bluuebunny/crossref_metadata_2025 huggingface dataset:
Sex hormone-binding globulin predicts the incidence of hyperglycemia in women: interactions with adiponectin levels
Authors: Bonnet F , Balkau B , Malécot J M , Picard P , Lange C , Fumeron F , Aubert R , Raverot V , Déchaud H , Tichet J , Lecomte P , Pugeat M , _ _
Published: May 2009

Objective

Previous evidence has suggested that a low sex hormone-binding globulin (SHBG) concentration is associated with insulin-resistance and a low adiponectin concentration. We investigated the association between SHBG and the risk of hyperglycemia in each sex and we determined potential interactions between SHBG and adiponectin levels in the development of dysglycemia.

Design

We used a nested case–control design in the large prospective study, Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR). We studied 227 men and women who were normoglycemic at baseline but hyperglycemic at 3 years (glycemia≥6.1 mmol/l or type 2 diabetes). They were matched for sex, age, and body mass index with 227 subjects who remained normoglycemic at 3 years.

Results

At baseline, the concentration of SHBG was significantly lower in women who subsequently developed hyperglycemia than in those who remained normoglycemic, with no difference for men. In multiple regression, SHBG at baseline was as an independent determinant of plasma adiponectin levels, in both women (P<0.0001) and men (P=0.002). In multivariate conditional logistic regression taking into account physical activity and changes in waist circumference over the follow-up, plasma SHBG remained significantly associated with the development of hyperglycemia in women but not in men. These associations persisted after adjustment for fasting insulinemia, high fasting glucose, and adiponectin levels.

Conclusions

These findings suggest that a low SHBG level is a strong risk marker for dysglycemia in women, independently of both adiponectinemia and insulinemia. SHBG may therefore improve the identification of women at risk of diabetes.
Evaluating the Power Output of the Smith-Root GPP 5.0 Electrofisher to Promote Electrofishing Fleet Standardization
Authors: Martinez Patrick J. , Kolz A. Lawrence
Published: May 2009

The Smith-Root (S-R) series of GPP (gas-powered pulsator) electrofishers are widely used in boat-mounted electrofishing systems. Sampling in waters having different conductivities requires adjustment of the electrofisher controls to maintain consistent output power. However, the current meter supplied on GPP electrofishers provides an average rather than a peak measurement, and because no voltmeter is included, determining peak power output is not possible. As part of an overall effort to promote standardization of electrofishing operations, we used static electrical loads to measure the output characteristics of the commonly used S-R GPP 5.0 electrofishers under simulated electrofishing conditions. The range of resistance values to be simulated with static loads was extrapolated from in-water measurements of five electrode configurations consisting of paired, half-submerged, spherical anodes in combination with a 5.5-m-long flat-bottom aluminum-hull boat serving as the cathode. We measured the power output of GPP 5.0 electrofishers while they were connected to static loads of 114, 19, 9.5, and 5.7 Ω to simulate a wide range of ambient water conductivity values (approximately 100–1,000 μS/cm). These measurements of GPP 5.0 power output will provide electrofishing fleets with an improved understanding of electrofisher operational controls and performance and allow for a more consistent method of selecting electrofisher settings.
IGF2 mRNA-binding protein 2: biological function and putative role in type 2 diabetes
Authors: Christiansen Jan , Kolte Astrid M , Hansen Thomas v O , Nielsen Finn C
Published: May 2009

Recent genome-wide association (GWA) studies of type 2 diabetes (T2D) have implicated IGF2 mRNA-binding protein 2 (IMP2/IGF2BP2) as one of the several factors in the etiology of late onset diabetes. IMP2 belongs to a family of oncofetal mRNA-binding proteins implicated in RNA localization, stability, and translation that are essential for normal embryonic growth and development. This review provides a background to the IMP protein family with an emphasis on human IMP2, followed by a closer look at the GWA studies to evaluate the significance, if any, of the proposed correlation between IMP2 and T2D.
Angiotensin II enhances the increase in monocyte chemoattractant protein-1 production induced by tumor necrosis factor-α from 3T3-L1 preadipocytes
Authors: Asamizu Sachie , Urakaze Masaharu , Kobashi Chikaaki , Ishiki Manabu , Norel Din Amal Khalifa , Fujisaka Shiho , Kanatani Yukiko , Bukahari Agussalim , Senda Satoko , Suzuki Hikari , Yamazaki Yuh , Iwata Minoru , Usui Isao , Yamazaki Katsuya , Ogawa Hiroshi , Kobayashi Masashi , Tobe Kazuyuki
Published: May 2009

