bluuebunny/crossref_metadata_2025 huggingface dataset:
Amorphous Diffusion Bonding: New Technology Towards a Seamless Reeled Tubing System
Authors: Cameron G. , Ikeda A. , Tochikawa T. , Higuchi K.
Published: December 2007

A new Amorphous Diffusion Bonding (ADB) technology is being developed to overcome the known problems involved in shop welding and field weld repairs of coiled tubing and their poor fatigue properties. The objective of the technology is to join long lengths of seamless tubing prior to reeling using a high speed diffusion bonding system in conjunction with a thin film of amorphous metal. The new technology is part of an overall project to develop a high fatigue resistance seamless coiled tubing.

The key technology of ADB involves finished ends of tubulars being butted together with an amorphous thin film filler metal between the ends. The amorphous film at elevated temperatures creates a diffusion of atoms across the interface and encourages a mutual diffusion of the filler metal and joining metal in the local area of contact.

Extensive laboratory testing has been carried out during a feasibility study including metallurgical examination and small scale bend and reverse bend fatigue testing. Additionally, a small amount of full scale fatigue testing has been undertaken and further testing has been scheduled for the future. The results indicate a bonded joint that is/has; homogeneous with the parent metal; no deformation; a small smooth upset; resistance to fatigue equal to that of the parent metal.

From the tests carried out to-date the indications are that the bonded joint has a superior fatigue life to that of the TIG welded joint by an order of magnitude in excess of three and it is evident that this can be improved on.

This paper centers on whether Amorphous Diffusion Bonding is a valuable and applicable contribution to seamless reeled tubing systems within the oil industry.
Zero Extrusion Casing Patch
Authors: Macrae J.
Published: December 2007

Casing failure is a serious problem for drilling or production operations. The standard method of repairing failed casing is with a casing patch. Existing patches have design limitations that prevent them from returning the casing to its original specifications. A new seal geometry has been developed that addresses many of the problems in existing patches. The new seal geometry produces a zero extrusion gap that greatly increases the reliability of the seal. This geometry is based on a flexible fin profile that is integral with the body of the casing patch. The integral fins are designed to produce an interference fit with the casing. The development of this seal profile takes into account casing tolerance and operational requirements. The resulting patch has a stout body with a thin seal profile. The inherent toughness of the metal fin allows the patch to exceed the pressure rating of the casing.
Fit for Purpose Reeled Systems: A Case History
Authors: Young L. M. , Burge P. M. , Johnston C. A.
Published: December 2007

The modern era of coiled tubing drilling began in mid-1991. Since then, upwards of 300 wells or sections of wells have been drilled using coiled tubing. The majority of these applications has used conventional coiled tubing service units in conjunction with a workover hoist or conventional rig to complete portions of the program. A few modified units have been used to perform re-entry drilling work. The first horizontal re-entry conducted entirely using a hybrid coiled tubing service unit has been described by Eide et al 1.

During 1996, two fit-for-purpose "reeled systems" were commissioned. The reeled system concept embraces the surface equipment, downhole directional drilling system and the man/machine interface into one integrated package. These systems integrate the benefits of continuous tubing, the ability to snub into live wells and the option to rotary drill using drill pipe. The systems have been designed for use with coiled tubing and or jointed pipe over a range of applications from re-entry drilling, underbalanced drilling and field maintenance.

This paper describes, through a review of the benefits of coiled tubing drilling, the background to the development of these systems. A description of the process followed from initiation to commissioning of the reeled systems is also provided. A case history of the first use of coiled tubing drilling techniques in the Gulf of Mexico is discussed.
Evaluation of Slimhole Production Performance
Authors: Azari Mehdi , Soliman Mohamed
Published: December 2007

The petroleum industry is focusing on cost reduction and efficiency more than it ever had. Slimhole drilling and completion technology offer significant cost reduction potentials to the oil and gas industry. To provide an insight into slimhole technology, production, stimulation, conformance, perforation, tools, and testing aspects of reservoirs with wellbore diameters from 4- to 10-in. and tubing IDs from 1.25- to 4-in. are detailed here.

Productivity of both vertical and horizontal slimhole wells, with and without hydraulic fractures, is compared with wells having standard wellbore sizes, Also provided are comparisons of wellbore hydraulics, including nodal analysis, minimum gas rates required to lift fluids off the well, and friction pressure losses occurring inside tubings. Furthermore, the effect of wellbore diameter on transient pressure testing, as well as on coning and cresting aspects of slimholes are detailed.

