bluuebunny/crossref_metadata_2025 huggingface dataset:
An observational nationwide register based cohort study on lamotrigine versus lithium in bipolar disorder
Authors: Kessing Lars Vedel , Hellmund Gunnar , Andersen Per Kragh
Published: September 2011

It is not clear whether the effectiveness of lamotrigine versus lithium differs for patients with bipolar disorder treated in clinical practice. We compared rates of switch to, or add on of, another psychotropic, and rates of psychiatric hospitalization for patients treated with lamotrigine or lithium in clinical practice. Using linkage of nationwide Danish registers we identified 730 patients who received lamotrigine and 3518 patients received lithium subsequent to a diagnosis of bipolar disorder in psychiatric hospital settings during a period from 1995 to 2006. The overall rate of switch to or add on of another psychotropic (the opposite drug of interest (lithium or lamotrigine), antidepressants, antipsychotics or other anticonvulsants than lamotrigine) was increased for lamotrigine compared with lithium (HR = 2.60, 95% CI: 2.23–3.04), regardless of whether the index episode was depressive, manic, mixed or remission. In addition, the overall rate of psychiatric hospitalization was increased for lamotrigine compared with lithium (HR = 1.45, 95% CI: 1.28–1.65), as were the rates for patients with a depressive (HR = 1.31, 95% CI: 1.01–1.70) and patients with a manic (HR = 1.65, 95% CI: 1.31–2.09) index episode. Rates did not differ significantly between the drugs for patients with a mixed index episode and for patients in remission. It is concluded that in daily clinical practice, treatment with lithium is in general superior to treatment with lamotrigine.
Ginsenoside Rb3 exerts antidepressant-like effects in several animal models
Authors: Cui Jihong , Jiang Lingxi , Xiang Hui
Published: September 2011

Total ginsenosides have been shown to have therapeutic actions as antidepressants. We report a major active ingredient of total ginsenosides, the ginsenoside Rb3 (Rb3), which may have antidepressant-like effects. Using the forced swim test, tail suspension test, and learned helplessness procedure, we found that Rb3 had significant anti-immobility effects in mice in the forced swim and tail suspension tests and reduced the number of escape failures in the learned helplessness procedure. In a reserpine-induced syndrome model, Rb3 attenuated hypothermia, palpebral ptosis, and akinesia. In the chronic mild stress model, chronic Rb3 administration reversed the decrease in locomotor activity, novelty-suppressed feeding, and sucrose preference. Furthermore, neurochemical tests were performed to support our hypothesis that biochemical variations (i.e. brain-derived neurotrophic factor and the monoamine neurotransmitters 5-hydroxytryptamine, dopamine, and norepinephrine) are involved in Rb3’s antidepressant-like effects. Finally, we found, using whole-cell patch-clamp recordings, that the action potential transmission in neurons within the somatosensory cortex was excited by Rb3 perfusion and blocked with Panax notoginseng total saponins extracted from leaves. This study provides evidence for the mechanism of action of the antidepressant-like effects of Rb3.
Adaptation of Acidithiobacillus bacteria to metallurgical wastes and its potential environmental risks
Authors: Kratošová Gabriela , Schröfel Adam , Seidlerová Jana , Krištofová Dana
Published: September 2011

Metallurgical wastes – oxygen converter sludge, dust from cast iron production, lead matte, and slag from recycling of used lead batteries – were treated with Acidithiobacillus bacteria. Bacterial activity and adaptability on waste and some waste mixtures were investigated. Acidithiobacillus bacteria may easily attack oxygen converter sludge, lead matte and slag and affect the mobility of metals. Cast iron dust is not a suitable substrate for applied bacteria due to the absence of reduced sulfur and reduced iron in its mineralogical composition. Nevertheless, the pure culture was able to adapt to the mixture of this waste with slag. Disposal of these metallurgical wastes deserves special attention due to potential attack by microorganisms and consequent pH changes. According to subsequent release of hazardous substances to the environment, this phenomenon can lead to evident environmental risks.
Nucleosome-coupled expression differences in closely-related species
Authors: Guan Yuanfang , Yao Victoria , Tsui Kyle , Gebbia Marinella , Dunham Maitreya J , Nislow Corey , Troyanskaya Olga G
Published: September 2011

Background

Genome-wide nucleosome occupancy is negatively related to the average level of transcription factor motif binding based on studies in yeast and several other model organisms. The degree to which nucleosome-motif interactions relate to phenotypic changes across species is, however, unknown.

Results

We address this challenge by generating nucleosome positioning and cell cycle expression data for Saccharomyces bayanus and show that differences in nucleosome occupancy reflect cell cycle expression divergence between two yeast species, S. bayanus and S. cerevisiae. Specifically, genes with nucleosome-depleted MBP1 motifs upstream of their coding sequence show periodic expression during the cell cycle, whereas genes with nucleosome-shielded motifs do not. In addition, conserved cell cycle regulatory motifs across these two species are more nucleosome-depleted compared to those that are not conserved, suggesting that the degree of conservation of regulatory sites varies, and is reflected by nucleosome occupancy patterns. Finally, many changes in cell cycle gene expression patterns across species can be correlated to changes in nucleosome occupancy on motifs (rather than to the presence or absence of motifs).