Monocyte chemoattractant protein-1 (MCP-1) and angiotensin II (Ang II) in adipose tissue are thought to induce systemic insulin resistance in rodents; but the precise mechanism is not fully clarified. We examined the mechanism of Ang II-induced and/or tumor necrosis factor-α (TNF-α)-induced MCP-1 production from 3T3-L1 preadipocytes. The MCP-1 protein and MCP-1 mRNA expression in 3T3-L1 preadipocytes were increased significantly by stimulation with TNF-α. We found no significant increase in MCP-1 concentrations by Ang II alone; but it enhanced the TNF-α-induced MCP-1 mRNA expression in a dose-dependent manner. Then, we examined the effect of Ang II and/or TNF-α on phosphorylation of extracellular signal-regulated kinase (ERK), p38MAPK, and IκB-α. Ang II and TNF-α clearly enhanced ERK and p38MAPK phosphorylation. IκB-α phosphorylation was enhanced by TNF-α, but not by Ang II. The MCP-1 mRNA expression induced by TNF-α and co-stimulation with Ang II was inhibited by either ERK inhibitor, p38MAPK inhibitor or NF-κB inhibitor. Moreover, Ang II enhanced the activation of AP-1 (c-fos) induced by TNF-α. Our results suggest that Ang II may serve as an additional stimulus on the TNF-α-induced MCP-1 production through the ERK-and p38MAPK-dependent pathways probably due to AP-1 activation.
Support for the Reliability and Validity of a Six-Item State Anxiety Scale Derived From the State-Trait Anxiety Inventory
Authors: Tluczek Audrey , Henriques Jeffrey B. , Brown Roger L.
Published: May 2009

Identifying the most efficient and theoretically appropriate methods to assess patient anxiety in fast-paced medical environments may be beneficial for clinical purposes as well as for research. The purpose of this study was to examine the reliability and validity of two previously published six-item versions of the State form of the State-Trait Anxiety Inventory (STAI) and to identify the version that would be most appropriate to use with a sample of parents who had infants with normal or abnormal newborn screens. In the current study, confirmatory factor analyses were conducted to evaluate the fit of the two six-item forms with STAI data collected at three time points from 288 parents of 150 infants. Study groups of parents were based upon infant newborn screens and subsequent diagnostic testing to include cystic fibrosis (CF; n = 26), congenital hypothyroidism (CH; n = 39), CF Carriers (CF–C; n = 45), and healthy infants (H; n = 40). The results showed the version containing items 1, 3, 6, 15, 16, and 17 of the State form of the STAI to be a better fitting model across all three time points, and it had better internal consistency than the version containing items 5, 9, 10, 12, 17, and 20. Both short forms were highly correlated with the 20-item STAI score, and all internal consistency reliabilities were greater than .90. It was concluded that the version containing items 1, 3, 6, 15, 16, and 17 of the State Anxiety scale was a reliable and valid instrument for this study sample.
Reliability and Limitations of the Durometer and PressureStat to Measure Plantar Foot Characteristics in Native Americans With Diabetes
Authors: Cuaderes Elena , Khan Myrna M. , Azzarello Joseph , Lamb W. Lyndon
Published: May 2009

Neuropathy with excessive weight-bearing activity may lead to foot changes that place it at risk for ulceration. Information about instruments to measure plantar skin hardness and pressures of the foot in adult Native Americans with diabetes is presented. Skin hardness was measured at 10 sites (plantar side of the hallux, third and fifth toes, first, third, and fifth metatarsal heads, medial and lateral midfoot, heel, and the dorsal aspect between the hallux and second toe) with a durometer. The PressureStat yielded data about barefoot, static pressures. The durometer was shown to be reliable (r = .62 to .91) at all sites of the foot except at the third and fifth toe, the medial midsection of both feet, and at the third metatarsal head and between the hallux and second toe, the dorsal aspect of the left foot. With four raters, concordance was found to be acceptable at the hallux, the third toe, the first, third, and fifth metatarsal heads and the heel (W = .61 to .86) for the PressureStat. Since most diabetic foot ulcers occur at the hallux, first, third, and fifth metatarsal heads, both the PressureStat and durometer may be reliable screening tools to determine the degree of risk.
Development of the Military Women’s Attitudes Toward Menstrual Suppression Scale: From Construct Definition to Pilot Testing
Authors: Trego Lori L.
Published: May 2009

The Military Women’s Attitudes Toward Menstrual Suppression scale (MWATMS) was created to measure attitudes toward menstrual suppression during deployment. The human health and social ecology theories were integrated to conceptualize an instrument that accounts for military-unique aspects of the environment on attitudes toward suppression. A three-step instrument development process was followed to develop the MWATMS. The instrument was pilot tested on a convenience sample of 206 military women with deployment experience. Reliability was tested with measures of internal consistency (α = .97); validity was tested with principal components analysis with varimax rotation. Four components accounted for 65% of variance: Benefits/Interest, Hygiene, Convenience, and Soldier/Stress. The pilot test of the MWATMS supported its reliability and validity. Further testing is warranted for validation of this instrument.
Reliability and Validity of the Jefferson Scale of Empathy in Undergraduate Nursing Students
Authors: Ward Julia , Schaal Mary , Sullivan Jacqueline , Bowen Mary E. , Erdmann James B. , Hojat Mohammadreza
Published: May 2009