The performance of slimhole wells compares favorably to standard wellbore completions for the parameters investigated in this study.
A New Rate Gyroscopic Wellbore Survey System Achieves the Accuracy and Operational Flexibility Needed for Today's Complex Drilling Challenges
Authors: Noy K. A. , Leonard J. G.
Published: December 2007

This paper describes a new wellbore survey system based on inertial guidance aerospace technology which has been designed for today's more complex operations such as extended-reach and horizontal drilling. The system performs a survey as the tool moves continuously through a wellbore, and probes can be pumped down through drillpipe to inclination angles in excess of horizontal. In addition, a unique quality assurance technique and control procedures quantify and optimize system performance in the field.

Development and operation of the system is described along with laboratory test results. Field test runs are compared with other survey systems and, finally, a commercial run in Canada is analyzed. In conclusion, results indicate that the system meets its specification for a high degree of precision, quality assurance techniques have been validated, and survey speed and operational flexibility have been enhanced.
Visualization of a Logging Information System Through Object Oriented Modeling
Authors: Suryanarayana K. , Cherukupalli P. K. , Rao T. V. S.
Published: December 2007

An extensive analysis and design effort went into the development of a comprehensive logging information and processing system (CLIPS). The objective of the study was to analyse the existing procedures and systems and to propose a design and implementation plan for the CLIPS.

The analysis of the overall logging environment is based on object-oriented modelling, which visualises and abstracts the application domain. Each element of the environment is decomposed into coherent units and studied in-depth. These include usage pattern of both open and cased hole logs, log data processing and interpretation, data communication between different log interpretation centres, information resources available for handling the data, data medium for transportation and storage and formats for data exchange and inter-program communication. A natural fallout of this study is the expected usage pattern of logs. Study of various scenarios, related to open-hole log data processing, field studies and cased hole log data evaluation, has lead to better understanding of the usage domain, commonality and uniqueness of each type of specialisation.

Clarity of objectives in the labrynth of log data management, processing and interpretation has been achieved by the visualiation using object modelling. Issues relating to system architecture, storage organisation and data management, database interface, communication system have been resolved with relative ease due to the extensive formalisation using object-oriented design and modelling.
Borehole Nuclear Magnetic Resonance: Experience and Reservoir Applications in West Kuwait Carbonate Reservoirs
Authors: Latif A. Abdel , Sungur D. , Stockden I. , Cao Minh C.
Published: December 2007

Recently introduced nuclear magnetic resonance well logging has been tested and evaluated in West Kuwait and is now being used to better define effective reservoir porosity in the most complicated reservoirs and under difficult conditions, including oil-base drilling muds.

A number of West Kuwait carbonate oil reservoirs are difficult to evaluate because of the complexities of their pore systems. Borehole imagery has helped to define fractures and faults in wells and, thus remove a major uncertainity in formation evaluation. Standard open hole well logs provide porosity and saturation which are often not enough in evaluating these complex carbonate reservoirs with high-resistivity. In fact, apparent porosity and saturation may be misleading as to what fluids and at what rates will flow from a given zone. Low porosity layers can have the highest permeability within a reservoir and similarly the highest porosity layer may be comprised of micropores and be impermeable. Moreover, zones which correctly calculate high water saturation with standard well logs may flow oil with no water while tar mats may be misleadingly interpreted as an oil zone.

Borehole nuclear magnetic resonance helps to define the potential of the most complex carbonate reservoirs in West Kuwait. Borehole NMR, in addition to providing porosity independent of lithology, can be related to pore size once hydrocarbon effects are accounted for. Understanding pore size distribution within a reservoir helps to define effective porosity, identifies the presence of microporosity and quantifies irreducible water saturation when used with standard well log evaluation.

The definition of effective porosity and pore size distribution allow better determination of reserves. Initial estimates of permeability without any modeling of specific reservoir rock types have related well to the independent assessment of permeability by acoustic technique and wireline formation testing.

Our assessment of borehole nuclear magnetic resonance has been very encouraging. It has been possible to use borehole NMR to better identify reservoir facies, predict well productivity and select completion zones. Many other reservoir and geological applications are being examined at present time.
The Theory and Reality of Long-Term Monitoring Programmes at Sullom Voe, Shetland [1974-1996]
Authors: Ritchie W. , Kingham L. V.
Published: December 2007

This paper summarises 20 years of scientific monitoring at Sullom Voe, Shetland and considers the evolution of the various programmes in relation to both conceptual and operational changes.
Taking Account of Negative Publicity in Project Economics
Authors: Holgate M J. M. , Davies G. J. , Kerr S. A. , Johnston F.M. M.
Published: December 2007

The high profile publicity generated by the Greenpeace campaign against the deep sea disposal of the Brent Spar demonstrated the power of public opinion to affect corporate image and operational decisions. Regulatory approval is not the only constraint on the granting of a licence to operate and corporations now ignore stakeholder values at their peril.

