bluuebunny/crossref_metadata_2025 huggingface dataset:
Revegetation Trials in Western Siberia: The Growth of a Cooperative Effort
Authors: Younkin W. E. , Martens H. E.
Published: December 2007

The removal of barriers to Western involvement in the Russian economy has made it possible for joint cooperation in the solution of environmental problems facing that country. One such problem is the large terrain and vegetation disturbances associated with oil and gas exploration and development activities in Western Siberia. While studies to select adapted species and test terrain stabilization techniques for Arctic and Subarctic regions in North America have been underway for over 20 years, little was known of similar work in the former Soviet Union. In 1991 and 1992, Amoco environmental specialists, in consultation with the local gas association, brought in a number of revegetation species proven in the North American Arctic and put them into test gardens on the Yamal Peninsula. First year results were favorable and in 1992 the tests were expanded to include various plant establishment methods for the sandy soils common in the region. In 1993 a joint Russian/American team was formed and studies utilizing a combination of species and methods from both countries were undertaken at the most northern site. The results of these studies are reviewed and summarized.
Exploration and Production of Hydrocarbons Under the Impact of More Stringent Environmental Requirements: How Does a Central European Producer Tackle This Problem?
Authors: Böning Heinrich
Published: December 2007

In Germany, hydrocarbon reservoirs are frequently located in areas designated as nature or landscape protection zones, or at least as farmland or forest.

In addition, environmental discussions are making the public increasingly sensitive and statutory environmental requirements are impeding the implementation of industrial planning and decision-making processes.

In order for exploration for and production of hydrocarbons to remain calculable, economically and ecologically reasonable solutions must be found which are acceptable to all concerned. This necessitates competent communication and coordination and a high degree of cooperation both within the company and vis-à-vis residents, authorities, ministries, interest groups and partners.

Within the scope of these activities, environmental concerns for BEB can be roughly grouped in the three main categories

Legislation/permit procedures Emissions/immissions/damage Upgrading/recultivations/restitutions.

The entrepreneurial challenge in solving these tasks necessitates an environmentally-oriented management and a change of strategy towards a preventive-proactive approach which also take into account ecological aspects and thus co-responsibility for environmental quality in an appropriate manner.

The present paper describes two examples of this structural change, the first initiated by the lawmaker and the second by the company itself.
Researching Employee Assistance Program Resources in Southeast Asia
Authors: O'Donnell W. J.
Published: December 2007

The paper will describe visits to four (4) Southeast Asian countries and the efforts to discover what resources are available for expatriates and nationals to address problems traditionally encountered in employee assistance programs.

Specific resources for treatment of chemical dependency (alcoholism, drug addiction) in the Philippines, Singapore, Indonesia, and Thailand will be discussed. Both professional and self-help resources will be covered. Counseling resources for other psychological and emotional problems will be included.

Prior to discussing resources in specific countries, a discussion of the definition of an EAP as well as the history of the EAP movement will be briefly described. The various models of service and the EAP core technology and actual mechanics will also be explained.
Safety Issues Regarding Temporary Wellhead Pressure Control Equipment Used in Wireline Service Operations
Authors: Fehrmann G.Z.
Published: December 2007

SPE Member

Wireline operators employ pressure-control equipment when performing slick, braided, and E-line service operations on pressurized (live) wells. This pressure-control equipment, commonly referred to as lubricator stacks or risers, is mounted temporarily on top of the wellhead for the purpose of controlling well pressure and fluids as the services are being performed. To ensure the safety of personnel, property, and the environment, several new enhancements have recently been made to lubricator equipment and associated well entry technology.

This paper will present an overview of these enhancements and how they:facilitate proper selection of equipment for particular well environments and pressure conditions, andprovide operators with procedures for proper inspection and maintenance of the equipment to insure its integrity.

The paper will also discuss various methods and design improvements that can eliminate the uncertainty of equipment selection for H2S and standard service.

This information is being presented with the hopes that a better understanding of equipment and processes will enable operators to make proper selections of temporary wellhead pressure-control equipment, and thus, ensure safer conditions for both personnel and the environment.

Introduction

The process of moving tools in and out of a live wellbore using a pressure-control system or stack was originally referred to as "lubricating the tools" into and out of the well, and thus, the equipment has come to be known as a "lubricator." Operators also use the term, "riser," but for purposes of this paper, the equipment will be referred to as a "lubricator" or "lubricator stack."

