bluuebunny/crossref_metadata_2025 huggingface dataset:
Experience in Drilling Deep Wells through Two Trouble Zones with Different Characteristics
Authors: Pereira C. R. , Perez J. R.
Published: December 2007

The purpose of this paper is to describe the experience obtained by Lagoven, S.A. Petróleos de Venezuela, during the drilling operations in Block "B", southern Lake Maracaibo. A 5 7/8" directional hole was drilled through two trouble zones with different characteristics. The zones are the Upper Cretaceous, Colón formation, and the Lower Cretaceous, Cogollo group. The Colón is composed of a highly hydratable, pressurized shale which requieres high drilling fluid densities for control. The Cogollo group is composed of fractured limestones with normal pore pressure. Lost circulation and differential sticking are the problems associated with these formations. In addition, the Cogollo group contains the productive zones in this area.

This study highlights the techniques, equipment, and materials which allowed the successful completion of the well, offering new drilling alternatives for future wells in this area.
Application of Genetic Algorithm on the Distribution of Gas-Lift Injection
Authors: Martinez E. R. , Moreno W. J. , Moreno J. A. , Maggiolo Ricardo
Published: December 2007

In this paper is described the application of a genetic algorithm (GA) to the problem of optimizing production in oil fields operating under the gas lift method. The chosen computational methodology proves to be very effective and efficient in the execution of the task. The method provides assistance to the production engineer en the problem of assigning optimum gas-injection rates to each individual well given an available total gas supply for the field. This development is incorporated as an important utility in a system for computer aided analysis and optimization of gas lift wells developed in Corpoven S.A. (CORPOLAG).

The gas-lift optimization system is implemented by means of a genetic algorithm that executes an "intelligent search" in a "gas-injection rate" space. It obtains automatically and with a reasonable small computational effort a distribution of gas-injection rates for the wells in the field. This gas-injection rate is compatible with the restriction of the available gas supply for the field, and maximizes the total quantity of produced liquid.
Horizontal Drilling in a Reservoir under Secondary Recovery
Authors: Cicchitti A. O. , Martinez R. A.
Published: December 2007

Puesto Hernández Field is located in the north of Neuquén province, and it extends as far as the south of the Mendoza province in Argentina. In 1969 the field began to be developed, producing at present (September 1993) 47,175.0 stbd (7500.0 m3/d) of oil with 387 producing wells. The cumulative oil production is 194.63 MMstbo (30.90 MMm3).

In 1976 waterflooding was started in the Avilé sand reservoir, responsible for the 83% of the cumulative production. The present recovery is 30% of the OOIP and 41 % final recovery is expected to be reached.

A considerable reserve volume from the Avilé reservoir is still undeveloped because it lays underneath the Colorado River, which goes from north to south through the oilfield. Horizontal drilling has been chosen as a suitable technique to produce such reserve.

In this report the estimation of the geometric characteristics of the well and its location, the productivity index (through a probabilistic calculation) and the selection of the lift system are considered. Also, aspects related to well drilling and completion are mentioned.

Through data obtained from the open hole logging, pressure measurements and production records, the estimates considered are finally compared. The succesful result of this well will allow the development of the reserves with the drilling of producing and injector horizontal wells.
Horizontal Well Transient Pressure Testing in Coalbed Reservoirs
Authors: Sarkar P. , Rajtar J.
Published: December 2007

The dual porosity, anisotropic properties of coal beds make them good candidates for horizontal well completions. This paper presents an analysis of transient pressure response of a horizontal well in a coalbed reservoir. In general, the early time pressure response is distorted by the effect of wellbore storage. The general practice in such cases is to evaluate the time to the end of wellbore storage in a horizontal well using infinite conductivity fracture solutions. In this paper, a new, semi-analytical solution is developed to account for wellbore storage and skin effects on the pressure response of a horizontal well. This solution is developed for semi-infinite, anisotropic coalseam reservoir with single phase gas flow. With this solution, type curves can be generated for particular applications, allowing for calculation and verification of reservoir parameters including sorption properties of coals. Examples of the type curves are presented. An example of the analysis is given.
Methanol as Fracture Fluid in Gas Wells
Authors: Hernández J. M. , Fernández C. T. , Scianca N. M.
Published: December 2007

This paper describes the experience obtained by Pluspetrol in the use of Methanol as fracture fluid in gas wells. It analyzes the physio-chemical properties, enumerating their advantages and disadvantages. It describes the fracture procedure, the precautions and security measures taken and finally compares the results obtained with other fluids.

