bluuebunny/crossref_metadata_2025 huggingface dataset:
The Nigerian Experience in Health, Safety, and Environmental Matters During Oil and Gas Exploration and Production Operations
Authors: Oyekan A. J.
Published: December 2007

Since crude oil was first discovered in commercial quantities in the Country, in 1956, Nigerian oil and gas exploration and production activities have steadily increased as petroleum assumed strategic importance in the nation's economy. However, just as occurs in many parts of the world, crude oil and gas SEe found and produced in Nigeria sometimes in very hostile and unfavourable environments. The search for oil and gas takes explorers to the hot regions of the Northern parts of the country, the swamp jungle location of the Niger Delta, as well as offshore locations in the Atlantic Ocean. Each terrain, whether land, swamp or offshore, in deep or shallow waters, present unique health, safety and environmental implications and challenges to the operators, as well as, to the Government regulators. From a background of existing Nigerian Laws and operational experience, this paper details the programmes that have been put in place to guarantee a healthy workforce, ensure the safety of personnel and equipment, and protect the Nigerian environment during oil and gas exploration and production operations, as well as their documented effectiveness

The paper discusses the performance of the Petroleum Industry by analysing the health, safety and environmental records available from 1956 - 1990.

The records of major incidents related to safety and environment over the period are discussed and evaluated. The paper notes that relatively speaking, in spite of the Bomu 2 and Funiwa V oil well blowouts in 1970 and 1980 respectively which caused extensive environmental damages and the Anieze, Oniku and KC 1 gas well blow-out of 1972, 1975 and 1989 respectively, which resulted in the loss of the rigs drilling the locations concerned, the safety performance records in the Nigerian oil and gas exploration and production activities in the past thirty-five years have been satisfactory compared with the records of similar operations in most other parts of the world. Also, the paper notes with satisfaction that from the records of the number and volume of crude oil spills from 1976, the number of oil spill incidents have steadily decreased over the past fifteen years, reflecting the increased effectiveness of the administrative and regulatory control that have been put in place, as well as the commitment and responsiveness of operators to such controls.

The paper concludes with the assertion that for a continued guarantee of a healthy workforce, safety and personnel and equipment, and protection of the environment, emphasis should, as is presently the case, continue to be placed on the education and training of the personnel to create awareness of related problems, on preventive maintenance of existing facilities, and on the installation of adequate safety and pollution control equipment on the oil production and handling facilities.
Produced Water Discharges from Gas/Condensate Platforms: Environmental Considerations
Authors: Jacobs R. P. W. M. , Marquenie J. M.
Published: December 2007

The Nederlandse Aardolie Maatschappij B.V. (NAM) is the largest gas producer In the Netherlands. The company operates a number of gas/condensate platforms on the Dutch continental shelf in the North Sea. From 8 of these platforms produced water is discharged directly into the sea. An extensive sampling, analysis and testing campaign was carried out in 1989 to characterise physical, chemical and ecotoxicological properties of these streams.

The total volume of water discharged from the NAM platforms was about 210,000 m in 1989. The average volume per platform was relatively small (about 70 m per day), certainly when compared to oil producing platforms. The^ total volume of oil discharged was about 160x10 kg, 50-70% thereof being present in the form of dispersed oil. The total volume of all organic substances, including polar compounds, Was about 400x10 kg.

The complex mixture of organic and inorganic components and their concentrations in the effluents indicate, with effluent EC/LC.- values between 1 and 420 ml/1, an acute toxic hazard to organisms directly exposed to the discharges. Acute toxic effects are, however, not expected beyond a distance of 50 m from the discharge point. A risk of sublethal effects cannot be excluded within distances of several hundred metres to a few kilometres from the discharge points. The dissolved organic components are most probably the prime cause of the acute toxicity, of which the volatile aromatic hydrocarbons are the most significant. These compounds were observed at concentrations of up to 480 mg/1.

Relatively high concentrations of metals were observed in the ' effluents. However, these metals did not contribute significantly to the acute toxicity of the streams. This suggests that metals were not present in a bioavailable form.

All effluents contained components which have the potential to be bioaccumulated by organisms. Polycyclic aromatic hydrocarbons, with concentrations ranging from 0.5 to 70 mg/1, were the major contributors.
The Elimination of Waste Emissions from Oil and Gas Production Operations
Authors: Callaghan D.
Published: December 2007

The principal waste streams have been identified from the production operations of all Shell Exploration & Production (E&P) companies. A phased approach has been identified to meet our target of eliminating over time all emissions, effluents and discharges that have a negative impact on the environment.

In the short/medium term, changes in operational procedures, together with "end of pipe" technology will be used to reduce emissions. In the longer term, fundamental changes to the production process will be required to eliminate the problem as far as possible at source, to re-use waste streams within the process and return any remaining unwanted material to the producing reservoir, without additional contamination.