Evidence has been reported in support of the reliability and validity of the Jefferson Scale of Physician Empathy (JSPE) when used with physicians, medical students, and nurses. This study examined the psychometrics of a modified version of the scale in undergraduate nursing students. The modified version of the JSPE was administered to 333 nursing students at different levels of training. Three underlying constructs, that is, “Perspective Taking,” “Compassionate Care,” and “Standing in Patient’s Shoes” emerged from the factor analysis of the scale that were consistent with the conceptual framework of empathy, thus supporting the construct validity of the scale. The coefficient alpha was .77. Scores of the empathy scale were significantly correlated with the scores of the Jefferson Scale of Attitudes toward Physician–Nurse Collaboration (r = .38,p < .001). Women scored higher than men, and those with more clinical experiences scored higher than others. It was concluded that the empathy scale used in this study is a psychometrically sound instrument for measuring empathy in undergraduate nursing students.
Ecological vulnerability in wildlife: An expert judgment and multicriteria analysis tool using ecological traits to assess relative impact of pollutants
Authors: Lange Hendrika J. De , Lahr Joost , Van der Pol Joost J.C. , Wessels Yolanda , Faber Jack H.
Published: May 2009

Nature development in The Netherlands often is planned on contaminated soils and sediments of former agricultural land and in floodplain areas; however, this contamination may present a risk to wildlife species desired at those nature development sites. Specific risk assessment methods are needed, because toxicological information is lacking for most wildlife species. The vulnerability of a species is a combination of its potential exposure, sensitivity to the type of pollutant, and recovery capacity. We developed a new method to predict ecological vulnerability in wildlife using autecological information. The analysis results in an ordinal ranking of vulnerable species. The method was applied to six representative contaminants: copper and zinc (essential metals, low to medium toxicity), cadmium (nonessential metal, high toxicity), DDT (persistent organic pesticide, high toxicity), chlorpyrifos (persistent organophosphate insecticide, high toxicity), and ivermectin (persistent veterinary pharmaceutical, low to medium toxicity). High vulnerability to the essential metals copper and zinc was correlated with soil and sediment habitat preference of a species and with r-strategy (opportunistic strategy suited for unstable environments). Increased vulnerability to the bioaccumulating substances cadmium and DDT was correlated with higher position of a species in the food web and with life span and K-strategy (equilibrium strategy suited for stable environments). Vulnerability to chlorpyrifos and ivermectin was high for species with a preference for soil habitats. The ecological vulnerability analysis has potential to further our abilities in risk assessment.
Improvements in Downhole Fluid Identification by Combining High Resolution Fluid Density Sensor Measurements and a New Processing Method: Cases from a Saudi Aramco Field
Authors: Palmer Richard , Silva Andre , Saghiyyah George , Rourke Marvin , Engelman Bob , van Zuilekom Tony , Proett Mark
Published: May 2009

Accurate chemical and physical properties of hydrocarbon and formation water are required for efficient reservoir and production management. During exploration and field development, a sample of formation fluids is frequently required. One method to obtain reservoir fluid samples is with a pumpout wireline formation tester (PWFT) in which the objective of sampling is to collect a representative fluid sample with minimum rig time. Sampling mixed phases or immiscible fluids has been a long standing challenge for fluid identification using PWFTs. The mixing of fluids that are flowing inside the tool increases sensor noise, making the interpretation of fluid type and amount of contamination difficult, if not impossible. Consequently, these noisy sensor readings are often ignored and attributed to fluid transitions during of sampling. This erratic behavior has been observed with most sensors, including resistivity and optical sensors. With the introduction of a new high resolution fluid density sensor and improved data handling techniques, it is now possible to identify these mixed fluid flow regimes of hydrocarbon and water more precisely. The new fluid density sensor monitors the frequency change of a vibrating tube that is filled with the fluid sample quickly and reliably. The high accuracy of this technique enables the determination of additional fluid properties, such as density, water salinity, and fluid compressibility. Furthermore, the new processing methods provide a clearer understanding of the flow behavior, enabling more accurate estimates of fluid contamination. Data from the tool can also be used to observe changes in fluid properties over depth intervals and to aid in the identification of fluid interfaces and compartments.
Real-time Geology/Petrophysics in Complex Carbonate Reservoirs
Authors: Eyvazzadeh Ramsin , BinNasser Rami , Kersey David
Published: May 2009

Geosteering technology has played a key role in enhancing hydrocarbon production and recovery in many reservoirs throughout the world. Traditionally, Logging While Drilling (LWD) measurements are used to determine petrophysical parameters, such as porosity and hydrocarbon saturation in order to geosteer wells in the reservoir. However, in many complex carbonate reservoirs, fluid flow characteristics are generally difficult to predict and the most porous intervals are not always the best reservoirs as intervals of equivalent porosity can exhibit large variations in permeability. In addition, changes in depositional and digenetic environments provide for a complex geology that poses challenges in well placement.

A new technique has been developed that utilizes LWD data and neural network analysis to determine key geological and petrophysical parameters such as lithology, permeability, hydraulic flow units and reservoir quality indicators. These parameters are determined real-time to place wells into the most productive reservoir intervals.