The use of Methanol as fracture fuid requires a complete knowledge of its properties and compliance with all precautions and security measures necessary. If all the proper information is taken into consideration, the use of Methanol is more adventagerous when compared to other fluid
A Mobility Driven Fingering Approach to the Field-Scale Simulation of Oil Recovery
Authors: Zolotukhin A. B. , Frick T. P.
Published: December 2007

A stochastic simulation technique introduced recently has been successfully employed for the study of various unstable growth processes (polymerization, electrochemical deposition, dielectric breakdown of insulators, etc.) of different physical nature. Uncertainties in reservoir characterization and instable displacement processes necessitate the application of models based on stochastic and fuzzy rather than deterministic approaches.

For a field-scale simulation of oil recovery a Mobility Driven Fingering (MDF) model has been developed. This approach is a further generalization of the Permeability Driven Fingering (PDF) model for multiphase flow. The main new feature of the MDF compared to the PDF model is that the growth of the displacing fluid cluster is governed by the actual mobilities of phases at the displacing front. Results of a field-scale stochastic simulation based on the MDF model with biased randomness are quite different from those obtained by conventional deterministic modeling techniques.

The application of the MDF model to the field-scale simulation of oil displacement can reveal different instability phenomena such as viscous fingering and oil trapping, and how they affect the overall field performance. The model has been proved to be a useful tool for screening different instability phenomena caused by reservoir heterogeneity as well as differences in fluid mobilities.
Horizontal Re-entry Drilling Experiences in Non Consolidated Sands in Eastern of Venezuela Existant Vertical Wells
Authors: Sandoval D. A. , Garcia A. A. , Herrera C. J.
Published: December 2007

This paper describes the horizontal reentry drilling experiences in non consolidated sands achieved by Lagoven, S.A., a subsidiary of PDVSA, in some existing wells at Eastern of Venezuela. Re-entry well planning, mud type, operational problems observed, are developed in this paper. Also, previous horizontal drilling experiences in the area are referred here. A total of 11 existing vertical wells have already been drilled, reaching horizontal drainage sections between 800 to 1600 ft. An excelent response of the sands for the medium radius application was observed.
A Thermodynamic Approach to Determine Convergence Pressure in Multicomponent Systems
Authors: Rivas O. R.
Published: December 2007

A new thermodynamically sound procedure is developed in this work to unequivocally determine the convergence pressure for multi-component hydrocarbon mixtures by a two cell model. Convergence pressure is an important parameter used to determine liquid vapor equilibrium constants by means of Equilibrium Ratio Charts extensively published by the Natural Gas Processors Association (NGPA).

The method is based on assuming that multicomponent mixtures, in both the gas and liquid phases, can be represented thermodynamically by two kinds of cells or pseudo-components which are forced to have identical properties in both phases. The difference in the actual compositions of the phases in equilibrium are taken into account by having a different cell ratio in the liquid cell from that in the gas phase. The properties or characteristics of the pseudo-components are determined based in the distribution of the real components in the cells. These distributions are given in terms of the Boltzman factors of the individual chemical species, based on the concepts of the local composition theory, widely used in the thermodynamic of solutions.

Once the two cells are defined, we have an equivalent binary system whose convergence pressure is the critical pressure of a mixture of the two cells, whose critical temperature is the temperature of the system.
Simulation of Naturally Fractured Reservoirs Using the Hybrid Finite Differences/Boundary Element Technique
Authors: Vieira M. A. , Maraven S. A. , Roegiers J. C.
Published: December 2007

Rock deformability can greatly affect the response of naturally fractured reservoirs when subjected to changes in fluid pressure. This paper describes two numerical models that were developed to understand some of the fluid-rock interactions that can take place in this type of reservoir. Both models were used to study the response of a small ‘sugar block’ reservoir dissected by a large number of fractures and subjected to a number of field conditions and production rates. Results obtained during this preliminary phase indicate that fracture deformability plays a fundamental role in reservoir performance, and the associated compaction can represent an additional drive mechanism, even if significant reductions in fracture permeability are expected.

The newly developed models are useful reservoir management tools which allow to investigate the effect of matrix porosity and permeability, fracture aperture, mechanical properties, anisotropy and production rates on reservoir performance.
Jet Frac Porta-Skid - A New Concept in Oil Field Service Pump Equipment
Authors: Cooper Bob , Lewis Bill
Published: December 2007

This paper was prepared for the 44th Annual Fall Meeting of the of the Society of Petroleum Engineers of AIME, to be held in Denver, Colo., Sept. 28-Oct. 1, 1969. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal, provided agreement to give proper credit is made.