Carbon dioxide is currently regarded as a special case and will be reduced by minimising the amount of energy consumed and /or wasted in the production process.
Environmental Program with Operational Cases to Reduce Risk to the Marine Environment Significantly
Authors: Cline J. T. , Forde R.
Published: December 2007

Amoco Norway Oil Company's environmental program is detailed, followed by example operational programs and achievements aimed to minimize environmental risks to the marine environment at Valhall platform. With a corporate goal to be a leader in protecting the environment, the appropriate strategies and policies that form the basis of the environmental management system are incorporated in the quality assurance programs. Also included in the program are necessary organizational structures, responsibilities of environmental affairs and line organization personnel, compliance procedures and a waste task force obliged to implement operations improvements. An internal environmental audit system has been initiated, in addition to corporate level audits, which, when communicated to the line organization closes the environmental management loop through experience feed back.

Environmental projects underway are significantly decreasing the extent and/or risk of pollutionfrom offshore activities. The "cradle to grave" responsibility is assumed with waste separated offshore and onshore followed by disposal in audited sites. A $ 5 MM program is underway to control produced oily solids and reduce oil in produced water aiming to less than 20 ppm.When oil-based mud is used in deeper hole sections, drill solids disposed at sea average less than 60 g oil/kg dry cuttings using appropriate shaker screens, and a washing/centrifuge system to remove fines. Certain oily liquid wastes are being injected down hole whereas previously they were "burned" using a mud burner. Finally, a program is underway with a goal to eliminate sea discharge of oil on cuttings through injection disposal of oily wastes, drilling with alternative muds such as a cationic water base mud, and/or proper onshore disposal of oily wastes.
Strategies for Baseline/Environmental Impact Studies in Nigeria: A Case Study of the Isampou Manifold Spill
Authors: Odu C. T.
Published: December 2007

In order to assess the environmental impact of site activities and ecosystem change brought about by stress, basic baseline data are necessary to characterize the normal environment so that environmental quality control programmes can be developed with a firm ecological base.

The programme and methodology adopted in our field surveys to assess the character, magnitude and extent of pollutant effects on soil, vegetation and water, as a basis for economic assessment of pollutant effects on agriculture, forestry and the aquatic system and for preparing environmental impact statements, are presented.

These techniques were modified and adopted in the environmental impact study of the Isampou Manifold Oil Spill, a study which circumstances made necessary seven years after the oil spill. Reliance on the extent of pollution soon after the incidence was based on the determination of total hydrocarbons at creek bottoms as well as on the determinations of nickel/vanadium ratios.

Hydrocarbon contents of creek banks and creek bottoms were within biogenic levels at the time of field sampling. Ni/V ratios were high in heavy impact areas and decreased in areas of medium and very light impact areas. Use of the Ni/V ratio as evidence of past oil pollution agreed closely with a sketch of the extent of crude oil pollution drawn by the Shell Petroleum Development Company seven years earlier.

There were no abnormal vegetation features. The presence of 10-15 years old Musanga cecropioides at the edge of the manifold slot and creeks indicated that vegetation above water level was not affected by the oil spillage.

The physico-chemical properties of the waters, plankton composition and density of the species found, as well as the presence of endoproct bryozoan in the benthos showed that the aquatic system had by the time of sample collection, completely recovered from the oil spillage.
Cutting Cleaner: A Long-Term Field Test
Authors: van Elsen R. P. H. , Smits M.
Published: December 2007

This paper presents the results of a long tera field test of the Cutting Cleaner, which is used for the treatment of Wet oil contaminated cuttings (WOCC) produced then drilling with Oil Based Mud (OBM). It was concluded that it is possible to reduce the oil content of cuttings to an average of 1 - 2 %. The recovered base oil can be reused to make new oil based mud.
Chemical Monitoring of Mud Products on Drilled Cuttings
Authors: Hughes T. L. , Jones T. G. J. , Tomkins P. G. , Gilmour A. , Houwen O. H. , Sanders M.
Published: December 2007

An increasing area of concern for offshore drilling practices is the environmental impact of discharged drilled cuttings contaminated with drilling fluids. The standard retort anal-ysis is of limited accuracy and chemical specificity. Anticipating future requirements for a more complete accounting of mud chemicals discharged to the environment, we present here results for chemical monitoring using a modern comprehensive chemical analysis technique, Fourier transform infrared (FT-IR) spectrometry. A description is given of sampling methods found to be practical and the main calibration requirements are discussed. The techniques developed in the course of this work give a good mineralogical breakdown of mud solids (commercial and drilled solids) in addition to the environmentally relevant measurements relating to mud on cuttings. The possibility of using the new technique for the rigsite monitoring of drilling cuttings is demonstrated. Cuttings samples simultaneously from the flow line, shaker screen, desilter and mud cleaner were analysed. It is found that mud polymers and other organic additives can be measured with sufficient accuracy to measure the removal of mud products by discharged cuttings. The technique is also applicable to quantify the losses of oil-based mud on cuttings. Field testing has shown that the instrumentation used is sufficiently robust and simple to use for rig-site application.
An Assessment of Surface Mud System Design Options for Minimising the Health, Safety, and Environmental Impact Concerns Associated with Drilling Fluids
Authors: Minton R. C. , Bailey M. G.
Published: December 2007

