bluuebunny/crossref_metadata_2025 huggingface dataset:
The Advantages, Costs and Pitfalls of International Drills and Exercises
Authors: Neilson David E
Published: December 2007

The paper analyses the benefits, financial implications and potential drawbacks of the oil industry holding response exercises and drills. The paper gives guidelines on how to maximise the investment both in financial terms and in personal effort. In addition discussion is held on the drivers, objectives and who should do what in a sample numbers of countries. The authors personal experience will assist the reader in avoiding problems, how to overcome issues in the development and management of drills internationally

The paper looks at what is expected in different part of the globe, what really is required for best industry and government preparedness. Also explored are be the changing trends of expectations, requirements and what really works world-wide. The scope of industry operations covered in the paper is upstream exploration and production activities and transportation. Highlighting the effectiveness of numbers of people involved, innovative use of exercise injects and some low cost but effective options will also be explored.

The pitfalls that could devalue the drill are also discussed. Such problems as industry and governments not being equally skilled in such issues as response management and the ability to drawn on appropriate resources. In certain cases these problems can defeat the initial objectives of holding the drill. Guidance will also be given on how to decide who and when organisations should be involved in the development and planning phases of the exercise.

Finally the summary and conclusions give opinion on why industry carry's out drills, what the benefits should be, is it worthwhile and how well we do it ?.

Internationally there still remains an imbalance of what is understood or what is required of an oil spill response exercise. In some countries a program of preparedness drills is required by law, in most others, the level and frequency is left to industry and individual organisations. Although recently, countries that are signatories to the OPRC convention are required to have in place a published programme of exercises. Whatever the regime, it is important that the event is organised and executed to maximum benefit. It is also important to understand that oil spills, are in most cases connected to some other issue of emergency response. This could be ship salvage, damage to exploration and production (E&P) facilities or process plant. In many cases the resources required to respond to the pollution and the other emergency element are similar and therefore lead to the need to prioritise resource utilisation. It is essential that these other issues are recognised and included in any exercise.

Expectations of what is required or what represents a successful drill or exercise will vary greatly between certain parties The perception by the public of a successful exercise will differ from the view of industry and government.
The Development and Promotion of Enhanced Health, Safety and Environment (HSE) Performance in the Underwater Engineering sector by Voluntary Industry Action
Authors: Andersen O C , Read Tony (AD)
Published: December 2007

The management of HSE in the underwater engineering sector is likely to be of increasing importance as more and more offshore productions comes from deepwater operations. The use of ROVs for very deepwater operations will be complimented in many cases by the continued use of divers for installation, inspection and maintenance of facilities at shallow depths.

The International Marine Contractors Association (IMCA) has, throughout the last 25 years itself and through its predecessors – the Association for Offshore Engineering Contractors (AODC) and the Dynamic Positioning Vessel Owners Association (DPVOA), been active in promoting health and safety in their sector of the offshore industry.

Initially involved with the underwater contractor (diving) industry, the work of self-regulation has now spread to the offshore contracting industry at large. A large number of Codes of Practice, Guidelines, Standards and Safety Notices have been jointly developed and issued over the years-initiatives often, unfortunately, prompted by the incidence of undesirable events in the sector to an acceptable level.

Although initially developed by, and for the member companies’ own use, increasingly these Codes, Guidelines and Standards have been subject of discussion with and adoption by national authorities and organisation acting on behalf of the contractors’ international customers. They are now generally recognised as international standards throughout much of the industry.
Characterization of Regional Landforms and Landscape Analysis in Support of an Oil Field Development in the Remote Arctic Timan Pechora Region of Russia
Authors: Barringer Jennifer J. , Schlegel Michael , Terry Sarah , Zilm Leslie
Published: December 2007

Conoco and their Russian partners, Arkangelskgeoldobycha conducted field programs from 1994 to 1996 in support of environmental baseline studies and civil planning and design work for the future development of the Northern Territories in the Timan Pechora area of Russia. A major component of both the environmental and engineering design work was characterization of landforms and landscape analysis in this remote arctic tundra environment. A landform/landscape analysis was performed to assist in siting of future facilities, pads, roads, and pipelines in locations that would minimize environmental impact on the tundra. The field assessments were conducted by a multi-discipline team consisting of geologists, geotechnical engineers, hydrologists, botanists, and arctic landform specialists from Russia, Alaska, and Canada. All of the collected information (soils, vegetation, permafrost, geothermal, etc.) was compiled, charted, digitized and entered into a Geographic Information System (GIS). The GIS has been and will be used to evaluate terrain conditions and potential sources of engineering construction materials, environmental baseline mapping and monitoring, and will assist in permitting for the Northern Territories Fields.