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

Increasing demands of the free world oil industry call for pumping equipment that can be moved to any location in the world within a matter of hours. Many times these locations are remote and inaccessible to conventional equipment. Offshore drilling and production requires equipment capable of a production requires equipment capable of a high degree of portability and operation in a minimum of floor space. High performance pumping equipment is an performance pumping equipment is an example of this type service. To meet these demands containerized turbine-powered fracturing pumping units have been developed suitable for movement by air cargo plane, helicopters, boat and land vehicles. Basic features include small size, containerization, high horsepower, and high mobility. Each unit consists of three sections: A standard Halliburton HT-400 pump, a transmission and accessories section, and a gas turbine power section. Each section is interchangeable with the same section in all other units. This equipment is now available to the oil industry and is scheduled for operation in the Eastern Hemisphere after blowout pumping jobs are completed in South Louisiana.

Introduction

The petroleum industry is supported by numerous, highly-specialized, service companies. Creating, providing, and operating equipment capable of pumping fluids beyond the capacities of pumping fluids beyond the capacities of normal drilling rig components is one such service. Generally, operating time at the well site for this service is brief and long periods may elapse before service is again necessary on any given location Normally, this pumping equipment is made available where ground transportation is feasible with equipment mounted on trucks or trailers. (A truck-mounted unit may be viewed in Fig. 1). Marine installations commonly are equipped with service company skid units permanently installed on the rig. (A permanently installed on the rig. (A typical offshore skid is shown in Fig. 2).
Simulation of the Santa Barbara Field, El Tejero - Bosque Area
Authors: Todd M. , Cabrera J. , Achong C. H.
Published: December 2007

A numerical compositional simulation based reservoir engineering study has been made of alternative recovery processes for the Santa Barbara field, El Tejero-Bosque area.

The Santa Barbara field reservoir is comprised of two productive zones, the Naricual and the Cretaceous, totaling about 2,500 feet of thickness. The reservoir is estimated to have originally contained 4.6 billion barrels of stock-tank liquids in the form of condensate in the gas zone and black oil in the oil zone, and 20.5 trillion scf of gas.

This paper describes the results of a mechanistic study, designed, to examine the physical mechanisms that govern fluid hehavior, transport and production in the reservoir. The study utilized numerical models of two prototype regions, of the reservoir, representing different reservoir characteristics. The process investigated include straight depletion, pressure maintenance at 8000 psi and 6000 psi by injection of either inlet (separator) or outlet (dry) gas from the local cryogenic gas plant, re-injection of separator gas produced, and water injection into the oil column.

Also were investigated the effects of completing the wells, above or below the gas oil transition zone. The hydrocarbon fluid column at Santa Barbara is highly unusual, characterized by a variation in com position with depth, being an undersaturated rich gas at the top and an undersaturated oil at the botton, both separated by a transition zone. It was determined that condensate recovery is highly sensitive to reservoir pressure performance, and independent of the composition of the gas injected Best recoveries were obtained with injection of dry gas high pressure.
Audits Emphasize Need for Long-Term Relationship to Improve Prevention
Authors: Bobillier A. A. Y. , Keary Tim
Published: December 2007

Sedco Forex is a drilling contractor that operates approximately 90 rigs on land and offshore, worldwide. Similarly to clients and regulatory bodies, Sedco Forex has developed safety drilling policies, standards and regulations to minimize hazards at the drilling site. The effort imposed on field supervisors to follow these internal and external requirements has increased, a trend that shows little sign of abatement.

It has been found that field training and regular inspections by Line Management are a key ingredient in reducing injuries. Methods of promoting education, measuring compliance with standards and evaluating progress are used by field supervisors with encouraging results.

Join audits are still identifying many inconsistencies in the overall approach to HSE management at the rig site. The Oil Companies main operating risks differ from the Contractors. Training needs vary, emergency response procedures may be conflicting, and even HSE statistics are not always comparable.

This paper proposes solutions to improve this situation and help the key players who must make it happen i.e. the line management.
Worldwide Spill Response Strategy
Authors: Clayton E. W.
Published: December 2007

Soon after the spill in Valdez, Chevron, like most of the other oil companies, undertook a detailed review of its prevention, preparedness and response efforts. To accomplish this, Chevron assembled a task force with representatives selected by the heads of our major operating companies throughout the world and of key staff organizations. One of the major outputs was the Guiding Principles for Oil and Chemical Spills to Water. It outlines Chevron's policy for dealing with all aspects including defining responsibilities, encouraging mutual aid within the company, and organizing company-wide internal support teams for response worldwide. The company-wide resource teams are: the Advisory & Resource Team, the Worldwide Spill Response Team, 13 Functional Teams and the Mutual Aid Manpower Pool. In addition to developing these internal company resources, Chevron also obtained access to external spill response resources, such as Oil Spill Response Limited (OSR), the Marine Spill Response Corporation (MSRC), and the PetroAssist Network. The Chevron Emergency Response Staff ties all this together through publishing a directory of the internal and external resources for operating companies’ use. The Emergency Response Staff also is coordinating two company-wide drills per year to help keep the company in a ready state for response to a major spill incidents.
Occupational and Ecological Safety Management in Russian Oil and Gas Industry in a Massive Transition
Authors: Volchkov S. V. , Prusenko B. E.
Published: December 2007

