bluuebunny/crossref_metadata_2025 huggingface dataset:
The Development and Application Offshore of a Direct Test of Well Fluid Scale Inhibition
Authors: Collins Ian R. , Chilcott Neil P. , Thornton Alex
Published: December 2007

Where wells are protected by scale inhibitor squeeze treatments, it is critical that there is an effective means of determining whether the produced fluids are inhibited against scale formation. Conventionally this is achieved by determining the minimum concentration of inhibitor required to prevent scale formation in the laboratory and then taking wellhead samples which are sent to an offsite laboratory for analysis to determine the concentration of inhibitor that they contain. Whilst this method can be an effective monitoring technique for inhibitor concentrations in excess of the minimum inhibitor concentration (MIC), it can introduce risk when wells are close to the MIC owing to the time required to turn around samples. Additional problems arise with poor sample preservation and the often-low frequency of sampling. A more robust approach to managing producing well scale risk is to utilise an on-site test that can be simply performed on freshly taken wellhead samples. The greatest value arises from a test, moreover, that is independent of laboratory determined measures of scale inhibition effectiveness.

In this paper we report the development, field validation, and routine application on the Miller Field in the North Sea of a direct test for the degree of scale inhibition exhibited by wellhead samples. The test, as described, relies upon the stressing of samples with excess barium or sulphate ions and the monitoring of turbidity developed in the solution. In contrast to other stress tests that have been reported previously, the test described relies upon simple robust equipment and is straightfoward to perform allowing samples to be taken routinely and monitored in near-real time.

The recent introduction of the stress testing technology on the BP operated Miller Field has already provided significant rewards with respect to HSE and scale management in one of the harshest barium sulphate scaling environments in the world.
Effect of PPCA and DETPMP Inhibitor Blends on CaCO3 Scale Formation
Authors: Chen T. , Neville A. , Yuan M.
Published: December 2007

PPCA and DETPMP are two common commercial scale inhibitors used to control mineral scaling in the oil and gas industry. Normally, PPCA is regarded as a nucleation inhibitor and DETPMP as a growth inhibitor. In this paper, the effect of PPCA and DETPMP blends on the inhibition efficiency of calcium carbonate scale formation is presented.

In this paper, calcareous scale formation was studied both in the bulk solution and on the metal surface in supersaturated scale formation solutions, which represent typical waters encountered in oil and gas production. The effect of inhibitor blends on scale formation is studied. It shows that the inhibitor has a different inhibiting effect on precipitation in the bulk solution and deposit formed on the metal surface and reasons for this are discussed. It also demonstrates that bulk precipitation and surface deposition are two different processes and both processes should be studied to completely understand an industrial scaling system.
Control of Inhibitor Squeeze Via Mechanistic Understanding of Inhibitor Chemistry
Authors: Tomson Mason B. , Kan Amy T. , Fu Gongmin
Published: December 2007

Chemical scale inhibitors are commonly used to prevent or inhibit scale formation in production. The most economic treatment of scale inhibitor is normally via chemical squeeze. However, there is little agreement regarding the primary mechanism by which the threshold scale inhibitors are retained in producing oil or gas formations as a result of squeeze procedures. Recent advances in phosphonate/rock interaction research at the Rice University Brine Chemistry Consortium have significantly improved our knowledge of what controls inhibitor placement in the formation. It is commonly suggested that reservoir type determines how an inhibitor is retained in a formation. Our research suggests that the pill chemistry is also an important determinant for retention of carbonate reservoir. Acidic pills are mostly retained near the well bore while more neutralized pills move farther into the formation. Three calcium nitrilomethylenephosphonate (NTMP) solid phases, an amorphous phase and two crystalline Ca2.5HNTMP phases with pKsp = 22.6 and pKsp = 24.2, are particularly important toward inhibitor retention. The relative sizes of these solid phases formed is governed by the pill composition and acidity. These results can be explained by a solution phase controlled sequence of reactions. All of this information has been incorperated into a new squeeze design software program, SqueezeSoftPitzer.
A New Class of Green Mineral Scale Inhibitors for Squeeze Treatments
Authors: Bazin B. , Kohler N. , Zaitoun A. , Johnson T. , Raaijmakers H.
Published: December 2007

The oil industry is currently facing severe restrictions concerning the discharge of oilfield chemicals into the environment. For most of the actual widely used mineral scale inhibitors, the future will depend on the possibility of their reinjection into disposal wells. Another alternative could be the deployment of biodegradable chemicals. For this purpose a new class of "green" scale inhibitors, the Carboxy Methyl Inulins (CMI), has been evaluated in its ability to prevent carbonate and sulfate scale deposition by squeeze treatments.