The methods employed in the performance of this landform/landscape analysis are presented and discussed.
Good Safety Results – A Question Not of Regulations But of Communication
Authors: Schlemm F.
Published: December 2007

The technical world which we have created and in which our employees have to go about their responsible work day by day places high requirements upon the consciousness of everybody who has to carry out these tasks. Technical integrity of the facilities, safety on the job for the employees and sufficient training to maintain the integrity of the facilities and be able to carry out work safely is a prerequisite. We have innumerable rules, regulations and instructions, with all of which nobody can be familiar. However, it is important that everybody knows that safety exists and that he studies the areas with which he is not familiar before beginning his work. Nevertheless, even routine jobs again and again conceal the danger of critical actions which also often result in injuries. Therefore a living communication system throughout the company, involving every employee, is of major importance. The presentation deals with the methods used to ensure such communication, reports on the verifiable technical integrity resulting from the assessment of conditions, and describes how training is integrated into daily events. Under the keyword „HSE Documentation" these methods are made understandable for everybody.
Human Factors: the Trade Union Response
Authors: Spiller Roger
Published: December 2007

The paper identifies the major influences on the way workers respond to health and safety in the workplace. the special nature of the oil and gas production industry demonstrate the importance to Health and safety of the health, particularly mental health, of the workforce.

High stress levels caused by the culture of the industry, demands of shareholders, working conditions and locations have potential for significant human intervention. Long and unusual working hours and shifts have debilitating effects. Contractorisation, short term contracts and competitive tendering all contribute to the human cost of the industry. The human resource has a limited capacity and needs preventative maintenance if it is to function efficiently. In recent major incidents, due to "Human Error", the technical fix was unable to prevent the initiating or subsequent events.

Promoting safety without promoting good and equitable conditions of employment, will fail. Motivation in the absence of a positive employee view of the employer is pointless. Working with the workforce with their trade unions can provide that positive view.

The author is responsible for health and safety issues covering the 420,000 members of the skilled and professional union MSF in the UK and Ireland. Prior to this he was responsible for organising offshore workers in the UK.

Let all who build beware The load, the shock, the pressure Material can bear. So, when the buckled girder lets down the grinding span, The blame of loss, or murder, Is laid upon the man. Not on the stuff – the Man. Rudyard Kipling Hymn of Breaking Strain 1935
Past and Future in Oil and Gas E&P Environmental Reporting
Authors: Molinari M. , Ratti S. , Ranghieri F.
Published: December 2007

In order to improve the level of its stakeholders information, to evaluate its own strategy in consideration of competitors' best practices and to identify the gap between companies performances, Eni-Agip Exploration & Production Division jointly with Fondazione Eni Enrico Mattei carried out a competitive environmental benchmarking. This study selected and analysed several environmental reports published annually by companies operating in the energy sector, particularly Oil and Gas E&P Industry. Although the comparison of reports is in practice not as obvious as it is in theory, the above analysis was capable of benchmarking E&P companies reports from both the qualitative (policies, programmes and practices) and the quantitative (data, objectives and indicators) points of view. The analysis produced interesting suggestions not only for communication purposes, but also for internal management objectives. Eni is fully aware that it is necessary to enhance the degree and the transparency of the information, the communicative effectiveness and, as a consequence, to give the public a better opportunity for judging the company environmental performances. The disclosure of programmes and objectives, the definition of significant performance indicators, the amplification of site level data, the indication of the benefits obtained from environmental expenditures, the information on social aspects and impacts are all issues to be taken into account for future environmental reporting.
Environmental Performance Index Development, Description and Deployment at PT Caltex Pacific Indonesia
Authors: Yunan Arief , Anggoro Suwito , Priatna Rachmat
Published: December 2007

PT Caltex Pacific Indonesia (CPI), a production sharing contractor for Pertamina, has a long time experience in utilizing safety, health and environmental performance measures. These traditionally included Loss Time Injury (LTI), Motor Vehicle Accident (MVA) and number & volume of oil spills as End-of Process measures. In 1996, CPI conducted a Safety, Health & Environmental (SH&E) Management Systems Assessment (MSA) using a weighted protocol. CPI extracted specific environmental protocol elements from the MSA protocol and developed an environmental performance metric. This metric, a process measure, was established as a CPI Corporate Performance Measure for 1997. This paper describes how the environmental performance metric was developed, its description and deployment in CPI and its integration with the established Safety and Health metrics.

Safety, Health and Environment is a key enabling strategy of CPI's strategic plan. Metrics to measure safety and health performance have been in place for a long time., However, there was no measure for our environmental efforts. With the recent emergence of the ISO 14001 environmental management system and CPI's adoption of a rigorous safety, health and environmental management systems process, it was decided that the best measure of our environmental performance was the rate of development and integration of environmental management practices into our normal business practices.