Conclusions

Our observations suggest that alteration of nucleosome occupancy is a previously uncharacterized feature related to the divergence of cell cycle expression between species.
Significant linkage at chromosome 19q for otitis media with effusion and/or recurrent otitis media (COME/ROM)
Authors: Chen Wei-Min , Allen E Kaitlynn , Mychaleckyj Josyf C , Chen Fang , Hou Xuanlin , Rich Stephen S , Daly Kathleen A , Sale Michèle M
Published: September 2011

Background

In previous analyses, we identified a region of chromosome 19 as harboring a susceptibility locus for chronic otitis media with effusion and/or recurrent otitis media (COME/ROM). Our aim was to further localize the linkage signal and ultimately identify the causative variant or variants. We followed up our previous linkage scan with dense SNP genotyping across in a 5 Mb region. A total of 607 individuals from 139 families, including 159 affected sib pairs and 62 second-degree affected relative pairs, were genotyped at 1,091 SNPs. We carried out a nonparametric linkage analysis, modeling marker-to-marker linkage disequilibrium.

Results

The maximum log of the odds (LOD) score increased to 3.75 (P = 1.6 × 10-5) at position 63.4 Mb, with a LOD-1 support interval between 61.6 Mb and 63.8 Mb, providing significant evidence of linkage between this region and COME/ROM. The support interval contains over 90 known genes, including several genes involved in the inflammasome protein complex, a key regulator of the innate immune response to harmful exogenous or endogenous stimuli. Parametric linkage analysis suggests that for a sib of an affected individual, the recurrence risk of COME/ROM due to this linkage region is twice the recurrence risk in the population. We examined potential associations between the SNPs genotyped in this region and COME/ROM, however none provided evidence for association.

Conclusion

This study has refined the 19q region of linkage with COME/ROM, and association results suggest that the linkage signal may be due to rare variants.
Experimental infection of Bama miniature pigs with a highly virulent classical swine fever virus
Authors: Sun Yuan , Jiang Qian , Tian Da-Yong , Lin Huan , Li Hong , Han Qiu-Ying , Han Wen , Si Chang-De , Hu Shou-Ping , Zhang Zhuo , Qu Lian-Dong , Qiu Hua-Ji
Published: September 2011

Background

Currently, larger domestic pigs are only animals widely used in vaccine evaluation and pathogenicity study of classical swine fever virus (CSFV). This study was aimed to create an alternative animal experimental infection model of CSFV.

Results

Twenty specific-pathogen-free Bama miniature pigs were randomly divided into two groups and rooms, infected and non-infected, and the pigs in the infected group were inoculated intramuscularly with 104, 105 or 106 TCID50 (median tissue culture infective dose) CSFV Shimen strain (n = 5 × 3) or left uninoculated to serve as in-contact pigs (n = 3). The uninfected control pigs (n = 2) were housed in a separate room. Clinical signs, body temperature, viraemia, tissue antigen distribution, pathological changes and seroconversion were monitored. Clinical signs were observed as early as 2 days post-inoculation (dpi) in all infected pigs (though mild in contact pigs), but not non-infected control pigs. All inoculated pigs showed viraemia by 6 dpi. The in-contact pigs showed lower levels of viraemia. At 10 dpi, seroconversion was noted in five of the 15 inoculated pigs. All inoculated or one in-contact pigs died by 15 dpi.

Conclusions

These results show that Bama miniature pigs support productive CSFV infection and display clinical signs and pathological changes consistent with CSFV infections observed in larger domestic pigs.
Generation of a recombinant rabies Flury LEP virus carrying an additional G gene creates an improved seed virus for inactivated vaccine production
Authors: Tao Lihong , Ge Jinying , Wang Xijun , Wen Zhiyuan , Zhai Hongyue , Hua Tao , Zhao Bolin , Kong Dongni , Yang Chinglai , Bu Zhigao
Published: September 2011

The rabies Flury Low Egg Passage virus (LEP) has been widely used as a seed virus to generate inactive vaccine. Here, we established a reverse genetic system for LEP and generated a recombinant LEP virus (rLEP-G) that carries two identical G genes. This recombinant virus showed similar properties to those of LEP with respect toin vitrogrowth, neurotropism index, and virulence in mice. rLEP-G produced 4.3-fold more G protein than did LEP in BHK-21 cells. The inactivated vaccine generated from rLEP-G induced significantly higher virus neutralization titers in mice and dogs than those produced in response to LEP-derived vaccine. Our results suggest that rLEP-G is an improved seed virus candidate for inactivated rabies virus vaccine manufacture.
Noise and Health—Sleep Disturbance in Adults
Authors: Kawada Tomoyuki
Published: September 2011

Noise and Health—Sleep Disturbance in Adults: Tomoyuki Kawada, Department of Hygiene and Public Health, Nippon Medical School—Factors modifying the effect of environmental noise on sleep include sex, age, susceptibility, personality and the health status, including past and present history of disease.