Although it is difficult to quantify son issues such as negative publicity and stakeholder concerns, there is an increasing need to integrate conventional economics with public opinion when evaluating different possible development options. This paper seeks to set out a process for incorporating negative publicity directly into project economics.

We started with an outline study of the effects of two high profile incidents of negative publicity: Hoover’s "Free Flights To America" promotion, and the ill-fated launch of Unilever’s manganese accelerator soap powder. The results showed that there were two distinct outcomes: the effect on the corporate image and the direct effect on the project, such as the launch of a new product.

The next step was to identify a number of possible outcomes to an escalating scenario of negative publicity within the oil and gas sector. The economic consequences of each possible outcome are expressed as risk assessed values which are the product of the probability and the cost of each outcome.

To show this, we took a hypothetical case of handling of sour gas in a new field development and looked at the possible outcomes from four options for handling the gas: flaring, gas re-injection, power generation and sea water absorption.

The methodology developed in this paper outlines a process for quantifying stakeholder values and potential negative publicity in the planning stages of potentially sensitive projects. The process provides a logical and transparent framework that encourages the exploration of these softer issues. It is designed to provide indicative, rather than definitive values to show whether the inclusion of risk assessed costs would alter the decision based on conventional economics. The process also provides a guide for developing a consistent basis for decision making, checks the sensitivity of the development option to negative publicity and highlights the cost critical areas.
Environmental Risk Assessment in E&P Activities
Authors: Walls A. H. , Reid S. , Shepherd J. , Urbanus J. , Bishop G. , Rogers C. , Whitehead A. , Backwell L. , Buchanan I. , Hainsworth D. , Duff A. A.
Published: December 2007

Environmental Risk Assessment is a key element of a successful Environmental Management System. Hazards arise in all oil and gas exploration and production activities and risk management decisions should be based upon an understanding of these hazards, both in terms of environmental effects and the probability of occurrence. The purpose of the assessment process is to ensure that environmental risks are evaluated in a comprehensive and structured manner and that rational approaches are adopted to both the setting of acceptance criteria and the decision making and prioritising which forms an integral part of the risk management process.

This paper outlines various complementary techniques which can be employed to assist the risk management process and discusses their potential application in the preparation of an Environmental Case.
The Heavy Oil Storage Tank Project
Authors: Lucas Donald , Littlejohn David , Orlando Ernest , Lindsey Rhonda P.
Published: December 2007

The Heavy Oil Storage Tank (HOST) project is a joint effort of California and Federal Agencies, the Western States Petroleum Association (WSPA), and the Ernest Orlando Lawrence Berkeley National Laboratory (LBNL). The project goal is to develop and test new methods to determine if the hydrocarbon emissions from heavy oil storage tanks in central and southern California are large enough to require new emission controls. Results to date show that existing current methods are inadequate for estimating the hydrocarbon emissions from these tanks. The work at LBNL is jointly funded by WSPA and the U.S. Department of Energy (DOE), with in-kind funding from several state agencies and oil companies. The project is directed by a working group with representation from all members. Decisions are made by group consensus; no votes are taken, and no one member has veto power.
Assessment Methodology and Results for Waste Minimization in the Natural Gas Industry
Authors: Mesing George E. , Fillo John P. , Evans James M.
Published: December 2007

The goal of this assessment was to identify and evaluate waste minimization alternatives (WMAs) as they may apply to natural gas industry (NGI) operations. Economic evaluations were performed to document WMAs that may or may not be cost effective for use by the NGI. Because many NGI operations and resulting waste streams occur in various segments of the industry, WMAs identified for waste streams generated from a particular NGI segment may be applicable to similar waste streams generated in other NGI segments (e.g., waste oils from compressors at compressor stations, gas plants, and storage reservoirs). Approximately sixty waste stream categories were identified from drilling/exploration, production, processing/conditioning, compression and transmission, and underground storage operations. From the 60 waste stream categories, approximately 30 priority" waste stream categories and 170 potential waste minimization alternatives were identified for further evaluation using a priority screening process.

A computer model (GRI WMIN-Econ) was developed for performing consistent economic analyses. Using the DOS executable economic model, operators and/or managers can modify the parameters in the assessments, or create new evaluations using a new set of parameters and assumptions.

