bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Process for Securing Partners for International Farm-outs
Authors: Bagge M. , Finalle L.
Published: December 2007

Companies have difficulty securing partners to farm in to international exploration and development projects. The objective of this paper is to describe a better process to accomplish international farm-outs. Companies of all sizes now pursue business internationally, including many emerging international companies based outside the United States. The time for farm-outs is traditionally short. This factor and the need for global participation amplify the difficulty of finding the right companies for an opportunity and supplying them with the right information to do the requisite analyses and get approvals in time.

The solution developed includes three fundamental elements: 1) an ability to quickly connect with the right people at the right companies, based on relatively real-time intelligence, 2) generation of an improved technical or commercial story, including use of an appropriate economic model for the fiscal regime, and 3) capability to provide the relevant information, including workstation projects whenever pertinent or possible, in a timely, convenient manner. A detailed description of the process will explain the key elements, why they are necessary, and what advantages result.

A new process is required to improve farm-out success, which will lead to the pursuit of more exploration and development projects worldwide. Traditional relationships remain a key component but must be combined with ever-evolving intelligence on companies’ organizations and their preferences. Better technical and commercial analyses to describe opportunities are imperative. Key information must be identified and distributed for maximum effect. Finally, the use of technology can make access to and use of all the key information easy and convenient. Online data rooms (ODRs) can provide quick, convenient access to the right information, including information memorandums (IMs), supporting documents, workstation projects, and economic models.

The process or parts thereof can be employed for most companies seeking to farm-out some level of participation in international opportunities. The process is most important when opportunities have global appeal and yet are associated with a less-known geologic setting, particular engineering challenges, or an unfamiliar fiscal regime.
Accurate and Credible Reserves Requires more than Best Engineering Practices
Authors: Douglas J. , Nguyen T.
Published: December 2007

Proposal

For many years, reserve determination has focused on engineering best practices. As various regulatory agencies increase their scrutiny of how oil and gas companies are determining their reserves and assigning value to those reserves, relying only on engineering best practices is no longer adequate. Reserve determination and subsequent public disclosure of those reserves needs to have a collaborative effort with emphasis on:

Process Security, and Technology

This paper will look at each of these 3 areas, and explain the importance of each area as they pertain to reserve determination and disclosure. It is not enough to have each of these items individually addressed. A solution that addresses these areas must be tightly interwoven and utilized in a seemless architecture. This paper will propose such a solution.
Development of a Nanocomposite Gel for Lost Circulation Treatment
Authors: Lécolier E. , Herzhaft B. , Rousseau L. , Néau L. , Quillien B. , Kieffer J.
Published: December 2007

The problems due to lost circulation events may represent a major source of expenses for drilling operators, even if their consequences do not have all the same level of gravity. Probably the most problematic situations are the naturally fractured formations where the operator may face total loss with no mud return in the annular.

The voids or large fractures encountered in this case are often far too large to be plugged with conventional Lost Circulation Material. For these severe losses, the failure of extreme solutions as cement injection may even lead to loss of the well. Recently, treatments based on cross-linked pills have shown their effectiveness to plug large fractures under downhole conditions of pressure and temperature.

This paper describes the research and development process to formulate a new cross-linked pill usable to control severe losses: this new pill is a nanocomposite organic/inorganic gel. Formulation strategy, laboratory procedures and experimental results will be described. The gelation time, the viscosity before setting, the gel strength formed and the dependence of these parameters with pressure, temperature and physico-chemical environment are characterized with specific experimental devices. Particular components of the formulation give excellent visco-elastic properties to the nanocomposite gel, enhancing the ability to sustain pressures peaks.