A drilling fluid surface system design concept is proposed that resolves the Environmental, occupational hygiene and safety issues associated with conventional designs. Automation of the chemical handling and dosing system is the central element of the concept which, when fully integrated into the system, permits a significant reduction in the surface volume requirements. This, in turn, results in weight and capital cost savings, offsetting the cost of the processing and treatment plant, and a smaller overall footprint for the system.

Adoption of the design philosophy results in a safe, healthy working environment in which all of the waste streams are managed so as to minimise the overall environmental impact of the drilling process.
Successful Application of New Technology in Antrim Shale Completions
Authors: Minthom J. W. , Garvin T.
Published: December 2007

The Antrim shale in the Michigan Basin has been a horizon of much interest to operators in recent years. However, sand flowback into tubing and casing sometimes impedes well production by plugging artificial lift pumps used to unload water from the Antrim formation. This paper explores a way to control sand flowback in a well during production by placing epoxy-coated sand in the fracture. A stream of catalyzed liquid epoxy resin is added to the blending tub containing surfactant, fracturing sand, and fracturing gel to achieve the processes.
Application of Microseismic Technology in a Devonian Shale Well in the Appalachian Basin
Authors: Fix J. E. , Frantz J. H. , Lancaster D. E.
Published: December 2007

Microseismic logging technology was applied to a Devonian Shale well in the Appalachian Basin to evaluate the height and orientation of a hydraulic fracture. The technique was used in the Sterling Drilling and Production Company Jarvis No. 1143, which is the Gas Research Institute's (GRI) Comprehensive Study Well No. 2 (CSW 2). The well, completed in the Devonian Shales, is located in Calhoun County, WV. This was the first application of the fracture mapping procedure in the Appalachian Basin; it was performed as part of GRI's efforts to understand fracture growth and orientation in the Devonian Shales. The procedure was also unique in that it was the first time the seismic data were collected in a gas-filled wellbore and after a well had been produced for an extended period of two years. The microseismic logging analysis results on CSW 2 indicate a 200-ft fracture height with an orientation trending Ν34°E. Also presented in this paper are the results obtained from a series of hydraulic fracture diagnostic tests performed on the CSW 2 prior to the microseismic logging experiment
Field Application for Quick-Setting Cement
Authors: Huck D. R. , Lansdell P. A. , Sikorski D. L.
Published: December 2007

Quick Setting Cement (QSC) is a special cement formulation which rapidly develops compressive strength and significantly reduces waiting on cement (WOC) time compared to conventional cement systems. The description of the cement properties and case histories are given.

The case histories show the advantages of QSC system for use in the following situations.

* On lost circulation zones encountered while drilling. * To stabili ze unconsolidated ground when drilling through fills associated with strip mining. * For lower drilling costs when open mines are encountered by reducing the WOC time when an additional string of casing has to be set. * To shut off large water flows that would otherwise prohibit further drilling.
A Comparison of the Fluid-Loss Properties of Borate-Zirconate-Crosslinked and Noncrosslinked Fracturing Fluids
Authors: Zeilinger S. C. , Mayerhofer M. J. , Economides M. J.
Published: December 2007

Static leakoff experiments with filterpaper, using borate- and zirconate-crosslinked hydroxypropylguar (HPG) fluids, have resulted in practically the same Ieakoff coefficients. This is in contrast to previous, dynamic, Ieakoff tests suggesting that borate-crosslinked fluids perform better. Within the temperature range where the polymers are thermally stable (200°F), there were no temperature effects after correcting for the filtrate viscosity. Under constant pressure differentials, both fluids exhibited compressible filtercake behavior with the Ieakoff coefficient approximately proportional to powers of 0.2 for borates and 0.17 for zirconates. When pressure was increased, imitating pumping and, then decreased, imitating closure, characterization of the pressure-dependent fluid loss using the Ieakoff coefficient as the descriptive parameter indicated a fluid-loss hysteresis for both fluids. During the pressure increase from 0 to 1400 psi both fluids showed a two-range response: incompressible behavior at low pressures and compressive behavior at higher pressures. In this range, the Ieakoff coefficient was practically constant. A comparison of the stress-sensitive properties has shown that while zirconate filtercakes exhibit decidedly viscoelastic properties, borate filtercakes are merely elastic. This can be attributed to the differences in the nature of the bonding of these polymers. Finally, filterpaper and core experiments, done with noncrosslinked fluids, have shown no filtercake-type behavior for a large range of core permeabilities, but rather a viscous flow dependent on porous medium characteristics.
Horizontal Well in the Devonian Shale, Martin County, Kentucky
Authors: Bellinger C. E.
Published: December 2007