Economic assessments were performed and documented for 16 priority WMAs. Of the 16 cases evaluated, seven showed positive economic benefits based on the assumptions used. Three alternatives were not economically feasible. Six alternatives, while not economically feasible under certain assumptions, can be economic depending on the specific case assumptions. The overall technical approach taken for this waste minimization assessment is presented in Fig. 1.
Using Salinity-Toxicity Relationships in Toxicity Identification Evaluations (TIEs) for Produced Water
Authors: Pillard D. A. , DuFresne D. L. , Giddings J. M. , Fillo J. P. , Evans J. M.
Published: December 2007

Under the 1993 general discharge permit for produced waters on the Outer Continental Shelf, discharges must be tested periodically to determine chronic toxicity to marine organisms. If toxicity is observed, regulators are likely to require the permittee to undertake Toxicity Identification Evaluation (TIE) studies to determine the cause of toxicity. Information on the toxicity of total salinity or individual ions is essential for guiding TIE studies with produced waters. The Gas Research Institute is sponsoring the development of such information for three common marine test species: mysid shrimp (Mysidopsis bahia),sheepshead minnow (Cyprinodon variegatus), and inland silverside minnow (Menidia beryllina). Based on test results, Salinity-Toxicity Relationship (STR) models are being constructed that will predict the survival of these three species upon exposure to a produced water of known ionic composition. Similar models for freshwater organisms are already in use. When routine biomonitoring indicates that a sample of produced water is toxic to one of the test organisms, the STR model can be used to determine whether the ionic composition of the sample is a contributing factor. If the predicted toxicity of the sample is similar to the measured toxicity, the effect can be presumed to be due to an excess or deficiency of one or more ions, or of total salinity. The STR model can then be used to identify the ion or ions in excess or deficiency, and to suggest strategies for eliminating the sample toxicity by restoring the appropriate ion balance. If the STR model predicts that the sample should not be toxic based on its ionic composition, other sources of toxicity (e.g., trace metals) are implied.
Development of a Title V General Operating Permit for Oil and Gas Sources in Texas
Authors: Studlick M. H. , Dewlen D. J. , Martino P. A.
Published: December 2007

Title V of the Clean Air Act (Act) requires major air emission sources to obtain a federal operating permit that includes all applicable emissions limitations and regulations. The Act allows the issuance of Title V permits for numerous similar sources under one general operating permit (GOP). A project for industry to partner with the Texas state regulatory agency to develop a GOP for oil and gas sources was funded by American Petroleum Institute (API). The advantages of GOPs for the regulatory agency and industry are: 1) Economy - A single proposed GOP, not individual applications, is subjected to public notice and comment. 2) Consistency - Facilities with identical equipment have identical permit terms. 3) Certainty - GOP applicants know what the permit terms will be since the permit was negotiated prior to the call for applications. Additionally, a survey was conducted to identify potential states to be targeted in a second phase of the project. This paper will discuss the mechanics of how the GOP was developed, some unique features of the Texas GOP and lessons learned that can be applied to development of GOPs in other states.
Multi State Area of Review Variance Program
Authors: Simmons Jerry R. , Jones J. Stephen
Published: December 2007

Background

The U.S. Environmental Protection Agency (EPA), Underground Injection Control Program (UIC) has recognized that conditions can exist that make it necessary to perform well-by-well Area of Review (AOR)s and that wells in a basin, producing trend, region, field, or portion of such areas could be exempt from an AOR through a variance program. The variance could be granted for the following conditions: Underground Source of Drinking Water (USDW) is absent; reservoir is underpressured relative to the USDW; local geologic conditions preclude upward movement that could endanger USDW; and other compelling evidence exists, A scientific methodology to identify areas for AOR variance was developed at the University Missouri-Rolla. This methodology has been applied in several states and to date, has been effective in all applications. In order to apply that methodology, it is necessary to have reliable subsurface information, (i.e. depth to groundwater, reservoir and aquifer pressures, well construction data, well abandonment information, etc.) To effectively perform a variance over large areas, subsurface and well information in electronic format is essential. Through a contract with the U.S. Department of Energy (DOE), Office of Fossil Energy. Bartlesville Project Office, BDM Petroleum Technologies has been assisting several states in AOR variance projects and electronic well information data.
Pneumatic Control Devices In Production Areas - Significant Methane Emission Sources?
Authors: Breninger T. L. , Learned A. O. , Melrose G. L.
Published: December 2007

Natural gas is commonly utilized as the supply source for pneumatic control devices at small and medium sized tank batteries and for onshore wellhead separation, dehydration, and compression equipment. A pilot study to determine the quantity of methane emissions from these control devices was performed as part of the Natural Gas STAR Implementation Plan for Marathon Oil Company. It was quite comprehensive in that emissions from approximately 160 pneumatic control devices at 50 different production sites were measured. Control devices measured included pressure, level, and temperature controllers. The total losses from these high and low-bleed pneumatic control devices were small, with continuous-bleed level controllers emitting the largest quantity of methane. Retrofitting of these level controllers with low-bleed nozzles should be considered to reduce these losses. Based upon this pilot study, there is no economic justification to further quantify emissions from high and low-bleed pneumatic control devices in the study area because emissions that justify corrective action can be detected without measurement.
Determination of Methane Emissions From Crude Oil Stock Tanks
Authors: Newsom Vick L.
Published: December 2007

There are approximately 250,000 tank batteries currently in operation in the US exploration and production (E&P) industry. Most of these batteries do not have any type of control system on them to capture the organic vapors generated by breathing losses, working losses and flashing losses. If the pressure drop from the low pressure separator to the stock tank is greater than a few pounds, then the potential for significant emissions due to flashing losses is present.