Jar Tests and Tube Blocking Tests, performed on actual reconstructed injection and production waters show that the CMI inhibitors exhibit competitive inhibiting performances compared to currently used scale inhibitors. Core tests for the determination of CMI adsorption / desorption properties in static and dynamic conditions help to predict inhibitor squeeze lifetime and to design its implementation in future squeeze applications.

It is finally concluded that the Carboxy Methyl Inulins may already be considered as viable alternate mineral scale inhibitors to currently used but not biodegradable chemicals.
Barium Sulphate Oilfield Scaling: Mathematical and Laboratory Modelling
Authors: Bedrikovetsky P. G. , Lopes R. P. , Gladstone P. M. , Rosário F. F. , Bezerra M. C. , Lima E. A.
Published: December 2007

The formation damage in scaled-up production wells caused by incompatibility of injected and formation waters have long been known. Precipitation of salts results in permeability decline. Among the most onerous of all scaling species is that of sulphates, particularly barium and strontium sulphates.

We study effects of porous media on the BaSO4 scaling kinetics.

A new methodology for determination of reaction rate coefficient from coreflood tests consists of the sequence of diffusivity reaction free tests, of transient tests with chemical reaction, and of simultaneous injections of both injected and formation waters with quasi steady state concentration profiles for barium and sulphate ions. The diffusivity tests serve for dispersivity coefficient determination. Quasi steady state tests allow determination of the reaction rate coefficient versus velocity. The transient test data as compared with the mathematical modelling data validate the model and the data of steady state test data treatment.

An analytical model developed is used for treatment of quasi steady state test data. The transient tests are treated by a numerical model.

The main result of the work is proportionality between the reaction rate coefficient and flow velocity for the parameter range studied.
Measurment and Prediction of Salt Formation in the Presence of Hydrate Organic Inhibitors
Authors: Masoudi R. , Tohidi B. , Danesh A. , Todd A. C. , Yang J.
Published: December 2007

Organic inhibitors (e.g. methanol, ethanol, ethylene glycol, triethylene glycol) are generally used to reduce the risk of gas hydrate formation in drilling and production operations. The addition of organic inhibitors has a significant adverse effect on the solubility of salts, increasing the risk of salt deposition. A better understanding of salting-out problems is necessary for effective design and implementation of flow assurance strategies in such complex systems.

In this communication we present an experimental investigation on the effect of methanol, ethanol and ethylene glycol on the solubility of several salts, including halite, sylvite and antarcticite. The results show that ethylene glycol has a much lesser adverse impact on salt deposition than methanol and ethanol. The details of an experimental set-up used for measuring salt solubility and salting out are described. The set-up could also provide valuable information on the effectiveness of various inhibitors used for preventing salt deposition in the presence or absence of gas hydrate organic inhibitors.

In addition, a novel predictive numerical approach is proposed to model salt formation in brine solutions with or without hydrate organic inhibitors. The model is based on the equality of the fugacity of salt in the solid phase and aqueous phase, which are calculated by an equation of state. The validity of the new developed model is demonstrated over a wide temperature range (i.e., −20 to 125 °C), salt concentration up to saturation point and hydrate inhibitor concentration up to 50 mass%.
First Lateral-Flow-Controlled Maximum Reservoir Contact (MRC) Well in Saudi Arabia: Drilling & Completion: Challenges & Achievements: Case Study
Authors: Nughaimish F. N. , Faraj O. A. , Al-Afaleg Nabeel , Al-Otaibi Uthman
Published: December 2007

This paper describes case histories of a successful drilling and completion experience of two tri-lateral Maximum Reservoir Contact (MRC) wells that were recently completed in Haradh field, Saudi Arabia. Equipping these two wells with down-hole monitoring and lateral flow-control, combined with the introduction of new completion practices, provided effective reservoir management solutions. A number of different MRC well designs were drilled and completed in different fields in Saudi Arabia, however, the subject two MRC wells were the first to provide minimum inter-lateral separation distance of three hundred meters. Moreover, these two MRC wells were the first to be completed with seven inch tubing string and tree, and equipped with per-lateral flow control option to selectively shut-in any water baring lateral in order to extend the life of such wells.

The objective behind the introduction of this new class of well design, the so called (MRC), which is generally defined as well with reservoir contact of five km and beyond, was to improve individual well productivity and hence reduce the unit development cost and to better develop hydrocarbon assets1.