Objective

The effects of noise on sleep and habituation of sleep to noise were summarized.Results and conclusions:1) The effect of noise on sleep is associated with physical changes, such as changes in heart rate, blood low volume, breathing and the immune and neurocirculatory systems. During sleep, specific changes in these indicators are noted during different sleep stages. There are individual and sex differences, and it is important to understand the effects of noise on sleep considering several related factors. 2) Habituation to noise is also an important phenomenon that must be addressed while considering the effects of noise on sleep. Habituation is dependent on the type and sound level of the noise. In occupational ields, shift work and job stress should be considered to determine the association between noise and sleep, which is important to retaining a good quality of working life.
Prediction of Poisson's Ratio and Young's Modulus for Hydrocarbon Reservoirs Using Alternating Conditional Expectation Algorithm
Authors: Al-Anazi Bandar D. , Al-Garni Mohammed T. , Muffareh Tale , Al-Mushigeh Imad
Published: September 2011

Rock mechanics is the theoretical and applied science of the mechanical behavior of rock, the branch of mechanics concerned with the response of rock to the force fields of its physical environment. In hydraulic fracturing, rock mechanics is important in the determination of mechanical properties and the in-situ stress state of reservoir rock, the calculation of deformation and failure behavior of the rock mass caused by the treatment, and the determination of the fracture's final geometry

Knowledge of mechanical properties variation is of great importance for Petroleum Engneering. mechanical properties is often measured in the laboratory from cores. Lab measurements is expensive and time consuming. Many correlations and models were used have been proposed to estimate mechanical properties using some lab measurements data. Different artifacial intelegence techniques were implemented in several studies. This work describes the use of Alternating Conditional Expectation Algorithm technique to estimate Poisson's Ratio and Young's Modulus as a function of Depth with lab porosity Overburden Stresses Pore Pressure, Minimum Horizontal Stress measurements and Bulk Density (RHOB),DT Compressional and DT Shear from logs data In this study, 602 data points of lab measurements and log data were used The proposed models evolved estimates Poisson's Ratio and Young's Modulus with good accuracy with correlation coefficient (R2) of 0.994 and 0.974
Modelling of a Down Hole Pulsating Device
Authors: Nagib Mohamed , Solomon Isu , Isaac Ugbogu , Nasr Ghasem. G.
Published: September 2011

An increased awareness of drilling costs amidst the volatile nature of the market has necessitated pushing the frontiers of drilling technology to improve efficiency thereby saving costs. It is in view of this trend that the concept of drilling using a downhole pulsating device was conceived. This method sought to optimise drilling performance by manipulating two drilling parameters; the weight on bit and transient hydraulic fluid effects in order to obtain an empirical model for subsequent simulations which Consist of includes a pilot well drilled on paper. The downhole pulsating device is fitted in the bottomhole assembly and primarily comprises of two valve plates sitting flush against each other. The bottom plate is static in the wellbore allowing fluid to pass through its centre while the top valve is rotated around the wellbore circumference by the rotor of the mud motor, thus constraining the flow in the flow path. Transient hydraulics generates pulses which impact on the drilling performance and it has been proven to enhance the rate of penetration.

It was noted that there is a momentary underbalance as the downhole pulsating device undergoes through a complete opening cycle. Hence there is a need to use a rotating head to secure the well. A further advantage of this method is economically viable and it is only requires fitting the downhole pulsating device through a sub into the drill string.

A model of fluid flow across a downhole pulsating device was generated using a two parameter, second degree polynomial equation, which includes the force generated and transferred to the bit, and the opening ratio of the downhole pulsating device within a unit time interval. It was also demonstrated that drilling with a downhole pulsating device exerts more hydraulic horsepower on the drill bit and provides better cleaning for the bit.
Effects of Induced Migration of Fines on Water Cut during Waterflooding
Authors: Zeinijahromi Abbas , Lemon Phillip , Bedrikovetsky Pavel
Published: September 2011

Permeability decline during corefloods with varying water composition, especially with low salinity water, has been widely reported in the literature. It has often been explained by the lifting, migration and subsequent plugging of pores by fine particles, which has been observed in numerous core flood tests with altered water composition. This effect can be considered to provide a relatively simple method for mobility control during waterflooding. In previous research, the Dietz model for waterflooding in a layer-cake reservoir with a constant injection and production rate was combined with a particle detachment model to investigate the effect of fines migration and induced permeability decline on reservoir sweep efficiency. In this work, the analytical model was extended to waterflooding with a given pressure drop between injection and production wells. The modelling showed that permeability decline in the water swept zone, caused by the alteration of the injected water composition and induced fines migration, may be able to improve waterflood performance by delaying water breakthrough and reducing the water cut at producing wells.
Effect of Near Wellbore Condition on Electrical Submersible Pump Design
Authors: Noui-Mehidi Mohamed N.
Published: September 2011