Due to the perception by the Clinton Administration that global warming is an issue that needs to be addressed by the US industry, the methane emissions from stock tanks will come under increased scrutiny.

This paper discusses a method for determining methane emissions from stock tanks and how controlling these emissions can aid industry in its work with the Environmental Protection Agency on the Natural Gas STAR program.
The Competing Influence of Technology, Depletion, and Economics on Petroleum Drilling Productivity: How Persuasive is the Evidence in the Gulf of Mexico Outer Continental Shelf?
Authors: Iledare Omowunmi O.
Published: December 2007

The purpose of this paper is to apply a region-specific- hybrid model of oil and gas reserve additions to determine whether the negative impact of depletion on the finding rate of new reserves has been more than offset by the positive effects of technical progress and economic incentives in the US Gulf of Mexico OCS region. Our model results confirm expectation of diminishing returns in the rate of change of drilling productivity with respect to basin maturity. We also found strong evidence, to suggest that as technology improves over time, better drilling choices are made and the rate of change of drilling productivity with respect to incremental drilling rises with time. Overall, we found strong statistical evidence to suggest that the positive influence of technical progress and economic incentives on drilling productivity has been strong enough to offset the negative impact of resource depletion on the finding rate of oil and gas reserves in the US Gulf of Mexico OCS during our study period.
Best Practices in Project Evaluation and Influence on Company Performance
Authors: Schuyler J. R.
Published: December 2007

How do respected companies perform their project evaluations? Do better project evaluation practices and decision policies lead to better company performance? As an initial step to find out, a "Decision and Evaluation Best Practices Survey" has been conducted. Twenty-one companies are participating, thus far, providing a cross section of the petroleum industry. The survey results form a nascent "best practices" database. The author reflects upon the survey data and his experience to describe characteristics of good evaluation management. Because resource allocation decisions are so important, policy and evaluation practices should receive attention comparable to the other technical disciplines. Recent trends in evaluation techniques are discussed, including an increased use of decision analysis.
Hybrid Risk Modeling, Synthesizing Deterministic, Stochastic, and 3-D Geocellular Techniques: Example from Jackson Field, Eromanga Basin, Queensland, Australia
Authors: Holtz Mark H. , Yeh Joseph , Hamilton Douglas S.
Published: December 2007

Risk is inherent in the outcome of all reservoir characterization oil volumetries. This risk comes from the very small sample of information relative to the total reservoir volume and the error in data measurement. To incorporate the risk into reservoir characterization, some qualitative aspects are best modeled deterministically, whereas other data can be modeled statistically. Probability distributions were generated for original oil in place (OIP), original mobile OIP, original residual OIP, and remaining mobile OIP by combining geologic characteristics modeled deterministically using a 3 -D computer technique with statistical probability functions of petrophysical attributes.

The risk-assessment model applied in this study integrates wireline-derived petrophysical data with results from 3-D geocellular reservoir computer modeling. Model development is based on deterministically setting the net-pay volume derived from geologic flow-unit geometry and risk assessing the variability of the petrophysical characteristics within the flow unit. The net-pay volume is a result of the sum of the cell volumes meeting the pay cutoff criteria within the gross volume of a given flow unit. Wireline petrophysical properties have been analyzed within the flow-unit structure. Petrophysical properties were statistically analyzed to determine the best probability function that described their variability. The Weibull probability function was found to best describe the frequency distribution of porosity, whereas the gamma function best models initial water saturation and bypassed oil saturation. Monte Carlo stochastic simulation was then used to combine the deterministically derived net-pay volume with the petrophysical probability functions to generate oil-in-place density distributions. The resultant skewed nature of the OOIP frequency distribution is best modeled by a gamma function.

Risk assessment verifies that the 3-D geocellular model OOIP results are a good representation of proved and probable (2P) volumes. Geocellular model results are virtually identical to the mean value derived from stochastic simulation. Because of the skewness of the OOIP distribution, the mean OOIP is a conservative value; therefore, the 3-D geocellular model OOIP can also be considered conservative. The mode is nearly 10 percent larger than the mean, displaying a strong probability of larger volumes and quantifying the upside of the 3-D model.
The Timing of Investment in E & P: Uncertainty, Irreversibility, Learning, and Strategic Consideration
Authors: Dias M. A. G.
Published: December 2007

This paper analyzes the problem faced by an oil company with investment rights over the tracks subject to relinquishment requirements, which limit the time the company can hold the tract before developing it. Some concepts of the modem Real Options Theory are described briefly, with focus on the timing aspects: economic uncertainty and irreversibility incentive the learning by waiting, and delays the investment; technical uncertainty incentives the learning by doing, and generally speeds investment up. The technical uncertainty (existence, quality and volume of reserves) is dominant for the exploratory investment decisions, whereas the economic uncertainty (oil/reserves prices and costs) is dominant for the development decisions.