Various reservoir and drilling challenges were encountered during the planning and execution phases of this project. Meeting the required minimum inter-lateral separation distance, expected production rate, and providing selective flow-control form each lateral were the main drivers for the current well design. Other challenges such as loss circulation, torque and drag limitations, well control, and formation damage were encountered while executing the project and were overcome successfully using different creative techniques that are also discussed in depth in this paper.
An Effective Fluid Formulation to Remove Drilling Fluid Mud Cake in Horizontal and Multi-lateral Wells
Authors: Nasr-El-Din H. A. , Al-Otaibi M. B. , Al-Qahtani A. A. , Samuel M.
Published: December 2007

Cleanup of drilling fluid filter-cake in long horizontal and multilateral wells is a difficult task. Both mechanical (water jetting) and chemical means (acids, oxidizers, and enzymes) have been used in the field. However, these methods have limitations, which can adversely affect well performance. Water jetting introduces large amounts of water into the formation, and can cause loss of well productivity through sanding and water blockage. Acids and oxidizers are very reactive and non-specific species. Enzymes can be used to degrade starch and xathan polymers. However, they are not effective in heterogeneous formations where there are high permeability streaks, which will require using large volumes of the treatment fluids, but with poor performance.

This paper examines using a combination of enzymes and a new class of viscoelastic surfactants. In this system, enzymes are used to degrade starch, whereas the visocelastic surfactant is used to increase the solution viscosity.

Extensive lab studies were conducted to examine compatibility of visocelastic surfactants with enzymes. The apparent viscosity of the enzyme/viscoleastic surfactant solutions was measured as a function of shear rate (57 to 1,740 s−1) and temperature (77 to 212°F). Surface tension was measured at various temperatures up to 284°F. Static (a HPHT fluid loss cell) tests were performed to assess the effectiveness of the combined system in cleaning filter cake formed by water-based drilling mud.

Experimental results indicated that the viscoelastic surfactant is compatible with the enzyme system. The low shear viscosity of the combined system is high enough to lift suspended solution during well flowback following the treatment. The addition of the viscoelastic surfactant to the enzyme solutions significantly reduced the surface tension of the enzyme solutions. This will reduce the time required to lift treatment fluids from the formation. The efficiency of the enzymes in degrading the polymers did not significantly change due to the presence of the surfactant.
Increased Assurance of Drill Cuttings Re-Injection - Challenges, Recent Advances and Case Studies
Authors: Guo Quanxin , Geehan Thomas , Ovalle Adriana
Published: December 2007

The handling of drill cuttings and wastes is both an environmental and economic issue in drilling operations. With ever-tightening environmental regulations and the green operation initiatives of operators, drill cuttings re-injection (CRI) into a subsurface geology often is the preferred option as it allows operators to achieve zero discharge since oily cuttings are returned to their place of origin.

When the technology started about a decade ago, injection into a single well had a maximum slurry volume of approximately 30,000 bbl. Now, particularly in very large projects, several million barrels of slurry may be injected into a single well. This represents more than a 1000 times the volume of a typical hydraulic fracturing job or more than 100 times that of those earlier cuttings re-injections. In some cases, the success of the CRI operation is critical because there either are no back-up options or the economic and environmental impacts are too significant.

This paper describes the challenges faced in CRI projects, along with recent advances and experiences gained in tackling these challenges through modeling, cuttings slurry and operational procedure design, monitoring and verification. For example, much progress has been made recently in slurry rheology design and operational procedure selection such as suspension/displacing to avoid loss of injectivity and to maximize disposal capacity and minimize HSE issues.

The authors also will present a risk-based approach, which integrates deterministic software and tools, available data, knowledge and experience, for modeling of geological and operational uncertainties and potential risks to increase the quality assurance. Case examples will be presented to illustrate the value of this integrated approach. Best practice guidelines and recommendations will be provided on data collection, design and engineering, operation and monitoring.
MWD Survey Accuracy Improvements Using Multistation Analysis
Authors: Chia C. R. , de Lima B. C.
Published: December 2007

Multistation analysis is a technique that provides drillstring magnetic interference compensation to magnetic surveys. This technique is now in common use in the industry, and this case study data verifies the capabilities of the multistation technique to improve measurement-while-drilling (MWD) azimuth measurement quality and accuracy. This study quantifies a significant improvement to standard MWD surveyed position uncertainty using actual survey data from drilling assemblies used in more than one hundred and twenty runs in over thirty-five different wells worldwide.

The use of multistation analysis, and the subsequent reduction in wellbore position uncertainty demonstrated can significantly reduce the overall surveying and drilling costs for the well, removing the need for correction runs and allowing for the penetration of smaller targets than previously possible with standard MWD surveying. This correction technique can be applied on a real-time basis at the point of surveying. Forecasting of the magnetization effects of the bottom hole assembly (BHA) using the same software, will also allow the driller to place the well more accurately. In some cases the use of multistation analysis with standard MWD surveys will enable the removal of one or more gyrocompass surveys from the survey program. This can reduce overall surveying time and cost, and the exposure of the BHA to additional stuck-in-hole risks that occur when running wireline surveying tools through drillpipe in extended-reach wells.