Columbia Natural Resources, Inc. and Columbia Gas System Service Corporation, subsidiaries of the Columbia Gas System, and the United States Department of Energy (DOE) have successfully drilled and completed a horizontal well in the Devonian Shale in Martin County, Kentucky. The objective of this co-funded project is to assess the effectiveness and economic feasibility of applying horizontal drilling and stimulation techniques to enhance the production of natural gas from the Devonian Shale. Columbia's well is one of three wells in a DOE program called "Horizontal Wells in the Devonian Shale."

Drilling began June 1, 1990 and ended July 7, 1990. The well contains a three-part profile, a conventional vertical section, an angle building or curved section and finally the horizontal section.

The well reached a measured depth (MD) of 6,263 feet, 3,754 feet true vertical depth (TVD) and a horizontal displacement of 2,872 feet was achieved in the desired direction, N12°W. Both air and foam were used as drilling fluids. The vertical section, tangent section between the curves and the horizontal sections of the well, were drilled using conventional rotary drilling methods. Downhole motors were used to build angle in the curved sections.

Thirty-five gas shows were detected by the mud logger while drilling; measured flow rates exceeded 1 million cubic feet per day (MMcfd) at TD.

Mud and geophysical log information were used to establish discrete completion zones. A 5-1/2″ production string equipped with five Payzone Packers and FO Completion Tool established six completion zones: an openhole/slotted liner section at the bottom; three zones isolated by the external packers with access to the formation through sliding sleeve FO completion tools; and, two zones which were cemented.

Overall, this application of horizontal drilling has proven that additional reserves can be developed in the Devonian Shale by its application. The current economics could be greatly improved by developing additional technology.
Ellenberger Stimulation - Past, Present And Future
Authors: Gibbs Max A.
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the Regional Gas Technology Symposium of the Society of Petroleum Engineers of AIME, to be held in Omaha, Neb., Sept. 12–13, 1968. 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 publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the 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.

The concentration of ultra-deep well completions in the Ellenberger formation of West Texas' Delaware Basin present a unique opportunity to study the state of the deep well stimulation art.

Some 125 wells, many 20,000 feet and deeper, have been completed in the past several years, and each of these wells has been stimulated to some extent. A wide variety of completion techniques and stimulation methods have been used to cope with the extreme depth, temperature, and gross pay thickness of these wells.

At one time, effective stimulation was considered almost impossible in the Ellenberger, but with improved materials and techniques developed specifically for the Ellenberger, better results are being realized. With measurable stimulation results to work from, treatment design has begun to conform to established tenets, except on a much larger scale.

These results can be further improved by adapting to more powerful and effective hydraulic programs, and with better hydraulics, the use of programs, and with better hydraulics, the use of proppants to supplement what has heretofore been proppants to supplement what has heretofore been acid fracturing.

Introduction

The Ellenberger formation of West Texas'Delaware Basin presents an unparalled opportunity to study ultra-deep well stimulation design. The concentrated amount of drilling, and the diversity of completion techniques afford sufficient number of well histories to make generalized summaries meaningful. Much of the experience gathered in the Ellenberger will be directly applicable to deep carbonate reservoirs in other areas, and to deep well stimulation in general.

Since the discovery of commercial gas production in the Ellenberger, approximately production in the Ellenberger, approximately 125 wells have been completed in eight fields of the Delaware Basin. Each of these wells has been stimulated to some extent, and many have been treated quite heavily.
The Chronic Toxicity of Mineral Oil-Wet and Synthetic Liquid-Wet Cuttings on an Estaurine Fish, Fundulus grandis
Authors: Jones F. V. , Rushing J. H. , Churan M. A.
Published: December 2007

One of the major factors concerning oil-wet cuttings discharges is the long-term effect on the aquatic environment This study investigates the survival and growth of the mud minnow, Fundulus grandis. when exposed to different concentrations of mineral oil-wet and synthetic liquid-wet cuttings in flow-through bioassay chambers.

The test fluids were a low aromatic mineral oil-based mud (MOBM) and a synthetic liquid-based mud (SBM). Each test fluid was added to a container of dried water-based cuttings which contained minimum hydrocarbons. The fluid and cuttings were mixed to obtain the desired test concentrations. The study tested three concentrations (1%, 5%, and 8.4% by dry weight) of each fluid on the cuttings.