Most components in a lubricator stack are manufactured with threaded end connections that employ elastomeric O-ring seals so that the components can be connected easily without special tools. Equipment working pressures range from 2,000 to 20,000 psi (13.79 to 137.9 mPA). Most lubricator stack components are sized to the tubing in the well or the equipment that must be run in the tubing, and the ID sizes range from 2 to 9 inches (50.8 to 228.6 mm). In recent years, manufacturers of lubricator components have been requested to size their equipment to standard API wellhead ID sizes. Since lubricator equipment is mounted temporarily on the wellhead, it does not fall within the API specifications, and compliance is not mandatory. However, most manufacturers of lubricator equipment try to adhere to API 6A specifications.

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Investigation of Pore-Blocking Mechanism in Gravel Packs in the Management and Control of Fines Migration
Authors: Bigna Yann , Oyeneyin M. S. , Peden J. M.
Published: December 2007

The migration of fines into gravelpacks from both unconsolidated reservoirs and through the injection of fluids from the wellbore, is characterised by permeability reduction which may be gradual or instantaneous depending on the invasion process and the pore blocking mechanism. In an attempt to define the maximum allowable levels of fines that can be tolerated by a typical gravelpack which will ensure optimum production capacity over the economic life of the well, an experimental project on pore blocking mechanisms in gravelpacks was initiated in the Department of Petroleum Engineering at Heriot-Watt University in order to define the gravelpack permeability decline as a function of production time.

In this paper, the results of the experimental studies which show the trends of gravelpack permeability reduction as a function of the pore blocking phenomena are presented. Five prevailing pore blocking mechanisms were identified, each characterised by the profile of permeability reduction against time. Based on the characteristic profiles, specific pore blocking mechanism models were developed to quantify gravelpack impairment as a function of gravel-fines size ratio, fines concentration, and fluid production rate. These models have been incorporated into a computerised well performance model which can be utilised to predict both the initial and lifetime performance of a gravelpacked well.

Specific case studies, using field data, to illustrate how the well performance model can be utilised to conduct sensitivity analysis of the productivity index to fines concentration, gravel size and production time. Application of the studies to the analysis of gravelpacked well performance especially with respect to maximum allowable level of fines injection during water flooding for injection wells or formation fines production level for specific commercial gravels are presented. The paper also illustrates how the system can be used to predict possible plugging time of a typical gravelpack.
Utilizing Snubbing Is a Cost-Effective Tool for Gravel Pack Operation on the Gullfaks Field
Authors: Kristiansen T. S. , Hauge Torleif , Kolsto Johan
Published: December 2007

Utilising a snubbing rig has proven to be cost effective for gravel pack applications on the Norwegian Gullfaks field. A snubbing rig is less expensive to use than the drilling rig, but more importantly, deploying a snubbing rig releases the drilling rig for drilling operations. Use of the drilling rig for sand control operations delays the drilling progress on the platforms and consequently delays the production from all the upcoming wells. The total cost of delayed drilling operations, including the impact on delayed production, varies between 1 to 5 Mill NOK/rig-day ( 150 000 - 700 000 USD/Day) on the Gullfaks field. These values will, however, change over time and will be less important as more wells are drilled and completed.

This paper describes the economical potential and the technical advantages of using a snubbing rig for gravel pack operations on the Gullfaks field. Field examples and experiences gained from different gravel pack operations are included.
Numerical Model for Predicting Complex Sulfate Scaling During Waterflooding
Authors: Roque Claude , Renard Michel , Van Quy Nguyen
Published: December 2007

This paper is in two parts. The first part describes the experimental investigation enabling the precipitate to be identified as a single complex-structure solid. The second part describes a numerical model for predicting solid deposits.

In constructing the model, consideration was given to the experimental observation given above. Likewise, the concept of an equilibrium constant applied to each sensitive ion was used in the place of solubility products, which had become inadequate to describe an equilibrium in which the solid phase has a complex composition.

Comparisons were made between deposited masses, determined by computing and by experimental measurements for several water pairs. Quite satisfactory agreement was obtained in each case.

Several measured families of equilibrium constants were introduced into the model, corresponding to water pairs that are often encountered in reservoirs. With this database, the model is able to provide a mass deposit curve for a water pair having any composition. An example of prediction is given. It has to do with an industrial case applied to production.
Evaluation of Potassium Carbonate as a Non-Corrosive, Chloride-Free Completion Fluid
Authors: Houchin L. R. , Foxenberg W. E. , Zhao Jun
Published: December 2007

The use of Potassium Carbonate as a non-corrosive, chloride free completion fluid has gained acceptance by several operators in the Middle East and North Sea. These brines can be formulated to reach a specific gravity of 1.52 (12.5 lbm/gal). The formulated brines possess physico-chemical properties such as high solubility, low crystallization temperature, low intrinsic viscosity, low corrosivity, etc., which make them candidates for utility as completion and/or packer fluids. Theoretically, these properties should provide a brine completion fluid which is operationally functional, corrosion resistant (high pH) and which eliminate the potential for chloride stress cracking of corrosion resistant alloys. However, the significance of these benefits is unpublished and other obvious potential incompatibilities were apparently not evaluated.