The main analysis method is based on a direct comparison of MWD survey data before and after multistation correction, against independent overlapping gyro survey data. The results achieved by this study are translated directly into improvements in current industry standard error models, and this paper proposes a standard error model for multistation analysis corrected MWD survey data.
A Case Based Knowledge Repository for Drilling Optimization
Authors: Perry P. B. , Curry D. A. , Kerridge J. D. , Lawton J. , Bowden D. , Flett A. N.
Published: December 2007

Drilling knowledge management applications are often criticized as lacking in structure and providing little value return to users due to lack of relevant content and difficulty of use. The drilling optimization group of a major service company identified knowledge management as one of the enabling technologies for service delivery and embarked on an initiative to create a knowledge management system that addressed these key weaknesses.

Previous collaboration with a major operator led to the development of a generic best practice system for drilling performance optimization. We have now supplemented that system with a separate but linked knowledge tool that allows us to capture and share the specific technical lessons learned by our engineers in their project work. This new tool promotes sharing of new knowledge amongst our optimization engineers. It gives company-wide access to the new knowledge they create. And the new knowledge it captures is used to update the generic best practice system.

Proven knowledge engineering techniques were used to create an ontology of the drilling optimization domain, which was in turn used as the basis for the new knowledge tool’s structure. The knowledge tool is used to capture all projects undertaken by the group and the main technical and process lessons learned in those projects. It is therefore a repository for case-based drilling performance knowledge. Entries created by applications engineers are processed and reviewed by technical experts prior to publication to the global community. The knowledge is structured according to problem, operating practice and the applicable phase of the project. A key element is the physical description of the downhole environment in which each lesson was learned. A structured search facility allows engineers to locate lessons learned and performance achieved in drilling environments that are physically equivalent but geographically distinct to those of the well they are studying.

This paper shows how knowledge engineering and knowledge management techniques have been adopted to structure drilling knowledge, increasing its quality and ability to be re-used. We show how the new knowledge tool aids rapid location of relevant knowledge and further how the use of structured knowledge facilitates integration of different knowledge tools and updating of best practices. Several case histories are presented that show how use of the system has delivered real drilling performance improvements by communicating learning across geographic boundaries.
Improving the Success Rate of Collaborative Drilling Projects
Authors: Morrice William , Vann Martin
Published: December 2007

There is a growing trend toward collaborative relationships between traditional operating companies and major service companies, either for specific projects, or in the guise of longer-term technical partnerships. Often these relationships are characterized as a vehicle for transferring technology and sharing best practices. Clearly defining expectations and success criteria for all parties is essential, but not always straightforward. Issues related to job security, competence, and internal competition often arise, which can cause such projects to fail if not recognized and managed. This paper describes a process to establish and maintain collaborative relationships, improving the prospects of success.
Extending the Boundries of Casing Drilling
Authors: Fisher Antony , Reid Doug , Tan Ming Zo , Galloway Greg
Published: December 2007

Proposal

Shell has targeted casing and liner drilling as one of five mature technologies for an accelerated uptake within its group E & P companies. A 9 5/8" surface casing drilling job performed onshore Brunei in September 2003 utilized a new design of casing drill shoe that extends the depth range of rotary casing drilling. The convertible drill shoe has a novel feature that allows the cutting structure and blades to be extruded outwards once section TD is reached. By this process, the drill shoe converts to a cementing shoe, allowing the casing to be cemented in place. The cementing shoe and next hole section can then be drilled without interference from the casing drill shoe cutting structure and blades. Application of the extrusion process allows a more aggressive and durable cutting structure on the casing drill shoe and hence allows deeper, more resistant formations to be drilled.

The paper will describe the planning, implementation and subsequent results from this world’s first convertible casing drill shoe job that led to a world record depth achieved for this type of rotary casing drilling, and a cost effective option for setting vertical surface casings.
Integrated Team Approach to Zonal Isolation Creates Value
Authors: Luckanakul Nat , Davidson John P. , Weber Lawrence , Hibbeler Jeff
Published: December 2007

Best Practices for cementing are well established in the industry however there remains the continuous challenge of effectively employing these best practices in balancing the need for drilling performance and the need for delivering the best possible well to production. For multi-zone monobore completions where the cemented tubing annulus is the single means for zonal isolation, this becomes a critical goal. Such is the case with the majority of wells drilled in the Gulf of Thailand. Desire to meet this challenge led to the creation of a full-circle process that both provides the methodology and initiates the inter-disciplinary communication necessary to improve zonal isolation and the added value it will bring. Components of the full-circle process employed in Thailand include: creating a cementing "scorecard" to focus operations on cementing best practices; forming a cross-disciplinary team of drilling, completion; production and contractor personnel to review bond logs, adjusting drilling practices; and communicating to all involved in the process.