Growth rates during the 30-day period were modest with fish in 1% MOBM losing weight. The highest percent growth rates were obtained with fish cultured in 5% SBM and the controls. However, overall growth was not significantly different between treatments. Mean growth did show a significant difference between controls and 5% SBM, and other treatments.

The cuttings of the 5% and 8.4% concentrations of both treatments looked like paste. These pastes may have slowed the movement of organics off of the cuttings beds and affected biodegradability and growth rates. Cuttings in the controls and 1% concentrations stayed suspended in the water column longer when disturbed and looked more like loose gravel. Uptake of the MOBM occurred in the internal organs and tissue offish. No such uptake was obsen/ed in the fish tissue with the SBM; a very low level of synthetic liquid was detected in one gut sample only. This may be the major reason for the variations noted in growth rates.

Fish mortality during the study was related to the buildup of anaerobic conditions and insufficient aeration. Fish survival for the entire study was 94% This study, in association with bioaccumulation investigations, provides information on the chronic effects of discharged cuttings in the environment.
Emergency Systems for Divers
Authors: Påsche A. , Holand B. , Oftedal G.
Published: December 2007

Accidents during operational diving have on some occasions resulted in situations where the divers have been left in the diving bell or welding habitat at the sea bottom for several hours. In some of these situations, there have been casualties due to hypothermia. As a result, the diving industry and authorities have required that emergency equipment be developed and installed in the diving systems.

The early emergency systems consisted of passive insulation systems and a lung powered CO2-scrubber/respiratory heat exchanger. From tests as well as actual emergency situations, it has been 'pointed out that certain improvements are required. The systems should include some means of preventing urine-wetting of the insulation system. In addition, the divers are reluctant to undress their regular diving suit as they are concerned that they would later be unable to put it on again during the rescue operation.

The aim of the reported project has been to develop and test a new emergency system. New elements are a urine collection system and an evacuation system which could be used as a hot water suit and prevent the necessity of changing suits. The evacuation suit was tested during a simulated dive to 450 metres and fulfilled the requirements for prevention of cold water shock.

The passive insulation system and the lung powered CO2-scrubber/ rebreather have further been improved ergonomically and with regards to thermal properties.
Unsaturated Medium Hydrocarbons Pollution Evaluation
Authors: Di Luise G.
Published: December 2007

When the so called "porous unsaturated medium", that' s the vertical subsoil section between both the ground and water-table level, is interested by a hydrocarbons spill, theproblem to evaluate the pollution becomes difficult: considering, essentially, the natural coesistence in it of two fluids, air and water, and the interactions between them. The problems tend to increase when a third fluid, the pollutant, immiscible with water, is introduced into the medium: a three-phases flow, which presents several analogies with the flow conditions present in an oil-reservoir, will be established. In such a situation, it would be very useful to handle the matter by the commonly used parameters in the oil reservoirs studies such as: residual saturation, relative permeability, phases mobility, to derive a first semiguantitative estimation of the pollution.

The subsoil pollution from hydrocarbons agents is one of the worldwide more diffused causes of contamination: such events are generally referable to two main effects: accidental (oil pipelinebreakdowns, e.g.), and continuous (underground tanks breaks, industrial plants leakages, e.g.)
Quantification of Log-Core Correlation Using the Formation Microscope
Authors: Williams G. R. , Sharma M. M.
Published: December 2007

The FMS tool makes extremely dense conductivity measurements, approximately 7000 per foot. These measurements have been most commonly used to generate images approximating core photographs. The images have been used for geological interpretation and fracture identification.

The main issue addressed in this paper is the comparison of rock property measurements made at different length scales. Small core plugs are often taken to represent larger sections of conventional core and comparisons are made with logs. FMS data can provide a quantitative measure of the variation that can be expected from this process. This measurement can be used to estimate the required sampling density of core plugs necessary to represent the formation in the vicinity of the wellbore to a specified degree of accuracy. It can also be used to determine the expected degree of agreement when comparing core and log data.
Reservoir Testing Using a Down Hole Shut-In Tool: Field Cases
Authors: Pacheco E. , Da Prat G.
Published: December 2007

In this paper, a brief description is given to operational procedure involved in acquiring transient data using a down hole shut-in tool. Field cases (Maracaibo Lake are presented to show the advantages of this technique in active wells and for cases where reservoir pressure is below bubble point. A comparison is made between this technique and the one that is based on simultaneous measurements of tran sient flow rate and pressure. The benefits both from an economic point of view and from the reservoir evaluation side using this method are presented. A main result derived from this work is that the use of the down hole shut-in tool reduced the build-up time by a factor of 10 in some cases for tests conducted in Maracaibo Lake fields. A considerable saving in differed oil production was gained besides the benefits of having pressure transient data not strongly affected by wellbore storage and phase segregation which permits a better reservoir evaluation.
Compositional and Pseudo Compositional Simulations Comparison for Complex Volatile Oil Reservoir Modelling
Authors: Sanchez N. , Rattia A.
Published: December 2007