This new technique integrates core descriptions, logging and laboratory measured core data from several offset wells to develop cluster based models that are used to train log data to determine rock types and their inherent petrophysical characteristics. The prediction model is then used in a real-time analysis to geosteer wells into high-pay intervals.
Reservoir Saturation Monitoring in Saudi-Aramco; Benefits, Challenges and Opportunities
Authors: Ariwodo Izu , Al-Hasan Ali H. , Al-Belowi Ali R.
Published: May 2009

Oil production from the giant oil fields of Saudi Arabia is said to be one of the big levers that drive the world economy. Saudi Aramco has been providing the support of this lever with over 70 years of oil production. To maintain its level of production, Saudi Aramco has had to place some of its fields on a water injection scheme, for pressure support and to enhance reservoir recovery. Hydrocarbon sweep and water contact movement through these reservoirs is then monitored through saturation logs.

In Saudi Aramco, hydrocarbon saturation within the reservoir after water has swept through is typically measured with two types of tools: A Gamma ray (GR) detection tool. This tool acquires GR in two modes, namely the sigma/capture mode and the Carbon-Oxygen/inelastic mode.A resistivity tool. This can be logged in cased hole with a cased hole formation resistivity, and in barefoot completions using the slim induction tools.

Both types of monitoring devices, when logged under the right environmental conditions have been found to add significant value to the way we manage our reservoirs. Some of the Saudi Aramco business drivers for logging these tools are: Reservoir management and optimizations.Optimal well placement.Location of the pool of attic or bypassed oil.Calibration of reservoir simulation models.Identification of cost saving workover opportunities.

The existing reservoir monitoring tools in the market are dogged with some challenges. The measurement envelope of the GR tools are very shallow, therefore they suffer from washouts and near wellbore fluid effects, while the resistivity tools require a good knowledge of the flood water salinity for accurate saturation computation. Thus, it is critical that these tools are logged under the right conditions.

In spite of the above challenges, Saudi Aramco continues to look ahead for cost-effective solutions through collaboration with service companies.

This paper will review some of the benefits that Saudi Aramco has derived from over 200 Reservoir Saturation Monitoring (RSM) logs acquired annually, while also highlighting some challenges and opportunities for the future development of these tools.
Advances in Micro-CT Based Evaluation of Reservoir Rocks
Authors: Sarker M. R. H. , Siddiqui S.
Published: May 2009

From the very early days of hydrocarbon exploration and production, cylindrical rock samples known as cores have been used as identifying reservoir samples for determining important physical properties such as porosity, permeability, grain density, and important rock-fluid interaction properties such as wettability, capillary pressure and relative permeability. All of these properties are needed to predict and improve hydrocarbon recovery. Converted medical X-ray CT-scanners have provided the oil industry with many important rock and rock-fluid properties in a non-destructive manner. Although medical CT-scanners have seen constant improvement in speed since their inception in the early ‘70s, the spatial resolution has not improved from the typical 350-450 mm range. Typical pore sizes of reservoir rocks vary from sub-micron to few microns and therefore the oil industry has been looking for alternatives such as micro and nano CT-scanners. Micro CT-scanners have been used successfully to extract valuable information from cuttings-sized rock fragments (Siddiqui et al., 2005) and constant research involving micro CT-scanners can eventually eliminate the need for cutting cores, which is time-consuming, risky and expensive. This paper first presents an exhaustive review of the state-of-the-art in micro CT-based petrophysical research. It describes the various techniques used by researchers for image reconstruction, artifact reduction, segmentation, network extraction, pore body-pore throat distribution leading to the building of realistic pore network models and then determining different petrophysical properties using methods such as Lattice-Boltzman Method (LBM), Finite Element Method (FEM) and Monte-Carlo simulation (MCS). The paper presents some specific applications in petroleum engineering, identifies the areas in which deficiency exists and suggests possible improvements. The paper also discusses future directions in micro CT-based research for obtaining various petrophysical parameters.
Collaborative Development of a Slim LWD NMR Tool: From Concept to Field Testing
Authors: Akkurt Ridvan , Marsala Alberto F. , Seifert Douglas , Al-Harbi Ahmed , Buenrostro Carlos , Kruspe Thomas , Thern Holger F. , Kurz Gerhard , Blanz Martin , Kroken Asbjorn
Published: May 2009

Nuclear Magnetic Resonance (NMR) was identified as a critical technology for reducing uncertainty and minimizing risk during the planning phase of a major field development project. The reservoirs in the subject field contain heavy oil/tar in the flanks, and accurate knowledge of viscosity trends becomes essential for the placement of water injectors. Since NMR logs can be used to estimate heavy oil viscosity, the development plan required running logging while drilling (LWD) NMR logs in the extended-reach horizontal injectors, in addition to some selected producers.

A program heavily based on slim hole drilling presented a practical challenge for the execution of the development plan, since at the time no service company offered slim hole LWD NMR services. Considering the business impact of this technology gap, the operator decided to collaborate with the service industry to develop LWD NMR technology for hole sizes ranging from 5⅞- to 6⅛-in. Within a year, a joint project was established with a major technology provider for the development of a slim LWD NMR tool. The first two prototypes were delivered for field testing in less than 18 months.

