bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Regression Analysis To Relate Safety and Environmental Outcomes to Incidence Factors
Authors: Jablonowski C.J.. J.
Published: February 2011

This paper addresses the need for more-rigorous quantitative analysis of health, safety, and environmental (HSE) data. Regression analysis is proposed and demonstrated as a tool to be used within the data-analysis function of an operator's safety-management system (SMS). It is argued that regression analysis can provide incremental value relative to qualitative or basic statistical analysis. A case study is employed to demonstrate how specific hypotheses can be tested in a systematic way. Results from such studies can be brought to bear on operational and safety-management policy decisions. As results of such studies accumulate over the long term, resources will be allocated more efficiently and new best practices will emerge.
First Correlation of NORM with a Specific Geological Hypothesis
Authors: Smith Andrew L
Published: February 2011

It is now possible to relate most oil and gas reserves to six stratigraphic black shale formations which include the majority of the world's oil and gas source rocks (Ulmishek and Klemme, 1990). From 1997 the US Dept of Energy attempted to predict the activity of NORM and other factors which may affect the activity and / or occurrence of NORM in E&P production operations (Chriss 2002). Black shales are the source rocks for petroleum trapped within Uranium deposits (IAEA 2009).

According to current ideas kerogen† is the organic constituent of sedimentary materials that is associated with petroleum formation. Kerogen is considered by petroleum geologists as being of two different varieties: humic kerogen associated with poor oil sources and sapropelic‡ kerogen, related to subaqueous sediments and associated with rich oil sources. Oil and gas is formed by the thermal cracking of organic matter (kerogen) trapped in sedimentary rock.

Two hypotheses regarding NORM in E&P production operations need to be considered. The first hypothesis is that NORM is produced by locally high U and Th concentrations in the reservoir rocks. If this is generally true, NORM scale will be largely controlled by the geological formation and lithology. The second hypothesis is that NORM is released from ordinary geological media during normal geological processes. If this is generally true, the potential for NORM scale precipitation may be predicted largely from basin setting and history.

A worldwide survey comprising a comprehensive review and detailed analysis of reported NORM activity in oilfield scales has now determined which of these hypotheses prevails. For the first time management will now have the ability to predict the magnitude of NORM in E&P facilities worldwide.
Qualification of Well Barrier Elements - Test Medium, Test Temperatures and Long-Term Integrity
Authors: Vignes Birgit
Published: February 2011

This paper presents the challenges related to qualification and testing of well barrier elements related to the long-term integrity test, the exposed medium, the temperature, and how the testing and qualification are performed. The paper shows that the International organization for standardization (ISO)/ American Petroleum Institute (API) standards for well barrier elements such as drill pipe, BOP, packers and bridge plugs, subsurface safety valves, casing and tubing connections, gas lift equipment, and cement can be improved in relation to long-term integrity testing, the test temperature and the test medium.

NORSOK D-010 is a well integrity standard developed by the Norwegian petroleum industry and available at www.standardnorge.no. The standard defines the well barriers as an envelope of one or several barrier elements preventing fluids or gasses from flowing unintentionally from the formation, into another formation or to surface. The standard states that the permanent well barrier should have long-term integrity properties. The long-term integrity test of well barrier elements is not described in NORSOK D-010 or in any other relevant ISO/API standard. The industry does not perform long-term integrity tests and this paper discusses the factors that need to be considered.

The paper illustrates that the industry needs to further concentrate on qualification of the well barrier elements. The well barrier elements will impact well integrity and the possible degradation of the construction of the wells. The control of the well barrier status and quality is an important HSE factor in order to avoid incidents and major accidents caused by unintentional leaks and well control situations. Knowledge of well integrity status at all times enables the companies to take the right action in a proactive manner and thereby prevent incidents from occurring.
Thermal Streamline Simulation: Steam Floods
Authors: Zhu Z. , Thiele M. R. , Gerritsen M. G.
Published: February 2011

In this work, we extend our previous work on thermal streamline simulation to steam floods. Steam floods exhibit large volume changes and compressibility associated with the phase behavior of steam, strong gravity segregation and override, and highly coupled energy and mass transport. To overcome these challenges we implement a pressure update along the streamlines and a Glowinski θ-scheme operator splitting. We tested our streamline simulator on a 2D horizontal quarter-five-spot steam flood, a 2D vertical cross section steam flood with gravity override, and a 2D multi-well example. We compared our thermal streamline results with those computed by a commercial finite-volume thermal simulator on both accuracy and efficiency. For the cases investigated, we are able to retain solution accuracy while reducing computational cost and gaining connectivity information from the streamlines, which is useful for reservoir engineering purposes.
Method to Improve Well Model Efficiency in Reservoir Simulation
Authors: Edwards David A. , Guyaguler Baris
Published: February 2011

Modeling of complicated reservoir processes requires sophisticated field management algorithms that request many well model solves in each simulation timestep. Most field management strategies require the wells to be solved in three different modes: "operating" constraints (all well constraints and those imposed from group/field management strategies), "deliverable" constraints (well rate and pressure limits only), and "potential" constraints (well pressure limits only).