This measure was called the Environmental Performance Index (EPI). This paper describes how the EPI program elements were extracted from the 1996 SH&E MSA audit process, how the 1996 baseline was determined, and how the 1997 EPI target was established. This paper elaborates how the action plans were developed to achieve the 1997 EPI and deployed through all operating teams throughout CPI organizations. Results of the 1997 achievement and challenges are also discussed in this paper.

The paper concludes that environmental performance improvement can be measured. It can only succeed through top management commitment and continuous communication and participation by all operating teams. It is a viable process to ensure conformance with ISO 14001 and continuous improvement in environmental performance.
Further Experience with Drug and Alcohol Testing in the Workplace
Authors: Ajayi P A , Adediran N A
Published: December 2007

The problem of substance abuse in the workplace is real and the cost to industry prohibitive. In June 1996, we reported an increasing need for drug testing in our workplace in Chevron Nigeria offshore operations and a significant positivity rate in the period between Jan 1993 and Dec 1995. The partial implementation of a drug testing program and employee awareness campaigns have slightly reduced the need for drug testing and indeed the pattern of substance abuse over the last 18 months compared to our earlier report.

In the current study period, 17 drug and alcohol tests were conducted. Of these 15 were contract staff and 2 were Chevron employees. 9 subjects were expatriates and 8 nationals. A total of 8 positive tests were recorded, all in contract employees – 3 for drugs and 5 for alcohol. 2 nationals tested positive to marijuana and 1 expatriate tested positive to both marijuana and benzodiazepines. 5 subjects tested positive to alcohol (3 nationals and 2 expatriates).

The Company Drug and Alcohol Policy has been reviewed and approved by management. It has been presented to and discussed with regulatory bodies and Workers Unions. Safety sensitive positions have been identified and employee awareness programs designed. Staff training is ongoing, and, random drug screening should commence in the near future using the double barrel method. Screening tests will be conducted by the Chevron Nigeria medical team using the Latex agglutination inhibition technique. This will be backed up by a second screening technique to eliminate false positives. Only screen positive specimens will be sent out for confirmatory tests. Blood alcohol concentration is estimated using Alco Sensor IV. It is hoped that random screening, when commenced, will further reduce substance abuse in our workplace.
Occupational Health Program: Beyond the Law
Authors: Varela Claudia P.
Published: December 2007

This paper presents the results of Hocol's occupational health program which is implemented jointly with the company's contractors. Hocol, an oil exploration and production company based in Colombia, produces 35,000 bopd and is a member of the Nimir Petroleum Group. The company has 180 employees and nearly 800 permanent contractors.

Even though Colombian Occupational Health laws are amongst the most stringent in the world, Hocol goes even beyond the legal requirements, making an emphasis on a healthy lifestyle, a good quality of life and a safe and healthy environment on which all of its employees work and live. The company's O.H policy and program performance have received both national and international recognition, as a result of the high level of commitment and motivation of all its employees and contractors. Having been a Shell Company before it was acquired by Nimir, it has maintained all of Shell's policies and procedures and has adapted them to the Colombian milieu. This has ensured Hocol's compliance with current legislation and a good performance record. Hocol has gone one step ahead with the establishment of a continuous improvement system and a quality assurance policy in Occupational Health, which contributes to the well-being of its employees, and at the same time, preserves the company's assets and the environment, making the company an efficient and competitive one and maintaining its leadership position in the oil market.

In this paper, results are presented regarding some of the company's occupational health activities, including health promotion, risk assessment evaluations in company and contractor's operations, periodic audits regarding performance evaluation, preparation of management reports on findings and recommendations for further improvement in the occupational health arena. Our past and present experience in health protection and health promotion is also described.
Evaluation of Subsurface Radium Transport and Potential Radiological Doses Related to Injection of NORM
Authors: Williams G. P. , Tomasko D. , Smith K. P. , Blunt D. , Arnish J. J.
Published: December 2007

Disposal of petroleum industry wastes containing natural occurring radioactive material (NORM) via subsurface injection is modeled using two different methods to estimate the potential radiological doses to individuals consuming water from a shallow aquifer. In the case study, it was assumed that the NORM was accidentally released into the drinking water due to casing failure during disposal. This study models the transport of radium in the aquifer to receptor points located at various distances from the injection well. Radionuclide concentrations at the receptor points were compared to drinking water standards recommended by the U. S. Environmental Protection Agency. The potential doses associated with subsurface injection of NORM were below drinking water standards even assuming a casing failure during disposal and the subsequent release of the entire volume of NORM wastes.