The paper contains the general overview of the current situation in technological and ecological safety management in Russian oil and gas industry under the conditions of a massive transition to the market economy. The legal basis for occupational and ecological safety in Russia is discussed. The newly adopted laws and regulations of different level and the necessary and not yet adopted regulations are under consideration. The system of governmental bodies control over different types of hazards and ecological issues is analyzed. The newly organized in Russia and traditional for the market economy technologies and methods as risk management and insurance are analyzed too. The vision of the paper is to summarize all these issues as to the needs of oil and gas industry of Russia and to the western companies engaged in the E & P in Russia. The main trends in the system of technological and ecological safety management in Russian oil and gas industry are discussed too as the new organizational structures, fees penalties and so on. The practical conclusions and recommendations for oil and gas engineers are also in the scope of the paper. The paper mainly deals with upstream sector onshore and off-shore and pipeline construction and operation.
Safety and Health Assessments: A Systematic Approach
Authors: Dujmovich T. J. , Setiawan Hardi
Published: December 2007

Success of safety and health prpgrams has historically been determined by the performance metrics (fatalities, injuries and illnesses) of an operation. Programs are generally reactive having been formulated or implemented as a reaction to performance metrics.

Proactive safety management, however, analyzes the programs and systems that are in place to generate performance metrics. By focusing assessments on the systems that are in place in each operation, we are able to determine strengths that can be utilized to correct observed deficiencies. Performance metrics improve as a result of the system being better managed.

By adopting a proactive approach in our seismic operations, we successfully improved our performance metrics by reducing our contractor LWC rate from 9.S in 1990 to 0.5 in 1992 and our total recordable rate during the same period from 14.7 to 1.7. This improvement has occurred in remote areas with extreme environmental conditions.

Techniques used include conversations with senior management to determine their perception of the systems in place. While strategies and implementation steps may vary, the fundamental principals upon which the systems are based remain consistent throughout the corporation. Conversations with line personnel further verifies these beliefs. Employees are observed for proper work practices and are interviewed about the task that they are completing. These interviews are nonconfrontational and foster strong communication between management and employees. Positive features as well as opportunities for improvement and recommendations are cited. This allows the findings to be presented in a positive light. Participation of representatives from the organization being assessed is critical as this enables the process to serve as a training function also. While this approach has been critical to improving performance metrics, it has also enabled improvement in the management of business systems with improvements in productivity as high as 60% realized.
Environmental Review Using Structured Analysis Technique (ERUSAT)
Authors: McCubbin R. N. , Poblete B. R. , Hoffman B. E. , Bugden Brian , Palmer P. J.
Published: December 2007

Environmental Review Using Structured Analysis Technique (ERUSAT) provides a method to comprehensively review the environmental regulatory requirements that would affect the engineering design of an offshore drilling and production platform. It is used to identify scenarios/issues which could result in environmental non-compliance and provide a means of addressing potential design modifications which would alleviate the environmental concerns.

The method is qualitative, requiring an experienced multi-disciplinary team to identify scenarios/issues from the review of all pertinent environmental legislations, development and design conditions, previously conducted HAZOP studies and third party studies that could potentially affect the platform design and to discuss potential design modifications leading to a recommendation for further task force/contractor review. The study is meant to be an integral part of the engineering process of the project, similar to the other safety studies performed on the platform design.

The approach is similar to other structured analysis techniques, such as Hazard and Operability (HAZOP) studies, but requires the identification of issues/scenarios rather that potential causes of undesired events. The review requires several steps: Step 1: Identification of potential issues/scenarios;Step 2: Critical review of identified issues/scenarios;Step 3: Recommendations (where warranted) for changes in practices or design or for a more detailed study to determine solutions.

The ERUSAT study document thus produced, will now be a living document for the operating company to be updated regularly in response to environmental legislative changes, technological advances in pollution abatement equipment, operational experience, etc..