Because these three modes often have very different solutions, the well model often starts from a solution that is far from the actual one; this results in an unnecessarily high number of well Newton iterations.

In this study, a well model that has three solve-spaces corresponding to the three modes results in a significant reduction in the total number of well Newton iterations and a corresponding reduction in overall simulation run times as demonstrated in a suite of real field cases.
Step By Step Developing And Implementing A HSE Culture Project
Authors: Vikland K. M. , Gjøsund G.. , Fagernes E..
Published: February 2011

Oil and gas companies operating on the Norwegian Continental Shelf (NCS) have recently implemented behavioral safety programs. The aim of these programs is to improve safety behavior and culture because of negative health, safety and environmental (HSE) results. The "Step By Step Developing And Implementing A HSE Culture Project" presented in this paper aims to prepare the organization for an imagined future with good HSE results. The central premise of this project is that everyone in the organization together builds and forms their organizational culture and identity with HSE as the foundation. To fulfill its intentions the HSE culture project has different steps. Firstly, the organizational characteristics were examined and analyzed. Secondly, the organizational characteristics were used to design the organizational model. Thirdly, the organizational model was implemented in the organization. This is a systemic organizational approach to HSE: (i) employees are involved in every step of the project to make sure that the design of the organizational model reflects how they think and act. (ii) HSE is an integrated part of how the organization does their business.

Diversity in perception, understanding and knowhow related to several topics and aspects came out as a potent organizational characteristic in the examination and analysis at the beginning of the project. Because of this, diversity is the basis of the organizational model. Traditionally, diversity and safety have been considered a problem in terms of risk perception, work practice and goals.

The results from the project so far indicate that employees and managers at every level have adopted the concept of the HSE culture project by using the terminology in the organizational model. The focus now is on operationalizing the content in the organizational model "from speech to action;" for instance, how to make use of diversity to achieve good HSE results and an overall good performance. At this point in the project, the conclusion is a continuation of the HSE culture project as an everyday process. Managers have a decisive role to make this happen, and it is of crucial importance that managers at every level understand the correspondence between saying and doing. Suggestions on how to make this happen will be presented.

The "Step By Step Developing And Implementing A HSE Culture Project" is taking place at GDF SUEZ E&P Norge AS (GDF SUEZ Norge), which is the Norwegian affiliate of GDF SUEZ Exploration & Production.
Major Accident Indicators for Monitoring and Predicting Risk Levels
Authors: Haugen S.. , Seljelid J.. , Mo K.. , Nyheim O. M.
Published: February 2011

Monitoring of risk is a key element in the overall risk management process. Monitoring major accident risk is difficult because accidents are rare and monitoring therefore requires use of indirect measures rather than statistics. Extensive efforts are presently put into developing good indicators which can predict trends in major accident risk, as a basis for taking actions when risk is increasing. This paper presents a method for developing major accident risk indicators which uses a risk model as a basis. The risk model includes all key factors which influence the major accident risk, including human and organizational factors, and also describes influences between the factors. This gives a multi-level risk model, from which indicators can be identified. Through regular monitoring of these indicators, the major accident risk level can be followed closely. The method is described step by step and an example of application is also briefly presented.
An Integrated Modeling Framework for Decision Support in Ecosystem-Based Management: Case Study Lofoten/Barents Sea
Authors: Carroll JoLynn , Smit Mathijs
Published: February 2011

Ecosystem based management is today the foundation of international regulatory frameworks for managing the oceans and seas. The approach enables sustainable use of marine goods and services while maintaining good environmental status and preventing subsequent deterioration. However we lack holistic models capable of supporting ecosystem based management decision-making. Standard methods for regulatory risk assessment are based on precautionary principles and worst case assumptions. Although these methods are useful for environmental management and risk mitigation they have limited value in ecosystem-based management approaches where comparative risk/benefit assessments are essential. Advanced models are needed that simulate in more realistic detail the marine biosphere and allow prediction of actual potential impacts and uncertainty intervals instead of worst-case risks only.