Maraven S.A is considering to initiate a gas injection project in a large and geologically complex volatile-oil reservoir, located in Lake Maracaibo-Venezuela. This paper describes the methodology used to carry out sensitivities to evaluate the feasibility of using a pseudo compositional option of a black-oil simulator to conduct the 3-D simulations. The first task of the study was to decide whether geological complexities or phase behavior had a larger influence on reservoir performance. Therefore, 1-D sensibility runs were carried out using a fully compositional simulator, and a pseudo compositional simulator to compare compositional effects, grid-block size required to reduce numerical dispersion, effect of displacement pressure, and the use of different injection gases. In the following phase, 2-D simulations were conducted to investigate the effects of heterogeneities on recovery, and the feasibility of lumping the sedimentological facies into flow units without modify the original sedimentological reservoir description.

The results showed that the simulated behaviour with the pseudo-compositional simulator were more sensitive to grid-block size, and numerical dispersion. Also, indicated that adecuatelly modelling of internal reservoir heterogeneities is quit relevant.

The simulation results, allowed to observe that the pseudo compositional simulator formulation does not take into account the miscibility mechanism for multiple contacts of gas and reservoir oil. Also, at the current reservoir pressure small differences were observed in the results of both models, and large reductions in running time were obtained in the pseudo compositional runs.

The previous results enhanced with the ability to permit a better description of the reservoir heterogeneities, indicated superiority of the pseudo compositional model to carry out the 3-D simulations.
Safety System – Gas Treating Plant
Authors: Fridman O.
Published: December 2007

This paper presents a new system to improve safety and reliability of a gas treating plant. The geographic location of the plant, isolated on a hilltop in the subtropical jungle in the north of Argentina, increases the importance of this system. The entire system is handled by Programmable Logical Control, which takes its information from four different sources: Manual Shutdown, Gas Sensors, Ultraviolet/infrared Fire Detectors, and Data Acquisition System. It is a real time monitoring and control system. Input information is processed in the PLC and action is taken automatically in accordance with the results of the analysis. The system can take the following actions: Close the flowline valves from the wells, Open the vent valves, Cut off the energy supply, Stopping the gas and propane compressor, Turn on the fire pumps, Shut down the furnaces, Activation of the alarms.

The difference between this system and other systems in similar plants lies in its flexibility and speed which help to avoid unnecessary plant shutdowns. All the elements connected with the PLC are tested every two seconds. In the control house, there is a panel that can operate the system manually if there is a problem with the PLC. It also features a mimic with LED for each data source. The color of the LED indicates one of the following conditions: Normal operation, Caution, Changing condition, Alarm.
Optimizing Field Development of Deep Cretaceous Fractured Reservoirs, Lake Maracaibo, Venezuela
Authors: Franseen R. , Vahrenkamp V. C. , Van der Graaff W. J. E. , Muñoz P. J.
Published: December 2007

The Deep Cretaceous carbonate reservoirs of Lake Maracaibo, Venezuela, produce mainly from open-fractures. Any improvement in production rate requires optimal access of the wellbore to open fractures. Well tracks with maximum rates of open fracture interception have been calculated using computer models for a structure defined by the Icotea fault in Block IX. Optimum well tracks are towards azimuth 330° with deviation 60° in the West Flank and towards azimuth 030° with deviation 60° in the East Flank.

The open fracture networks consist of incompletely cemented or leached fractures which contain a "channel and island" structure of interconnected porosity. This structure, in combination with the high rock matrix strength and the subparallel strike of the open fractures relative to the E-W trend of the present-day maximum horizontal stress, indicate that it is unlikely that the conductivity of individual fracture will be reduced drastically upon pressure depletion.

The reservoir geological model established for Block IX is consistent with data obtained from the West Flank of Block I, some 40 km to the north and therefore has regional validity.
Cross Borehole Electromagnetic Induction for Reservoir Characterization
Authors: Wilt M. , Morrison H. F. , Becker A. , Lee K.
Published: December 2007