This paper compares a new analytical model for radial injection with a step-function source term with a simple mixing model and shows how these tools can be used to evaluate subsurface injection of NORM wastes.
An Environmentally Sound Geophysical Source - The Transition Zone Marine Vibrator
Authors: Weber Wolf D. , Johnson Graham R.
Published: December 2007

For several decades seismic exploration companies have worked in cooperation with oil companies to target and develop oil and gas reservoirs. Environmental protection continues to be an integral part of successful source developments in the geophysical industry.

The Transition Zone Marine Vibrator combines an environmentally sympathetic low pressure output with excellent geophysical performance.
Sea Surface Fire Risks, a Model Based on World Data
Authors: Bonn R. J. C. , McDonagh M. , Webb S. P.
Published: December 2007

Offshore installations face a risk from fires on the sea surface. The potential severity of these events for exploration and production operations can require risk analysis. This paper reports on the successful development of a model to predict the probability of a major sea fire incident adjacent to an Exploration or Production (E&P) installation.

The model uses three new sets of data:

oil spill data from the E&P industry in the North Sea. data on large hydrocarbon spills World-wide, extracted specifically for this project from all available databases. results from recent empirical testing, which is referenced.

When linked to a consequence prediction, this method allows the safety risk from such hazards to be quantified with reasonable accuracy for the first time.

The model covers the probability of release to the sea surface, the probability of its ignition and the probability that fire will spread to a large area of the fuel. The model can differentiate between:

different types of installation (e.g. fixed or floating), different fuels, geographic locations, and weather conditions.

Data on the variation in probability for these factors is included.
Regional Environmental Impact Assessments
Authors: Furuholt Edgar , Kinn Sigurd Juel
Published: December 2007

The Petroleum Act from 1985 established the requirements for preparing Environmental Impact Assessments (EIA) for both the exploration and operation phase of the petroleum activity on the Norwegian shelf. The EIAs prepared separately for each new development project has received increasing criticism from environmental and fishery authorities, especially because of insufficient evaluation of the combined environmental effects caused by the total oil and gas activities in an area.

A revision of the Petroleum Act in July 1997 established the legal basis for requiring Regional EIAs (REIA). The first REIA according to the new requirements is now being finalized. The new system shows a number of important benefits compared to the former system and gives a much better basis for evaluating the total environmental and socioeconomic effects in an area. To be able to meet the increasing demands for better cause-effect descriptions of environmental impacts, some of the latest developments in quantitative methods have been used to predict regional impacts from emissions to air and discharges to water.

The preliminary results of the REIA for the Haltenbanken area show small estimated environmental impacts despite the large activity in the area. This may at first sight seem surprising, but seen on a regional level, the emissions and discharges are relatively low compared to background levels. Another reason for this is that all the installations are quite new or still under construction, and that they have been constructed to meet stringent environmental standards.
Environmental Evaluation of Marine and Fluvial Seismic Survey (Adriatic Sea and Po River; Italy)
Authors: Trovarelli L. , Ceffa L. , Consiglio M. , Fantoni R. , Piccoli F. , La bella G. , Servodio R.
Published: December 2007

During 1995 and 1996 AGIP partecipated in two projects in order to detect the effects of seismic prospecting, using airgun, in the Adriatic Sea and Po River ecosystems.

As regard the Adriatic sea, a shallow water basin with limited exchanges, high productivity and fishing resources heavily exploited, the results have clarified the acute, subacute and behavioral effects on fish cephalopods, bivalves and decapods impacted by pressure waves of different severity originated by an airgun positioned at different distances.

The exploitable fraction of fishing stock population seems not to be affected by airgun seismic prospecting: acute and subacute effects are very rare and present only at minimum distance, while completely reversible effects on behaviour were experienced; on the contrary, experiments on eggs, larvae and juvenile stages highlighted greater effects although limited at distance of 3–5 meters from energy source.

As regard the fluvial contest, the project was structured in three main phases: (1) evaluation of the effects of the energy source on the ichthyic river fauna, (2) measurement of the vibration level primed on the river banks, (3) acquisition of a 2D seismic line of 150 Km inside the riverbed using an off-shore acquisition methodology able to fit the river constraints and the exploration needs.

The results brought to the following conclusions: (a) negligible effects on the fauna, (b) the vibrations primed to the banks were measured at a level lower than a magnitude order respect to the safety limits specified by the DIN rules, (c) the acquisition configuration also satisfied the data quality at the exploration targets.