An integrated team approach developed within the context of the full-circle process has successfully linked the goals of the Subsurface Operations and Production Departments resulting in the creation of more production opportunity and maximized recovery rates. The CBL Review Team (CBLRT) created in late 2002 consists of drilling, completions and reservoir engineers, along with logging and cementing experts from the representative service providers. In many cases members of the Asset Management team also attend the regular weekly meetings. To date, the team has reviewed over 450 wells.

This paper presents the full-circle process model and shows how improving zone isolation, evaluation methods and field results can be adapted for application in other operating environments.
Well Intervention Management in Oman Fields
Authors: Aihevba Leste O.
Published: December 2007

The Northern Oil Directorate of PDO (OND) manages some of the most important assets in the country, contributing just a little under 50% of Oman's daily production. Over the last 5 years, the production has seen a rapid decline. The challenge of arresting this decline to maximize the reserves is being met by a significant increase in the level of well intervention following re-emphasis on four major areas: Proper well surveillance, Acceleration of reserves by Optimization activities, Maintenance of NFA by restoration activities and Conservation of reservoir energy by management of water-floods. Major well services challenges are in the areas of well and reservoir surveillance, failed ESP replacements, well integrity (casing, tubing and packer) repairs, additional perforations, water shut off, gas lift optimization and multi lateral re-entry. Well Services expenditure has more than doubled in 4 years, with over 5000 entries, (utilizing hoists, coiled tubing, Wireline, pumping units) expected in 2004. Management of this rapidly increasing level of activity was imperative to realize value for the asset from the increased expenditure.

This paper discusses the process applied to management of Well Services activities with a refocus on lowering intervention costs, increasing net oil rewards and reducing deferment, building on the principle that every action costs money, and should therefore result in some oil in the tank. It takes us through the approach of integrated analysis of information from an increased level of surveillance activities to generating a more robust portfolio of intervention candidates. It highlights the improvements made on candidate selection, ranking, activity proposal generation, resource allocation, activity execution, performance management, KPI tracking and after action reviews. It concludes with a description of the feedback loop being embedded to ensure continuous improvement, the benefits realized so far and what more needs to be done.
Window Exit Sidetrack Enhancements Through the Use of Solid Expandable Casing
Authors: Rivenbark Mark , DeMong Karl , Al Faraj Omar
Published: December 2007

Proposal

When most operators think of solid expandable casing, they primarily focus on their application as it relates to solving hole problems while minimizing any loss of hole size incurred by running a casing string. A new application for solid expandable casing quickly growing in popularity uses the tubulars to sidetrack through a milled window. Solid expandable casing can minimize, if not eliminate, many of the obstacles associated with sidetracking.

The historic drawback of losing hole size through the window exit can be largely eliminated by using solid expandable casing. These tubulars enable the hole section to be drilled beyond the expandable casing with larger drill pipe and bottomhole assemblies (BHAs), including measure-while-drilling (MWD) and logging-while-drilling (LWD) tools, which may have been impossible with a conventional sidetrack. Larger production tubulars and related completion equipment add to the value generated by using the solid expandable casing. This technique can also be instrumental in initiating slot recoveries that might not otherwise be economically viable.

As with other applications of solid expandable casing, a successful installation requires proper pre-job planning. This paper reviews issues critical for success and also looks at specific examples of installations performed to date. Other technologies associated with expanding the solid casing will also be discussed in the context of wells already completed or in the planning stages. The economic benefits of this technique will also be explored.
Characterization of Heterogeneity Using Inverse Model Equipped with Parallel Genetic Algorithm
Authors: Kwon S. I. , Sung W. M. , Huh D. G. , Lee W. S.
Published: December 2007

This study presents the development of reservoir characterization inverse model equipped with ANN type of ISGA and MSGA parallel processing algorithms. In order to efficiently run the developed model, homogeneous PC-cluster was constructed by connecting four PC which have the same features. The model was adapted ANN to automatically determine optimum GA parameters of operator, number of individuals and operation rate, which is appropriate for the reservoir heterogeneity.

By utilizing the developed model in this study, inverse calculation was conducted for the synthetic reservoir system with the aid of an ISGA-PP. As a result, it was found that convergence is stably progressed. In the result of permeability distribution, it shows that low permeable zone in central area for the system studied is appeared to be little different comparing to the result obtained by Kriging method which is using only static data. In the matching result of pressure, maximum relative error of 1.54% was presented at OP-4, and hence, the calculated permeability distribution is thought to be quite reliable. When MSGA-PP was applied to the same reservoir system as ISGA-PP, it converged stably similar to ISGA-PP. The difference between ISGA-PP and MSGA-PP is appeared only at convergence rate and the resulting permeability distribution is very similar to each other.