This paper presents results from an extensive laboratory evaluation as to the suitability of potassium carbonate brines as completion fluids. Data from average weight loss and stress cracking corrosion (SCC) tests confirm both low general corrosion rates and little or no tendency toward stress corrosion. However, this low corrosion potential is not significantly lower than other chloride free brine alternatives such as sodium bromide.

At test temperatures as high as 300°F, no evidence of 13 Chrome Stainless Steel stress cracking was identified in any of the completion brine systems tested, including chloride and bromide based fluids. Furthermore, fluid-fluid and fluid-rock compatibility test results indicate that carbonate based brines produce precipitation reaction products when intermixed with a range of synthetic and natural formation waters. Single-phase, brine flow tests on Berea cores showed an almost total loss of permeability after exposure to potassium carbonate brines.

Guidelines are presented to assist the completion engineer in thoroughly evaluating completion fluid brine chemistries as to functionality and formation compatibility.
Analysis of Radial Core Experiments for Hydrochloric Acid Interaction With Limestones
Authors: Frick T. P. , Mostofizadeh Behdokht , Economides M. J.
Published: December 2007

Radial experiments of acid interactions with low permeability limestone cores were performed for a clearer understanding of controlling phenomena whose quantification would have a considerable impact on the matrix stimulation design of carbonate formations. The effects of injection rate, temperature, core permeability and acid concentration are demonstrated and compared with an analytical model which is based on a fractal geometry of the dissolution patterns. An optimum injection rate for the most efficient spending is identified. The shape of the wormhole pattern has been investigated under different conditions. Computer tomography before and after the treatment and thin sections were applied to analyze the dissolution patterns. The special laboratory considerations for conducting these experiments are presented in detail. A dimensional analysis comparison of the results in the radial cores with previous work in linear cores is also shown.
ESEM Observations Coupled With Coreflood Tests Improve Matrix Acidizing Designs
Authors: Simanjuntak A. B. M. , Haynes L. L.
Published: December 2007

A new laboratory procedure has been developed to study formation damage mechanisms and improve acid stimulation designs using an Environmental Scanning Electron Microscope (ESEM) coupled with core flood tests. An ESEM has the unique capability of observing a sample, wet or dry, in its natural, uncoated state. The core plugs used in core flooding experiments can be observed at the same locations, before, during and after treatment with workover and completion fluids, without any cleaning, drying or metal coating processes. The direct effects of the stimulation and completion fluids on the formation minerals can be seen along with any changes to the initial porosity. The ESEM is combined with energy-dispersive X-ray spectroscopy (EDS) to allow elemental analysis of precipitates or observation of changes in the elemental composition of the clay minerals.

This paper describes both the analytical procedures and the results of acidizing sandstone cores. The core material was observed by ESEM before, during and after laboratory core flood tests. This has resulted in a more effective acid stimulation treatment design through a better understanding of the fluid/rock interactions.
Converting Semisubmersible Drilling Units to Floating Production
Authors: Bowie R. D. , Tan P. L. , Corcoran G. C.
Published: December 2007

Converting semi-submersible drilling units to long term site specific Floating Production Service is becoming more frequent. This paper will present the latest classification and other regulatory requirements for this type of service.

The paper concentrates on Gulf of Mexico service and offers information regarding ABS interaction with Government Authorities such as USCG, MMS and flag states such as Panama and Liberia. ABS requirements for production risers, subsea templates and the role of ABS as a CVA for MMS are also discussed.

Fatigue assessment methods and joint detail enhancement are discussed together with surveys that are necessary to ensure that the unit will be capable of operating in one location for an extended period of time.
BP's Well Construction Strategy - A Way Forward?
Authors: Nims D G , Doig M J , Townhill R
Published: December 2007

To accelerate its North Sea Miller Platform drilling programme BP introduced an integrated incentive drilling contract with its two main drilling services contractors, Santa Fe the drilling contractor, and Baroid Engineered Drilling Services Limited the drilling engineering services contractor.

The objective in setting up the integrated incentive contract was to build mutual understanding by all parties of the common business drivers and to align the parties to deliver an end product, "the well", as opposed to the provision of a series of individual services. The anticipated benefits include increased commitment and focus from the contractors resulting in improved drilling performance. The paper will outline the implementation and results of this new contracting philosophy.
Fast Tracking to a Quality Operation
Authors: Schaeffer P. H. , Hartt M. A.
Published: December 2007

In the present times of fixed revenues and flat crude prices, an operator must control variable costs in order to remain competitive. Drilling costs are an important part of Capex and reduction of these costs in both Exploration and Development phases has become vital to improve profitability and increase attractiveness of marginal prospects/fields. Significant improvements from advancements in technology will more likely be evolutionary rather than revolutionary and contract rig rates are/have been at all time lows. Thus, the need and the challenge to drill economically will continue.

