bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Exposure to Persistent Chemicals in Hazard and Risk Assessment
Authors: Cowan-Ellsberry Christina E , McLachlan Michael S , Arnot Jon A , MacLeod Matthew , McKone Thomas E , Wania Frank
Published: June 2009

Fate and exposure modeling has not, thus far, been explicitly used in the risk profile documents prepared for evaluating the significant adverse effect of candidate chemicals for either the Stockholm Convention or the Convention on Long-Range Transboundary Air Pollution. However, we believe models have considerable potential to improve the risk profiles. Fate and exposure models are already used routinely in other similar regulatory applications to inform decisions, and they have been instrumental in building our current understanding of the fate of persistent organic pollutants (POP) and persistent, bioaccumulative, and toxic (PBT) chemicals in the environment. The goal of this publication is to motivate the use of fate and exposure models in preparing risk profiles in the POP assessment procedure by providing strategies for incorporating and using models. The ways that fate and exposure models can be used to improve and inform the development of risk profiles include 1) benchmarking the ratio of exposure and emissions of candidate chemicals to the same ratio for known POPs, thereby opening the possibility of combining this ratio with the relative emissions and relative toxicity to arrive at a measure of relative risk; 2) directly estimating the exposure of the environment, biota, and humans to provide information to complement measurements or where measurements are not available or are limited; 3) to identify the key processes and chemical or environmental parameters that determine the exposure, thereby allowing the effective prioritization of research or measurements to improve the risk profile; and 4) forecasting future time trends, including how quickly exposure levels in remote areas would respond to reductions in emissions. Currently there is no standardized consensus model for use in the risk profile context. Therefore, to choose the appropriate model the risk profile developer must evaluate how appropriate an existing model is for a specific setting and whether the assumptions and input data are relevant in the context of the application. It is possible to have confidence in the predictions of many of the existing models because of their fundamental physical and chemical, mechanistic underpinnings and the extensive work already done to compare model predictions and empirical observations. The working group recommends that modeling tools be applied for benchmarking PBT and POPs according to exposure–emissions relationships and that modeling tools be used to interpret emissions and monitoring data. The further development of models that combine fate, long-range transport, and bioaccumulation should be fostered, especially models that will allow time trends to be scientifically addressed in the risk profile.
Revisiting Bioaccumulation Criteria for POPs and PBT Assessments
Authors: Gobas Frank APC , de Wolf Watze , Burkhard Lawrence P , Verbruggen Eric , Plotzke Kathleen
Published: June 2009

Scientists from academia, industry, and government reviewed current international regulations for the screening of commercial chemicals for bioaccumulation in the context of the current state of bioaccumulation science. On the basis of this review, several recommendations were proposed, including a scientific definition for “bioaccumulative substances,” improved criteria for the characterization of bioaccumulative substances (including the trophic magnification factor and the biomagnification factor), novel methods for measuring and calculating bioaccumulation properties, and a framework for screening commercial chemicals for bioaccumulative substances. The proposed framework for bioaccumulation screening improves current practices by reducing miscategorization, making more effective use of available bioaccumulation data that currently cannot be considered, reducing the need for animal testing, providing simpler and cheaper test protocols for animal studies in case animal studies are necessary, making use of alternative testing strategies, including in vitro and in silico metabolic transformation assays, and providing a scientific foundation for bioaccumulation screening that can act to harmonize bioaccumulation screening among various jurisdictions.
Environmental Persistence of Organic Pollutants: Guidance for Development and Review of POP Risk Profiles
Authors: Boethling Robert , Fenner Kathrin , Howard P , Klečka Gary , Madsen Torben , Snape Jason R , Whelan Mick J
Published: June 2009

Environmental persistence is an important property that can enhance the potential of a chemical substance to exert adverse effects and be transported to remote environments. The persistence of organic compounds is governed by the rates at which they are removed by biological and chemical processes, such as biodegradation, hydrolysis, atmospheric oxidation, and photolysis. The persistence workgroup in a recent Society of Environmental Toxicology and Chemistry (SETAC) Pellston workshop (Pensacola, FL, USA, January 2008) focused on evaluating persistence of organic compounds in environmental media (air, water, soil, sediment) in terms of their single-medium degradation half-lives. The primary aim was to provide guidance to authors and reviewers of chemical dossiers for persistent organic pollutants (POPs) and persistent, bioaccumulative, and toxic substances (PBTs) proposed for action. A second objective was to provide a summary of the current state of the science with respect to POP fate assessment. Assessing the persistence of chemical substances in the environment is not straightforward. A common misconception is that, like many chemical properties, environmental persistence is an inherent property of the substance and can be readily measured. In fact, rates of degradation of a substance in the environment are determined by a combination of substance-specific properties and environmental conditions. This article addresses how persistence can be evaluated based on an assortment of supporting information. Special attention is given to several critical issues, including transformation products, nonextractable residues, and treatment of uncertainty and conflicting data as part of a weight-of-evidence assessment.
Use of Measurement Data in Evaluating Exposure of Humans and Wildlife to POPs/PBTs
Authors: Swackhamer Deborah L , Needham Larry L , Powell David E , Muir Derek CG
Published: June 2009