The paper outlines the ERUSAT approach, explains the customizing of a commercially available HAZOP software package to facilitate the documentation of the study, summarizes the results of the review sessions, and highlights the potential application of the technique to the current development project and other future onshore/offshore complex industrial projects.
Drilling Fluids: Economics and Planning To Achieve Environmental Targets
Authors: Morrish D. P. J. , Kwant J. W. H. , Holgate M. J. M. , Day N. F.
Published: December 2007

Drill cuttings re-injection (CRI) is rapidly becoming the North Sea operator's favourite option in reducing the environmental impact of drilling operations and meeting current and projected UK legislation. Shell U.K. Exploration and Production (Shell Expro), operator in the U.K. sector of the North Sea for Shell, Esso and other co-venturers, is planning CRI in its Brent Field based on both environmental and economic considerations. The paper discusses how environmental legislation as well as the company target setting regime has produced a favourable economic perspective within which to view environmental projects such as CRI.
Strategies and Mid-Term Environmental Investments in the Venezuelan Oil Industry
Authors: Corrie C. L. , Sanchez J. C.
Published: December 2007

In 1992 umprecedented measures were adopted in Venezuela to enhance the national environmental legislation: existing regulations regarding air and water pollution control, waste management, environmental impact studies and others were amended, and a new law establishing penalties against environmental offenses was adopted. Also, a mayor step in the involvement of public, environmental and industry organizations in policy development and implementation was made with the creation of a National Environmental Regulation Committee, which will review the existing regulations and will propose new ones.

Petróleos de Venezuela, S.A. (PDVSA), the state oil company, contributed to the development of the new environmental measures, which allowed the company to review their strategies and to prepare a mid-term investment plan to comply with the emerging regulatory requirements. This paper summarizes the more significant aspects of the new environmental measures, the implications for PDVSA and a brief description of the company's mid-term investments in environmental proyects. PDVSA has invested US$ 350 millions in the last 5 years to meet the requirements of the Venezuelan regulations, and have planned to invest US$ 800 million for the period 1994-2000.
Environmental Covenants: A New Strategy Towards Sustainable Development?
Authors: Herenius T. A. , Kuyper J. , Williams S.
Published: December 2007

In 1989 the Dutch Government published the National Environmental Policy Plan (NEPP). In this plan it was stated that, by the year 2000, certain maximum allowable risk levels for waste streams to the environment should not be exceeded and that by 2010 those risk levels should be negligible.

The NEPP requires reductions in the national emissions and discharges of 50-70 % by 2000 and 80-90 % by 2010 compared to the emission/discharge levels in 1 985. It was realised that these targets could not be met by solely issuing new legislation, as this is often a lengthy procès which does not normally lead to cost effective solutions. It was therefore proposed that legislation be supplemented by voluntary agreements, (Environmental Covenants), between government and industry sectors on how to achieve these reductions.

In august 1992, the Dutch E&P industry started discussions with the government about an Environmental Covenant. It is expected that a Covenant will be finalised early 1994.

To support the Covenant discussions profiles of the different emissions to water, air and soil have been calculated up to 2010 and a methodology has been developed to help identify how the E&P industry should allocate the finite resources available to enable it to make the largest contribution to the achievement of the NEPP goals.

The methodology combines the available scientific data, current emission levels, and societal preferences to estimate overall preference factors for unit reductions in the various E&P industry emissions and discharges.

These factors are used with conventional evaluation methods to establish the relative environmental cost effectiveness of a portfolio of possible environmental improvement projects. After ranking on the basis of cost-effectiveness, marginal and cumulative cost-benefit curves and tables are produced which can be used for project selection.
Environmental Impact Assessment Using Remote Sensing Technology: Methodology and Case Studies
Authors: Janks J. S. , Prelat A. E.
Published: December 2007

Landsat remote sensing technology was used to provide environmental assessments of oilfield operations. Landsat sensors, launched in 1972, are particularly adept at providing historical analyses. Exploration, production, and abandonment phases (e.g., oil spills, well sites, production pits, and seismic activities) were assessed. Deforestation was evaluated in the Oriente region of Ecuador, production facilities in a midcontinent (USA) oilfield, and oily waste in the southern USA. Remote sensing identified exposed hydrocarbons, sludge, thermal anomalies, and production pit locations. Deforestation patterns were characterized and quantified.
Produced Waste Management in the Canadian Petroleum Industry
Authors: Jamaluddin A. K. M. , Vandamme L. M.
Published: December 2007

The production of heavy oil under primary or secondary recovery, like that of conventional petroleum fluids, is accompanied by a large volume of produced water. The disposal of that water can be expensive as the produced water contains contaminants including total dissolved solids (TDS), total suspended solids (TSS), oil, and grease. In addition, most heavy oil reserves occur in shallow and unconsolidated sandstone formations, which produce a considerable amount of sand. The disposal of the produced sand can also be expensive. The major contaminants in that sand stream are hydrocarbon and chloride.