To resolve this problem, an international consortium of petroleum industry partners has established a project to develop an integrated modeling framework for ecosystem based impact assessments of the marine environment. The framework is initially being developed for applications in the spatially managed area of the Lofoten/Barents Sea to address the combined effects of fisheries and petroleum activities. The region is rich in petroleum resources and is also a key spawning and egg/larval drift area for several important North Atlantic commercial fish species. This integrated modeling framework includes an ecosystem and ecotoxicology module, which integrates existing ecosystem models for adult fish, fish eggs & juveniles, phyto- and zoo- plankton, chemical fate and ecotoxicology. Here we describe the model system and development process and show how such approaches are of value toward providing stakeholders with more quantitative information on the environmental risks and benefits of petroleum development activities in potentially contentious areas.
New Approach to Risk Monitoring for Acute Environmental Spill to Sea on the Norwegian Continental Shelf
Authors: Vinnem J. E. , Wagnild B. R. , Heide B..
Published: February 2011

A holistic approach to risk monitoring for acute environmental spill to sea from all petroleum activities on the Norwegian Continental Shelf has been developed. The approach yields risk indicators based on reported discharges, as well as indicators based on precursor events which may result in spills if several barriers fail. Well kicks that have reservoir blowout potential have the highest indicator value. The second largest value is other hydrocarbon releases which may lead to secondary blowouts, riser/pipeline failure or structural damage and hence release of stored oil. External events that may cause structural damage to the extent that stored oil is released or secondary blowouts, is also a significant category. The suitability of the method is dicussed thoroughly.
Trial Teleconsultation Sessions On Castoro 12 In North Caspian Sea
Authors: Kevlishvili G.. , Mika F.. , Sanctis S. De
Published: February 2011

In the view of continuous improvement we wanted to explore the possibilities to improve the management of health on offshore location (Kashagan Project) in Kazakhstan (Urgent and non-urgent medical cases). The scope of this program was to determine the feasibility of implementing tele-consultations and e-health based on the use of narrow and medium internet lines that are easily available and with relatively cheap technologies. With this scope, we launched pilot tele-consultation program creating communication bridge between an offshore operating barge (Castoro12) and a private multidiscipline clinic (Doctor Plus) located in Atyrau. The communication tools used to enable the data transfer between these two locations were Skype software, digital camera, web camera and 12 channels ECG.

Another aspect of the study was to monitor and verify the level of satisfaction of both users - doctors and patients/employees.

During this pilot program we carried out 34 consultations, 23 in synchronous (real time) mode and 11 in "store and forward" one. The last were performed as part of the Cardiovascular Diseases Prevention Program. Out of 23 multidisciplinary urgent and emergency medical cases 17 remained and completed their treatment offshore, while 5 patients had to be evacuated on shore, three of which were hospitalized.

This short and limited experience proved the efficiency and cost-effectiveness of telemedicine even when simple technology is used, and verified sufficient level of satisfaction of both medical personnel and employees/patients. This allows us to recommend wide use of technically simple tele-medical systems, combination of real time telecommunication with store-and-forward method, using narrow or medium bandwidth, based on Internet.

Search for multidisciplinary and certified medical canters with qualified medical personnel operating on 24/7 basis is recommended. In future, the rapid development of ICT opportunities will enable tele-consultation practices to be applied to other sites in remote and isolated areas.
Managing Tuberculosis in Oil and Gas Industry
Authors: Mika F.. , Martin A.. , Cox Rob
Published: February 2011

Tuberculosis (TB) still represents the leading cause of death due to a single infectious agent. It is a resurgent disease in most regions of the world, particularly in non-developed and developing countries

Today TB, together with Malaria and HIV/AIDS, represents one of the major health related burdens for the O&G Industry. Being preventable it is also a challenging health related issue.

Many countries have developed their own National Tuberculosis Programs, and it is with these programs that O&G industry, together with NGOes has to interact and develop its specific prevention programs. But how and to which extent? How to manage the sick or TB positive employee? How to screen the employees and possible contacts? Which actions to undertake in case of a sickness being detected in the field?

To answer at the above questions, and many other related to TB, OGP/IPIECA created a task force with a scope of preparing and issuing a guiding document that will help the Managers and supervisors in O&G industry to manage Tuberculosis. The document is not a new textbook of tuberculosis, but a simple guideline for prevention and management of the disease in field operations and their practical implementation.

The document was published in 2010. Its’ main chapters are: The importance of effective TB management; Relevance to O&G facilities; Clinical aspects of tuberculosis; Workplace programmes for TB management; and Appendices. These last ones, five of them, are giving the concrete guidelines on TB detection, Development of TB program, and Responding to a suspected case

Being TB a serious health burden to O&G operations OGP/IPIECA issued a document to help and support the Management in coping with all the aspects of this disease. The document has the ambition to become the reference point for the industry on this issue.
Assessing the Physical Ecological Impact (Footprint) of Industrial Development on Landscapes Beyond Protected Areas
Authors: Willis K. J. , Jeffers E. S. , Tovar C.. , Smit M. G. , Hagemann R.. , Collin-Hansen C.. , Weissenberger J..
Published: February 2011

A tool to measure the potential ecological impact (footprint) of developments outside of protected areas is novel and long overdue. Whilst there are numerous methods currently available for mapping important regions for conservation within protected areas, there are few suitable tools available for assessing the ecological value of landscapes that are ‘beyond the reserves’. Given that this accounts for over 88% of the world's terrestrial surface, a systematic tool for determining the ecological value of these landscapes could be relevant to any industrial development that results in a parcel of land being transformed from ‘natural’ to ‘industrial’.