The typical final formulation, which is easily prepared on site (dry blend formulation) gives remarkable properties regarding pumping through drill pipes, adjustment of setting time and especially strength of the lost zone sealing.
Field Validation of Acidizing Wormhole Models
Authors: Glasbergen G. , van Batenburg D. , van Domelen M. , Gdanski R.
Published: December 2007

In matrix acidizing of carbonate reservoirs, the generation of wormholes is a major key to success. Numerous papers have been written that describe the formation and propagation of such wormholes. Generally, these models have been based on sound chemistry and physics. Some of the models have been validated against laboratory experiments that are generally conducted in a linear geometry. However, in order to use the models in the design of matrix acid stimulation treatments, the models need to be validated under radial flow conditions that dominate field treatments.

Radial flow, competing wormholes, permeability contrasts, and reservoir height are example parameters that cannot easily be validated in laboratory experiments. Scaling of the models to field conditions might be required. Two types of models have been written for aiding in treatment designs. One model, called a linear-type model, is fully consistent with the decades of linear flow tests conducted in the laboratory. The second model, called a symmetry model, is exceedingly difficult to validate in the laboratory. This paper evaluates both models against treating pressure responses from field treatments.

A matrix treatment simulator was used that includes such effects as multiple formation layers with independent formation parameters and allows for modeling zonal coverage. The formation parameters include permeability, porosity, mineralogy, acid reactivity, skin damage, and permeability contrast. The well parameters include height of the layers, wellbore tubulars, friction pressures, etc. This simulator was an ideal framework for evaluating the two acidizing wormhole models. This paper demonstrates the key issues related to the interaction between the wormhole models and zonal coverage.
First Implementation of Hydrajet Fracture Acidizing in Deepwater Offshore Brazil Fields
Authors: Rodrigues V. F. , Neumann L. F. , Rosolen M. A. , Fernandes P. D. , Lima C. , Surjaatmadja J. B. , Gonzalez C. M. , Carneiro F.
Published: December 2007

The placement of multiple fractures in horizontal, deviated wells is usually more difficult than placement in vertical wells. When completed with uncemented preperforated liners, such treatments become much more difficult and often are ineffective using conventional stimulation methods. When found in offshore locations, these wells present even more problems.

Recently, in the shallow waters offshore Brazil, a relatively new hydrajetting technology was used with great success. However, additional complications arose when hydrajet fracturing was elected to stimulate a subsea well. This process requires dual high-pressure connections to the wellbore, including placement of a tubing string inside the full length of the well. Maintaining the hydrajet tool in position during each fracturing stage was a big issue in a floating rig. The need to pull tubing between stages of the stimulation process also poses a challenge.

Because this operation occurred in a subsea well, it was the first such application ever attempted worldwide. Extremely detailed planning was essential to the ultimate success of the operation. This paper discusses the rigorous planning involved in implementing multistage hydrajet fracture acidizing in a subsea well offshore Brazil. During the operation, all challenges, mechanical or otherwise, were meticulously scrutinized, including the proper operation of the stimulation vessel and riser motion. This paper also presents post-treatment production results evaluated and compared to other stimulation attempts in offshore horizontal completions in the area.
Accurate Measurement of the Hydrogen Sulfide Content in Formation Fluid Samples—Case Studies
Authors: Elshahawi H. , Hashem M.
Published: December 2007

The Hydrogen Sulfide (H2S) content of subsurface hydrocarbon reservoirs has a profound impact on completion, surface production, and process design. The H2S content of crude oil directly impacts the sale value of the produced hydrocarbons, while the H2S content of produced water can result in significant production problems, which can lead to detrimental effects on hydrocarbon transport and sales specifications.

In theory, the H2S content of reservoir fluids can be determined from samples collected by wireline formation tester tools. In practice, however, measurement is complicated by the partial-to-total loss of the gas by absorption/adsorption onto the metal components of the downhole tool, storage bottles, and transfer/analysis system, particularly those made from iron. H2S readily forms non-volatile and insoluble metal sulphides by reaction with many other metals and metal oxides, and analysis of the fluid samples can therefore underestimate the true H2S content. Therefore, many practical challenges must be overcome to accurately determine H2S levels in formation tester samples. These include metallurgical design considerations, sampling environment and system selection as well as the timing and type of H2S analyses.