The Stockholm Convention on Persistent Organic Pollutants (POPs) recognized that POPs resist degradation, undergo long-range transport, and accumulate in remote ecosystems. The Stockholm Convention also acknowledged that indigenous communities, particularly in the Arctic, were at risk because of the biomagnification of POPs and contamination of their traditional foods. This recognition was largely based on environmental monitoring data and demonstrates the need to have adequate guidance on data collection and use. Although long-range transport, persistence, and bioaccumulation models are important for screening potential POPs and for assessing human exposure, environmental measurement data are needed to confirm predictions. Indeed the Stockholm Convention (Annex E) requires monitoring data for assessing “exposure in local areas and, in particular, as a result of long-range environmental transport.” However, there is relatively little guidance available on the most appropriate environmental measurement approaches, particularly for new candidate POPs, and on how to create a weight of evidence based on such data. We provide guidance on how to assess existing data that have been generated by monitoring programs and individual studies on the exposure of top predators and humans to candidate or potential POPs, as well as considerations for collecting new additional data. Our overall recommendation for assessing exposure in humans and top predators is to use or obtain direct measurements of the compound of concern from a significantly and uniquely exposed population (indigenous populations, remote populations), as well as data demonstrating biomagnification within food webs and time trends if possible. These data must be from the appropriate sample matrix type, collected and analyzed using accepted methodologies, reviewed for quality assurance, and interpreted correctly in order to be used to assess exposure.
Evaluation of Bioaccumulation Using In Vivo Laboratory and Field Studies
Authors: Weisbrod Annie V , Woodburn Kent B , Koelmans Albert A , Parkerton Thomas F , McElroy Anne E , Borgå Katrine
Published: June 2009

A primary consideration in the evaluation of chemicals is the potential for substances to be absorbed and retained in an organism's tissues (i.e., bioaccumulated) at concentrations sufficient to pose health concerns. Substances that exhibit properties that enable biomagnification in the food chain (i.e., amplification of tissue concentrations at successive trophic levels) are of particular concern due to the elevated long-term exposures these substances pose to higher trophic organisms, including humans. Historically, biomarkers of in vivo chemical exposure (e.g., eggshell thinning, bill deformities) retrospectively led to the identification of such compounds, which were later categorized as persistent organic pollutants. Today, multiple bioaccumulation metrics are available to quantitatively assess the bioaccumulation potential of new and existing chemicals and identify substances that, upon or before environmental release, may be characterized as persistent organic pollutants. This paper reviews the various in vivo measurement approaches that can be used to assess the bioaccumulation of chemicals in aquatic or terrestrial species using laboratory-exposed, field-deployed, or collected organisms. Important issues associated with laboratory measurements of bioaccumulation include appropriate test species selection, test chemical dosing methods, exposure duration, and chemical and statistical analyses. Measuring bioaccumulation at a particular field site requires consideration of which test species to use and whether to examine natural populations or to use field-deployed populations. Both laboratory and field methods also require reliable determination of chemical concentrations in exposure media of interest (i.e., water, sediment, food or prey, etc.), accumulated body residues, or both. The advantages and disadvantages of various laboratory and field bioaccumulation metrics for assessing biomagnification potential in aquatic or terrestrial food chains are discussed. Guidance is provided on how to consider the uncertainty in these metrics and develop a weight-of-evidence evaluation that supports technically sound and consistent persistent organic pollutant and persistent, bioaccumulative, and toxic chemical identification. Based on the bioaccumulation information shared in 8 draft risk profiles submitted for review under the United Nations Stockholm Convention, recommendations are given for the information that is most critical to aid transparency and consistency in decision making.
Multimedia Partitioning, Overall Persistence, and Long-Range Transport Potential in the Context of POPs and PBT Chemical Assessments
Authors: Scheringer Martin , Jones Kevin C , Matthies Michael , Simonich Staci , van de Meent Dik
Published: June 2009