In the evaluation of computing efficiency of ISGA-PP and MSGA-PP against GA-SP, the result shows that the efficiency of parallel processing system is more greater as the number of individuals increases. Also, regardless of the number of individuals, the calculating time in parallel processing system was greatly reduced by 3.6 times comparing to serial processing system of GA-SP. Finally, inverse calculation was carried out with MSGA-PP-ANN. As a result, it converged much more faster than MSGA-PP without having a artificial neural network system. It was expected that the model takes only superior individuals at the beginning obtained by optimum GA operator set, which have greater fitness values.
The Function of Gas-Water Relative Permeability Hysteresis in the Sequestration of Carbon Dioxide in Saline Formations
Authors: Flett Matthew , Gurton Randal , Taggart Ian
Published: December 2007

The injection of carbon dioxide (CO2) into saline formations for the purpose of limiting greenhouse gas emissions has been proposed as an alternative to atmospheric venting of carbon dioxide. To date, research of the subsurface interactions of injected CO2 in saline formations have focused on two main areas: dissolution of CO2 into saline formation waters and the geochemical/mineralisation effects of the injected CO2 on the formation rock matrix. Both of these topics investigate forms of potential permanent sequestration or trapping of CO2.

It is proposed that trapping of CO2 as a residual phase due to imbibition of water is another form of permanent sequestration of CO2. This paper will outline the role that gas-water relative permeability hysteresis can have towards the success of storage for a geological CO2 sequestration project. This process is similar to the experience of aquifer encroachment on depleted gas reservoirs where water traps gas along its path.

During the injection phase of a geological CO2 sequestration project, the movement of CO2 is dominated by a drainage relative permeability state, as CO2 displaces brine, the wetting phase in the formation. After injection, the governing force on the injected fluid is gravity. CO2, at most reservoir conditions, is more buoyant than brine and thus injected CO2 will tend to migrate up-dip along the top seal. The migration of the CO2 plume, over hundreds of years, is dominated by both drainage and imbibition relative permeability effects. At the head of the migrating plume, drainage relative permeability is prominent as water drains away from the migrating plume. At the tail of the migrating plume, imbibition relative permeability dominates as water imbibes behind the migrating plume trapping CO2 as a residual phase. Thus the amount of mobile CO2 diminishes over time, as more of the plume dissolves and is trapped as a residual phase.

A reservoir simulation study was conducted to investigate gas trapping in a geologic sequestration project. Many subsurface parameters were varied, including the effects of gas-water relative permeability hysteresis. The results of these parametric changes were monitored with regard to the effects on migration, pressure build up at the geological seal and the fraction of CO2 in the formation that is either mobile, dissolved or trapped as a residual phase. It is demonstrated that the factors determining the long term outcome and hence success of a sequestration project includes: the permeability field, the degree of dissolution and the degree of gas trapping as a residual phase. Trapping CO2 as a residual phase is shown to have a constructive impact on the success of a geologic sequestration project.
Understanding Fluid Phase Using A Seismic PVT Chamber
Authors: Evans Brian
Published: December 2007

As oil fields produce liquids (oil or gas/condensate), they undergo pressure change, with the pressure reducing as a function of production rates. Equally, the high production of water from a reservoir can cause major reduction in pressures of gas fields resulting in an increase in the gas cap size and a consequent loss of gas to the surrounding formations.

The injection of water or CO2 into reservoirs or underground storage areas causes an increase in local pressure which in turn, has the potential to cause local increases in permeability in the reservoir or at the storage site. Time-lapse three dimensional (3-D) seismic methods are used to monitor the fluid movement during both fluid extraction in producing fields and injection of water or CO2 for EOR or storage purposes.

However, little is understood about the seismic effects caused by variations in both pore pressure or rock matrix stress as a result of these operations. During 2003, a low pressure/volume and temperature (PVT) chamber was built at Curtin University to simulate such effects, and to establish the seismic reflection response under these variations.

Past research has shown that variations in pressure can cause tuning effects which appear to be identical to bright spots occurring. In that research, it was shown that a variation in pressure causes a change in formation density which can cause a rotation of the AVO fluid line, and this highlighted both the fact that this attribute can be used for sensing variably pressured compartments in 3-D data (missed pay zones) as well as indicate that a bright spot is not always gas-associated but can be pressure-associated in a producing field.

This paper discusses the development of this research and the applications of this unique PVT chamber.
The Mapping of Hydraulic Flow Zone Units and Characterisation of Australian Geological Depositional Environments
Authors: Biniwale S. , Behrenbruch P.
Published: December 2007

The Carman-Kozeny formulation has been used as a basis to provide a new perspective of flow zone units (FZUs), by mapping similar rocks in terms of "Characteristic Envelopes", for different geological depositional environments. A large amount of data, covering several fields and different Australian basins, has been analysed.