The arrival of technical information in the exploratory phase comes from two sources with opposite effects on the investment start up: information from the company itself exploration, and information from the neighbors tracts exploration. The second effect is one strategic aspect, and can be modeled by the Game Theory, usually as a non-cooperative game between the tracts owners, in the same geographical area. This non-cooperative game creates an another waiting effect: many companies can prefer to wait some of the neighbors investments (and get some "free" information) before start their own (and expensive) exploratory investment.

Some results for the development investment decisions are presented, using the Paddock, Siegel & Smith model, with the Barone-Adesi & Whaley analytic approximation, through an Excel spreadsheet. Also are presented some results from the interactions of two sources of economic uncertainty: the reserves value uncertainty and the development cost uncertainty. Although this effect can be small, the cost uncertainty lowers the total economic uncertainty (reducing the value of the option to defer), since the cost fluctuations are positively correlated with the oil/reserves prices, and the cost uncertainty is lower than price uncertainty. Some conclusions and suggestions are presented.
Development of Marginal Fields through Technical and Commercial Innovation - A Case History from the UK North Sea
Authors: Rattey R. P. , Suller J. N.
Published: December 2007

The biggest development in the North Sea for a decade has attracted industry attention as one of the most innovative projects to date. Seven economically marginal fields with different owners and different hydrocarbons have been brought together to create the £1.6 billion Eastern Trough Area Project (ETAP). Innovation on both technical and commercial fronts has been created by an unprecedented level of cooperation between companies. This paper outlines the basis of the project and the approach adopted to its formulation which resulted in novel technical and commercial solutions.

The challenge for today's North Sea, with ever decreasing field size, is to reduce development costs/bbl to acceptable levels and to do this through working the two available levers: cost and the number of barrels. The ETAP solution to reduce cost and add barrels is to combine small fields into a single project with development cost/bbl similar to a single giant field, but with the reservoir risk mitigation inherent in accessing multiple independent reservoirs. This approach created many hurdles, both technical and commercial, and has stimulated innovative solutions.

Technical hurdles include the need for long distance sub sea multiphase tiebacks in excess of 35 Km which have innovative chemical control and multiphase metering. Commercially, the project presented a major challenge as all parties agreed that a conventional unitisation of all the fields into unified ownership interests was neither practical or desirable in light of the range of fluid types and reservoir uncertainty. Accordingly a structure was developed to a) share Capital and Operating costs equitably, b) provide for production rights and production allocation and c) encourage full utilisation of the shared facilities.

The significant cost savings needed to make ETAP viable were largely achieved in the conceptual design phase by designing shared and centralised facilities for both oil and gas field management. In the current project execution phase additional cost savings are being delivered through further application of "alliance contracting" with the contractors for design, fabrication and installation of the facilities and for the development drilling.
A Control Volume Scheme for Flexible Grids in Reservoir Simulation
Authors: Verma Santosh , Aziz Khalid
Published: December 2007

The commonly used Cartesian and hybrid local grid refinements have the disadvantage that the base grid is always Cartesian, which makes it difficult to align along reservoir heterogeneities. Also, the locally orthogonal Voronoi and A;-orthogonal perpendicular bisector (PEBI) grids are only useful for isotropic or limited anisotropic permeability distributions. The finite-difference approach proposed in this paper overcomes limitations of existing flexible gridding schemes in modeling full, anisotropic and asymmetric permeability tensors and permeability heterogeneity. The new scheme assumes uniform properties inside control-volumes and it can be used for control volumes formed around vertices of triangles in two-dimensions and tetrahedrain three-dimensions. It can thus be used with Voronoi grids in two-dimensions, and median (i.e. CVFE) and boundary adapting grids (BAG) in two- and three-dimensions. Applications of Voronoi grids in three-dimensions are limited due to geometrical considerations. The proposed method can also be used with grids constructed to align along major reservoir heterogeneities, wells and streamlines. Several applications of this method for two- and three-dimensional problems are presented.
Calculating the Impact of Fluid Migration on Steamflood Operations
Authors: Chiou C.S. , Weinstein H.G. , Miller D.D. , Eggenschwiler M.E. , Djabbarah N.F.
Published: December 2007

Operating decisions for steamfloods can be improved by accounting for fluid migration across pattern boundaries. a new parameter, called Fluid Migration Index (FMI), is based upuon simplified steamflood material balance considerations and can easily be calculated from field injection and production data. This parameter can be used to correct individual pattern performance. The validity of the fluid migration index was further checked with available subsurface information. Reservoir simulation, with a newly-designed internal accounting system that can track fluid movements across pattern boundaries, was used to corroborate the FMI concept and also to calculate true allocation factors of well production from surrounding patterns. Simulation results show improved accuracy in calculating fluid migration and evaluating pattern performance. It is anticipated that using the results of this paper will improve current steamflooding policies and optimize the design of future projects.