For the identification and assessment of persistent, bioaccumulative, and toxic (PBT) chemicals and persistent organic pollutants (POPs), overall persistence (Pov) and long-range transport potential (LRTP) are important indicators. In this article we first give an overview of methods to determine Pov and LRTP and discuss the influence of multimedia partitioning of semivolatile organic chemicals (SOCs) on Pov and LRTP. Next, we summarize the most important features of various multimedia fate and transport models that can be used to calculate Pov and LRTP. Complementary to environmental fate models, field data provide important empirical information about the spatial distribution and time trends of SOC concentrations in the environment. We discuss the role of field data in the estimation of Pov and LRTP and give an overview of important field studies showing the levels and trends of various groups of chemicals in different parts of the world. Then, we address key topics in the field of PBT and POP assessment that require further research, such as the formation of transformation products, the influence of atmospheric aerosols on the degradation and transport of SOCs, and the effect of long-range transport by ocean currents. In addition, we describe the most important types of uncertainty associated with estimates of Pov and LRTP, which are mainly uncertainty of chemical property data and uncertainty of the design of environmental fate models. Finally, we illustrate the characterization of SOCs in terms of Pov and LRTP with the example of the consensus model for Pov and LRTP Tool that is provided by the Organization for Economic Cooperation and Development.
Use of (Eco)toxicity data as screening criteria for the identification and classification of PBT/POP compounds
Authors: Solomon Keith R , Dohmen Peter , Fairbrother Anne , Marchand Marcelle , McCarty Lynn
Published: June 2009

Characterization of “significant adverse ecotoxicological effects” of persistent organic pollutants (POPs) presents particular challenges. In the various international conventions on POPs and persistent, bioaccumulative, and toxic substances, guidance on classification is not detailed and, in some cases, is unclear. This paper focuses on several key issues in relation to selection of assessment endpoints, use of appropriate effect measures, and uncertainty in the face of limited data. Because POPs are persistent and bioaccumulative, measures of effect should be based not on concentrations in environmental matrices but rather on residues in the body of the organism or in tissues that are causally linked to adverse responses. To obtain these data, currently used toxicity testing methods may need to be modified or substantiated by toxicokinetic information to ensure that substances with POP-like properties are adequately characterized. These data can be more easily matched to environmental monitoring measurements of body or tissue residues for the purposes of assessing whether adverse effects occur in the environment. In the face of persistence and accumulation in the food chain, and considering the extent and suitability of available data, a suitable policy on the use of uncertainty factors may need to be applied when making judgments about toxicity. This paper offers guidance that can be used to identify candidate POPs that have the potential to cause significant adverse effects in the ecosystem.
Integrated Approach to PBT and POP Prioritization and Risk Assessment
Authors: van Wijk Dolf , Chénier Robert , Henry Tala , Hernando Maria D , Schulte Christoph
Published: June 2009

This article summarizes discussions at the SETAC Pellston Workshop on “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs” and provides an overview of other articles from that workshop that are also published in this issue. Identification of persistent, bioaccumulative, and toxic substances (PBTs) and persistent organic pollutants (POPs) and evaluation of their impact are more complicated than those for other chemicals and remain a challenge. The main reason for this is that PBT substance and POP assessment is associated with higher uncertainty and generally requires more data. However, for some data-rich PBTs and POPs, that identification and assessment of impact are feasible has been clearly demonstrated. New scientific developments and techniques are able to significantly increase the certainty of the various elements of PBT and POP assessment, and the current scientific literature provides many successful and illustrative examples that can be used as methodologies to build on. Applying multiple approaches for assessment is advisable, because it will reduce uncertainty and may increase confidence and improve the quality of decision-making.
Introduction to Special Series: Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs
Authors: Klečka Gary M , Muir Derek CG , Dohmen Peter , Eisenreich Steve J , Gobas Frank APC , Jones Kevin C , Mackay Donald , Tarazona José V , van Wijk Dolf
Published: June 2009

There is a growing sense of urgency among scientists and environmental policy-makers concerning the need for improving the scientific foundation supporting international regulations for identifying and evaluating persistent, bioaccumulative, and toxic (PBT) substances and persistent organic pollutants (POPs) in the environment. The current national and international regulations define PBTs and POPs in terms of fairly strict criteria that are based on the state of the science in the late 1970s and early 1980s. Since then, an evolution in the state of the science has produced new insights into PBT substances and an array of new methods to identify PBT chemicals. The development of regulatory criteria has not kept up with the rapid development in environmental chemistry and toxicology, and as a result, scientists often find themselves in the situation where guidance on PBT and POPs criteria is limited and, in some respects, out of date. With this background, a Society of Environmental Toxicology and Chemistry (SETAC) Pellston Workshop brought together experts from academia, government, and industry to reach consensus on the significance of advancements in our understanding of the behavior and potential impact of POPs and PBTs in the environment, the current understanding of the state of the science, as well as recommendations for policy-makers to improve and coordinate national and international regulations on this issue. The workshop builds on the outcome of a previous Pellston workshop, held in 1998, which focused on the evaluation of persistence and long-range transport of organic chemicals in the environment, and is linked to other recent Pellston workshops, among them the Tissue Residue Approach for Toxicity Assessment workshop held in 2007. The results of this workshop are conveyed in a series of 9 articles, published in this issue of Integrated Environmental Assessment and Management, and describe the coordination of science, regulation, and management needed to more effectively achieve a common goal of managing chemicals on our planet.
Optimization of Coiled Tubing Interventions to Stimulate Extended Reach Water Injection Wells in a Field in Saudi Arabia
Authors: Beheiri Faisal I. , Saudi Mohammad M. , Metwally Sayed A. , Al-Shammari Nayef S. , Al-Meshal Fahad , Sierra Leopoldo
Published: June 2009

Drilling wells with longer horizontal sections to maximize the reservoir contact has brought many challenges to the well interventions using Coiled Tubing (CT). In most cases, the complexity has pushed the CT interventions to the limits, driving the development of new solutions to extend the reach to the total well depth.