The prototypes have been run in nearly a dozen wells to date and in a variety of environments, including extended-reach wells with high salinity muds. Data obtained from drilling and reaming runs agree very well with those from other porosity tools, including wireline NMR. Furthermore, close coordination and cooperation between the operator and the service provider during testing runs have resulted in significant improvements in downhole firmware, data acquisition modes and signal processing.

Two factors weigh heavily for the successful fast delivery of the project goals: clear requirements from the operator, and proven expertise in NMR tool design from the technology provider. Given continuing reliable and robust performance from the prototypes, the slim LWD NMR service is expected to be commercially available shortly. In fact, the high level of confidence gained from early field tests has already allowed the use of the data in critical well placement decisions in some wells.
Neural Network Prediction of Porosity and Permeability of Heterogeneous Gas Sand Reservoirs
Authors: Hamada G. M. , Elshafei M. A.
Published: May 2009

Analysis of heterogeneous gas sand reservoirs is one of the most difficult problems. These reservoirs usually produce from multiple layers with different permeability and complex formation, which is often enhanced by natural fracturing. Therefore, using new well logging techniques like NMR or a combination of NMR and conventional openhole logs, as well as developing new interpretation methodologies are essential for improved reservoir characterization. Nuclear magnetic resonance (NMR) logs differ from conventional neutron, density, sonic and resistivity logs because the NMR measurements provide mainly lithology independent detailed porosity and offer a good evaluation of the hydrocarbon potential. NMR logs can also be used to determine formation permeability and capillary pressure.

In heterogeneous reservoirs classical methods face problems in determining accurately the relevant petrophysical parameters. Applications of artificial intelligence have recently made this challenge a possible practice. This paper presents a successful application of Neural Network (NN) to predict porosity and permeability of gas sand reservoirs using NMR T2 (transverse relaxation time) and conventional open hole logs data. The developed NN models use the NMR T2 pin values, and density and resistivity logs to predict porosity, and permeability for two test wells. The NN trained models displayed good correlation with core porosity and permeability values, and with the NMR derived porosity and permeability in the test wells.
From Issues to Solutions – Introducing the Multi Function Logging while Drilling Tool for Reservoir Characterization in the Greater Burgan Field of Kuwait Oil Company
Authors: Al-Azmi Khalid H. , Al-Enezi Hamdah , Kotecha Rohitkumar , Al-Sabea Salem , Archibong Ekpo , Al-Khaledi Ahmed , Oyeyemi Oluwafemi
Published: May 2009

The Greater Burgan Field consists of three sub fields (Ahmadi, Burgan and Magwa). Drilling commenced in this field in 1938 and it went on stream in 1946. Most of the production comes from a giant oil reservoir in a siliciclastics depositional environment. This giant oil reservoir has intercalating sand shale sequence with the upper part having mixed lithology. Co-existing together are argillaceous glauconitic sandstones, calcite, dolomite and anhydrite with pyrite and siderite.

With increasing demand of oil in the world, it has become necessary to improve oil production. As a result, the various field development assets of Kuwait Oil Company (KOC) are tasked to increase the number of horizontal wells in order to access thin reservoirs in the field. This has prompted these teams to increasingly rely on Logging While Drilling (LWD) services as well as improved geosteering practices in order to efficiently access the untapped energy resources buried several thousand feet below the earth;s surface.

Evaluating these wells becomes an issue especially if the wells are drilled in areas that might add to the reserves of the asset. Resistivity anisotropy is a major issue, especially if it occurs with influence of other bed boundary effects like resistivity of adjacent beds or polarization horn effects. Water coning issues in the field makes it even worse to interpret the resistivity data as they become spiky. Complexity of the resistivity signature in a mixed lithology environment makes petrophysical evaluation difficult.

With the recent introduction of the Multi-Function LWD tool where most of the basic measurements are collocated in one LWD collar, it is now possible to make measurements with similar environmental influence prior to significant invasion of the formation. In addition, the introduction of capture gamma ray spectroscopy and formation sigma in real time has improved the petrophysical evaluation of this complex resistivity environment with mixed lithology in wells that are difficult or even costly to consider wireline logging.

This paper aims at highlighting horizontal well drilling issues occasionally encountered in the Greater Burgan Field and the recent introduction of the Multi-Function LWD service to help address these formation evaluation issues.
Pressure and Temperature Effect on Petrophysical Characteristics: Carbonate Reservoir Case
Authors: Benzagouta Mohammed S. , Amro Mohammed M.
Published: May 2009

The conducted study is aimed to investigate on temperature and pressure variation applied to carbonate reservoirs and their petrophysical characteristics mainly permeability.

In the laboratory, intensive runs of flooding experiments were carried out at different effective pressure up to 4000 psi and temperature reaching 100 °C using carbonate samples from Middle East reservoirs. This investigation was aimed to examine fluid circulation behavior coupled to probe on textural examination of the carbonate samples. This latter was achieved by the use of ordinary microscope and scanning electron microscope (SEM).