The number of electrical submersible pumps (ESPs) used as an artificial lift process is increasing worldwide, due to their efficiency and their ability in increasing production rate substantially. Yet ESP's field implementation needs a proper design to achieve the lift efficiency needed. In case of deep and ultra deep wells, which are drilled frequently, selecting the right ESP configuration and arrangement is critical to the success of the lifting operation. The wellbore space, the rate targeted and the costs involved are among the crucial parameters for the choice of an ESP system. Reservoir conditions or at least near wellbore conditions are not taken directly into consideration while designing the ESP system. The overall ESP design — including the number of stages and motor size — is determined by pre-defined wellbore parameters, and intake and discharge pressure. The present analysis reveals the effect of skin on the targeted ESP design and the associated system characteristics.
Plans for Chemical Enhanced Oil Recovery in a North Oman Carbonate Field
Authors: Soek Harry , Jaboob Musallam , Singh Maniesh , Jabri Ahmed , Stoll Martin , Faber Rien , Al Harthy Khalfan , Al Mjeni Rifaat , Wunnik John van
Published: September 2011

Most of PDO’s carbonate fields in North Oman have been producing for many years, initially on depletion in the early days but were quickly put on water injection to maintain reservoir pressure and safeguard long term ultimate recovery. As these fields mature into early middle age, EOR options have been under review to further increase recovery.

Given the reservoir properties and the prevailing fluid & gas conditions for these carbonate fields, thermal technologies are not considered an optimal choice. Gas floods would potentially feature but were screened out due to the overall balance between gas requirements, cost and potential reward. Chemical floods with potentially attractive high recoveries were selected for further assessment.

The goal is to demonstrate that chemical technology can produce economic incremental oil from a waterflooded carbonate reservoir containing a low-viscous light oil. The reservoir selected has undergone a successful waterflood implementation with good control on historical voidage and production allocation. The potential follow up chemical flood is then planned to be introduced in a phased manner. This starts with phase behaviour and core flow experiments in the lab to find a suitable chemical formulation to optimally mobilize waterflood residual oil. This is then followed by field trials such as a Single Well Chemical Field Test to back up lab experiments, extensive logging, a MicroPilot test and a planned potential multi-well pilot. Full field implementation is then dependant on the results of the earlier project phases and will have to balance against the perceived rewards, risk and cost. The results to date, learning's and key findings along with the selection strategy and challenges will be discussed in this paper. This study and field work will provide a foundation upon which the future potential for chemical flooding in North Oman carbonate fields can be evaluated and implemented.
Experimental and Simulation Study On Use Of Surfactant and De-Emulsifier Blend Additives In Steam Flood As EOR Technique In Heavy Oil Reservoir
Authors: Tiamiyu Olanrewaju M. , Boukadi Fathi
Published: September 2011

Continued research and field application of steam flooding have confirmed an early conclusion that the process is a powerful method for recovering heavy and intermediate gravity crude oils. This experimental study investigates the feasibility of using low concentrate solution of blend of surfactant and de-emulsifier as an additive to steam flooding. This research is also designed to search for optimization of the process of steam flood through recovering additional oil via using a steam with low concentration of surfactant and de-emulsifier mixture without the production of oil-water emulsion. To achieve these goals, four flow experiments are conducted as follows: (1) conventional water flood (2) surfactant solution flood (3) conventional steam flood and (4) low concentration surfactant added steam flood (SASF). Injection of steam with low concentration surfactant improved oil recovery compared to either surfactant solution or conventional steam flood. A comparison of the obtained results of the four undertaken experiments results in three major conclusions, which are (1) addition of 0.1% volume of surfactant and de-emulsifier blend into steam drive improves its performance and consequently recovers 13% OIIP additional oil compared to conventional steam flood, (2) using higher concentration of surfactant (0.1% vol.) into steam flood will not produce any significant increase in additional oil recovery and (3) the inclusion of de-emulsifier in the surfactant added steam run results in non production of oil-water emulsion. The results of this study have validated the proposed technique of surfactant and de-emulsifier blend additives in steam flood as an EOR process. Furthermore, this technique is expected to have significant impact to attain potential incremental oil recovery, if applied in current projects of conventional steam flood and/or water flooded reservoirs.
Challenges in Interpreting Well Testing Data from Fractured Water Injection Wells with a Dual Storage Phenomenon
Authors: BinAkresh Saud A. , Anisur Rahman N. M.
Published: September 2011

Injection wells are widely used in the petroleum industry to support oil production. Water is injected into the reservoir for filling in the void space left by produced oil and to maintain the reservoir pressure. These injectors are frequently tested by means of falloff tests to assess their injectivity. In most of the injectors, water is injected under fracturing conditions, which induce large fractures over time; however, most falloff tests on these wells do not exhibit any clear fracture behavior. Instead, prolonged storage effects with a long unit-slope line on the log-log plot are observed in the data. The observed storage coefficient values are found larger than the typical values in regular wellbores by one or two orders of magnitude.