Audio-frequency cross-borehole electromagnetics (EM) is an interesting alternative to existing techniques for reservoir characterization. With this method signals may be propagated several hundreds of meters through typical sand/shale reservoirs and data may be collected at high accuracy with a high sensitivity to the subsurface resistivity. A vertical component, cross-borehole EM field system has been designed and built by Lawrence Livermore and Lawrence Berkeley laboratories for reservoir evaluation and monitoring. This system was deployed at the British Petroleum test facility in Devine, Texas for testing and the the UC Richmond field station facility for a saltwater monitoring experiment. The Devine site is in a region of simple, flatlying geology so that collected data could be unambiguously interpreted with layered models. The results of the test showed that crosshole EM profiles in wells spaced 100 meters apart data could be repeated in 24 hours to better than one percent and that the profile data could be fit to layered models within this same tolerance. The derived models showed a close correspondence with the borehole induction log. At the Richmond facility we injected 120,000 liters of 1-ohm-m saltwater into a shallow aquifer for the purpose of testing geophysical monitoring methods. Differences between cross-borehole EM profiles collected before and after the injection reveal a clear anomaly that can be attributed to the saltwater. Although the anomaly is of the proper dimensions and magnitude for the amount of saltwater its irregular shape has made it difficult to fit to our simple three dimensional prism models.
Field Tests of the Poseidon Pump
Authors: Gie P.
Published: December 2007

Since May 1991 a POSEIDON pump of the rotodynamic type has been running on the SIDI EL ITAYEM field in TUNISIA, logging more than 3500 operating hours (end of November 91) without a major problem. This pump is one of the practical results of the POSEIDON project, launched in 1984 by TOTAL, IFP and STATOIL, to develop the concept of multiphase pumping: the final target being a subsea multiphase boosting station.

Prior to the Tunisian test, this pump had been tested satisfactorily on the two phase loop of IFP at SOLAIZE (FRANCE), and it was this which decided the partners to send the prototype, wihout any modification, to the real active field test rig specially prepared to accommodate multiphase equipment.
Low-Conductivity and Short Fracture Half-Length Type Curves and Analysis for Hydraulically Fractured Wells Exhibiting Near Radial Flow Profile
Authors: Azari M. , Knight J. W. , Coble L. E. , Soliman M. Y.
Published: December 2007

Some actual buildup pressure responses from deep, hydraulically fractured wells or wells which sanded out during the fracturing treatment have yielded pressure responses similar to radial flow. These cases show no apparent bilinear or linear flow regimes on the log-log plots. The same type of near-radial flow response can also be observed in wells with short fracture half-lengths, high linear skin on the fracture, or in wells with very low fracture conductivities.

New type curves parameterized in terms of SwfDe3Sc where Sc is a function of wellbore radius, linear fracture skin, fracture conductivity and half-length were developed for analyzing such systems. Applications of the new type curves parameterized in terms of SwfDe3Sc illustrate accurate evaluation of the above parameters governing fracture flow in the presence of wellstorage. The provided analysis procedure computes fracture conductivity and half-length, formation permeability, and wellbore storage. Field and theoretical example problems are also included which illustrate the consequences of performing the analyses assuming radial flow. Type-curve analysis based on radial flow assumptions produce accurate permeability values but appreciable error in fracture half-length and conductivity values.
Role of Solution Gas in Primary Production of Heavy Oils
Authors: Sarma H. , Maini B.
Published: December 2007

The objective of this study was to investigate the role of gas nucleation in the primary production of heavy oils under solution-gas drive. We were particularly interested in determining the effect of gas nucleation on mobility of heavy oils in a porous medium.

A novel apparatus was designed and assembled to carry out simulated solution gas drive experiments in a 200 cm long sand pack. Recombined oil was injected into one end of the sand pack at constant pressure (equal to the saturation pressure) and was produced from the other end at constant back pressure. The oil production rate and the pressure profile within the sand pack were measured at various values of pressure drawdown. Experiments were conducted using two heavy oils.

The experimental data show that, contrary to some speculations in the literature, the nucleation of gas bubbles under the solution-gas drive adversely affected the bitumen mobility. However, another hitherto unaccounted for mechanism was involved: even at the highest pressure drawdown the gas appeared to flow primarily as a dispersed phase and the apparent trapped gas saturation was very high. It is suggested that the heavy oil/gas mixture was flowing in form of an oil continuous foam.

The in-situ formation of an oil continuous foam can lead to recovery of a much higher fraction of the original oil in place under solution gas drive. Therefore this factor should be taken into account in developing the strategies for primary production of heavy oil under solution gas drive.
Integration of Reservoir Data for Fault Identification: A Synergetic Approach
Authors: Suarez M. , Fiume G. , Camperos S.
Published: December 2007

Integration of reservoir data has become a powerful tool for reservoir description. A field case is presented where definition of a fault was achieved by integration of well test and seismic data. It was not clear whether or not the system was faulted, and this particular point was a key factor in the plans for exploitation of the reservoir. Using the integrated data base, a two way approach was followed. First, vertical seismic data was analysed, sequentially, using an integrated data base, results from a well test were interpreted to verify the existance of the barrier to flow. Results matched between very acceptable ranges, fault was undoubtedly identified and confidence in a synergetic, multidisciplinary study provided better characterization of the reservoir.
Slim Hole Multiple Radials Drilled with Coiled Tubing
Authors: Dickinson W. , Dickinson R. , Herrera A. , Dykstra H. , Nees J.
Published: December 2007