Results indicated that permeability reduction can be controlled by variation in pressure and temperature: permeability reduction corresponds to pressure and temperature increase. It has been found that a wise permeability reduction start to be recorded above a value of 50 °C with reference to initial permeability at 25 °C. Furthermore, the permeability reduction has reached 59 % at an effective pressure of 4000 psi and a temperature of 100 °C compared to initial permeability at 725 psi and at 25 °C. According to the overall results, the effect of temperature on permeability reduction in the applied carbonate samples is as important as that of the effective pressure.

Various processes can be suggested for such diverse changes. However, packing and compaction leading to rock deformation and elasticity rock property remain among the main factors responsible for such statement. In addition, and based on the experimental and textural work led, it is important to notify that no formation damage has been notified.
Advances in Sampling Methods Using a New Dual Port Straddle Packer Pumpout Tester in One of Saudi Aramco's Oil Fields
Authors: Silva Andre , Palmer Richard , Hajari A. A. , van Zuilekom Tony , Engelman Bob , Rabbat Ashraf
Published: May 2009

Collecting high quality fluid samples with a pumpout wireline formation tester (PWFT) configured with a conventional probe in carbonate reservoirs is often a challenging operation. Straddle packers are far more suitable than probes for sampling low permeability, heterogeneous carbonate reservoirs. A large volume of whole mud is trapped between the packers when they are initially inflated. The mud must be partially voided before formation fluid begins entering the packed-off interval. Before pumping begins, the near borehole region is occupied with contamination as a result of drilling overbalance and mud filtrate invasion. Uncontaminated reservoir fluid begins entering the packed-off interval after an adequate volume of contaminated fluid has been removed. Water-based mud filtrate (WBMF) and crude oil tend to separate in the packed-off interval as a result of fluid density difference and immiscibility. Moreover, a water oil interface forms at some level within the packed-off interval. As pumping continues, this oil/water fluid contact levels off at the inlet port, and both water and oil will continue to flow through the inlet throughout the sampling process. This complicates fluid identification and makes obtaining a low contamination single phase sample problematic. By taking advantage of a dual inlet port straddle packer and a new fluid density sensor, it is possible to verify the occurrence of fluid segregation within the packed-off interval. The new dual port straddle packer design enables independent opening and closing of the top and bottom ports to observe fluid segregation. By sequencing these port valves and sample chamber valves, we demonstrate how low contamination samples are obtained faster than with a single port system.

This paper provides a description of the new sampling techniques based on samples collected in a Saudi Aramco oil field, as well as examples that show the fluid segregation effect between the packers. It compares the pumping times of a straddle packer vs. an oval pad pumping in similar reservoir conditions. This paper also describes the process used to collect both water and oil samples and the challenges associated with sampling at the oil/water contact (OWC). It also presents the lab results that verify the low contamination level samples obtained by using the new methods.
World's First 3-7/8" Multi-lateral Short Radius Re-entry Completed With Ultra-Slim ICD System
Authors: Al-Mumen Adib A. , Al-Essa Ghassan A. , Infra Morry , Bu-Zaid Sami , Salerno Giovanni
Published: May 2009

Saudi Aramco has successfully used inflow control devices (ICDs) in the past few years to equalize production profile and enhance recovery from new and re-entry horizontal wellbores. This approach was limited to hole sizes of 5-1/2" hole and bigger. These success results led to working over old wells in mature fields, originally completed with 4-1/2" liners/casings, with ICD completion systems to prolong production life.

The paper will describe the drilling, completion and successful installation of the world's first ultra slim-hole ICD system, run across the mother bore of a short radius re-entry 3-7/8" tri-lateral horizontal section. The paper will highlight the following: The directional plan approach used to ensure the ICD completion will go past the branch out points, all the way to the total depth of the mother bore.The completion equipment, which consisted of ultra slim ICDs and swell packers for zonal isolation.Operational problems encountered and corrective actions for future re-entries.

The paper's summary will show the production performance of the well and how the completion was successful in compartmentalizing and distributing the flow from the mother bore and other laterals.
Changes in Shale Strength Resulting from Interaction with Invert Emulsion Drilling Fluids
Authors: Hemphill Terry , Duran William , Abousleiman Younane , Tran Minh , Nguyen Vinh , Hoang Son
Published: May 2009

Most wellbore stability problems occur while drilling shale intervals. Although the drilling industry invests large amounts of time and money each year to deal with the problem, the interaction between drilling fluids and shale is complex and not well understood. Generally speaking, fewer wellbore stability problems occur when drilling with invert emulsion drilling fluids (IEF) than with water-based drilling fluids (WBF). In this paper, the theory governing the interaction between shales and invert emulsion drilling fluids is briefly reviewed.

A new testing device developed by the University of Oklahoma was used to study changes in rock strength of shale cores exposed to invert emulsions. Two shale samples, one from a deepwater environment and another from an onshore environment, were exposed to invert emulsions having varying chemical activity (water phase salinity) levels. The stresses required to fail the samples were directly measured under in-situ conditions. The results showed that under some conditions the invert emulsion strengthened the samples and under other conditions the shales were weakened. These results are interpreted using current osmotic pressure and membrane efficiency theory of invert emulsions.