The number of these extended wells has grown significantly in recent years in Saudi Arabia, especially in new development fields like the study area, where more than 100 extended reach power water injection wells were placed in the reservoir flanks. The water injection wells in this study area are a typical example of complexity due to the combination of large bore tubular, lower reservoir pressure, and long horizontal openhole completion, with lengths between 4,000 to almost 8,000 ft.

During the initial CT interventions in this field, several challenges were encountered, e.g., stuck CT due to pressure differentials and slack-off weight through severe doglegs, tight spots, and other obstructions. Extensive knowledge was gained by performing an extensive simulation and study of the horizontal section geometry, and analyzing the operational data. Based on the findings, a combination of techniques was introduced to the CT intervention procedure, to extend the reach and minimize the operational problems and costs.

The key components of our new implemented methodology were buoyancy reduction by using nitrified fluids and friction reduction by using new viscoelastic surfactant (VES) friction reducer. In addition, combinations of other techniques were employed, e.g., optimizing the pull tests frequency in openhole and improving CT movement practices. This paper shows the effectiveness of the new cost effective and reliable methodology to maximize the CT reach up to 8,000 ft allowing the distribution of the acid stimulation throughout the entire horizontal sections.
Evaluation of Gas, Water, WAG Injections, and Infill Wells for Improving Recovery of One of Iranian Reservoirs
Authors: Sadooni M. , Shahbazi K. , Hashemi A. , Abdali M. R.
Published: June 2009

Increasing demand for energy has forced oil companies to resort to secondary and tertiary methods to increase the recovery from the existing reservoirs. In this paper, enhancing the recovery factor of one of Iranian reservoirs which is a naturally fractured reservoir was investigated. For this reservoir, it is estimated that 96.5 percent of oil is contained in the matrix and 3.5 percent in the fractures. The field is an undersaturated reservoir with no active gas cap and no strong water aquifer.

In this paper, injections of water, gas, water alternating gas (WAG), and infill wells on this field was investigated to increase the recovery factor. Eclipse100 was employed to simulate the reservoir. The simulated results showed that gas, water, and WAG injections had insignificance improvements on oil recovery. However, it was found that infill wells contribute an appreciable increase in recovery. The amount of increase for drilling five infill wells was around five percent.

Since development of existing resources contributes a major role on the supply of oil for the future oil market (around 45 percent by 2030), these results are used to screen the various methods for increasing the recovery of such reservoirs.
Short-Term and Long-Term Aspects of a Water Injection Strategy
Authors: Stenger Bruno A. , Al-Katheeri Abdulla B. , Hafez Hafez H. , Al-Kendi Salem H.
Published: June 2009

This paper reviewed the water injection strategy of a supergiant carbonate oil field operated by ADCO onshore Abu Dhabi since 1973. This field was subjected to peripheral waterflooding in order to maintain reservoir pressure and provide a mechanism to sweep the oil. In addition to traditional parameters in waterflooding such as for instance, reservoir heterogeneity, mobility ratio and depletion rate that control the waterfont shape, the presence of three oil-bearing reservoirs juxtaposed across strike-slip fault planes added a new variable to the complexity. Fault juxtaposition was interpreted to create limited pressure communication and fluid crossflow between reservoirs. The usual way of computing the voidage replacement ratio based on well production and injection rates was therefore insufficient to gain a complete understanding of the water injection strategy. Two different solutions of the voidage replacement ratio were computed using a full-field reservoir simulation model history-matched for both pressure and saturation changes. After accounting for all surface facilities constraints and under a certain set of assumptions, results of this model indicated that crossflow magnitude was minimized when certain pressure differences were maintained between these three reservoirs. Alternatively, there were some indications that higher crossflow could result in some additional oil recovery. A simple methodology to manage production and water injection targets on a quarterly basis while accounting for the communication between reservoirs was discussed. Finally implications for an on-going development were reviewed.
Flow Anisotropy Analysis From Multiwell-Testing of Sabiriyah Field, North Kuwait
Authors: Alkouh Ahmad , Chen Her-Yuan
Published: June 2009

The Sabiriyah field in north Kuwait showed a depletion drive mechanism and a water flooding plan was needed. The Mauddud reservoir was tested through a Waterflood pilot which incorporated a pulse test data. The objective of the test is to assess reservoir connectivity, properties and water flow direction. The field's test data were matched through a pressure distribution with a slight heterogeneous and a homogeneous match. Using the field data, a small range of anisotropy orientation N10°E to N7°E was found. This orientation correlates to the sand fairways in the direction of SW-NE mentioned in the literature.