Results are presented of a joint project between Statoil and University of Oxford, UK to develop an automatic web-based tool that can assess the ecological value of land outside of protected areas. Ecological factors currently considered within this tool include i) biodiversity, ii) vulnerability, iii) fragmentation, iv) connectivity and v) resilience. The tool has the capability to provide ecological valuations for parcels of land at 300m resolution and uses data that are publicly available and have mostly global coverage. We present results for three case study areas in Canada, Algeria and the Russian Federation to demonstrate its potential and how it can be used to plan development within a concession area in order that damage to local ecosystems and ecosystem functioning is minimized.
Performance Standards For Safety Critical Elements - Are We Doing Enough?
Authors: Dhar Rahul
Published: February 2011

Safety Critical Element (SCE) lifecycle management involves identification of Major Accident Hazards (MAHs); selection of the Safety Critical Elements by identifying structures and plant which can cause, contribute to, prevent or help recover from a major accident event; and to develop the performance standards for the identified SCEs. It also involves alignment of maintenance routines, inspection and testing, performance history etc. required to maintain the SCE in a suitable condition. Managing deviations and impacts on management of change also form a part of the lifecycle management of SCEs. The continual monitoring of the status of the hardware barriers and performance assurance tasks enable the operating staff and the management to analyse the ongoing conformance of the SCEs with their performance standards. This provides opportunities for improvement and possibilities for further risk reduction.

The purpose of this paper is to elaborate on the Safety Critical Element (SCE) lifecycle management process for new and existing facilities. It aims to highlight weaknesses in lifecycle management of Safety Critical Elements and helps the reader to identify improvements both in terms of the processes and content of the Performance Standards. It further highlights the benefits of the use of Safety Critical Elements and Performance Standards in achieving overall improvements and risk reduction.
Estimating Onshore Plant Effluent Concentrations Using OPEM
Authors: Binay N. P. , Smit M. G. , Frost T. K. , Stone K.. , Firth S..
Published: February 2011

When assessing environmental risks from industrial discharges it is a prerequisite to properly estimate concentrations of many chemicals in the discharge effluent. For many chemicals (e.g. hydrocarbons, metals) analytical methods are available and effluent concentrations can directly be measured. However, for many man-added, process chemicals (e.g. biocides, corrosion inhibitors) no analytical methods are available and concentrations need to be estimated based on the amounts used and physical chemical behaviour of the components. For this purpose a designated model was developed to be applied to oil refineries and terminals. The Onshore Plant Effluent Model (OPEM) estimates the annual average effluent volume and concentrations of chemical components in the discharged water from upstream oil plants.

OPEM can be tailored to a specific facility by using a generic process diagram in which all relevant parts of the process can be included; creating a system that represents the facility that the model will be run for. To be able to run and provide accurate output, the model needs information including composition of each process chemical, physico-chemical properties, effect thresholds (i.e. PNECs) and basic toxicity data. This data is stored in databases that form an integrated part of OPEM. Another input for the model is the characterisation of the inflows. Here a selection can be made from flows of oil with traces of water and chemicals from a specific field, flows of chemicals that are applied directly to the system and additional water flows like rain and drainage water. Finally, mass balance data must be entered, which represents a quantification of the inflows or chemicals used.

OPEM uses dilution and mass balance equations to calculate the effluent concentration of each component in any part of the facility including the discharged effluent. For every chemical component OPEM produces a pie-chart presenting the origin of the component (where is it used and in which process chemicals).

Even though developed for upstream oil industry, OPEM is a generic model that can be used for complex effluent concentration calculations for any process facility. Estimated effluent concentrations of chemical components together with the information on the origin of the components are an important input for environmental risk management.
Analysis of Causes of Hydrocarbon Leaks from Process Plants
Authors: Haugen S.. , Vinnem J. E. , Seljelid J..
Published: February 2011