The experience we gained during these surveys proves that the synergy between Oil Company, State and Research Bodies can produce and improve knowledge, profit and services to Community with the use of geophysical prospect in full safety compliance with respect and protection of the environment.
Accumulated Concentration Fields in the North Sea for different Toxic Compounds in Produced Water
Authors: Rye H. , Reed M. , Ekrol N. , Johnsen S. , Frost T.
Published: December 2007

The dilution and transport of produced water from 95 different sources in the North Sea area have been calculated by means of the PROVANN numerical model. The model calculates the concentration fields as a function of the space co-ordinates x, y and z and time. Amounts of releases are specified on a yearly basis, including the amounts of produced water, dispersed oil and, for some fields, concentrations of dissolved compounds. The simulations include simultaneous calculations of the releases from all sources expanding over a time period longer than a year. The calculations are also based on a three-dimensional and time varying current field for the North Sea generated by an external hydrodynamic model.

Calculations are made for concentration fields for dispersed oil in produced water as well as the dissolved compounds para-cresol and naphthalene. The two latter compounds are assumed to be some of the most potential ones with respect to possible adverse effects on biologic life.

The paper explains the method used in determining the expected concentration levels of these compounds. The model has been validated by comparing the results against measured data. The sensitivity of the model is considered for various inputs like degradation rates. Some comments are also made on the potential use of such models in order to determine loads on marine biota in the sub-lethal concentration range.
Managing Non-Technical Risks Associated with Seismic Operations in Sensitive Areas
Authors: Rojas A. , Rocereta M. , Rodriguez J. , Laschiazza J. A. , Ruiz J. , Barker G. , Smith R. , Heaton K.
Published: December 2007

Companies pursuing exploration opportunities in sensitive areas are increasingly challenged to manage the nontechnical risks associated with these operations. Company management, local communities, the international community and other stakeholders want to be assured that safety, health, environmental, social and other nontechnical risks associated with exploration activities are appropriately managed. Failure to identify and manage these risks can have significant business implications, including project delays, cost overruns and abandoned projects. A formalized risk assessment and management process is required to successfully manage these risks.
A North Slope, Alaska ICS Training Program
Authors: Hoffman R. W. , Brassfield T. J.
Published: December 2007

Since 1990, the North Slope oil fields have been endeavoring to train incident management teams (IMT). Considerable progress has been made in developing teams that can manage incidents on the North Slope. Despite this progress, recent agency concern has been raised over the lack of IMT progress on lessons learned from one mutual aid drill (MAD) to another. A review of North Slope MAD critiques shows patterns in agency comments on North Slope IMTs. On the other hand, North Slope tactical teams generally obtain good reviews. A comparison of training programs amongst IMT, Fire, and Spill Response departments shows a discrepancy in the training programs for IMT and Tactical Teams. Tactical Teams have a much more diverse and specific training curriculum than the IMT. This discrepancy seems to remain after a comparison of typical North Slope IMT training to national agency IMT training programs. For the IMT to progress beyond the current plateau, a training program more balanced between specific ICS activities and general IMT/ICS processes needs to be achieved. The recently proposed NS IMT training protocol would go a long way to achieving this balance.
Integrated Risk Management - The Millennium Key to Sustainable Development
Authors: Smith A. L.
Published: December 2007

Health, Safety and Environmental risks are issues of concern to all management and engineers1, within the international Oil & Gas E&P industry2, especially those petroleum engineers interested in the management of risk. This paper will show that the main objective of integrated risk management, is that it contributes significantly to achieving business objectives and thereby provides the key to sustainable development in the next millennium.3
A New Approach to Economical Waterfloods
Authors: Homolka George A. , Peacock Robert, A.
Published: December 2007

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Laboratory and field studies have shown that bypassing and channeling injection water from injection to production wells can be precisely controlled by the use of a suspension precisely controlled by the use of a suspension of micron-sized particles. The percentage of permeability reduction obtained in this way was permeability reduction obtained in this way was found to be dependent solely on the initial core permeability and the quantity of suspension permeability and the quantity of suspension used. The suspended particles are capable of high-percentage permeability reduction even in very permeable materials. The block produced this manner is uniform throughout the porous zone treated and cannot be dislodged by either forward or reverse flow of water or brine.

Data obtained from 30 injection and over 100 production wells in two oil fields show that this process does, in fact, divert floodwater from old channels to the hydrocarbon-bearing regions of the reservoir. This has resulted in decreased WOR and reversal of production decline curves.

Introduction

There can be no doubt that early water breakthrough is detrimental to the economics of a waterflood operational This is because, after a breakthrough has occurred, a substantial portion of the injection water tends to follow portion of the injection water tends to follow the water that broke through so that it will bypass the hydrocarbon-bearing strata. An over-all result is a decrease in the production of oil and an increase in that of water.

A premature water breakthrough may be caused by several factors. Of these, the most common are horizontal and vertical variation in reservoir permeability, naturally occurring and artificially induced fractures, over-injection of floodwater, and the existence of zones of high water saturation in the reservoir. A premature water breakthrough may be caused by premature water breakthrough may be caused by any of these factors or a combination of them.