In the realm of areas that an operator influences, improving operational performance is the prime candidate for reducing drilling cost with immediate results using currently available technology/equipment. This paper discusses the "Fast Track" program introduced by Exxon in floating drilling operations offshore Malaysia that combines the development of ‘Cost Effective Drilling Programs’ with sharply increased ‘Rig Productivity’ to optimize overall drilling performance/quality and safety.
Case Study of Cased-Hole Sidetracking Mechanics: Prudhoe Bay Field Re-Entry Program
Authors: Jordan T. T. , Hernandez Floyd , Parnell L. A.
Published: December 2007

Consistent success has been achieved in the sidetracking mechanics used in the Prudhoe Bay re-entry program: milling a section out of the casing, laying an effective balanced cement plug, and directionally drilling out of the open section.

Operational success and consistency in this sidetracking phase have been a key in making a re-entry sidetrack more economical than a new well or an extensive workover. The objective of this paper will be to discuss the operational procedures that have proven effective over a large volume of wells.
The Application of Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) in the Study of Drilling Bit Nozzles
Authors: Drakulic Radenko , Steiner Ivo , Grant Ian
Published: December 2007

Two non-destructive optical methods - Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV), as innovative methods in drilling process efficiency studies, were applied in velocity measurements of jets coming out of drilling bit nozzles.

Scientific papers and textbooks published on the subject contain results of the velocity distribution below a nozzle based on single-point measurements. This involved the use of Pitot tubes and Hot-wire anemometers, while LDV has only recently been introduced in jet bit studies.

Hydraulic parameters regularly monitored and calculated in drilling activities are jet velocity, hydraulic horsepower and impact force. Existing methods provide these parameters to be calculated only at the nozzle outlet. At the same time the area of important jet action, lying at the bottom of the hole and in between, is not adequately investigated. Recently developed PIV enables velocity measurements to be carried out simultaneously over the entire profile of the flow. PIV permits great range of velocities to be measured with high accuracy in various media, experimental setups and types of the flow.

In this paper a preliminary study of high jet velocities coming out from nozzles having circular, square, rectangular and elliptical openings is discussed. Testing facilities and results obtained both with PIV and LDV are presented.

Three-dimensional nozzles tested may have their application in drilling bit design, especially in PDC bits. Moreover, employed techniques allow effective evaluation of nozzles, better understanding of the high velocity jet behaviour and may significantly contribute to the optimization of drilling hydraulics. In addition, possible other applications of PIV and LDV in domain of petroleum engineering are discussed.
Gas Rises Rapidly Through Drilling Mud
Authors: Tarvin J. A. , Hamilton A. P , Gaynord P. J. , Lindsay G. D.
Published: December 2007

To understand the development of a gas kick, we must know the rate at which gas migrates upward through drilling mud. Migration rates measured in laboratory experiments are much greater than those commonly accepted by the drilling industry. To address this controversy, we use a computer simulator to model field data and test-well experiments in detail. Both the experiments and the Held data show that gas migrates as fast as 6000 ft/hr [0.5 m/s] through drilling mud. The field data show that gas migration can drive surface pressure up as fast as 3000 psi/hr [4.9 kPa/s], These conclusions agree with laboratory experiments and contradict what is generally accepted in die industry.

The results from the simulation of the field kick were incorporated in a case study. The study increases drill crew awareness of the speed at which gas can arrive at surface and demonstrates that a reduction in pump pressure can be a very late kick indicator.
The National Advanced Drilling and Excavation Technologies (NADET) Program: A New Collaborative Research and Development Initiative
Authors: Mock J. E. , Jelacic A. J. , Dorr P. M. , Perle M.
Published: December 2007

Geothermal energy, heat energy stored in the earth, is exploited for the generation of environmentally clean, reliable electric power and for direct heat applications such as space and water heating, aquaculture and agricultural operations, enhanced oil recovery, mining, and industrial processing. With 2800 megawatts of installed electric capacity generating 15 billion kilowatt-hours per year and 18 trillion Btu per year utilized in direct-heat applications in the U.S., expanded market penetration is often hampered by higher costs associated with geothermal energy development. A significant portion of these higher costs is directly or indirectly dependent on drilling wells to discover, delineate, and produce geothermal resources. The Geothermal Division of the U.S. Department of Energy has proposed a national R&D initiative involving government, national laboratory, industry, and academic stakeholders to develop less costly ways of penetrating rock. The goal of this proposed program is to develop an advanced and innovative drilling system by the year 2000 for use by the geothermal industry and other industry sectors including oil and gas, mining, underground storage, and civil infrastructure.
Drilling Operations, Deep Sea Drilling Project
Authors: Eberhart J.R.
Published: December 2007