Two cases were used to verify that the first peak of the pulse test can be used in an interference analysis with a decreased value of total compressbility. For all cases, the well's sequence is the same as the original response but the separation between the three well's pressure responses was not as clear as the original data.

The Papadopulos-Ramey's method was used to evaluate the two matches of the Sabiriyah's pulse test. The slight heterogeneous match was used and the results were consistence with orientation of N8E and anisotropy ratio of 32. Also, the decreased value of total compressibility in the ideal case was verified using this method. The second homogenous match could not be evaluated because the field had a slight heterogeneity that affected the transmissibility result. Also, the gap in the diffusivity between the three wells is high, which can not be presented by the anisotropy alone, compared to the three ideal cases. In addition, ideal homogeneous modeled pulse test of the field with orientation of N8°E verified that the gap in diffusivity between the wells cannot be modeled without varying and decreasing the total compressibility value for the three wells.
Real-Time Drill Bit Wear Prediction by Combining Rock Energy and Drilling Strength Concepts
Authors: Rashidi B. , Hareland G. , Nygaard R.
Published: June 2009

A central element to reduce drilling cost is to improve drilling operation by analyzing real-time data. Developing advanced real-time analysis tools is one way to improve the drilling operation. Two approaches which currently are used for optimizing the actual rotary drilling process are mechanical specific energy and inverted rate of penetration models. The mechanical specific energy method is defined as the work needed to destroy a given volume of the rock. It can act as a tool during the drilling operation to detect changes in drilling efficiency thus providing a method to optimize the drilling parameters to enhance instatanious rate of penetration. Rate of penetration models, on the other hand, can be used to calculate formation drillability considering the effects of drilling parameters, bits design and bit wear. Drilling optimization using rate of penetration models is done by changing the drilling parameters and/or bit design to find the optimum drilling scenario for an entire bit run. The mechanical specific energy log and the drillability ratio differ when mud weight is changed and when bits are worn. These two differences are due the fact that mechanical specific energy does not include bit wear as well as the effect of changing mud weight. By combining these methods and modifying the mechanical specific energy equations to incorporate these effects and the mechanical specific energy can be used as a real-time trending tool for bit wear estimations. In this analysis, wells from offshore Middle East and onshore North America are analyzed. The field results are very encouraging in that the bit wear for both roller cone and PDC bits can be predicted. The field validation of this new approach shows that the supplementary information on the bit wear status can in some cases benefit in the decision of when to pull the bit while it still is in the hole and thereby possibly improve overall economics of the drilling operation.
A New Cement Sealant System for Long-Term Zonal Isolation for Khuff Gas Wells in Abu Dhabi
Authors: Al-Suwaidi A. S. , Soliman A. Abou , Jammeli K. , Arif M. , Elatrache B. , Fattah T. , Agnani M. , Voon E.
Published: June 2009

Cementing gas wells in Khuff reservoir where sustained annular pressure has been reported in many wells, presents a big challenge offshore in Umm Sheif field in Abu Dhabi. The main challenges are preventing gas migration and achieving long-term zonal isolation using a competent cement sealant system able to withstand downhole stresses and high temperatures during production cycles.

An extensive study was carried out on two previously cemented wells, and an in-depth analysis was performed on the cement systems pumped in this field. The knowledge gained paved the way for designing, planning, and executing successful cementation on a recent well.

A mathematical model simulating downhole stresses in terms of pressure and temperature was used in designing the cement sealant system. Unlike conventional cement systems, properties such as high Poisson's ratio and low Young's modulus value compared to that of the rock were optimized in the new system to achieve mechanical resistance and durability.

This paper describes a case history whereby this cement sealant system was used to cement and secure the critical phases of this well. Cement evaluation logs across all the liners showed complete cement coverage and zonal isolation, especially across the Khuff gas reservoir.
Utilization of Acoustic Logging Technology to Identify Failed Barriers in Offshore Wells
Authors: Shnaib Fathi , Beaumont-Smith Peter , Alagba Tonye , Nasr Karim K.
Published: June 2009

The detection of the source of communication and pressure build up in the first or second annuli presents a huge challenge to the industry. Dubai Petroleum has been utilizing an acoustics based logging tool to pinpoint the source of high pressures in the annuli of its gas lifted oil producers and water injectors in its offshore operations. This paper presents a description of the technology and the findings from Dubai Petroleum's experience on several case histories.

An ultrasonic leak detection tool has been developed for down-hole applications, to take advantage of the unique properties of ultrasound energy propagation through various media. This data acquisition equipment has been developed to allow continuous logging operation on conventional electric line cable or memory mode on slick line. The movement of fluids across a failed barrier creates turbulence creating high frequency ultrasound waves that are detected by the tool sensor.