In this paper, we will show and discuss several falloff tests from water injection wells in giant oil fields in the Middle East. These tests were conducted over the years to show how the entire test duration is progressively dominated by larger wellbore storage with increasing fracture volume around the wellbore. As a result, the radial flow regime on the pressure derivative plot gets a little chance to develop within the stipulated test period. This abnormal behavior suggests that the wellbore is connected to additional storage volume due to a fracture system around the well, having been intersected by a section of it. Apparently, these fractures close gradually after shutting in the well for a pressure falloff test, manifesting as a prolonged storage effect in the data. The examples with real data will also illustrate the phenomenon of dual storage effect – one due to the wellbore, followed by another one due to the fracture volume. We will show how to use the appropriate fracture storage coefficients to estimate fracture dimensions.
A Comprehensive Look at the CRI Project Pilot Test in KSA
Authors: Al-Dossary Abdulla Faleh , Ahmad Iqbal , Al-Ghamdi Mohammed , Al-Hendi Adel , Al-Haj Haider
Published: September 2011

The current practice for offshore drilling operations requires dumping cuttings immediately after being treated at the site into the sea. In shallow waters; this practice will jeopardize the lives of sea creatures and hinder the marine traffic. Therefore, this method is not applicable for this field. There are three waste disposal methods to replace the existing method; first, the cuttings are treated on site and then shipped to land where they are dumped in special mud disposal pits. Ultimately, those pits are buried. The second option is to dump the cuttings after being treated in a sea trench near wells to be drilled. The third solution is to utilize the advanced waste management technology where the cuttings are injected back into its original environment. The last is considered to be the safest and most cost-effective method. Therefore, the company planned to implement this technique. As a step forward, Saudi Armco elected to test the feasibility of this technology. An old onshore disposal well was selected for this test. In this test, four formations were tested one after another to find out the most appropriate one for hosting the cuttings. This paper discusses and explains the test in detail. Moreover, the injection capacity of each zone tested will be projected against the test results using IPR (Inflow Performance Relationship) and OPR (Outflow Performance Relationship) curves methods.
Production Forecasting in Heterogeneous Reservoirs without Reservoir Simulation
Authors: Akram A. H. , Camilleri L. , Badr A.
Published: September 2011

As an increasing percentage of the world’s production comes from mature fields, there is a growing need for production enhancement techniques that are both rapid and easy to use for the practicing production engineers. For mature waterfloods, the ln(WOR) versus Np plot enables rapid well screening on the basis of incremental recovery factor, where WOR is the producing Water Oil Ratio and Np is the cumulative oil production. Published in-depth information on application of this tool is sparse. Yet, this is often the only tool available to the production engineer for evaluating development options, where a history-matched simulation model has not been maintained.

In this paper, the theoretical basis for the use of the ln(WOR) versus Np is reviewed and studied, and is used to arrive at practical guidelines for interpreting production data. Its applicability as a forecasting tool to single-layered and multilayered clastic, waterflooded reservoirs of varying heterogeneity is demonstrated. Numerical simulation models then predict the behaviour of this plot for a wide range of heterogeneities.

Production data is then analysed to show the applications of the theory for multilayered reservoirs. The ln(WOR) versus Np plots are analysed, and the impact of various factors is observed. The authors also demonstrate that, where applicable, this plot is the preferred decline curve for the following reasons: –Ln(WOR) versus Np does not require any pressure data; only surface well test production history is required.–It can be assumed that the ln(WOR) versus Np function is an approximate function of the reservoir only, and is decoupled from the outflow and facility constraints. This is especially useful when comparing artificial lift and drawdown strategies.–It is a decline curve model that provides a forecast of water cut, which is indispensable on waterflood projects.
Analysis of "Lower Limit Formation" in Low Permeability Sands of Ordos Basin
Authors: Xiao Liang , Mao Zhi-qiang , Shi Yu-jiang , Guo Hao-peng
Published: September 2011

With the analysis of reservoir resistivity and diagenetic facies, the reasons of causing "lower limit formation" are expounded in low permeability sandstones of Ordos basin, northwest China. The difference between dry layers and lower limit formations and corresponding recognition method are displayed. In dry layers, the formations undergo the destructive diagenic metamorphism, such as the kaolinite packing action and dense compaction, this lead the formation poor pore structure, low porosity and low permeability, in these kinds of layers, no fluids can be produced. In lower limit formations, the main diagenetic facies are positive, for example, the chlorite line edge feeble denudation diagenetic facies and unstable component denudation diagenetic facies, but some interlayers with destructive diagenetic facies (kaolinite packing action diagenetic facies, dense compaction diagenetic facies or carbonate cementation diagenetic facies) exist, these make formations’ porosity and permeability decrease and are lower than the conventional reservoirs, the physical property parameters are nearly the same with dry layers. The resistivities of lower limit formations are a little higher than dry layers, the resistivity boundary of them is 42 ohm.m. In reservoirs with porosity and permeability lower than the lower limit value of conventional formations, if the main diagenetic facies are positive (although they contain the interlayers with destructive diagenetic facies) and formation resistivity is higher than 42 ohm.m, oil or water can be extracted after some steps are taken.
Contractor HSE Management via Effective Mitigation of Risk in the Tendering Process
Authors: Elkhair Gamal Abou , Al-Haidar Adnan
Published: September 2011

Description

Effective Management of the Contractor HSE performance starts from an Effective Mitigation of risks in the Tendering Process. In Contracts for Oil & Gas Industry, the work force was mainly Company employees and since 1990 there has been a significant increase in the use of contractor staff which resulting shift in responsibilities/risk from the company to contractor.