This paper was prepared for the 40th Annual California Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in San Francisco, Calif., Nov. 6–7, 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 publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor 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 Deep Sea Drilling project is funded by the National Science Foundation for 12.6 million dollars for a period of 18 months to carry out a deep-earth sampling program. Scripps Institution of Oceanography of the University of California is the prime contractor and operator for the project. The project's scientific objectives are to provide new knowledge of the ocean basins, provide new knowledge of the ocean basins, their history and record of changing climate and evolving life for many millions of years. Physical evidence substantiating two Physical evidence substantiating two principal geological hypothesis (sea floor, principal geological hypothesis (sea floor, spreading and continental drift) has been recovered. The operational objective is to penetrate all sediments, recover samples of penetrate all sediments, recover samples of these sediments, make a shallow penetration of the basement and recover samples of the basement.

Drilling operations in the deep ocean basin are being conducted from the Glomar Challenger to obtain core samples of the sediment and basement in water depths to 20,000'. This paper will summarize the results obtained and paper will summarize the results obtained and the drilling techniques used on the first six legs of the program. The summary includes discussions on the drill ship, dynamic positioning, drilling equipment, drill string, positioning, drilling equipment, drill string, coring equipment, techniques used to obtain the cores, electric logging and the results obtained on the first six legs of this project.
What Really Wears Your Casing When New Hardmetals Are Used?
Authors: Carlin F. J.
Published: December 2007

Tool joint hardfacing was introduced nearly fifty years ago. The primary purpose was to prolong tool joint life by reducing outside diameter wear. Tool joint life was increased up to three times.1 The hardfacing adequately protected the tool joint but often times resulted in severe casing wear by abrasion.

The potential for casing damage resulted in the development of several improved types of hardfacing. Most prevalent are the smooth tungsten carbide type and iron base hardmetals alloyed with chromium. Test results by various manufacturers, users, and independent consultants indicate these new types of hardfacing are less abrasive than the tool joint steel. The primary type of wear for these hardfacing materials is adhesive. This change of wear mechanism from primarily abrasive to adhesive is a major reason why these hardfacing materials reduce casing wear. The surface finish is also a major contributor, since a smooth uniform finish reduces contact stress2.

Full sized casing wear tests were performed to evaluate not only the effect of the hardfacing, but the relationship between hardfacing and available tool joint tong space. Hardfacing on the tool joint outside diameter is normally three inches (76.2mm) while the remaining tong space of the tool joint pair is fourteen to eighteen inches (355.6 to 457.2mm). Most of the current available hardfacing materials were evaluated (fine particle, coarse particle, smooth tungsten carbide, machined smooth tungsten carbide, and three iron base hardmetals).

Test results indicate that when these new improved hardfacing materials are used casing wear is dramatically reduced and is significantly influenced by the steel portion of the tool joint tong space that is not hardfaced. The casing is in contact with the tool joint steel four to six times longer than the hardfacing. Since the major type of casing wear is adhesive wear for both the tool joint steel and the hardfacing material, selection of hardfacing material may be based on other criteria such as wear resistance, surface finish, ability to re-hardface, availability, price, and hole conditions.
Digitizing Rocks?: Standardizing the Process of Geological Descriptive Using Workstations
Authors: Saunders M. R. , Shields J. A. , Taylor M. R.
Published: December 2007

The preservation of geological knowledge in a standardized digital form presents a challenge. Geological data in themselves are fuzzy. Data sources range in scale from the macroscopic, e.g., outcrop, through the mesoscopic, e.g., hand-specimen, core and sidewall core, to the microscopic, e.g., drill cuttings, thin sections, and microfossils. Each scale change results in increased heterogeneity and potentially contradictory data. Finally, the providers of such data may vary dramatically in experience level. Hence the challenge!

To address these issues, a geological description workstation has been developed for cores and drill cuttings, and has undergone field trials. Over two thousand carefully defined geological attributes are currently available within a relational database. Attributes are stored in definitive digital form, allowing multiple users to select familiar usage, e.g., diabase v. dolerite. Data can be entered in one language and retrieved in other languages. The data structure allows groupings of similar elements, e.g., rhyolites into the acidic-igneous or volcanics subgroups, or into the igneous rock group, permitting different users to analyse details appropriate to the scale of the application.

