indicate strategy efficiency and to suggest strategy modification. The results also show that it is necessary to be careful in the use of water cut in an optimization process, because it can present several limitations. This study may help engineers to decide if it is necessary to run an optimization process to determine the parameter used to shut down wells. Furthermore, the results show the importance of a good estimation of the time to shut down wells and completions to reach the optimum potential of a production strategy.
Rheological Study for Surfactant-Polymer and Novel Alkali-Surfactant-Polymer Solutions
Authors: Bataweel M. A. , Nasr-El-Din H. A.
Published: February 2012

Mobility control during chemical flooding is one of the most important factors for enhanced oil recovery using chemical processes. Polymers are used to increase the viscosity of the injected fluid and improve the sweep efficiency by having a favorable mobility ratio during chemical flooding. Characterization of rheological properties of the surfactant-polymer (SP) and alkali-surfactant-polymer solutions is important for understanding the behavior of chemical slug in porous media.

An experimental study was conducted to measure the rheological properties of chemical flooding solution over a wide range of parameters. Effects of temperature, salt type, salt concentration, surfactant type and surfactant concentration on dilute aqueous solution of polymer used for high salinity enhanced oil recovery applications were investigated in details. In some cases the chemical slug was prepared in seawater and viscosity measurement was conducted at 90°C.

Amphoteric surfactant was used and showed compatibility with polymer solution and can be used in chemical flooding. Effect of concentrations of two types of surfactants, anionic and amphotaric on chemical slug viscosity was studied. Amphotaric surfactant was found to have a preferable rheological attributes when compared to anionic surfactant. Amphoteric surfactant can maintain viscosity of chemical solution at high salinity and no reduction in viscosity was noticed when this type of surfactant was added to the solution. On the other hand, reduction in viscosity was measured when anionic surfactant was added to the solution. Dynamic properties showed reduction when salts were added to the solutions.
Performance Assessment and Optimization of Liquid Petroleum Gas Demercaptanization Process (A Case Study)
Authors: Davoudi M.. , Khoramdel I.. , Bazregari B..
Published: February 2012

Propane and butane as LPG product containing undesirable sulfur compound which are causing a nasty smell of the product and bad copper plate corrosion. Decreasing of sulfur content tend to sale cost increasing. Total sulfur content of liquefied Petroleum product from a gas refineries located in south pars (south of Iran) presents fluctuation and off specification product occasionally. In this paper we intend to investigate and analyze the results obtained and describe the effects of important parameters on critical point of de-mercaptanization process. Also some modification is presented, based on data field, to decline the total sulfur of product and performance enhancement of process.