This paper details our successes in accurately measuring both high and low concentrations of H2S in downhole formation tester samples. It describes an integrated workflow by which ultra low H2S concentrations can be captured and preserved in formation tester samples until the tool is brought back to surface where the samples can be analyzed. This workflow includes a number of modifications to some commercial formation tester tools and sample chambers to ensure that the bulk of the H2S does not get absorbed by the time the tool arrives to the surface. Downhole measurements made close to the fluid entry into the sampling tool are used to cross check and verify the surface measurements. Finally, on surface, a number of techniques are used to measure H2S concentration in the sample bottles as soon as practical after the formation tester tool is brought to the surface. The paper demonstrates, through a number of case studies, that by following this comprehensive workflow, it is possible to capture and analyze hydrocarbon samples with minimal loss of H2S, regardless of the levels of H2S being measured.
OBM's Filtrate Damaging Effect on Gas Wells
Authors: Emiliani C. N. , Ripa G. , Sportelli M. , Cobianco S. , Del Gaudio L.
Published: December 2007

Formation damage of gas wells can occur during drilling and completion operations causing a first sensible impairment of the potential productivity.

When drilling gas wells in low permeability reservoir with strongly inter-layered formation, as in the Adriatic Sea, oil based muds (OBM) are often used in order to minimize differential sticking and clay destabilization problems. The OBM's filtrate generates through the mud filter cake, when exposed to completion brine may form emulsion droplets that are not easily and fully removed during production, causing a permanent damage to rock permeability.

This paper presents the study carried out to understand the damage mechanism which gas wells undergo when drilled with OBMs and the results obtained in engineering a system able to enhance production recovery for new wells.

Bulk experiments and coreflood tests have been performed both to investigate the interaction effect of OBM's filtrate with high density water-based pill and to assess its impact on the well deliverability. In bulk conditions, viscosity and microscopy characterization of tight w/o emulsions (up to 99:1 W/O) highlighted that low shear rate and very low emulsifier concentration in the mud filtrate promote very viscous and thermally stable emulsion. Besides linear coreflood tests proved dramatic permeability impairment when flushing CaCl2 brine through a mud filtrate saturated core, confirming the formation of a blocking phase in the porous media.

A prevention system has been engineered as a peculiar surfactant to be added to completion brine, able to prevent emulsions from forming instead of simply breaking it up.

Surfactant selection guidelines have been provided as result of various additives screening being focused on the main characteristics affecting the surfactant efficiency, like HLB and solubility in brine.
Calculation of Productivity of a Gas-Condensate Well: Application of Skin With Rate Dependent Pseudopressure
Authors: Jamiolahmady M. , Danesh A. , Rezaei A. , Ataei R. , Sohrabi M.
Published: December 2007

The most crucial region affecting well productivity is the perforated region. An accurate determination of perforation performance, required in the optimum design and well productivity estimation, could be made by fine grid simulation, but it would be costly with many technical limitations. The alternative practical approach is the use of a skin factor in open hole calculations resulting in the same flow performance as that of the perforated well. However most of the skin calculations done today are based on single-phase flow conditions.

In this work, we have developed a method to determine the effect of perforation on gas condensate well productivity by defining a skin factor to be used in the pseudo pressure application. The main problem is that pseudo pressure in such systems is a function of velocity and the conventional skin factor, which is calculated for a perforated well, cannot be used directly in open hole calculations. This is due to the fact that the gas and condensate relative permeability (kr) can increase significantly by increasing the flow rate, contrary to the common understanding. This effect, known as positive coupling, complicates the flow of gas and condensate near the wellbore even further when it competes with inertial losses at higher velocities typical of those around perforation tips.