This new tool is different from the conventional noise logs as its highly customized multiple sensitivities enable the detection of leaks as small as 0.02 Liters per minute with an accuracy of 1 Inch in the production tubing, casing and other completion equipment. It is also less prone to disturbances from distant noise sources.

The successful experience gained by Dubai Petroleum in utilizing this technology has confirmed that ultrasonic based well leak detector technology can accurately detect very small tubing and casing leaks.
Help Them Grow Or Watch Them Go!
Authors: Qutob Shereen Hussain
Published: June 2009

All industries are facing a looming shortage of experienced and committed employees and more so in the oil and gas industry. We are operating in turbulent times where "talent" is the scarce resource.

While companies are consistently worried about the bottom line and running smooth operations, they have somehow lost track of their main investment; their people. In order to remain competitive, companies today must invest in continually upgrading their people's skills; however this is not always the case.

With so much focus on the "war for talent" and the retirement of the experienced crew, a growing frustration among new candidates entering the workforce is the lack of direction or growth. We need to offer them "careers" in the process and not just jobs.

Today's workforce is mixed and comprises of Baby Boomers, Generation X along with the ever popular Gen Y. We must utilize the best of abilities each generation and in the process overcome the many misconceptions weighing down our workforce. Seniority or knowledge alone does not equal competence. More focus should be on developing the soft-skills in all employees. The investment has to be made from day one.

There will always be operational crises. That is the nature of our industry. However, if we do not seriously evaluate the situation of our current workforce and how we can productively move forward, then we are headed for disaster. We must offer our employees a well rounded experience where both their technical and personal skills are developed so they can ensure the consistent quality, excellence and safety in what we do. The shift to a development-minded culture must take place. It is inevitable. The dialogue between the generations must begin now!
Combination of a Unique Stabilized Bi-Center Bit and Vibration Dampening Tool Improve Hole Opening Performances Through Interbedded Formations in Saudi Arabia
Authors: Al Thuwaini Jamal , Emad Mohamed , Mohamed Hendrazid Wahby , Chafai Ridha , Murdock Andy
Published: June 2009

When control drilling interbedded formations due to lost circulation challenges, Bi-Center bits often fail to open the hole to the expected drill size. Possible causes include inconsistent downhole weight on bit due to formation changes, lateral and torsional vibration. Each leads to the pilot of the Bi-Center bit drilling an oversized hole which results in the bit drilling off-center, giving an undersized hole.

To combat this, a patented double profile Bi-Center bit was developed. Its elongated pilot section includes a unique mid-reamer section which improves lateral stability due to more balanced cutter forces. Also, the mid-reamer provides an additional gauge section immediately below the reamer which in conjunction with the pilot gauge has proven to reduce tilt and keep the pilot bit centralized, providing more consistent full gauge hole.

Additionally, vibrations generated by the drillstring are common during the hole-opening process. These affect not only the drilling performance but also the quality of the wellbore. A unique eccentric stabilizer, ideally located in tension in the BHA, provides vibration dampening in the drill-string. The V-Stab interrupts harmonic modes vibration as well as reducing the magnitude of shocks due to its unique geometry.

Caliper logs from field trials of a 10-5/8 × 12-/14" CSDX6413S-B1 Bi-Center bit with a 10-5/8 × 12" vibration dampening tool demonstrate excellent hole opening performance and improved borehole quality.

In contrast, logs for conventional Bi-Center bits run with the vibration dampening tool showed inconsistent hole opening and poor borehole quality in the same application.

This paper describes the benefits of the unique combination of these new technologies, presenting detailed drilling performance data showing how they resulted in significant performance improvement and cost savings in southern Saudi Arabia.
Managing a Successful Exploration Drilling Campaign in Saudi Arabia: A Case History
Authors: Ekpe J. , Alexeenko A. , Zeid A. , Ahmed B. , Haddad G.
Published: June 2009

The frontier exploration drilling campaign in the Kingdom of Saudi Arabia started in January 2006. LUKSAR, a joint venture between Lukoil and Aramco, took pragmatic approach to project management. Careful analysis of the campaign challenges included maximizing the local experience of service providers and proper planning to meet the drilling campaign targets. The first two wells have been drilled and tested successfully. The shortcomings of the first two wells were identified and resolved in wells three to five demonstrating significant improvement in performance.
Specific Design Process Associated With Simulation Tools Improve PDC Bi-Centre Application Definition, and Deliver Solution in Directional Environment
Authors: Al-Umran Mohammed , Al-Hameli Mohammed , Al-Mumen Adib , Cuillier Bruno , Boussa Badredine , Cortes Pierre , Dourfaye Alfazazi , Boussahba Hocine
Published: June 2009

Bi-centre bit performance in directional applications usually presents performance challenges in terms of efficiency versus power availability and dynamic issues. In most instances the bi-centre bit selection and/or development compromises overall rate of penetration (ROP) for steerability. Extensive statistical analysis combined with drilling simulations (numerical) revealed the importance in the overall performance of a highly efficient bit during the sliding time.