Data entry utilizes a graphical user interface, allowing the geologist to make quick, logical selections, in a standardized or custom-built format. Extensive menus, onscreen graphics and help screens allow "point-and- click" selection. Descriptive ranges, e.g., round to subrounded, are permissible. Error checking limits the potential for geological oxymorons. Entries for lithology, petrology, structures (sedimentary, organic and deformational), reservoir characteristics (porosity and hydrocarbon shows) and macrofossils are available. As data are selected and applied, the on-screen concatenated description is updated to provide immediate feedback, ensuring data correctness. Sampling points for thin-sections, core analysis, geochemistry or micropaleontology are also recorded.

Utilizing digital data storage, construction of geological logs using graphical, alpha-numeric (both abbreviated and complete words) and symbolic representations are possible. Geological descriptive data can also be combined with drilling and mud gas data, MWD and wireline logging data, and off-site analyses, to produce composite formation evaluation logs, thus enhancing the value of each data source through integrated information management.
An Efficient Procedure for the Quantification of Risk in Forecasting Reservoir Performance
Authors: Kalogerakis Nicolas
Published: December 2007

Once a reservoir have been satisfactorily history matched by fitting all production data taken up to the time of the study, the reservoir engineer proceeds with the computation of future reservoir performance under alternative depletion strategies. As part of this forecasting exercise a sensitivity analysis is often performed in an effort to quantify the deviation from the expected production levels should certain important reservoir parameters have a different value than that used in the history matched model. It is this uncertainty in the predicted reservoir production levels that is addressed in this manuscript. By using the statistical properties of least squares estimates, the uncertainty in all estimated reservoir parameters can be readily incorporated into the computations. The proposed methodology is illustrated with a typical example where 95% confidence intervals of individual well production rates as well as of the cumulative overall reservoir production are computed.
Risk Analysis of Well Performance: A New Approach To Optimize Well Deliverability
Authors: Johannessen Liv , Bakken Hilde , Leach P. R. L. , Tybero Geir
Published: December 2007

The Heidrun field, situated on the Norwegian Continental Shelf (Figure 1), is scheduled to come on stream in August 1995. Heidrun will be developed using a tension leg platform (TLP). The reserves are estimated to 119 M Sm3 (750 M STB) of oil and 45 GSm3 (1.6 TSCF) of gas. Heidrun consists of three main reservoirs, the Fangst Group, the Tilje Formation and the Are Formation where the Fangst Group contributes more than 70% of the total reserves. A total of seven Fangst oil producers will be pre-drilled and pre-completed to accelerate the build up period. These wells are all planned as gravel packed wells with high deliverability.

To optimize the completion design and maximize flowrate potential for the producers, a new approach to evaluate well performance was developed. The individual well deliverabilities were computed as a probability distribution directly reflecting the uncertainties related to the input variables rather than the more conventional single flow rate.

The results showed that the flowrate was likely to be restricted by the completion configuration rather than the reservoir deliverability. As a result, the current tubing size was increased and the Fangst well design rate was raised. By increasing the design rate, the pre-plateau period was reduced. This increased the NPV of the Heidrun project significantly.
Jet Pump Testing in Italian Heavy Oils
Authors: De Ghetto Giambattista , Riva Marco , Giunta Paolo
Published: December 2007

The paper presents the analysis and the results of the jet pump applications in the two biggest Italian heavy oil fields: Vega (15 °API) in offshore Sicily and Gela (9 °API) in onshore Sicily.

In both fields the water cut is as much as 50% and most of the wells produce in artifiCial lifting: ESP, diluent lift and rod pumps are the three methods used.

The tests with jet pumps were motivated by the need to use a cheaper artificial lifting method. The objective was, in fact, to reduce both the workover costs for replacing the failed pumps and the operating costs of the wells producing in diluent lifting.

Various jet pumps sizes, types and rate of the power fluids were experienced.

Accurate measurements of the pressure above and below the jet pumps were recorded allowing comparison of the field performance with the theoretical one.

The field test campaign finished in 1991/1992 and demonstrated that the jet pump, despite its low efficiency ( 30 - 60 % lower than expected ) and flexibility, is an efficient and cost-effective way to produce heavy oils.

The jet pump installation costs, in four wells, have been 6-9 times less than workover costs for replacing ESP.

We deem that the conclusions of the study can be useful also in the application of jet pumping in other heavy oil fields.
Value of Subsea Standardised Systems
Authors: Knudsen T. W. , Lindland H. J.
Published: December 2007

This paper reviews Statoil’s experience with standardisation of its subsea field developments, service and tool pool arrangements for several subsea fields and future plans for deep water applications. Aspects of maintaining standard specifications in a rapidly developing area of technology are discussed. Subsea standardisation, applied at the appropriate system design level and agreed with potential suppliers, will contribute to the economic development of marginal fields. Statoil’s strategy on how to adapt and integrate multiphase production systems into the architecture of its existing standardised systems and future deepwater field developments is also presented.