The methodology has been used for well-to-well correlation, reverse modelling for better identification of depositional trends, diagenetic affects and grain characteristics. It is also shown how photomicrographs, scanning electron micrographs (SEM), and log shapes can be incorporated in a detailed analysis. The method is ideal for validating plug samples used in special core analysis. It is shown how various data types, geological attributes and engineering parameters can be integrated. Results from such analysis can then be used in consistent model preparation and better quantification of petroleum recovery efficiency.
Knowledge Management Strategies to Combat Tomorrow's Challenges – Lessons from Woodside Energy
Authors: Chiri Khaled
Published: December 2007

Woodside's success is fundamentally due to its people. Success is derived from a very experienced, skilled workforce who through many years of experience, simply ‘know what to do'. When what the experienced workforce knows is captured in repeatable, sustainable business processes, knowledge, ‘good' practices and lessons learned captured and reused, then past performance can lead to future success.

The western world is suffering from an increasingly transient and ageing workforce. Additionally the oil and gas workforce is shrinking and experiencing a shortage of Petroleum Engineers and general Geosciences related degrees. Many key staff employees are contractors, secondees or permanent staff close to retirement.

Over abundance of information can also affect performance in one way or another. It causes delays and in some cases inaction as people tend to examine all available information before they make any important decisions. It is also a source of considerable distraction, for example as people try and manage their emails rather than think creatively.

To combat tomorrow's challenges and to effectively leverage our "local" strength and apply it at a "global" level, Knowledge Management has been adopted as a strategic choice. This paper outlines the approach taken and reveals the progress made to date. It also explains the steps and processes used to create an environment that is conducive to knowledge sharing.
Pressure and Pressure Derivative Analysis without Type-Curve Matching for Triple Porosity Reservoirs
Authors: Escobar Freddy H. , Saavedra Nestor F. , Escorcia Gerson D. , Polania John H.
Published: December 2007

Proposal

Currently, the study of naturally fractured reservoirs represents a constant-growing technology because of the high amount of this type of behavior in many reservoirs worldwide. Therefore, for an efficient exploitation is necessary to adequately model them, so a more realistic fracture-matrix flow behavior can be obtained and identified. However, by inspecting some well pressure tests, anomalous slope changes during a matrix-controlled flow period are observed. This behavior does not follow the one described by a dual porosity model.

Throughout the years, the pressure transient behavior of naturally fractured reservoirs has been extensively studied. Customary, dual porosity models have been widely utilized to describe the flow behavior taking place in the fracture/matrix system of naturally fractured reservoirs. However, a remarkable flaw of these models is their assumption of homogeneous matrix properties through the whole system. Recently, pseudosteady-state and transient-state triple porosity models have been introduced to take into account the existence of two domains in the matrix with different properties and one domain in the fracture net. There is no flow between the two matrix domains. On a semilog plot of pressure versus time, three parallel straight lines are observed when one domain has lower storativity and higher interporosity flow coefficient. Well pressure analysis for such systems was conducted using the conventional method or semilog type-curve matching.

In this study, pressure derivative is applied to triple porosity reservoirs so their typical characteristics and fingerprints are reported. A technique to analyze pressure and pressure derivative data without using type-curve matching is also provided. This technique uses characteristics lines, characteristics points and features found on the pressure and pressure derivative plot to obtain analytical expressions for a practical estimation of permeability, skin and the fundamental parameters of such systems. The proposed methodology was successfully verified by its application to field data cases and simulated pressure data.
Integrated Asset Modeling, a Quick Solution for Identifying an Infill Well Opportunity
Authors: Luciawaty Mery , Suyasa I Made
Published: December 2007

This paper describes an integrated asset modeling program designed to determine reserves that can be drained by an infill prospect within a mature asset. This model has proven its ability to reduce risks and improve reservoir decline management. It is able to quickly identify potential benefits of drilling without spending significant time building complex reservoir simulation models.

The West Java fields, operated by BP Indonesia, are located in the northwestern part of the Java Island. Production commenced in 1971 on these mature offshore assets with interdependent oil and gas systems. Over 50 separate reservoirs have been identified in these highly stratified structures and many wells produce hydrocarbon from multiple horizons (commingled production). The surface facility network is very complex integrating many producers, various production/compression systems and long pipeline sections.

As the fields become mature then there is an increasing need to drill more and more wells to recover untapped reserves and reduce production decline. Quick screenings are required to identify the possibility of drilling an infill well surrounding the existing producers or to access untapped hydrocarbon reserves.