Using a set of in-situ drilling and wellbore stress conditions, traditional elastic wellbore stability modeling is used to predict changes in pore pressure at the wellbore wall as a function of changes in invert emulsion chemical activity. Porochemoelastic modeling is also performed to predict changes in shale pore pressure as a function of time. The modeling results are compared to the shale strength data obtained in the laboratory.

Lastly rock strength measurements of shales exposed to IEF are compared to those exposed to WBF having the same chemical activity (water phase salinity) levels. The differences in performance are explained in terms of osmotic pressure and membrane efficiency theory.

With the laboratory and computer modeling results, the drilling engineer can better appreciate the effect of invert emulsion interaction with shales, which can enable better planning of future wells, especially those having narrow safe drilling windows.
Utilizing Expandable Casing Clad Enabled Short Radius Sidetrack in Wells with Casing Leaks
Authors: Al-BinAli Ali N. , Al-Baggal Zaki A. , Al-Mumen Adib A. , Aubed Yaser
Published: May 2009

Short radius re-entries are very common in Saudi Aramco. Short radius is the fastest and generally most cost effective way to deliver reentry wells whenever vertical wells are converted into horizontal wells. A casing leak across Arab-C formations is a common problem in some onshore fields. Arab-C formation is a high-pressure water bearing zone. Arab-C is located right above the cap rock of the pay zone. When leaks develop, water starts to flow from the high pressure zone to the pay zone (downhole cross flow) and the well will stop producing oil.

This paper will describe the use of expandable casing clad to repair wells with casing leaks across the high-pressure zone. In such wells, the leak was located across Arab-C in production liner. Then, the leak was squeezed off with cement. After that, the casing window was milled below the leak and a short radius curve section was drilled without penetrating the pay zone (Arab-D). Next, the expandable casing clad was utilized to enable drilling the low-pressure pay zone with low mud weight.

Utilizing this technique enabled Saudi Aramco to drill short radius sidetracks while insuring integrity of the well, provide Geosteering in the pay zone and facilitate the option to run flow control/isolation systems. By drilling such wells as short radius re-entries, long radius sidetracks with open hole expandable liner option were avoided. Consequently, significant rig time and cost savings were achieved. After the success of this technique, short radius drilling was still carried out with wells that had casing leaks, and the leaks were stopped.
A Window of Opportunity: Using Real-Time Data During Casing Exits
Authors: Joppe Lambertus , Wilson Steve B. , Fernandez Raj
Published: May 2009

Today's reserves are often stranded in deep, complex reservoirs and, due to economic or environmental constraints, sometimes have to be connected from a single drill site, resulting in wellbore construction methods such as extended-reach drilling (ERD) and multilaterals. Casing exits often play a crucial part in these types of wellbore construction methods. Milling a long window with low dogleg severity is the key to success since every subsequent run into the wellbore – rotary steerable system, liner and completion systems – will have to pass through the window unobstructed. The successful execution of a casing exit based on surface parameters alone becomes more and more challenging as depth and deviation of the application increases.

A system has been developed that measures all the physical parameters downhole at the window-milling assembly itself, and transmits them to surface for rig-site and remote viewing, enabling real-time control of casing exit operations. The system captures and processes all the milling parameters downhole and then uses measurement-while-drilling mud pulse telemetry or stiff-line / wired pipe to send selected and critical information to surface. The window-milling process can be enhanced by monitoring dynamic behavior such as mill vibration, weight on bit and bending moment to make real-time decisions and reduce risk and nonproductive time (NPT).

This paper describes the downhole performance sub technology and closed-loop control system, and demonstrates by a number of case histories the risk-reduction value of monitoring the downhole parameters in real time. The case histories presented includeboth drillpipe-deployed as well as coiled-tubing-deployed casing exit systems.
Successful Mitigation of Time-Dependent Shale Instability in Khafji Field through Drilling Fluid Design Optimization
Authors: Tan Chee Phuat , Qadmani Marwan Ahmad , Povstyanova Magdalena , Mohiuddin Mohammed Ahmed , Rahim Mohd Helmi Abd
Published: May 2009

Al-Khafji Joint Operations is developing the offshore Khafji Field in the X-Neutral Zone by drilling horizontal wells. These wells encounter shale formations namely Ahmadi Shale and Wara Shale before reaching the pay zones, and Intermediate Shale between KB-1 and KB-2 Sands. While drilling these shale formations, severe time-dependent wellbore instability problems due to shale sloughing were experienced. These problems have led to several stuck pipes and sidetracks.

A drilling fluid optimization study was conducted on seven offset wells in the field in order to evaluate the potential time-dependent wellbore stability mechanism(s) in Ahmadi Shale, Wara Shale and Intermediate Shale, to define appropriate mud type, salt type and concentration, and to develop solution and strategy to mitigate and/or manage the wellbore instability problems.

End of Well reports of selected offset wells were reviewed, and numerous time-dependent wellbore instability-related drilling events in Ahmadi Shale, Wara Shale and Intermediate Shale were identified. Both mud pressure penetration and chemical potential mechanisms were considered in the back-analysis of time-dependent wellbore instability in the shales. The analysis showed that the instability was attributed to insufficient salinity in the drilling fluid which resulted in pore pressure increase due to the mud pressure penetration mechanism being not counteracted by the chemical potential mechanism. As a consequence, the pore pressure increased near the wellbore wall which reduced the effective mud support and led to unstable wellbore condition.