The PSA Risk Level Project has collected near-miss data for all installations on the Norwegian Continental Shelf, since 1996, where one of the most extensive categories is the hydrocarbon leaks. The most detailed data are available for the period 2001–09. The leaks have been analyzed with respect to causes and operations being undertaken at the time of the leak. The Norwegian offshore industry has achieved a considerable reduction in the number of leaks since the period around 2000. It is demonstrated that reduction has not been achieved in several critical areas, which still may be considered a significant improvement potential. It is illustrated how new measures need to be implemented which are directed at the main causes of leaks, if further improvement is to be made.
Safety Leadership that Engages the Workforce to Create Sustainable HSE Performance
Authors: Read B. R. , Zartl-Klik A.. , Winter J. D. , Veit C.. , Samhaber R..
Published: February 2011

This paper focuses on what it takes to create sustainable HSE performance. It outlines the journey that an Oil & Gas Producer in Central Europe has taken to create a HSE Culture where health, safety and environment are an integral part of business. Since September 2004 this E&P company has been on a journey to change its HSE culture. This has required new understanding of what safety leadership actually is and the very powerful role that leadership has in engaging the workforce to create a HSE Culture which is committed to an injury free workplace.

The results achieved in HSE performance improvement that are presented in this paper are well documented through KPIs over a 5 year period. The business case and the commercial sustainability of the Safety Leadership approach is clearly presented through multi-million dollar savings. The experience of this change in approach is that it is sustainable and readily implemented; however, the fundamental principles are not well understood by many E&P companies. Many E&P companies are continuing to invest heavily in a flawed approach.
Decommissioning Concrete Structures - Environmental and Safety Challenges
Authors: Knudsen Søren
Published: February 2011

The OSPAR convention requires that almost all offshore oil and gas installations have to be removed when they are no longer in active use. There are currently approximately 832 oil & gas production facilities in the North Sea many of which will be abandoned in the coming decades.

In the decommissioning of offshore oil and gas installations, there is a continuous focus on keeping environmental and safety risks as low as reasonably practicable (ALARP). This paper will describe the assessment of decommissioning solutions from an environmental point of view, as a basis for submitting a decommissioning programme. The paper is primarily based on experiences gained from ongoing and completed decommissioning projects in the North Sea (Ekofisk tank, Brent Bravo/Delta and Frigg & MCP01). The focus of this paper is restricted to the decommissioning of concrete substructures.

Decommissioning concrete structures typically involves larger environmental and safety considerations than steel structures, as they tend to be more polluted from trapped oil, sludge, etc. Furthermore, several of these structures have not been designed with the intention for later removal and may involve large safety risks during a refloating operation.

Some of the major conclusions with regard to decommissioning of concrete substructures are: Ensuring a reliable decision-basis must not be under-estimated, as this is vital to support the difficult decommissioning options selection. This could be made by means of e.g. offshore sampling / surveysOnshore preparation, such as pilot-scale testing of tools and laboratory testing, can in some cases be beneficial and save time offshoreThe environmental and safety risk considerations play an important part in the fine balance between the company's wish to ensure a good reputation by removing all traces of their activities, and substantial practical safety and technical safety challenges associated with a ‘removal all’ operation.In some cases, partial removal or ‘leave in place’ could be the best decommissioning solution in relation to HSE.
HSE Compliance in Romania
Authors: Ebrahimian A.. , Stefanescu E..
Published: February 2011

Drilling activities in Romania have been ongoing for over 154 years. After world war two, Romania became a communist state under USSR thumb until 1989. Shortly after they became members of the EU.

People working in the Oil & Gas industry in Romania were exposed to safety hazard risks leading to a number of accidents with some fatalities. Since OMV took up the majority shares and ownership of Petrom, both HSE and QA/QC respected industry standards have been properly addressed and are now fully implemented on all rig operations on contract to OMV Petrom Romania.

In 2008 OMV Petrom -HSE/Drilling Department set up a Safety Observation Program and implemented use of this program on all OMV Petrom rig operations.

The objective was to encourage people working on OMV Petrom rigs to highlight hazards and associated risks so corrective actions could be implemented in order to mitigate all those hazards and associated risks. Our aim is to make a safer working environment at the rig-site to enable people to work in safe conditions. We will highlight the statistics from our Safety Observation Program in tables and charts in this SPE Paper.
Transforming HSE Performance, It's Not Harder Than You Think
Authors: Kraus Brian , Rowley Peter
Published: February 2011

Many of us who have interacted with senior executives from leading oil and gas companies over the last few years on the subject of HSE performance have observed a marked shift in their engagement on this aspect of their business performance. There seems to be a shared impression that HSE performance will have markedly increased impact on their businesses going forward. On the back of this very real concern, many are taking material actions to secure a step change in their safety and environmental performance: hiring respected mainstream operational personnel to lead their HSE function; investing in capacity/skills development for HSE professionals to increase their effectiveness in addressing the needs of the business; taking a hard look at the efficacy of established management and audit programs (too much paper, not enough results?); investing in information management systems so they can have access to real time reliable performance indicators; and, critically, initiatives to reduce accident statistics (especially focused on fatalities and contractors' activities) and deliver meaningful reductions in their environmental footprints.