International Association of OIL and Gas Producers (OGP) published "HSE Management Guidelines for Working Together in a Contract Environment" (Report No. 6.64/291, September 1999). Most Operators’ HSE Management Systems follow these Guidelines.

Application

Is the following sentence is true?

"There is a very little that Contracts Professionals can do to drive the Best Safety & Environmental Performance on Site." If it is true, HOW can they do it? Is this a paradigm that they should challenge?

How risk assessment is performed and how results are translated into Practical Contract Strategy?

Results, Observations & Conclusions

Significance of Subject Matter

Contracts Professionals can do the followings to drive the Best Safety & Environmental Performance on Site: Include a step in the Tender's process requiring specific technical outputs from Risk Assessment (for input into Tender requirements)Include a step in the Contract award process requiring specific technical output from HSE evaluation (for input to final contract)

Management of HSE in a business environment where two or more companies work together requires co-operation between them and a clear definition of the tasks and responsibilities of each of the parties.
Integrated Pre-Well Planning Process Improves Service Quality and Decreases Risk through Cooperation between Drilling and Geosciences
Authors: Aldawood J. M. , Ahmed K. , Al-Ansari Y. S. , Zubairi B. A. , Hanafi M. X.
Published: September 2011

Drilling complex wells with minimum risk and optimizing well placement with the least possible cost are key goals that oil companies strive to achieve. Service companies and operators apply several pre-well planning processes and methods to enhance drilling operations effectively and attain objectives. One of these processes involves a thorough understanding and application of the geological structure, not only within the reservoir section, but also in the over-burden where typically most of the time efficiency gains can be achieved. This can be best accomplished by fostering intense and effective communication between all stakeholders.

In this paper, the authors present the latest integrated pre-well planning (IPWP) process that defines a methodology for conducting a formal planning, a process incorporating all aspects of drilling, well design, formation evaluation, bit selection and bottom hole assembly proposal. It also lists key considerations required in planning, coordination, and successful implementation of these services on the customer’s well with a means to assess potential technical risks that may influence the success of the job.

The paper also describes a complex water injection well drilled in a Middle East onshore field where the integrated pre-well-planning process played a significant part in successfully achieving the aim of this challenging job.
Measuring the Reaction Rate of Lactic Acid with Calcite Using the Rotating Disk Apparatus
Authors: Rabie Ahmed I. , Nasr-El-Din Hisham A.
Published: September 2011

Lactic acid has been tested in various laboratories and applied in the field for acid fracturing. However, the rate of reaction of lactic acid with calcite has not been addressed before. This is mainly because of the complexity of the reaction kinetics and the thermodynamic equilibrium that limits the acid reactivity. Determination the reaction rate is a critical step for any successful matrix acidizing or acid fracturing. Therefore, the aim of this work is to conduct a detailed study on the reaction of lactic acid with calcite. Mass transport properties and the reaction kinetics are reported for such system for the first time using the rotating disk apparatus.

Core samples of 1.5 in. diameter and 1 in. length were cut from Indiana limestone and were used in the reaction rate experiments. The effect of lactic acid concentration (1, 5, and 10 wt%), temperature (80–250°F), disk rotational speed (100–1800 rpm), and different inorganic salts on the reaction rate was investigated. The diffusion coefficient of 5 wt% lactic acid was determined at low rotational speeds and reported at 80, 200, and 250°F. The data of the reaction rate measured at 1500 rpm and in a temperature range 80–250°F was used to determine the reaction kinetics. The activation energy and the reaction rate constant for the reaction of lactic acid with Indiana limestone was reported at 80, 150, 200, and 250°F.