As used in this paper, the term "standardised system" reflects an established subsea pool standard.

Standardisation does not mean that every project should be exactly the same. Nevertheless, similar projects should work to a standard specification, with standard designs for interfacing completions, workover-riser systems and intervention systems.
A Comparative Technical and Economic Analysis of Waterflood Infill Drilling and CO2 Flood in West Texas Carbonate Reservoirs
Authors: Guoping Xue , Malik Z. A. , Wu C. H. , Mamora D. D.
Published: December 2007

Waterflood infill drilling and C02 flood have been used to improve oil recovery from West Texas Carbonate reservoirs. This paper presents a comparative study of technical and economic analysis of waterflood infill drilling and CO2 flood in the Monahans (Clearfork) unit and Johnson J.L. 'AB' (Grayburg/San Andres) unit. Decline curve analysis is used to estimate the recovery efficiencies for different well spacings. An analogous study for West Texas reservoirs is used to estimate the C02 flood recovery. With waterflood infill drilling at IO-acre spacing, the recovery efficiency is estimated to improve to as high as 30% OOIP. However, economic analysis indicates that waterflood on a 10-acre well spacing is less profitable (ROR 8%) when compared to C02 flood (ROR 17%).
Pre-Production Pressure Analysis of Commingled Reservoir with Unequal Initial Pressures
Authors: Aly Ahmed , Chen Her-Yuan , Lee W. J.
Published: December 2007

This paper examines the effect of unequal initial layer pressures on the pressure and sandface rate responses of wells producing from commingled reservoirs. The main objective is to provide techniques and methodology to determine individual layer permeabilities and skin factors in commingled reservoirs with unequal initial pressures. The layer information obtained early in the life of the reservoir is very important for planing production schedule and economic decisions concerning the future of the wells.

The emphasis of this research is on the study of the wellbore performance during pre-production which is the period after completion but before any production on surface. The results of this study provide a useful foundation for the design of well test procedures to ensure that individual layer properties are measured adequately. As the pre-production well test requires no production on the surface, the environmental impact caused by flaring oil or gas during a conventional well test is alleviated.
Evaluation of Paraffin-Treating Programs in Rod-Pumped Oil Wells
Authors: Henson R. D. , Tangen T. J. , Horne P. T.
Published: December 2007

This paper will convey a philosophy of managing a paraffin program. The philosophy developed is a closed loop system which includes data collection, treatment selection, and performance evaluation. The key to a successful program is maintaining a focus on the problem.
The Denver Unit CO2 Flood Transforms Former Waterflood Injectors Into Oil Producers
Authors: Fox C. E. , Tugwell J. O. , Morell J. I.
Published: December 2007

The profitable conversion of off pattern water injectors to production wells is possible in CO2 floods. An initial water production period often precedes the breakthrough of oil into such injector-to-producer (ITP) conversions. At the Wasson (San Andres) Denver Unit in West Texas, time to economic oil production and initial economic oil production rates may be estimated by simulation or analog methods. Performance data from more than 25 wells is discussed in this paper.
Quantifying Skin Damage and Improvement in Horizontal Wells
Authors: Malekzadeh Dariush , Abdelgawad A. S. , Day J. J.
Published: December 2007

The potential for severe formation damage around horizontal wells exists due to the increased time of formation exposure to the drilling fluids as compared to the time that a vertical well is exposed to these fluids. This paper explains that the combined effect of the formation damage and the presence of impermeable barriers and low permeability regions in the vicinity of some sections of the horizontal wellbore will manifest itself as skin factor in well test analysis if the total drilled length of the horizontal section is used in the calculations. The purpose of this paper is to present practical new equations, based on a recently introduced concept in well performance analysis, for evaluating the effective length of the horizontal well contributing to unrestricted production. It is determined that the performance of a horizontal well with mechanical skin and of length Xf1 can be substituted by the performance of a horizontal well of length Xf2 with no skin. Xf2 is smaller than Xf1 for a damaged well and is greater than Xf1 for a stimulated well. By combining the concepts of equivalent horizontal well length and equivalent wellbore radius, one will be able to evaluate the performance of a horizontal well in comparison to its expected performance and to subsequently relate it to an equivalent stimulated vertical well. The new equations and guidelines can be used to determine the magnitude of formation damage around horizontal wells and to evaluate the success of a stimulation treatment.