Underpinning all of these actions is a clear sense that substantial, very well-intentioned activity and investment in HSE aspects of the business has not been hitting the mark and yielding too little return in terms of performance improvement. The very serious recent events on the US Gulf Coast and at a refinery in the US Pacific Northwest have added fuel to this fire. The need for approaches which will secure a step-change in performance on the front line in the global oil and gas industry has never been greater.

It is broadly accepted that accidents have their origin in behavioral dynamics. In addition, the linkage between behaviors of front line personnel (including design engineers) and the behaviors of their leaders up and down the line is well-understood.
Adaptive Regularization in the Ensemble Kalman Filter for Reservoir History Matching
Authors: Tong Yao , Zhang Yanfen , Oliver Dean S.
Published: February 2011

Using a small ensemble size with the ensemble Kalman filter (EnKF) to update numerical reservoir models has proved to be an efficient method of reservoir history matching but, unless some type of localization is used, the standard EnKF update with a small size ensemble can lead to poor parameter estimates due to spurious correlations between observations and model variables. To reduce the impact of spurious correlations on model variable updates, distance-dependent localization has been widely used and is frequently effective at eliminating spurious correlations beyond a predefined distance. However, distance-dependent localization is not always appropriate for assimilating non-local observations, or when the prior covariance is complex due to previous data assimilation. Since the updates of parameters and state variables in the EnKF algorithm are largely determined by the Kalman gain, an improvement in Kalman gain estimation will in turn result in improved estimates of state and model variables. Several adaptive Kalman gain estimation methods, including the bootstrap sampling method, have been proposed recently with promising results but with residual small-amplitude high-frequency noise in the estimate of the Kalman gain.

In this paper, we propose a thresholding method for improving the Kalman gain estimation to completely eliminate correlations that are unreliable. We show that by screening the Kalman gain using an adaptive, element-wise threshold level, much of the noise in the estimate of the Kalman gain is removed at a low computational cost. We apply the new thresholding method and the previously developed bootstrap screening EnKF to a deepwater field with approximately 200,000 unknown model parameters. Results from both adaptive EnKF methods are better than results from manual history matching and are comparable to results from a standard EnKF method with distance-based localization.
Using a Committee Machine With Artificial Neural Networks To Predict PVT Properties of Iran Crude Oil
Authors: Alimadadi F.. , Fakhri A.. , Farooghi D.. , Sadati S.H.. H.
Published: February 2011

Reservoir-fluid properties are very important in material-balance calculations, well testing, and reserves estimates. Ideally, those data should be obtained experimentally. Sometimes, the results obtained from experimental tests are not reliable or accessible.

In this study, we predict the pressure/volume/temperature (PVT) properties by a new artificial-neural-network (ANN) model using component mole percent, solution gas/oil ratio (GOR) (Rs), bubblepoint pressure (Pb), reservoir pressure, API oil gravity, and temperature as input data.

The employed ANN model is from the committee machine type. The designed model processes its inputs using two parallel multilayer perceptron (MLP) networks, and then recombines their results. The results obtained show that the committee-machine model is a dependable network for prediction of PVT properties in reservoirs among the other ANNs and empirical correlations.
Investigating the Evolution of Underwater Gas Releases
Authors: Borello L.. , Baldanzi E..
Published: February 2011

Underwater gas releases were investigated by experimental tests to analyze the potential hazards deriving from accidental ruptures of offshore pipelines in the oil & gas industry. The evolution of the gas released by the ruptures located in relatively shallow waters has been accurately analyzed in order to evaluate the hazards associated with the toxic and flammable gases reaching the sea surface. The experimental activity has been carried out to better characterize the gas dispersion source term.

An underwater gas release from a pressurized pipeline generates a subsea gas plume that breaks down in bubbles and could reach the neutral buoyancy level below the sea surface. The size and rising velocity of the bubbles affect the momentum of the gas reaching the sea surface, while the lateral spreading of the bubbles and the gas dissolution in water influence the bubbling area and the actual flow rate dispersed in the atmosphere. Another important phenomenon is the neutralization of the gas due to the diffusion in the air just above the sea surface. These parameters represent the basic information required to determine the behavior of the gas above the sea surface and the source term for atmospheric dispersion.

The experimental activity consisted in discharging a gas in an open tank filled with water. A set of lab tests was performed to evaluate the plume evolution for underwater releases of a neutral gas in shallow waters. The liquid velocity and gas hold-up were monitored along the plume length for different gas flow rates.