This paper will discuss a field proven design process and technology used to enhance bi-centre bit performance in challenging applications such as directional drilling. After years of extensive development and modeling of cutting structures, including the drilling of simulated wells combined with full scale bit laboratory tests, a process combining cutting structure, rock type and application objectives has been developed. This process, which models and simulates bit behavior during the drilling process, is based upon "bridgeable" software. Analysis using different cutting structures with various parameters in line with drilling objectives and combined with Varel's rock analytics software is used to predict and analyze bit behavior in term of directional tendencies and ROP.

This paper will also discuss the use of this process and the bit developed for a 5 5/8" in Saudi Arabia application. Offset PDC bits averaged 200 $/ft including hole opening cost the solution as a result of the modeling and simulated drilling resulted in an average of 113 $/ft in the same application.
Lessons Learned and Management Information used in the Successful Implementation of a Competence Assurance Process
Authors: Matroushi Salem Al , Kochanczyk Raymond , Baba-Ali Foudil , Mohammed Ahmed Amir , Shekali Khalid Al , Verkoelen Joannes , Dupuis Joseph
Published: June 2009

In 2004 ADNOC implemented the Competence Assurance Management System (CAMS) for new University and Higher College of Technology (HCT) Graduates. Today, there are over 700 participants in six ADNOC E&P Companies involving 36 functional disciplines; over 200 graduates have been integrated into supervisory positions. This accomplishment was delivered with significant Lessons Learned identified and subsequent corrections to the original plan.

The successful implementation of CAMS was built on developing a process with the support of line end users and implementation with substantial senior management support. A significant critical success factor contributing to this effort was the use of People Development elements of ADNOC's Performance Management System "Key Performance Indicators" (KPls) to encourage uptake. A second critical success factor was the creation and maintenance of a Management Information System which tracked the progress of individual Competence Development on a monthly basis.

This paper discusses the details and the Lessons Learned of how to implement a complex system across a diverse corporate culture. There will be a focus on how to identify what to measure and how to collect and report the significant data to keep Competency Development Systems on track and preserve the quality of the competencies learned.
Well Design, Execution & Collaboration: An Operator's Tool for the Planning and Drilling of a Deepwater Gulf of Mexico Well
Authors: Breidenthal John L. , Ochterbeck Christopher A.
Published: June 2009

As Exploration and Production (E&P) companies look to drill in record-setting water depths, facing extreme conditions and ever-increasing technical challenges, they will need the best people, processes and technology available in the petroleum industry. To compensate for this, Chevron's Deepwater Exploration and Production (DWEP) Business Unit undertook a project to optimize the use of their unique project management process, the Chevron Project Development and Execution Process (CPDEP). This project, called the Well Design, Execution and Collaboration Center (WellDECC), is a combination of people, processes, and technology working to use, align with and augment CPDEP throughout DWEP. This paper outlines the basic CPDEP phases and how WellDECC supports and enhances this process.

The CPDEP consists of five phases: identify and assess opportunities, generate and select alternatives, develop preferred alternatives, execute, and operate and evaluate. Chevron initially developed its current process in the upstream side of the business and ultimately adapted it for all projects. WellDECC was created using this process in 2004 with the primary objective of bolstering CPDEP within DWEP. WellDECC is currently in the last stage, operate and evaluate, as we enter 2008. In recent years, sharply increasing water depths have been accompanied by similar increases in technical challenges and drilling costs; a robust project management process is essential for success in this environment. Chevron Drilling and Completion (D&C) and the Geological and Geophysical (G&G) communities came together and developed the concept of WellDECC to be fully engaged in each of these phases.

One of the important considerations when planning WellDECC was the selection of an operating platform that would seamlessly integrate cross-functionality to best support CPDEP. Halliburton (Landmark and Sperry Drilling Services) was ultimately selected as the primary provider for WellDECC's tools and support. By combining 3-D earth-model visualization, well-construction engineer tools, real-time telemetry functions, real-time drilling parameters, Logging While Drilling (LWD) viewing and data storage, WellDECC has the people, processes and technology to best accomplish its mission.
New Application of an Inline Separation Technology in a Real Wet Gas Field
Authors: Hamoud Amir A. , Boudi Adnan , Al-Qahtani Saeed D.
Published: June 2009

The inline separation technology has attracted the attention of oil and gas field operators due to the considerable weight, space and cost savings that can be achieved. In addition, the inline separation technology can play a major role in de-bottlenecking and upgrading the existing production facilities.

Several gas wells are beginning to produce significant water. Older gas plant facilities were not designed to handle high water production. Compact inline separation technology has the potential of eliminating any water-related restriction on well production, and reducing the investment for upgrading existing conventional separators.