In this paper, the results of a systematic characterization of the produced water and sand, along with the evaluation of available options for treatment and ultimate disposal, are presented. In addition, a membrane process for water treatment and a flotation process for sand treatment are presented. The results indicate that the membrane process was successfully used to reduce the contaminants in the produced water and, hence, reduce the volume of water to be disposed of. In this process, 90% of the TDS was rejected. The flotation treatment was also successfully used to reduce the contaminants in the produced sands. In this process, more than 99% of the unbound hydrocarbons and chlorides were removed.
Ultrafiltration of Oily Wastewater
Authors: Bilstad T. , Espedal E. , Haaland A. H. , Madland M.
Published: December 2007

The petroleum industry and regulatory agencies are searching for alternative methods for treating drainwater from oil rigs. Membrane separation has proven to be an effective and economic alternative to conventional methods for oil-water separation. Drainwater from oil rigs may contain up to 5% oil in addition to different chemicals in varying concentrations. Drainwater typically is collected in a burner tank and burnt by flare to the atmosphere. This emission to air causes an unwanted environmental impact.

The summer of 1992 was used to test membranes and gather design information through pilot studies for a full-scale separation plant for treating oily drainwater. The results from the pilot testing were encouraging and a full-scale membrane plant was designed, however, not yet manufactured.

The membrane separation plant is tubular ultrafiltration (UF) and the pilot plant operation was on a batch basis with a volume reduction factor approaching forty. The UF membrane had a maximum permeate flux of around 300 l/m2/h at maximum 6 kg/cm2 inlet pressure and 3.8 m/s fluid velocity with a clean membrane. The flux typically dropped and approached 80 l/m2/h at the end of a day's operation. The retentate from UF separation was returned to the feed tank whereas the permeate was routed to the sewer. Design of a full-scale plant was performed using a flux value of 40 l/m2/h.

Cleaning of the membrane was performed with 0.3% nitric acid at 45 °C and the alkaline detergent Ultrasil 11 at 0.25% and 55 °C. The membrane flux did not always fully recover after each chemical cleaning. A 200 mg/1 Cl2 solution administered as sodium hypochlorite (NaOCl) would, however, restore the original flux.
Environmental Aspects of Produced Water From Offshore Platforms on the Dutch Continental Shelf
Authors: op ten Noort F. J. , Marquenie J. M. , Cofino W. P. , van Hattum B.
Published: December 2007

In a joint Industry program, the composition and the environmental risk of produced water discharges on the Dutch Continental Shelf was investigated, along with the investigation of existing heavy metal removal technology potentially suitable for offshore application. On fifteen gas platforms and four oil platforms on the Dutch Continental Shelf samples have been taken of produced water, which subsequently were analyzed for general physical/chemical waste water characteristics, oil and oil related compounds, mono- and poly-cyclic-hydrocarbons, other organics, heavy metals and radionuclides. The environmental risk of produced water discharges was evaluated on the basis of acute toxicity data from bio-assays, of data of individual compounds, fate determination and bio-accumulation. Finally, existing/proven technology capable of reducing volatile hydrocarbons (BTEX) and/or heavy metal content from produced water and that was potentially suitable for offshore application was investigated.

The following conclusions can be drawn from the program results:

– the general composition is presented in table 1; – the concentrations of chemical constituents in gas produced water are considerably higher than those in oil produced water; – gas produced water may be considered as moderately to practically non-toxic, according to the GESAMP* classification; – acute toxicity expressed as median lethal or effect concentration may vary over more than three orders of magnitude; – a dilution of 3.000 is required for gas platform produced water to attain the lowest 96-hr no-effect-concentration for the acute toxicity for the most sensitive species; – for gas platform produced water the dilution of 3.000 will be reached within 7 mins. at a distance of 50-300 m from the point of discharge. – no existing suitable technology for heavy metal removal was identified; – for removal of BTEX, air stripping seems to be a promising method.

* Joint Group of Experts on the Scientific Aspects of Marine Pollution.
Wellsite Mixing Minimizes the Environmental Impact and Reduces Costs During Pumping Operation
Authors: Chang D. J. , Gerke J. A. , Osborn F. A.
Published: December 2007

This article presents the environmental and financial benefits that have been achieved through continuous wellsite mixing techniques during pumping operations. Traditionally excess fluid volumes have been pre-mixed either at the base facility or at the wellsite prior to the start of most treatments. This excess was needed to compensate for the ‘dead volume’ remaining at the bottom of a storage tank, and in some cases to prepare for the optimum treatment volume which could only be determined during or after the pumping operation.