A benchmarking activity on underwater gas release models was performed comparing model equations with the experimental measurements. As a result of this work, a more accurate approach for determining the source term of atmospheric dispersion of a subsea gas plume is proposed.
Advanced Methods for Flash Fire Risk Assessment
Authors: Borello L.. , Podenzani F.. , Lorenzini F.. , Baldanzi E..
Published: February 2011

Flash fire is one of the main potential hazards of oil & gas operations. The development of the flammable cloud is directly correlated to the explosion risk. Gas cloud evolution strongly depends on the source term definition. Commercial models, specifically developed and tuned for industrial plants risk assessment often simplify the phenomena affecting the source term, introducing errors and non-conservative assumptions. Excessive simplifications become particularly critical in case of accidents in non obstructed areas, where an accurate evaluation of the extension of flammable (and explosive) clouds is fundamental to assess the risks for assets, personnel or population.

In this paper various phenomena characterizing the source term are analyzed in some typical discharge configurations, in order to introduce a robust methodology based on realistic assumptions. Diversity of scenarios has been investigated to examine the factors that can affect the gas dispersion.

The loss of integrity of a high pressure pipeline was studied in order to understand how the high momentum jet influences the atmospheric dispersion of the gas: computational fluid dynamics (CFD) simulations were compared with commercial models and ad hoc approaches.

The evolution of a thermodynamically dense gas cloud from zero momentum sources was analyzed in a benchmarking activity with literature data, CFD approach and commercial models.

The flammable gas dispersion from subsea ruptures was also investigated. Even for this kind of event the dispersion of the flammable gas is highly influenced by the source term, which is strongly uncertain. A dense/light gas released by a subsea rupture usually generates a bubbling area at sea surface. The surface gas source is characterized by an immediate dilution with air.

The main purpose of this study is the reduction of the errors associated with inaccuracies of the source term definition and gas dispersion in the consequence analysis studies.
Soil Contamination From High Velocity, Atomized Incidental Oil Releases, A Complete Predictive Approach
Authors: Borello L.. , Bonuccelli M.. , Raucci L.. , Antico L..
Published: February 2011

Oil wells blow-out events are characterized by the uncontrolled releases in atmosphere of multiphase hydrocarbon mixtures. The upper well section under blowout conditions is always characterized by the presence of annular flow with the most part of the oil transported in form of droplets. A further atomization occurs at the discharge, typically in critical flux conditions. The droplets ejected at sound velocity in the atmosphere exchange momentum with the gas jet rising at different elevations depending on the size, the jet momentum and the meteorological conditions. The granulometric distribution of the droplets also strongly affects the following aerosol dispersion and fallout. The aerosol dispersion follows two different mechanisms: Gaussian dispersion for the small droplets (with a spreading phenomenon strongly dependent on diffusion effects), ballistic dispersion (with a spreading dependent on stochastic variations in wind direction and speed). During the fallout phase a not negligible amount of oil mass evaporates changing both the droplets dimension and the oil compositions. The typically long duration of the blowout event makes a short term approach (with constant meteorological condition during the event) not realistic. A long term approach, taking into account the typical meteorological classes distribution and persistency in the involved area has to be considered for the correct prediction of the oil fallout to the ground. This process generates to the ground surface an areal source term for the following infiltration phenomenon. These areal sources are characterized by wide extensions and significant distances from the well (more than 10 km in some cases).

Most of the complex processes and phenomena, which are described above, result not completely treated in literature and specific models had been developed and implemented in a in-house software (3) as described in this paper. The overall model has been validated with real blowout contamination data.
Multiscale Parameterization and History Matching in Structured and Unstructured Grid Geometries
Authors: Bhark E. , Rey A. , Datta-Gupta A. , Jafarpour B.
Published: February 2011

We present the development and field application of a workflow for multiscale reservoir model calibration that seamlessly integrates production data into reservoir description from the facies to the grid-cell scale. To start with, the permeability field is parameterized using a novel grid-connectivity-based transformation basis that can be applied with any model geometry including unstructured and corner-point grids. The parameterization basis functions emerge from spectral decomposition of the grid-connectivity Laplacian and are related to the structural harmonics of the grid. To reconcile data with model resolution during history matching, we first use the coarsest scale basis functions to identify the large scale variability. Additional smaller-scale basis elements are then adaptively incorporated to successively refine the model to a level supported by data resolution. During refinement, the inclusion of more detailed basis functions into the parameterization is determined by generic modal frequency when the prior model is unavailable, or using prior information when available. In the final step of the workflow a streamline-based inversion is performed to locally adjust the reservoir model at grid-cell resolution along coarse scale preferential flow paths defined during the previous step using the parameterization.