A trial test of a skid-mounted inline separation technology (Deliquidizer) is being implemented at a wet gas remote header. The header has three flowing wet gas wells. The separated gas and liquid (water and condensate) streams will be monitored for flow rate and phase fractions using suitable multiphase flow meters. The separated gas will be flowed to the gas plant and separated liquids will be flowed in a separate flowline to the nearest oil processing facility. This will allow unrestricted flow of the gas wells without the need to upgrade the water handling facilities of the gas plant resulting in significant cost savings.

This paper discusses the concept, objectives and benefits of inline separation technology application in Saudi Aramco wet gas field. The field trial test loop, process conditions, equipment specifications, and future applications of this technology within Saudi Aramco will also be discussed.
Improved Performance of Downhole Active Inflow Control Valves through Enhanced Design: Case Study
Authors: Al Mubarak Saeed M. , Sunbul Ahmed H. , Hembling Drew , Sukkestad Tor , Jacob Suresh
Published: June 2009

Saudi Aramco has completed more than 100 multilateral wells with intelligent completions to monitor and control the inflow from the laterals in realtime without well intervention. The intelligent completion typically consists of isolation packers, multi-position downhole valves and downhole gauges. Field data has confirmed that the systems are functional in controlling inflow from laterals and that the flow characteristics of the downhole valves are varied due to different completion design and productivity index of producing zones. A field review was initiated to optimize the operation of the existing wells and to design a standardized valve design that suits different well completions and reservoirs.

This paper illustrates a case study detailing comprehensive analysis of downhole valves performance and design. It presents the process used to improve downhole valve design based on field data. The new design provides higher level of control at lower flow rates, hence enables finer adjustment of distribution of inflow among different laterals or segments. The modeling work is based on a new operating envelope so that inflow control valves can be used to produce rates that satisfy both reservoir management strategy and well production scheme. The modified insert chokes has been flow tested and installed in recent wells' completions. These wells will be flow tested to evaluate the performance of the new downhole control valves.
Evaluation of the Bitumen Intervals in a Carbonate Reservoir, Case Study in Abu Dhabi onshore field, UAE
Authors: Haggag Mostafa , Al-Yaaqoobi Amena
Published: June 2009

The field under study is an anticline carbonate reservoir onshore Abu Dhabi, UAE. It produces from Lower Cretaceous Reservoir. The integration of core data, log data and laboratory chemical analyses highlighted the presence of bitumen at the base of the reservoir in many wells. The bitumen has a negative impact on reservoir performance; it acts as a permeability barrier for production and injection, and also reduces effective porosity; i.e. affects both flowing and storage capacities of the field. Moreover, it reduces the recoverable oil from the field.

This paper discusses the methodology used to evaluate the bitumen in the reservoir in terms of the occurrence in the wells, the thickness, and the distribution across the field. It suggests the structure evolution of the bitumen to help in tracing it in non cored wells and also to define the bitumen intervals in new wells. The paper also highlights the technique used to incorporate the results in the 3D reservoir model.

Implementation of the results allows better understanding of the reservoir performance due to the presence of bitumen intervals and enhances the reservoir history match of the 3D reservoir model. The results are currently used as inputs in several ongoing full field reservoir studies such as PVT, and wax & asphalting scale deposit studies.
Comparison of 3D VSP and High Resolution Surface Seismic Images for Improved Reservoir Monitoring and Characterization
Authors: Mueller K. , Soroka W. L. , Baloushi M. N Al , Jeelani O. S. Al , Paulsson B. , Chavarria A.
Published: June 2009

Two 126 level 3-component 3D-VSP's (Vertical Seismic Profiles) were acquired coincident with a high-resolution surface seismic survey. Figure 1 shows the location of the first 3D-VSP on the crest of the field and the second 3D-VSP on the flank of the field. Using the surface seismic sources, 11712 shot points were used per VSP to collect 4.5 million traces per VSP, which produced a 6-9 km² final 3D-VSP image around each of the two wells. Due to the large offsets and high density of traces available it was possible to experiment with acquisition and processing methodologies to produce images that resolve thinner beds, see more structural definition and improve reservoir characterization. Results from the first phase of processing are very encouraging and show the 3D-VSP images to be able to resolve subtle faults that were not seen in older surface seismic data and have higher frequency content than the new 640 fold, high resolution surface seismic data. Source and receiver decimation tests are aiding in efforts to better understand how to acquire high quality 3D-VSP's in the future with minimal effort and cost. Efforts to expand the size of the 3D-VSP volumes around the wells have been successful. The largest image produced so far has been able to image more than 1.5 km away from the wellbore. The high quality VSP images and the fact that VSP's can be repeated at much lower cost than surface seismic makes this technology very attractive for future time-lapse reservoir monitoring studies.