Mixing at the wellsite facilitates better control of the chemical composition, density and rheological properties of the fluid before pumping the complex mixture into the well. Such mixing reduces the environmental risks (3), (9) as all the chemical handling is done under controlled conditions and preventive measures are implemented to contain any fluid spill. Additionally, continuous wellsite mixing cuts the cost of operation by eliminating waste disposal and tank cleaning following the completion of treatment.

The practices of continuous wellsite mixing are explained through the use of two specially designed mixing systems in operation today. Resulting environmental and financial benefits are shown through the implementation of these systems in pumping operations.
A Case Study of Environment Management Problems of Indian Oil Fields
Authors: Sharma V. P. , Singh I. J. , Kumar Tarkeshwar
Published: December 2007

This paper deals with the environment management problems of some Indian Oil Fields. It analyzes the typical field data of Air, Noise and Thermal Pollution. Treatment of typical drilling fluid effluent is also discussed. Recommendations to improve management of effluents are given.
Environmental Impact of Exploration and Production Operations on the Niger Delta Mangrove
Authors: van Dessel J. P. , Omuku P. S.
Published: December 2007

Mangroves can be defined as the brackish, tidal areas of sheltered tropical or subtropical coastlines and are considered to be environmentally very sensitive. The Niger Delta, in which Shell Petroleum Development Company of Nigeria (SPDC) operates, consists of more than 6000 km2 of these brackish water swamps. The Niger Delta ecosystem is particularly characterised by extensive networks of creeks, with tall mangrove trees at the creek edges, while further inland only short mangroves are found. Stilted roots are typical for these littoral plant formations. The fauna is characterised by fish and bird life, a large variety of species inhabiting the sediment (benthos) and patchy distributed wildlife. In the past 5 years, SPDC has embarked on a large number of environmental baseline and impact studies to assess the environmental impact of SPDC's operations on the mangrove ecosystem with the objective of minimising that impact. Geographically these studies cover the entire Niger Delta and they deal with various E&P related activities: seismic, drilling and production. SPDC has two operating divisions, covering the Eastern and Western part of the Niger Delta. This paper concentrates on studies carried out in the Eastern part of the Niger Delta and describes the area, its sensitivities and SPDC's effort at understanding the impact on the mangrove ecosystem. It also describes a number of existing guidelines aimed at minimising impact to the environment and preventing or remediating (potential) adverse impact on the mangrove.
Environmental Impact from Removal of Offshore Installations: The North East Frigg Field Case
Authors: Håbardsholm Lars , Robberstad Lasse
Published: December 2007

Put in production in December 1983, North East Frigg (NEF) was the first multiwell Subsea Production System (SPS) developed in the North Sea. The six wells drilled through a subsea template and the control station, an unmanned articulated tower, have been remotely controlled from the Frigg Field situated 18 kilometres away. In May 1993, the field was shut in, after having produced more than 11 BSCM of gas.

Having no detailed regulations for what to remove and how to plan abandonment and removal of installations, Elf Petroleum Norge as Operator prepared removal plans and performed a consequence analyses in order to assist our own and the authorities’ decision process.

The study was made in accordance with guide-lines for such analysis stipulated by the Norwegian Petroleum Act for all field development plans.

This paper presents the results of the consequence analysis performed. Environmental issues, socio-economic effects, safety and cost associated with the different removal, abandonment, re-use and disposal alternatives have been considered in accordance with prevailing legislation and the international legal framework.

The analysis concludes that a combination of abandonment on site and removal of parts of the installations for dumping in deep water is the optimum solution for this case.

Negative consequences for the environment or use of the sea are not expected. Re-cycling of materials could have a marginally positive effect on energy consumption and discharges to air, but the cost benefit ratio is very high.

Although the NEF field consists of very specific installations, it is expected that this first case in Norway will attract considerable interest both in terms of decision process and actual removal and disposal solutions. This is the first case for the authorities to handle, and it is expected to be used as an example when removal of other platforms is being prepared in the future.
Exploration and Production Waste Management Guidelines from the E&P Forum
Authors: Owens C. K.
Published: December 2007

The E&P Forum has produced guidelines for exploration and production (E&P) waste management. The guidelines address methods that could be considered in the development of area specific waste management plans in both developed and developing nations. The guidelines include discussion on the principles of waste management, development of waste management plans, identification and characterization of E&P wastes, and waste management and disposal options for these wastes. The wastes generated by E&P activities are summarized, and specific examples of applicable management options are presented for some of these wastes.
Oil Spill Dispersants: Do They Do Any Good?
Authors: Mulyono Mul , Jasjfi Epi , Maloringan Max
Published: December 2007

Decisions about using dispersants are made in the context of reasons for treating spilled oil which threats to valuable habitat and nursery areas or to vulnerable early stages of marine life. The potential use of chemical dispersants raises some primary questions, principally: Are they effective? Do they reduce the potential damaged caused by spilled oil. What factors affecting toxicity of Chemical Dispersants and Dispersed Oil?