The concept of effective horizontal well length developed in this paper was applied to the pressure drawdown analysis of well test data obtained on a horizontal well. A good match was obtained which were used to calculate the parameters of interest. Furthermore, the productivity index for this horizontal well was determined using the newly developed equation.
New Technique of Fracture Stimulating the Morrow and the Atoka Formations of Southeastern New Mexico
Authors: Pai V. J. , Keith M. M. , Edgeman Randall , Hust Pete
Published: December 2007

With improved gas pricing the Morrow and the Atoka formations of S.E. New Mexico are seeing substantial amounts of renewed activity. The paper presents background information such as lithology, formation properties obtained from X-Ray Diffraction and SEM Analysis and rock properties obtained from other sources. Casing and perforating programs along with completion and stimulation practices are also discussed. The paper lays emphasis on the recent use of the Binary Foam as a fracturing fluid along with case studies.

Additionally, the paper goes over the design of a Binary foam frac with the aid of 3-D design model and foam fluid rheology. Post frac productivity results along with the amount of proppant placed in the fracture are presented to help in future frac designs.
Field Measurement of Hydraulic Fracture Fluids: Case Study
Authors: Davidson B. M. , Saunders B. F. , Holditch S. A.
Published: December 2007

We performed intense quality control (JQC) on 54 hydraulic fracture treatments during 1992-93. Our detailed fluid testing in the field has indicated the complex nature of fracture fluid systems currently used by the industry. This paper documents our experience with fracture fluids blended in the field and tested under in-situ conditions. Several problems were encountered while performing intense quality control operations on these wells, including overcrosslinked gel systems and contaminated additives. Many of these problems became apparent only after evaluating the fracture fluids at bottomhole temperatures and shear rales. Many fluids that failed viscosity tests at bottomhole conditions looked to be adequate when tested at surface conditions.

The importance of quality control in stimulation operations has been investigated and its importance recognized by the industry.1-4 Intense quality control is performed on location using equipment carried in a rheology van. The rheology van contains two Fann Model 50 viscometers that we use to evaluate the fracture fluids at bottom hole temperatures and shear rates, and a complete wet chemistry lab. Analyses of fracture fluids with the rheology van has been described in a previous paper5 and GR1 publication.6

Intense quality control is not a new concept. IQC is routinely used in the evaluation of cement slurries. To test recommended mixtures of cement and additives, pilot tests are always performed on cement slurries prior to pumping to test recommended mixtures of cement and additives. Results of the pilot and blend tests indicate if a particular cement mixture will perform as designed. Similarly, we test fracture fluid systems at conditions designed to simulate reservoir temperatures in our IQC work. We use the chemicals and additives that will actually be pumped during the treatment. Using the actual chemicals is a critical part of IQC, and it is the reason that testing must be performed at the wellsite, prior to the treatment. Blended samples are collected during the fracture treatment and tested as the treatment is in progress. The tests performed during the treatment are compared to the pilot tests to ensure the fluid pumped down hole is performing as expected. We inventory all additives before, during, and after the treatment to verify the fracture fluid system is blended accurately.
The Use of Inert Gas to Test Potential Gas Storage Aguifers
Authors: Wingerter Jack R.
Published: December 2007

Factors for using inert gas generators to test a questionable cap rock in potential gas storage aquifers are presented and discussed. presented and discussed. The theory of inert gas generation is compared to field use. Mechanical and corrosion problems involved with practical application are presented. practical application are presented. Cost per MCF of inert gas is compared to natural gas. Recommendations for reducing mechanical and corrosion problems are presented as well as conclusions presented as well as conclusions concerning the practical use of the inert generator.

Introduction

Testing the adequacy of the cap rock to contain natural gas in potential gas storage aquifers may be accomplished in several ways. A water pumping test in many cases is sufficient and should be tried first. (Pulse testing is another alternative.) The most positive proof of the cap rock's adequacy positive proof of the cap rock's adequacy is to inject a gas. If, however, the cap rock should be inadequate, natural gas would not be desirable because of the hazardous conditions created by leaks into upper formations. Air should not be used because of the explosive conditions that would exist if natural gas were injected. Bulk storage facilities would make the purchase of an inert gas rather expensive. The use of an inert gas generator would seem to be the most realistic means of testing the field without risking the potential hazards of natural-gas, should it leak. Inert gas generation is not new. The first patent for an inert gas machine was applied for in 1911. Since that time, many types of inert gas generators have been built and used for various application throughout the industry. (Examples: gas re-pressurization, gas lift, well drilling, etc.) As early as 1924, a plant was built to produce inert gas from a mixture of boiler stack gas and engine exhaust. This project failed because of corrosion problems. In 1949, Pan American built a re-pressurization Pan American built a re-pressurization plant in Wyoming's Elk Basin. This plant in Wyoming's Elk Basin. This project developed severe corrosion problems project developed severe corrosion problems in the early stages. Over the years, costly maintenance and repairs have reduced corrosion to a workable level.