The above complications, which require information on velocity-location in the perforation region, have been tackled by proposing new techniques with an emphasis on their practicality. Sensitivity studies, comparing the results of developed methods with those using finite element methods, indicated the reliability of the proposed techniques. The methods can be used to estimate variations of skin due to long-term condensate banking and the need for any intervention and remedial action.
Analysis of Production Enhancement Related to Optimization of Propped Hydraulic Fracturing in Gazprom's Yamburskoe Arctic Gas Condensate Field, Russia
Authors: Butula K. K. , Maniere J. , Shandrygin A. , Rudenko D. , Zynchenko I. A.
Published: December 2007

Optimized hydraulic propped fracturing has proven to be the key to success for many operating companies in the West Siberian oil fields. The application of hydraulic propped fracturing stimulation in medium-permeability gas condensate formations was once considered uncertain because of mixed results in the past.

The particular conditions in a severe arctic and permafrost environment, however, required a range of specific completion and stimulation techniques for the Neocomian reservoir, including hydraulic fracturing.

The changes in fracturing treatment design in this gas condensate reservoir were made in adherence to an integrated project management approach, using forward modeling and reservoir and wellbore production simulation to mostly negate retrograde condensate effects.

The paper provides a comprehensive analysis of the work that was done on these gas condensate wells, focusing on the post-fracturing production analysis including production effects with time, factors affecting productivity, and post-fracturing production modeling.

Unprecedented productivity results, when compared to peer wells in the Yamburgskoe field, were realized from the treatments performed. The nine-well case history dataset presented in the paper confirms the effect of using this comprehensive approach to propped hydraulic fracture treatments in a Russian gas condensate reservoir.
Integrated Management of the Safe-Operating Window: It's More Than Just Density
Authors: Hemphill T.
Published: December 2007

The drilling of challenging wells, especially those in deepwater, high pressure / high temperature (HPHT), and extended reach environments, is often characterized by a narrow safe operating window between formation pore pressure and fracture gradient.Overstepping the window bounds can lead to unwanted incidents of well control and/or lost circulation. In the drilling literature, the management of the safe operating window while drilling has heretofore focused on the optimization of circulating pressure drop, hole cleaning, and rate of penetration, with little consideration of wellbore geomechanics.

Maintenance of wellbore stability (WBS) while drilling is critical to the success of today's challenging wells, yet applications of such modeling have largely centered only on predictions of surface drilling fluid density requirements.In this paper, an integrated approach using the following items is taken to show the utility of incorporating drilling fluid hydraulics and barite sag potential in the wellbore construction process.The use of this technology can help the drilling industry avoid unwanted surprises that can lead to unstable wellbores while drilling in today's technically-challenging environments.
Use of Streamlines and Quality Map in the Optimization of Production Strategy of Mature Oil Fields
Authors: da Silva Guimarães M. S. , Schiozer D. J. , Maschio C.
Published: December 2007

Proposal

Developed or mature oil fields can be considered as sets of reservoir that present production strategy already established and implemented, generally presenting production in the decline phase. Changes in geologic characterization or economic or technologic scenarios can demand changes of the production strategy, requiring the application of an optimization process. The optimization process of developed or mature oil fields presents different characteristics from fields in beginning of production, mainly regarding flexibility for changes. The existence of production data allows the improvement of the geological characterization of the reservoir and the reduction of the uncertainties allowing a more detailed optimization procedure.

The objective of this work is to develop an automated optimization methodology combining the utilization of three important tools: traditional simulation, streamline simulation and quality map. The traditional simulation is used to give reliability to the process. The streamline simulation and quality map are supporting tools employed to give more reliability and to bring up insights about the optimization process and speedup to the process, mainly in the control of water injection and production and in the possible allocation of news wells.