In order to prevent, or at least minimize, such premature water breakthroughs, a number of products has been developed for the purpose of products has been developed for the purpose of blocking those portions of the reservoir that preferentially conduct injection water to the preferentially conduct injection water to the producing wells. Some of these products such producing wells. Some of these products such as bentonite or silica flour have an appreciable particle size (100 to 1,000 microns) that makes them very suitable for plugging fractures or vugs in the reservoir. They cannot penetrate far into the reservoir rock itself penetrate far into the reservoir rock itself and alter its permeability. On the other hand, oil emulsions, polyacrylamide solutions and gels have been used with some success as blocking agents.
More Effective Measures for Environmental Control of the Offshore Oil and Gas Industry in Norway
Authors: Rye Henrik , Husdal Geir , Guttormsen Ralph , Leknes Einar
Published: December 2007

The study presented herein has covered improved regulatory measures with regards to environmental management and control in the Norwegian offshore oil and gas industry. The study has focused on the efficiency of the regulatory measures with respect to:

The predictability of the measures and the incentives for improvement they give to industry Cost benefit aspects and practical challenges of implementation.

A model for future regulatory measures is defined which recognizes the needs for achieving environmental control as early as possible in the field development phase so that the measures become more predictable and effective. Defined needs for more formal co-operation between the authorities and the industry and further recognition of the environmental management systems in the industry are catered for in the model.

The model presented in this study include:

Revised and improved Regional Environmental Impact Assessments (REIA) which will simplify and improve the Field specific Environmental Impact Assessments (FEIA), and improve the predictability for future activities in the region. The introduction of an Oil Industry's Common Environmental Plan (OICEP), which will establish common environmental goals and agreed principles for reaching these goals by the total industry. An "agreement concept" between the industry and government, which is formalized with each licensee through referencing the OICEP in the discharge permits.

The current CO2-tax has also been evaluated and it is proposed to replace this tax totally or partly by a CO2-fund controlled by the industry.
Advanced Equations for Natural Gas Flow Prediction
Authors: Francis M.A.
Published: December 2007

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Isothermal pressure-distance equations are given for linear and quadratic volume-distance distributions, both with and without the standard constant slope elevation correction. Basic applications to pipeline real gas flow, leveloff, and blowdowns are included. The relationship of transmission factors to Reynolds Number dependent efficiencies, velocity profiles, and orifice meter equations is discussed. Enthalpy effects on temperature prediction are considered.

Introduction

The description of isothermal gas flow has been restricted by usual integration methods in that pressure-distance polynomials are available only for the constant volume case. By expressing volume as a linear function of distance, with the partial derivative of volume with respect to partial derivative of volume with respect to distance held constant, an infinite number of simplified volume-distance distributions may be defined. Integration of the momentum balance equation, with this indicated substitution, leads to a family of pressure-distance polynomials in which the square of the pressure is expressed as a cubic equation of pipeline length.

The above method may be extended to a quadratic volume distribution, where a volume at the pipe section mid-point is estimated, and the resulting pressure-distance polynomials are expressed through pressure-distance polynomials are expressed through the fifth degree of pipeline length. If the momentum balance equation in the above cases contains an elevation term, it has the form of the Bernoulli differential equation and may be so integrated.

MOMENTUM BALANCE EQUATION

The momentum balance equation is given by Flanigan and has the form

(1) = 0

where the second and third factors are the inertia terms and the fourth and fifth deal respectively with elevation and friction effects. The Fanning friction term is the quotient of the shear coefficient and the hydraulic radius

.............(2)

where

.............(3)

(4) and R = dh ---4

Eq. (3) is in the form recommended by Shapiro and defines the friction factor as the ratio of the shear coefficient to the dynamic head. Eq. (4) gives the hydraulic radium for a circular pipe flowing full, see Daugherty. pipe flowing full, see Daugherty. Eq. (1) is in units of the foot-pound-second system and may be converted to gas flow units as given by Eq. (24). The primary steps in this process will be listed here and are similar to process will be listed here and are similar to those given by Johnson, Smith, and Uhl.
Stress Estimation in Faulted Regions: The Effect of Residual Friction
Authors: Wu B. , Addis M.A. , Last N.C.
Published: December 2007

This paper presents relationships for estimating horizontal stresses based on the assumptions that the in situ stress state in a petroleum basin is controlled by the bounding normal or thrust faults at a limit equilibrium and that the fault block is linear elastic and plane strain condition applies in the direction parallel to the strike of the fault. These relationships are an extension of an earlier study and include the effect of residual friction angles on the estimation of horizontal stresses at depth.