Two methods of combining water jet drilling and coiled tubing, the Ultrashort Radius Radial System (URRS) and the Quick Radial System (QRS), are described. Both provide multiple horizontal radials on a single horizon from a single vertical wellbore to penetrate near wellbore damage. The URRS requires section milling of the casing and underreaming of a cavity. The QRS penetrates the casing with abrasives. Typical field production results with both light and heavy oil are discussed.
Compositional Material Balance: Its Application to the Development of an Oil and Gas Field with Retrograde Condensation
Authors: Canel C. A. , Rosbaco J.
Published: December 2007

This paper presents a model developed to simulate the exploitation process of a field with liquid and gaseous hydrocarbons, in one or two phases. It combines the classic material balance technique with thermodynamic equations of state.

Its effectiveness as a tool for the reservoir engineer to analyze different exploitation alternatives is discussed.

An example is presented on how the model is applied for an oil field having a retrograde condensation gas cap.

Before the model is explained, material balance and equations of state are discussed.
Horizontal Well Optimization through Strength and Stability Analyses of Drillstrings
Authors: Prodonoff V. , Guz J. L.
Published: December 2007

The objective of this paper is to show the application of a computer program developed at CENPES (PETROBRÁS Research Center), which performs analysis of a drill string. In the case of a horizontal well it is possible to simulate several designs, with the goal of extending the length of its horizontal span and thus increase its productivity. The working and the basic characteristics of the program are described, as well as the analysis of the factors that influence and limit the maximum horizontal length pursued. Numerical examples are shown to validate the program and to calculate the lateral forces, drag, torque and buckling load, in order to verify the design.
Operational Geological Experiences of Horizontal Wells
Authors: Parra A. U. Lamus
Published: December 2007

During the years 1989 and 1990 LAGOVEN, S.A.. developed three horizontal well projects in Lake Maracaibo, TJ-1095, CLA-2273 and TJ-1112. In these wells an operational geological follow-up was made in order to define accurately the different structural depths of the geological column to be penetrated, and especially the structural depth (from top to base) of the different sands to be found at the reservoir target by using: geological correlations in a real time, cutting sample and up-dating the projection of the directional survey section.

The experience gained in the horizontal wells proved to be of incalculable value as it helped establish a geological-operational procedure which can serve as a basis for future operational projects.
Parallelization in Reservoir Simulation
Authors: Cheshire I. M. , Bowen G.
Published: December 2007

A new technique is presented for solving the linear equations arising in reservoir simulation using multiple processors in parallel. The Nested Factorization(1) algorithm is extented by domain decomposition in a highly parallel way while ensuring that the power of the method is retained as the computation is distributed over several processors.

The method is illustrated by the fully implicit solution of a three phase simulation of a 4800 cell problem on a 6 processor Silicon Graphics machine giving an overall speed up factor of about 2.8.
Production Impacts on ?P Friction in Horizontal Production Wells
Authors: Brice B. W. , Miranda J. R.
Published: December 2007

This paper confirms the high ΔP friction in the production section of a horizontal well as proposed by Dikken1. Available pressure transient data validates his theoretical pressure drops which are significantly greater than previously thought.

Due to short production intervals in most conventional wells (relative to horizontal wells) the phenomenon has minor impact on the conventional well. It can, however, play a significant role in the distribution of production in a horizontal well and needs to be considered when running reservoir models to properly evaluate reservoir performance. Because of the risks and costs associated with production logging it is not generally detected.

This simulation work uses pseudo reduced pipe diameters in ECL's Eclipse reservoir simulator. They generate pressure profiles along the horizontal producing section that match Dikken's1 pressure profiles. Eclipse simulator results indicate that friction loss along the production interval has an impact on coning performance.
Resistive-Capacitive Tomography
Authors: Callarotti R. C. , Di Lorenzo M.
Published: December 2007

In this paper we present novel solutions to the inverse problem as applied to low frequency electrical analysis of cores for the visualization of displacement fronts. From electromagnetic theory, we first derive a low frequency equivalent circuit for each volume element of the core. The model consists of parallel combinations of frequency independent resistances and capacitances whose value we obtain in terms of the electrical conductivity and permittivity of the core material with and without displacing fluid. We then describe two algorithms for the determination of the admittance matrix which represents the core, starting from the voltages measured at external core terminals, when the core is excited by low frequency currents applied at such external terminals. The first derived algorithm is based on what we define as circuital iteration starting from the edges of the core. The second algorithm is based on the iterated solution of Poisson's equation in the interior of the core (for the complex case which considers conductivity and permittivity). We determine the errors obtained in the solution of different discretized cores by comparing the iterated solutions with the values given by the solution of the direct (or forward) problem.