The reaction of lactic acids with calcite was controlled by mass transfer at low disk rotational speeds (up to 500 rpm) and surface reaction limited at higher speeds. The acid diffusion coefficient increased with increasing the reaction temperature. The presence of inorganic salts significantly reduced the reaction rate.
Successful Field Application of Surfactant Additives to Enhance Thermal Recovery of Heavy Oil
Authors: Srivastava P. , Castro L.
Published: September 2011

In this paper, we will describe successful field applications of a class of surfactants called Thin Film Spreading Agents (TFSA) to enhance thermal recovery of heavy oil. TFSA has been successfully applied in cyclic steam stimulation (CSS) applications in California and Alberta, Canada and three such case histories will be presented. In Canada, three oilsands CSS wells were treated with 250ppm of TFSA. After a certain number of steam cycles, all wells decline in production relative to the previous steam cycle. After 500 days of production the TFSA treated wells only declined 1.0%. The primary control group of wells declined 39%. The cumlative increase in production of the TFSA treated wells was 20% (6718 bbls/well) greater than the control group. In California, 17 vertical CSS wells in a sandstone formation were treated with TFSA to realize incremental oil recovery. Out of 17 wells, 14 showed an average incremental oil recovery of 5411bbls translating into a success rate of 82%. The average payout period was 13 days. The producer realized a net revenue increase of USD 26 million. In another field application in California, 44 vertical CSS wells in a sandstone formation were treated with TFSA to realize incremental oil recovery. Out of 44 wells, 32 showed an average incremental oil recovery of 720bbls translating into a success rate of 73%. The average payout period was three days and the producer realized a net revenue increase of USD 11.8 million. These field results establish the efficacy of TFSA in increasing recovery in thermal applications.
Unified, Automated and Map-based E&P Data Management
Authors: Waked Sahal , Al-Ghamdi Yasser , Al-Zahrani Abdulkarim , Al-Radhi Yassir
Published: September 2011

Increased demand for energy has placed oil and gas companies like Saudi Aramco at the forefront to meet market needs and has required expanded exploration and production activities. As a result, the amount of new exploration data acquired has grown exponentially. This unprecedented expansion of data requires the introduction of new and novel methods and solutions to ensure the value of this vast data is realized.

Saudi Aramco is implementing a unified seismic & well data management system that allows geoscientists and engineers to easily find, access, visualize and transfer data stored in distributed vendor and corporate data repositories. As an example, the Seismic Volume Management web-based system (SVM) was developed to optimize and streamline the E&P data stored across the enterprise. Geoscientists and engineers can now find seismic data using three types of searches: single/multi-field metadata queries, Google like search, or through a GIS map. Users also have the ability to subscribe to email notifications when any selected data located in vendor or corporate databases is changed or updated. Extending SVM features to manage well data will provide a significant improvement to current workflows. This unified data access solution will ensure that geoscientists and engineers spend more time performing E&P activities rather than searching and analyzing data.
An Economic Evaluation Model for Selecting Sand Management Technology
Authors: Lixin Ren , Xiaodong Wu , Benjing Dong
Published: September 2011

As we know, sand production can bring about both positive and negative effects. For example, besides borehole problems, sand production can improve the porosity and permeability of reservoirs. This is why the strategy to handle sanding problems can vary from stimulating sand production to sand control. So far, the industry has developed all kinds of sand management technologies, including treatments both on surface and downhole.

When we meet sand production problems in oil field development, we need to find a solution based on certain of sand management technologies. Conventionally, we conduct an analysis on sand production reasons and possibilities first, and then we pick a technical solution from some known technical alternates. However, generally, it is difficult to tell which option is the best, because when we make a technical decision, the main factor or even the only factor we take into consideration is the technical feasibility or technical advantages of a system. Some operators like to use high-tech solutions, some like to use normal ones. High-tech does not mean definitely to bring a bigger benefit than normal-tech. Unless we have compared the economic benefit of each technical solution within a given term, we cannot tell which one is the best solution.

Economic evaluation model (EEM) for sand management tech selection is seldom discussed in previous references. This paper launches an independent EEM that can help us select the sand management solution by economic benefit evaluation instead of by technical factors solely. Factors related to the model are detailed in the paper. Examples are given to show how to use the model.

In addition, some common issues in sand prediction models are discussed herein, suggestions on how to improve the models given. The paper believes the classification of sanding severity is quite necessary. A classification of sanding severity is proposed.
Management of Asphaltenes Deposition in a Giant Carbonate Onshore Oil Field, Abu Dhabi, U.A.E.
Authors: Misra Sanjay , Abdulla Dalia , Bazuhair Mohammed , Aboukshem Ali , Stenger Bruno , Katheeri Abdulla Al
Published: September 2011