Based on the drilling fluid optimization study together with input from mechanical wellbore stability analysis, recommendations on optimum drilling fluid design were made for drilling Ahmadi Shale and Wara Shale which were successfully applied in a planned horizontal well in the field.
Design of New, Fit-For-Purpose, Downhole Positive Displacement Motor Improves Reliability and Enhances Performance in 16-in. Vertical Sections
Authors: Azizov Azar , Hilthon Karl , Mounzer Fadi , Kent David
Published: May 2009

Saudi Aramco operates several deep gas reservoirs in the Kingdom of Saudi Arabia (KSA). Both vertical and horizontal K2 gas development wells have long 16-in. vertical sections. The 16-in. section is drilled as quickly as possible through several mid-depth hydrocarbon reservoirs to a competent seat in a dolomitic limestone. Since this section is fairly long (±5,000 ft) it represents one of the biggest challenges in the continuous drive for better rate of penetration (ROP) as well as reliability of downhole drilling assemblies.

These sections are typically drilled with various positive displacement motors (PDM) in a simple performance bottomhole assembly (BHA) setup with two roller-reamer type stabilizers to mitigate mechanical stuck pipe risks. Drilling through the interbedded formations with varying hardnesses using very aggressive 16-in. bits has proven to be challenging in terms of wear and tear on the drilling motors. Damage to the motors, such as stator chunking, bearing failures and even catastrophic connection twistoffs have occurred during these drilling operations.

One service provider currently uses 9½-in. motors in the 16-in. wellbores. To address tool integrity issues, the service provider upgraded to their standard offering, 12¾-in. motors. While incidences of housing and stator failure were eliminated, the combination of large, high flow rate tools in a land-based operation has not delivered the required performance on bottom. The drilling rigs currently employed for gas development drilling were not capable of pumping more than 1,300 gpm while optimum performance from the standard 12¾-in. motor comes with flow rates above 1,500 gpm. As a result, bit speed was too low, and ROP did not meet or exceed the 9½-in. motor runs and the standard 12¾-in. tools did not find widespread acceptance from the client.

A new, more robust 12¾-in. motor was developed, which was also designed to provide higher rotary speed output at available flow rates and pressures. To evaluate the performance of this new motor, a drilling dynamics diagnostic tool was run in a field testing program.

To date, several runs have been made with the new 12¾-in. motor in various fields in the Kingdom of Saudi Arabia. Various BHA incorporating different motor configurations and newly designed bits have been used. The drilling dynamics diagnostic tool was positioned directly behind the motor to obtaining a better understanding of the BHA and bit response for the various configurations.

This paper will focus on the significant reliability and performance improvements achieved through the introduction of the new motor, which was specifically designed for this challenging environment.
Minimizing Wellbore Damage in a Sandstone Reservoir Using Effective Mud Management Practices
Authors: Rabaa Ali S. , Phillips James E. , Al-Ammari Saleh M. , Mohamed Monir
Published: May 2009

Inducing formation damage in sandstone reservoirs through poor drilling fluids management is a crucial factor that can affect well productivity. An integrated team assigned to manage drilling horizontal producers for field development, developed a mud management plan to monitor drilling fluid properties and maintain mud system specifications to minimize formation damage in the field's sensitive sandstone reservoir. This paper discusses the implementation of the engineered oil-based drill-in fluid, particle size monitoring, and drilling and completion methods designed to minimize reservoir formation damage and help maximize well productivity.

A particle size distribution (PSD) analyzer was used in the field to monitor the PSD values of the particulates in the drill-in fluid (DIF) while drilling the sandstone reservoir. Core samples were selected and analyzed using a scanning electron microscope (SEM) to determine an average pore size value.

A diesel-based DIF was specifically designed to minimize formation damage. The DIF was formulated with a 70/30 oil water ratio and was treated with a sized calcium carbonate bridging agent to help minimize spurt/total loss. The engineered bridging agent was added to prevent formation damage that results from the invasion of fines. Overbalance pressures were also minimized to avoid the risk of differential sticking.

For better bridging results, the D90, D50 and D10 particle size distributions were instantaneously maintained in the programmed range while drilling the entire sandstone pay section with controlled rates of penetration (ROP). The % of drill solids as a function of total solids was also maintained at low levels with the use of centrifuges and addition of whole treated mud. Upon reaching the total depth (TD), the bottomole assembly (BHA) was changed to a reaming assembly and the entire open-hole section was reamed to TD.

After making a wiper trip, the operator tripped back to bottom without pumping to simulate hole conditions that would occur while running screens. Once the open hole was deemed in good condition the well was displaced to a solids-free invert emulsion mud maintained at the same density as the DIF. This fluid was circulated over a 230-mesh screen prior to running the screens to ensure that all fine sand and excess filter cake were removed.

To date, 26 wells have been successfully drilled and completed with sand screens using the abovementioned methodology. Testing results of the first three wells indicated minimum skin damage and good and stable production rates.