The result shows that re-orientation of the minimum principal stress is possible after faulting depending on the Poisson's ratio of the formation. Predictions based on the relationships are compared with the stress data obtained in normal and thrust fault conditions as well as with the change in the minimum horizontal stress induced by the pore pressure depletion. The results show that to match the field stress data, a relatively low residual friction angle (100 – 300) on the fault is required. This is further supported by the numerical modelling of the in situ stresses in the Cusiana field in Colombia, and is consistent with the residual friction angles measured in laboratory or back-calculated based on earthquake mechanism.

P. 59
Estimation of In-situ Stress Magnitudes from Measurements on Cores
Authors: Pestman B.J. , Kenter C.J. , VanMunster J.G.
Published: December 2007

In this paper, we propose a method to estimate in-situ rock stress magnitudes from laboratory measurements on core material. Once the principal stress directions have been established by some other technique, our method allows the identification of the minor and major effective horizontal stress, and it moreover allows the determination of their magnitudes.

The problem in determining the principal in-situ stress magnitudes on core material is that we are dealing with a polyaxial stress state and therefore we have to estimate several independent principal stress magnitudes in one experiment. This is achieved by using a stress memory effect in Acoustic Emission (analogous to the Kaiser effect) in combination with the damage surface concept (cf. the yield surface in plasticity). From the shape of this surface in stress space, as determined through special testing procedures, we are able to derive the magnitudes of the previously applied stresses and, in the case of core material, the in-situ stress magnitudes.

The method has been studied in laboratory experiments in a polyaxial apparatus on sandstone outcrop samples. In these experiments, we have first imprinted a representative in-situ stress state on a rock sample, and then we have performed reloading experiments to determine the shape of the damage surface. The experiments show that the method may allow us to determine the in-situ stress magnitudes with an accuracy of 10-15%.

P. 171
Micromechanics-Based Continuum Analysis for the Excavation of Large-Scale Underground Cavern
Authors: Yoshida H. , Horii H.
Published: December 2007

Mechanical behaviors of rock mass with discontinuities are of great concern. To find solutions to engineering problems such as a design of a large-scale cavern in jointed rock mass, a well-defined mathematical model must be settled, The number of joint involved in the rock mass is, however, so enormous that it is almost impossible to treat them individually. Hence, the jointed rock mass is replaced with an equivalent continuum. The point is how to ensure the equivalence between the two problems. "Micromechanics-Based Continuum (MBC) Modeling" provides a constitutive equation in the equivalent continuum problem with using an average operation of strain and stress over a representative volume element (R.V.E). In this article, the joints involved in the rock mass are regarded as microstructure and the MBC approach for the jointed rock mass is resented. Two examples of the application of the MBC approach to the excavation of large-scale cavern are examined and it is demonstrated how successfully the MBC approach answers the engineering problems.

P. 209
Model of Induced Seismicity Caused By Water Injection
Authors: Galybin A.N. , Grigoryan S.S. , Mukhamediev Sh.A.
Published: December 2007

A model of induced seismicity caused by water injection is considered. Analysis is based on the assumption of the existence of listric (curvilinear) faults. This presumes that shear stresses acting on the fault may be close to shear resistance at a certain part of the fault surface which is favorably orientated with respect to the principal tectonic stresses. Shear stress on the other parts of the fault is much less than the shear resistance. It is supposed that the pore pressure caused by water injection can propagate down the fault decreasing its shear resistance until shear stresses initiate propagation of shear fracture. Thus slip may occur on a part of the fault which is situated deeper than water injection depth. The slip, if happens dynamically, can be associated with a major seismic event.

Analysis has been performed to estimate possible locations of the event, its magnitudes and occurrence time. Results of these calculation agree with observations of seismic events reported for the Tatarstan oil province (Russia). It is believed that similar results can be found for other oil production regions.

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Effects on Core Quality of a Bias Stress Applied During Coring
Authors: Brignoli M. , Fanuel P. , Holt R. M. , Kenter C. J.
Published: December 2007

It is known that core damage is a crucial issue in rock testing, and, as a consequence, may have a large impact on several activities related to reservoir development -e.g. reserves estimation, sand production, reservoir compaction, etc. This is even more relevant for weak and unconsolidated formations as well as for laminated and fractured rock materials. Thus the possibility of evaluating and quantifying core damage may greatly improve data quality, predictions and performances. Laboratory experiments on artificial rock samples, carefully prepared under controlled conditions to simulate target reservoirs, have shown that the damage due to the in-situ stresses release can be reduced if a certain bias load is applied and maintained on the top of the core while coring. Such observations have been also confirmed by numerical simulations performed using a Finite Element code. Based on these results, Security DBS designed and manufactured a new coring tool, named Core Stress Monitor (CSM), in which a piston device provides the adjustable bias load. The tool was successfully tested by coring unconsolidated sand reservoir formations showing that there are no operational differences when comparing CSM and a standard coring tool. Comparative laboratory experiments on samples cored both with CSM and a traditional coring assembly seem to confirm the validity of the CSM tool in reducing stress release induced damage.
From Core Compaction To Reservoir Compaction: Correction For Core Damage Effects.
Authors: Holt R.M. , Brignoli M. , Kenter C.J. , Meij R. , Schutjens P.M.T.M.
Published: December 2007