The proposed methodology had been applied to an offshore field with water injection. The results show that the efficient control of fluid flow and the better understanding of the overall process provided by the supporting tools allow the determination of production strategy that improved the economic recovery of the developed or mature field studied. Additionally, the developed methodology allows the definition and the organization of the possible changes, making feasible the automation of part the process.
Determination of Gas Trapping With Foam Using X-Ray CT and Effluent Analysis
Authors: Nguyen Q. P. , Rossen W. R. , Zitha P. L. J. , Currie P. K.
Published: December 2007

Foam is used worldwide to improve acid placement in matrix acid treatments and redirect gas flow in improved oil recovery. Gas trapping is a major factor in foam processes: it affects foam mobility and controls diversion of liquids such as acid injected after foam. Most previous studies of gas trapping have relied on fitting effluent gas tracer profiles to a one-dimensional (1D) model for transport of tracer in the presence of trapped gas, including mass transfer between flowing and trapped gas. We present new experiments where X-ray computed tomography (CT) directly determines the gas tracer distribution in situ. The key is using a gas-phase tracer (Xe) visible in CT. The CT images show clearly that the standard 1D model used to interpret tracer effluent profiles is incorrect in its assumptions. For the first time here we compare the in situ tracer distribution from CT images to the trapped-gas saturation estimated from fitting the effluent tracer profile to the 1D model, augmented here for the effect of pressure variation along the core. The effluent profile is determined indirectly from the CT images in two ways: by imaging the tracer concentration in the flow line downstream of the core, and using a mass balance on tracer in the core. Estimates of trapped-gas fraction using the 1D model vary by as much as 0.2 among reasonable fits to the effluent data, and flowing gas fraction by as much as a factor of 1.5 or 2. The experiments span a range of foam qualities and injection rates in Bentheim sandstone. Model-derived estimates of trapped-gas fraction decrease with increasing gas injection rate and increase weakly with increasing liquid injection rate in our experiments. The CT images show a shift to a wider variety of fluctuating flow paths as liquid or gas injection rate increases.
A Methodology for Drilling Through Shales in Environments with Narrow Mud Weight Window (NMWW)
Authors: Araújo E. M. P. , da Fontoura S. A. B. , Pastor J. A. S. C.
Published: December 2007

Shales, in general, are the major source of wellbore stability problems. A particularly critical drilling scenario is the one that combines deepwater and shallow overburden, typical of ultra deepwater fields in Brazil. This scenario is characterized by high pore fluid pressure, low effective stresses, low fracturing gradients and narrow mud weight windows (NMWW). In order to drill under these conditions, it is necessary to establish means to increase the mud weight window. In this paper, we demonstrate that it is possible to increase the mud weight window by changing conveniently both drilling fluid pressure and salt concentration. A robust computational procedure is established in order to evaluate the size of the plastic zone around the wellbore as a function of the drilling fluid pressure and salt concentration and time of rock exposition to the drilling fluid. The final width of the mud weight window will depend upon the size of the failed zone that can be tolerated by the design.
Cost-Effective Drilling Optimization Technologies in Campos Basin
Authors: Paes P. , Aragão A. , Chen D. C-K.
Published: December 2007

This paper discusses a specially tailored cost-effective optimization program for drilling the Campos Basin and adjacent areas. Available well data show that the majority of the drilling problems are related to hydraulics issues such as lost circulation, kick, etc., and to equipment failure. Thus, with new and planned wells, the emphasis has been focused on the use of PWD sensors to closely monitor the ECD. Other important technologies used include vibration sensors and formation pressure evaluation, and related phenomena. Over the past three years, 62 drilling optimization operations were completed in Brazil, particularly in the Campos Basin area. They have substantially reduced the drilling cost, reduced non-productive time (NPT), and increased drilling efficiency. Most importantly, drilling optimization operations have added very little to the cost of the routine MWD services that had been in use.
Pulse-Rotating Jet System Acidizing in a Campos Basin Deepwater Horizontal Gravel Packed Injection Well
Authors: Pereira A. Z. I. , Calderon A. , Chagas C. M. , de Camargo C. , da Motta E. P. , de Miranda A. A. , de Santana J. P. F. , Acosta M. , Zacarias O. G. , Farias R. L. , Almeida V.
Published: December 2007

In most of its deepwater Campos Basin oilfields, Petrobras' strategy has been to develop the water flooding systems using horizontal gravel packed wells. Both drilling and gravel pack operations are only possible through the presence of a filter cake, formed on the formation face during the drilling process. Nevertheless, that film becomes an impediment to injection and must be removed to obtain good injectivity.