Recently observed production behavior in a maturing carbonate oil reservoir indicated that many production strings were getting plugged with solid scales, requiring tubing clean-out jobs. This is the main reservoir of a supergiant onshore carbonate oil field operated by ADCO since 1973. Some cases proved to be no more than calcium carbonate scaling following water breakthrough and the tubing blockage was successfully treated with acid washing. A number of plugged strings revealed that a non-mineral hard scale was the cause of the blockage. Upon analysis, such scales proved to have an organic composition rich in asphaltenes. While solvent washing was successful in removing the blockage, rapid reoccurrence was observed in many cases. The subsurface asset team embarked on a detailed reservoir monitoring and fluid compatibility study to establish causative factors. One of the aims of the study was to check a possible link between the asphaltenes deposition with a naturally occurring tarmat and a rich-gas injection pilot, both located in the severely affected part of the reservoir. This work revealed that although the severity of the problem is higher in the tarmat area, asphaltenes mobilization from the tarmat layer was not considered a realistic mechanism. Although PVT studies revealed that rich gas dissolution in the crude at reservoir conditions triggered asphaltenes instability and precipitation but occurrence of asphaltenes deposition in the field seemed unrelated to the rich-gas injection as the injected gas was moving in a different reservoir subzone. Most of the plugged strings were unlikely to have had gas breakthrough at the time of problem detection and no clear spatial relationship could be evidenced. A preferred explanation may be that asphaltenes precipitation is related to differences in crude oil composition within the studied reservoir. The reservoir might have seen successive oil influxes from two source rocks with wide distribution of mixing ratios. Asphaltenes originating from one of the source rocks might cause greater fluid instability even at the observed low concentrations. Production rate sensitivities indicated that asphaltenes blockage was retarded at higher production rates. Many asphaltenes dispersant/inhibitor chemicals were evaluated for effective tubing clean-out and preventing asphaltenes deposition. Some chemicals proved to be more effective in mitigation and prevention of asphaltenes deposition.
Hammer Drilling Technology - The Proved Solution to Drill Hard Rock Formations in the Middle East
Authors: Vieira Paco , Lagrandeur Craig , Sheets Kelly
Published: September 2011

The drilling of "hard rock" formations represents a considerable percentage in the overall cost of a well where these types of formation are present. Low rate of penetration, number of bits required and tripping time are the main factor contributing in the increase of the overall cost. Nowadays this is classified as Invisible Non Productive Time (INPT). Drilling through hard rock could be in some cases the limiting factor to economically develop significant hydrocarbon reserves in some areas. The improvement in the penetration rates in hard rock drilling is an opportunity to reduce overall well costs and the INPT. The Middle East area has in some of their field stratigraphic structure, the presence hard rock formation where the hammer drilling technology has proved to be the most efficient way to drill theses sections. Even though it is not a new technology because it was introduced in the early sixties, it has gained good momentum worldwide and the Middle East Area. Formations with UCS values above 25.000 psi have shown that hammer drilling technology has been able to improved rate of penetration in the factor of 20 and above, thus having a considerable impact in cost. This paper describes the engineering an operational result of the implementation of Hammer drilling technology in the Middle East and the future of the expanding trend if it is used in the area.
New Technique to Sidetrack Across Hard Formation in North Oman
Authors: Ahmed Al Salmi , Younes Al Haji , Saif Al-Hamhami , Isehaq Sabhi , Abduallah Al Fadhli
Published: September 2011

In a north Oman field, it is common practice to cement vertical pilot holes up to the kickoff point. A cement plug is then used to initiate the sidetrack through extremely hard formations. Previously, it has taken several attempts to sidetrack these holes and, in some cases, a mechanical whipstock had to be used.

There are challenges when trying to initiate the sidetrack because the formation hardness far exceeds that of the kickoff cement plug. As a result, the sidetracking assembly is repeatedly directed back into the relatively softer cement plug (i.e., vertically). Gravity also plays a role to some extent in bringing the sidetracking assembly back into the vertical hole, increasing the challenge.

This paper documents successful implementation of modifications to the slurry design and cementing procedure, as well as the successful use of a side-tracking method/technique in North Oman.

The compressive strength of cement has been increased from 5,000 to around 9,000 psi for standard, 17-lbm/gal, Class G cement.

The effect of oil-based mud (OBM) contamination has been examined and spacer designs have been improved to help ensure good mud displacement while performing cementing operations.

The sidetracking method and tools have also been improved with impressive results. This includes proper selection of the kickoff point based on the drill-speed log of the vertical pilot hole, selecting the correct combination and configuration (e.g., outside diameters of components and angle setting) for the bottomhole assembly (BHA), and using the correct application parameters and techniques while initiating the sidetrack, which is also called "time-drilling."

This paper investigates the new techniques applied in detail and clearly illustrates their development. Some case histories are also presented.
Seeing the Invisible: Predicting Fluid Paths with Innovative Curvature Attributes
Authors: Saleh Al-Dossary
Published: September 2011

Natural fractures and faults in the subsurface play an important role in fluid flow and accumulation. Therefore, identifying and mapping the distribution of fracture and fault systems is critical to understanding the fluid dynamics within a reservoir.

Although fractures and small-through faults are not easily identifiable using conventional 3D seismic techniques, their orientation and intensity can often be inferred using seismic attributes, such as coherence and seismic curvature.

This case study will demonstrate how seismic curvature was used to map small scale fractures in a Saudi Arabian oil field, which has been affected by premature water breakthrough. Premature water breakthrough is an increasing concern to all the geoscientists and engineers involved in developing the field. Curvature illuminates subtle fracturing that was difficult to detect with conventional seismic amplitudes. Using curvature allows geoscientists to map, for the first time, small-scale fractures believed responsible for bringing water prematurely to the top of the reservoir. The integration of image logs, zones of lost fluid circulation, production test and well test data has increased our interpretation confidence and helped optimize the placement of future horizontal wells.