Core damage is a permanent alteration of rock properties as a result of drill-out and retrieval of the core from the in situ environment to the surface. For reservoir rocks, stress release during coring is thought to be a major core damage mechanism. In this paper, we present a systematic approach to correcting core compaction data for effects of such damage. Our core damage quantification strategy has the following 3 steps:

– A synthetic rock, analogous to the reservoir rock with respect to rock mechanical and petrophysical properties, plus texture, is created under stress. Comparative tests are performed to simulate virgin compaction behavior, and the behavior of an unloaded and reloaded simulated core. – Based on these experiments, a simple elastoplastic model has been developed, describing both the core and virgin compaction behavior of the synthetic analogues. The model is currently in a preliminary stage, but we present it here as an important element in our strategy. – Tests with natural reservoir rocks are performed. Obtained parameters are fed to the mathematical model above, permitting a prediction of the expected compaction of the same rock sample placed in the reservoir.

A field example illustrating the use of this approach is presented. The results, based on measurements on synthetic and real cores, indicate that core damage corrections may be substantial, reducing the expected compaction by 25 - 50 % during reservoir depletion.

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Ekofisk Revisited: A New Model of Ekofisk Reservoir Geomechanical Behavior
Authors: Rhett Douglas W.
Published: December 2007

The Ekofisk Field, a giant North Sea oil field, has produced more than 1.2 billion barrels of oil since the start of production in 1971. Sea floor subsidence, which was discovered late in 1984, has occurred at approximately a constant rate of about 38 cm/year since then. Full field water flooding began in 1987. Over the past decade numerous, long term laboratory studies of reservoir chalks were undertaken to understand the effects of water flooding on chalk strength and to provide input data for reservoir simulators and geomechanics codes used to predict reservoir compaction and sea floor subsidence.

Recent laboratory analyses suggest that some protective mechanism, possibly oxidized, polar hydrocarbons adhering to portions of the chalk matrix, may protect the calcite matrix from intimate chemical interaction with formation brines. This observation has led to a new constitutive model of Ekofisk rock mass behavior consisting of two sets of ‘end member’ stress strain curves. The first set represents the reservoir rock prior to water flood invasion, when the rock mass behaves as an assemblage of dominantly elastic, low compressibility matrix blocks capable of moving independently of neighboring blocks. The second set represents fully water-contacted, fully water-weakened chalk that has undergone the transition from elastic to plastic behavior. In its fully water-weakened state the chalk is highly compressible and displays the high strain rates and large strains observed in water flooded intervals of the Ekofisk reservoir. The two sets of stress/strain curves are related by water saturation.
Microseismic Logging of the Ekofisk Reservoir
Authors: Maxwell S.C. , Young R.P. , Bossu R. , Jupe A. , Dangerfield J.
Published: December 2007

Microseismic events or acoustic emissions induced by petroleum extraction in the Ekofisk field operated by the Phillips Petroleum Licence 018 group in the Norwegian sector of the North Sea' were monitored for 18 days in April 1997. The monitoring consisted of a 6 level, triaxial VSP wireline tool deployed within the reservoir in the 2/4-C 11 a observation well located near the crest of the field. 2100 microseismic events were recorded, corresponding to roughly 5 per hour. The rnajority of the events were located in the upper part of the reservoir, predominantly in low porosity layers overlying relatively porous layers which are undergoing water flooding and compaction. Events were most accurately located near the monitoring borehole, with the position of events further away being more uncertain. A cluster of activity surrounded the nearby well C 16, confirming the event positioning accuracy. Within 300 m of the well, most events were precisely located to an accuracy of better than 30 m, and found to cluster along discrete lineations. These lineations, which are parallel to major structures in the region, are attributed to induced definition of preexisting fractures. Comparisons with simulations of the water flood front indicated that the saturated zones around the injection wells were aseismic. The position of the water flood front was not accurately enough known to test if any of the clusters of microseismicity were associated with it. However, compaction of the chalk may be strongest at the water front. If a significant proportion of the total acoustic activity is caused in association with the water front, then time-lapse microseismic monitoring could represent a useful tool for tracking the position of the water flood.

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