An integrated model connecting reservoir tanks, wells, pipeline networks and surface facilities was build support the infill decision. The model can handle naturally flowing, gas lifted and ESPed producing wells. There is no limit on number of wells and/or platforms that can be analyzed. Constraints can be considered at all levels, from well, joint, separator and the overall system. Moreover, production forecasting from the model can also accommodate constraints at the reservoir level.
Simulation of Production from Naturally Fractured Reservoirs with the Use of Effective Permeability Tensor
Authors: Teimoori A. , Tran N. H. , Chen Z. , Rahman S. S.
Published: December 2007

This paper presents a numerical model for simulating fluid flow and production from naturally fractured reservoir based on a flux continuous control volume mixed finite element approach. The main features of the present model are that it accounts for the heterogeneity of the fractured media by applying effective permeability tensor in each grid block and allows the direct calculation of fluid flow velocity. Flux continuous control volume mixed finite element technique is used to simultaneously solve two coupled partial differential equations for fluid pressure and velocity. Effective permeability tensor represents directional permeability in fractured media. Thus the model overcomes the existing problems in previous models in relation to irregular fracture patterns, flow interactions between matrix and fractures and effects of fracture characteristics (dimension, density and orientation). The model is validated against data published in literature and applied to a typical naturally fractured reservoir, where the fracture network was characterized by a hybrid object-based fracture characterization technique.
Application of Genetic Algorithm to History Matching for Core Flooding
Authors: Tokuda N. , Takahashi S. , Watanabe M. , Kurose T.
Published: December 2007

Recently it has become a common practice to construct 3D coreflooding simulation model to interpret water displacement experiments conducted under X-ray CT scanning. The unknown grid block parameters i.e. kro/krw and Pc curves are required to be optimized to get reasonable matching with experimental data such as changes of grid block water saturation. In order to evaluate the matching process efficiently a new automated history-matching program has been developed. This program applies Genetic Algorithm to optimize several coefficients for normalized kro/krw and Pc curves for each litho-facies.

Several blind tests were carried out on hypothetical coreflooding models by changing the conditions of velocity and wettability to investigate the degree of accuracy and limitation of the program. The result of the reproducibility of the relative permeabilities was excellent for both water-wet and oil-wet cases regardless the velocity of coreflooding. On the other hand, the degree of reproducibility was not necessarily satisfactory for capillary pressure curves especially in high velocity case.

Sensitivity of the controlling parameter in Genetic Algorithm such as crossover rate and mutation ratio was also investigated. The suitable values are estimated, though no simple trend was found.

The program was finally applied to the interpretation of actual water displacement tests on oil-wet carbonate cores. The program successfully gave a reasonable set of kro/krw and Pc curves for each litho-facies and demonstrated its capability of grid block parameter optimization.
CO2 Recovery and Utilization for EOR
Authors: Morsi Kamal , Leslie John , Macdonald Doug
Published: December 2007

In order to replace valuable natural gas presently used for pressure maintenance ADNOC is investigating capture of carbon dioxide (CO2) from several flue gas sources and its transport to a developed field for Enhanced Oil Recovery (EOR). A study was commissioned to evaluate available technologies and determine the optimum technical and economic configuration for capture and delivery of high quality CO2 for injection.

Three flue gas sources for CO2, were considered, appropriate capture technologies were chosen and a formal licensor selection process was performed. Key considerations in selection of technology and licensors were existence of successful commercial applications and utilities requirements (natural gas, power and cooling water).

The process configuration chosen involves placing the absorber equipment near the flue gas sources, with a common stripping operation located at a single site.

The study also included design of compression and pipeline facilities to deliver dense-phase CO2 to the nominated field, and booster pumps to raise the CO2 to required injection pressure.

The paper describes the process employed to select technologies and discusses the considerations involved to arrive at the final configuration.
Key Improvements for Client Source Inspection on Lump Sum (EPC) Oil and Gas Projects
Authors: Al-Abed Bassem I.
Published: December 2007

In consideration of lump-sum EPC (Engineering, Procurement and Construction) oil & gas Project needs and potential benefits of Client source inspection, a review of recent experience in Client Third Party Inspection (TPI) involvement at source on EPC Projects has been conducted. The review of Client TPI involvement at source has considered experience on several large EPC Projects.

This paper summarizes the findings of the review and recommendations for improvements. Four key themes that run thorough these recommendations are as follows: Improvements to the criteria for purchase order selection for Client source inspection involvement.Improvements to the criteria for inspector selection.The need for the Client Quality Manager to remain engaged with the technical scope of inspection activities.The importance of technical definition of inspection scope and requirements for inspection reporting.

The scope of this paper does not include requirements for specialist engineering witness of final factory acceptance or performance testing.