Introduction

In steamfloods with repeated patterns, it is frequently assumed that fluid is confined within the pattern such that there is no fluid migration across pattern boundaries. This assumption is not always valid. Fluid migration was reported in the Kern River and Deerfield steamfloods.1,2 Fluid migration has also long been recognized in the South Belrdige steamflood.3 Significant fluid migration from the structural crest of the Tulare formation to the flank has resulted in discrepancies in pattern oil recovery calculations between allocated production data and open-hole logs from infill wells. Reservoir pressure gradients due to dip, reservoir heterogeneities, and local variation in the injection and production conditions during the steamflood operation are probable causes for fluid migration.

If fluid migration across a pattern boundary is not properly accounted for, the commonly used pattern performance indicators, such oil/steam ratio and oil recovery, could be deceiving. Investment and operating decisions that are based on these misleading indicators could be in error. Therefore, there is a need to quantify the fluid migration and develop a methodology to evaluate its impact on steamflood operations.

Peake4 estimated the amount of fluid migration form a 16-pattern pilot study based on a simple steamflood material balance. Production data from the offset pilot provided evidence that the magnitude of the oil migration estimate was reasonable.

A new parameter, Fluid Migration Index (FMI), is introduced in this paper to quantify fluid migration. The validity of the parameter was checked with available openhole logs from infill wells. Reservoir simulation is coupled with analytical techniques to track fluid movements and characterize producing well performance. The objectives of the simulation study are to help understand the effects of fluid migration across field patterns and develop new procedures that better quantify these effects.
Recognition and Development of Low-Resistivity Pay
Authors: Worthington Paul F.
Published: December 2007

In unfractured reservoirs, low-resistivity pay zones can usually be identified with one or more of the following: laminated reservoir/non-reservoir sequences, formations with multi-modal pore-size characteristics, sediments with anomalously high surface area, and reservoir characteristics that extend beyond the range of applicability of interpretative algorithms, e.g. reservoirs containing very fresh formation waters. In all these cases, dry oil has been produced in the presence of high interpreted water saturations, in many different parts of the world. It is therefore important to have a generalised facility for recognising low-resistivity pay as early as possible in the life of a prospect.

A systematic procedure is described for the identification of low-resistivity and low-resistivity-contrast pay zones in primary reservoirs. The approach acknowledges that a reservoir rock is a coupled physicochemical system, the method is generic and robust, it is conceptually simple, and it is structured in a manner that is easy to understand. The scheme is modular and it is arranged hierarchically to reflect maturing data scenarios. Therefore it can be progressively refined during the appraisal and development stages. The essence of the method is the definition and calibration of reliable interpretative procedures through quality-assured reference data from key wells by admitting only validated reservoir characteristics. Examples illustrate how failure to do this can result in much loss of value.

The principal thrust is to facilitate the re-evaluation of other wells within the same reservoir system without the need for additional logging programmes. The proposed interpretation scheme also constitutes a basis for the incorporation of new logging technology when this becomes established. The end-product is a flexible petrophysical interpretation scheme for these complex reservoirs that benefits from cost-effectiveness, portability, a higher degree of exactness and consequently a reduced uncertainty.
Field Experience with the Maraflood Process
Authors: Gogarty W.B. , Davis J.A.
Published: December 2007

Introduction

This paper reviews field test experience with the Maraflood* oil recovery process with special emphasis on the evaluation of field testing in the Pennsylvanian aged Robinson sands of Southern Illinois. The Maraflood process utilizes a slug of micellar solution process utilizes a slug of micellar solution to displace in situ crude oil. This slug is, in turn, displaced by a bank of fluid of control mobility (referred to as mobility buffer). The flooding sequence is completed with the injection of drive water.

Detailed discussions on the nature of micellar solutions and laboratory experiments evaluating their performance have been previously reported. Initial field testing previously reported. Initial field testing was started in 1962 in the Robinson sand. Since that time, eleven tests have been reported. Six of these tests have been or are being carried out in the Robinson sand. Two other tests are in progress in Illinois, one in the Kirkwood or Cypress sand and the other in the Aux Vases sand. Three tests have been completed or are underway in Pennsylvania.