The present paper explains factors affecting the effectiveness and toxicity of oil spill dispersants using a case study of four different chemical dispersants recently used in Indonesia. Chemistry and physics of the dispersants are also presented in order to support evaluation of their effectiveness and toxicity properties.
Accumulation of Hydrocarbons (Base Oil, Crude Oil, and Fuel Oil) in Fish From the North Sea (Statfjord and Oseberg Oil Field Centre, Bank of Egersund), Bank of Halten, and Northwest of the Faroe Islands
Authors: Moe K. A. , Skeie G. M. , Aabel J. P. , Futsaeter Gunnar , Reiersen L. O. , Tjessem Kjell
Published: December 2007

Samples of different fish species were obtained at different sites in the North Sea, Bank of Halten and NW of the Faroe Islands and analysed by GC/MS for selected hydrocarbons. Petrogenic contamination of different origin was observed in almost all samples. Tainting, by organoleptic analyses of cod, was not traced.
Marine Environmental Monitoring Program
Authors: Ooi Bee-Hong
Published: December 2007

In the drilling for and production of crude oil and gas offshore, it is necessary to assess the effects of such activities on the marine environment. Environmental monitoring programs are conducted to collect data for assessing the effects and determining the degree of impact. They provide the bases for implementing appropriate measures to mitigate the impact.

Esso Production Malaysia Inc. (EPMI) has since its early years of operation in Malaysia in the seventies, conducted several monitoring studies to gauge the impact of its operations on marine waters. The studies entail physical, chemical and biological aspects, and use of the benthic community to track short and long term effects.

This paper describes the Seligi Environmental Monitoring Program commissioned by EPMI, and discusses observations made from it.
Macro-Cuttings Study to Accelerate Site Restoration in Tropical Rain Forests
Authors: Ericsson P. H. , Michaloud Georges
Published: December 2007

Exploration sites in tropical forests have historically been left unrestored, requiring the natural ecological succession cycle to reestablish the tertiary hardwood forest. Conoco and the University of Montpellier have been cooperating in a study of planting "macro-cuttings" to accelerate tree growth for site restoration in Gabon.

Macro-cuttings are typically 3 m (10 ft.) long and 1030 cm (4-12 in.) in diameter. The cuttings are cut from the trunk, branches or crown of a tree. For the purposes of this study, cuttings from 50 local tree species were planted in varying soil and light conditions.

In addition to those macro-cuttings planted at the time of cutting, some of the cuttings were sealed with wax and stored for two months. These were then planted in the same manner as the original, unwaxed cuttings. This storage method simulated the use of cuttings cut during site construction and used for later restoration at exploration sites.

The use of "macro-cuttings" raises the tops of the cuttings above planted or naturally occurring primary and secondary growth. This improves the competitive position of these trees relative to seedlings of the same species. If successful, this process would accelerate site recovery to tertiary growth conditions at a location by several growing cycles, providing a cost-effective and sustainable means of enhanced site restoration.

Sites used for the study were in Gabon at an abandoned Conoco camp site in Ezanga and at the Gabon Makokou research facility. First year results were mixed but encouraging. Second year results were affected by elephants having destroyed much of the site at Ezanga. There was, however, sufficient progress at Makokou to continue the study. The most recent results indicate 14 different species with observed shoot growth. Although the study is still ongoing, the practices employed and the successes realized suggest that the use of macro-cuttings to accelerate site restoration may prove to be practical and cost-effective.
Monitoring of Gas Treatment Plant Emissions, Changing Limits, Different Techniques
Authors: Waller S. L.
Published: December 2007

The LNG/Domestic gas plant operated by Woodside Offshore Petroleum at Karratha in Western Australia has a number of point emission sources to atmosphere spread over a 110 hectare onshore area. The amount of source monitoring was recently agreed with the Western Australia Environmental Protection Authority which set new emission limits for nitrogen oxides, sulphur oxides and hydrogen sulphide, as well as specifying the monitoring program to be instigated for these. Because the plant consists of a number of duplicate facilities, a monitoring program based on a limited number of representative equipment types has been developed.

This paper describes the history of emission monitoring at the site and Woodside's design of a mobile facility to measure source emissions and ambient concentrations adjacent to areas zoned as hazardous. Also discussed is the management of the atmospheric monitoring program and its rationale in a remote, arid location like north west Western Australia.