We demonstrate the suitability and effectiveness of the developed workflow through application to an offshore turbidite reservoir with frequent well intervention including shut-ins and recompletions. The static model has over three-hundred thousand cells, a complex channelized interpretation with faults, four injector-producer pairs with deviated wells and over eight years of production history including water-cut and pressure data. The grid connectivity-based parameterization effectively updates the prior regional permeability at scales and in locations warranted by the data, while preserving the geologic continuity and avoiding ad hoc redefinition of regions given the sparse well pattern. The multiscale calibrated permeability field indicates flow communication previously unrecognized in static geologic interpretation or manual history matching.
An Evaluation of Criteria for Dynamic Gridding during Reservoir Simulation of Water Flooding and Solvent Injection
Authors: Lavie G. , Torres J. A , Kamp A. M.
Published: February 2011

Some hydrocarbon recovery processes are characterized by the existence of sharp saturation and/or concentration fronts. Examples of such processes are VAPEX, in situ combustion, or water flooding of heavy oil reservoirs in presence of viscous fingering. In order to simulate correctly what happens around the fronts, small grid sizes need to be used. If however the whole reservoir is gridded very finely, computational time becomes prohibitive. In order to circumvent this problem, dynamic gridding, also callled, automatic mesh refinement may be used. During the computation, the computational grid is adapted to the dynamics of the flow. This requires the use of an estimator in order to decide where to refine or to coarsen the grid. In this work we studied dynamic gridding for a water flooding problem. We implemented this problem using the mixed hybrid finite element method in 2-D on a triangular grid. The resulting code was validated by comparison to a commercial reservoir simulator. From literature, we adapted an a posteriori estimator that had been derived for incompressible flow, and we used this to refine our grid on each time step. We show that the grid refinement criterion captures relatively well the sharp saturation front. Heterogeneities are also well captured. The code is able to reproduce some tendencies of viscous fingering, although more time is required to avoid definitely the numerical disperion and dynamic gridding influence. This work is a preamble for a second work considering simulation of the VAPEX process using dynamic gridding. For this we decided to switch to the finite volume method, for which a second code was developed which is shortly mentionned in the perspectives. We think that dynamic gridding may be a solution that will allow the simulation of processes such as VAPEX and in situ combustion at reservoir scale, using effective grid refinement in the region of the front.
Compositional Simulation Using the Advanced Peng-Robinson Equation of State
Authors: Wei Yizheng , Chen Zhangxin , Satyro Marco , Dong Chao , Deng Hui
Published: February 2011

During compositional reservoir simulations where underground fluid composition strongly affects the modeling of recovery processes, flash calculations are commonly employed to help determine the correct number of equilibrium phases, the corresponding compositions, and the phase amount of each phase.

Cubic equations of state (EOS) are widely used in the representation of volumetric and phase equilibria due to their simplicity and solvability. Commonly used cubic EOS such as Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) have well known limitations in predicting liquid phase properties for polar compounds.

In this paper, we present a compositional reservoir simulator equipped with the advanced Peng-Robinson EOS and an efficient and robust multiphase flash algorithm that can accurately predict the phase equilibrium. This method utilizes Michelsen's stability test (Michelsen, 1982) and a combination of accelerated successive substitution and a minimum-variable Newton-Raphson (MVNR) method for fast convergence.

The advanced Peng-Robinson (APR) EOS adds volume translation and a flexible attractive temperature-dependent term to the original PR EOS for accurate PVT and saturation property correlation for polar compounds. Examples of pure compounds and mixtures are tested. Computational results show that the developed simulator provides a more detailed description and better understanding of complex dynamic underground fluid phase behavior that may occur during oil recovery processes.
Probabilistic Collocation Based Kalman Filter for Assisted History Matching
Authors: Li Weixuan , Oyerinde Dayo , Stern Dave , Wu Xiao-Hui , Zhang Dongxiao
Published: February 2011

In this paper, we study the application of the probabilistic collocation based Kalman filter (PCKF) approach to history matching. Kalman filter is a classical approach for data assimilation and model calibration that has been widely used with success. It updates state variables (i.e., model input and output parameters) based on their correlations, which is challenging to compute efficiently for non-linear models. A popular alternative to estimating the correlations is to use an ensemble of models, which is the basis of the Ensemble Kalman filter (EnKF). The PCKF is an alternative to the EnKF in the sense that it estimates the correlations between the state variables from the Polynomial Chaos Expansion (PCE). The coefficients in the PCE are determined by the Probabilistic Collocation Method (PCM). In this paper, the PCKF method is applied to a synthetic reservoir model that mimics a deep water deposit of amalgamated channel complexes. This model exhibits complex flow patterns under different production scenarios making it useful for testing the PCKF algorithm. Acceptable history matches were obtained with a relatively small number of simulations. Our study suggests that PCKF may be a useful way to reduce the size of the ensemble required in Kalman filter methods, thus improving the efficiency of the history matching process.