The evolution of micellar solution flooding is reviewed in this paper with examples from six tests carried out in the Robinson sand. Test experience on these six tests is given first. Next, the development of the test pattern philosophy is discussed as covers the ten-year testing period. Then the progress of design and evaluation method is described by using examples from specific tests. Finally, economics are considered as related to fluid and project costs in the Robinson sandstone.

Test Experience

The micellar solutions used in all tests consisted of a surfactant, hydrocarbon and water. Small quantities of a cosurfactant and electrolyte were also added in most tests. Table 1 shows the compositional ranges of three categories of micellar solutions which have been developed for field use. The designation of oil-external and water-external in the table indicates the non-dispersed phase of the micellar solution. Systems falling within the three categories of Table 1 have been studied extensively in the laboratory.
Hydraulic Fracturing Technique for Low Permeability Coalbed Methane Gas Reservoirs
Authors: Zhao Jinzhou , Guo Dali , Hu Yongquan , Chen Wenbin , Tian Jidong , Ji Lujun
Published: December 2007

Coalbed methane is an unconventional gas resource. Although the resource is successfully developed in a few coal-bearing basins that are of the type of hydraulic seal with a middle or high permeability at shallow depth, the most methane resource in coal seam with pressure seal at shallow or deep are still not exploited by means of the existing technique. This paper describes the hydraulic fracturing technique for low permeability coalbed methane gas reservoirs, including the research & selection of oil base gel fracturing fluid system; real-time simulation of 3D fracture propagation; technology of controlling the fracture height growth & promoting the fracture length propagation; production performance prediction and optimal design of hydraulic fracturing treatment. A set of optimal design software for Windows 95 is developed for hydraulic fracturing in low permeability coalbed gas reservoirs based on the above-mentioned technique. Successfully treatment cases of applying the sophisticated technique in coalbed methane gas reservoirs of Middle China and North China are given in this paper.
Improvements in Perforating Performance in High Compressive Strength Rocks
Authors: Smith P. S. , Behrmann L. A. , Yang Wenbo
Published: December 2007

The productivity of wells damaged during drilling is directly dependent on the depth of the damage and the performance of the perforating guns. If the perforations by-pass the damaged zone then the well will have a low mechanical skin. Conversely, if the depth of damage is greater than the perforation length, the skin factor will be much higher, especially when the drilling damage is severe. While we normally associate drilling damage with low strength rocks, there are reported hard-rock fields with extensive drilling damage.

The performance of shaped charges is significantly affected by the compressive strength of the rock to be perforated; consequently, the ability to bypass drilling damage in formations with high rock strength is reduced. Previously reported work1,2 has shown a 75% reduction in total target penetration, compared to API Section I, in rock with an unconfined compressive strength of approximately 25,000 psi.

This paper describes the development and field testing of alternative charge designs aimed at improving performance in high compressive strength formations. So that the adverse effects of drilling damage can be reduced, computer simulations and laboratory tests showing the improvements achieved are presented. Field testing of the new charges and results achieved are shown.
The Experimental Investigation of Formation Damage Due to the Induced Flocculation of Clays Within a Sandstone Pore Structure by a High Salinity Brine
Authors: Bishop Simon R
Published: December 2007

Formation damage induced by the invasion of low ionic strength brines is well understood and frequently documented. However, very little has been recorded regarding damage induced by very high ionic strength brines. A formation damage reaction between specific pore lining clay species and saturated salt drilling mud has been identified with the potential for significant permeability impairment in the near-wellbore region. This reaction was found during a reservoir condition core flood investigation into well performance in a field in South America operated by BP Exploration. Damage levels around 70% were recorded in reservoir core samples. Characterization of the formation damage mechanism was carried out by scanning electron microscopy. This revealed that flocculation of the pore lining clays had occurred, due to the invasion of the very high salinity brine, producing significant pore throat bridging and plugging. The type and concentration of the clays was determined in order to predict if this damage mechanism was an issue in future investigations. Further testing with an alternative drilling system showed that a non-damaging mud could be formulated for this field. A subsequent formation damage investigation into the likely impact of saturated salt drilling mud on the productivity of a North Sea field operated by BP Exploration revealed a sandstone with an almost identical clay fraction. It was predicted that the same damaging mechanism would occur. Return permeability testing confirmed this and validated the mechanism. However, in this specific case the extremely high permeability of the formation significantly reduced the impact of the pore bridging and plugging. It is recommended that when high salinity water based drilling muds are being considered for inclusion in reservoir drilling programmes the clay fractions of the formation are carefully considered to identify potentially sensitive sandstones. Specific formation damage testing should then be carried out to assess the likely impact on well productivity and whether this is acceptable.