Special tools were developed to perform acidizing jobs, in one trip, just after the gravel packing operation. However, there were few alternatives to correct any eventual acidizing lack of performance, besides using coiled tubing and straddle packers, something that usually takes too much time.

Recently, a pulse-rotating jet tool system was applied in a well that could not be treated after the gravel pack operation. The tre atment, which is simpler and faster than those carried out with straddle packers, was performed in two stages: the first, using just HCl, and the last one, using mud acid.

The subsequent formation test performed after the HCl treatment showed a high skin value and an unacceptable injectivity index, due the need to keep the reservoir pressure above the bubble point. Even so, the test data in association with reservoir simulation, according with the field geology, showed that there was fluid injection throughout the entire horizontal section. Therefore, it was decided to perform a mud acid treatment, again, using the pulse-rotating jet tool system.

This time, a second formation test indicated an excellent injectivity index, confirming the pulse-rotating jet tool system effectiveness and creating perspectives for the application of this technique in future operations.

This paper will describe the technique, job details and the results obtained for this particular operation, which may be applied in other similar offshore environments.
Comparison of Techniques for Risk Analysis Applied to Petroleum-Field Development
Authors: Ligero E. L. , Madeira M. G. , Schiozer D. J.
Published: December 2007

Proposal

Petroleum field decision-making process is associated to high risks due to geological, economic and technological uncertainties, and high investments, mainly in the appraisal and development phases of petroleum fields. In these phases, it is necessary to model the recovery process with higher precision increasing the computation time to represent all possible scenarios. The necessity to speedup the process demands simplification of the process. The use of Monte Carlo technique, for instance, is normally not viable when numerical flow simulation is used to model the recovery process due to the high number of simulations required. The use of the derivative tree technique can be an alternative in such a case but it also yields a high number of simulations when several attributes have to be considered. An alternative, in such cases, is to use fewer attributes or to use a lower number of discretization levels. Another alternative is to simplify the reservoir modeling process with faster models. Several works are being presented recently about these techniques but normally they show applications but not a comparison among alternatives. The objective of this work is to compare these techniques taking into account the reliability and precision of the results and speed up of the process due to the simplifications. Monte Carlo and derivative tree techniques are compared using reservoir simulation, sensitivity analysis, experimental design and response surface method as supporting tools. These techniques are applied to an offshore field to quantify the risk in economic and technical parameters. The results show that it is possible to reduce significantly the number of flow simulation runs maintaining the precision of the results.
Rigorous Approach for Viscous-Oil Productivity Forecast Before Well Completion
Authors: de Andre C. , Cañas J. A. , Low S.
Published: December 2007

This paper describes an integrated and rigorous approach for viscous and middle oil reservoir productivity evaluation using petrophysical models calibrated with permeability derived from mini tests (Dual Packer) and Vertical Interference Tests (VIT) from open hole wire line testers (MDT *). It describes the process from Dual Packer Test and VIT pre-job design, evaluation via analytical and inverse simulation modeling, calibration and up scaling of petrophysical data into a numerical model, history matching of Dual Packer Tests and VIT with numerical simulation modeling. Finally, after developing a dynamic calibrated model, we perform productivity forecasts of different well configurations (vertical, horizontal and multilateral wells) for several deep offshore oil reservoirs in order to support well testing activities and future development strategies.

The objective was to characterize formation static and dynamic properties early in the field development process to optimize well testing design, extended well test (EWT) and support the development strategies in deep offshore viscous oil reservoirs. This type of oil has limitations to flow naturally to surface and special lifting equipment is required for smooth optimum well testing / production.

The integrated analysis gave a good overall picture of the formation, including permeability anisotropy and fluid dynamics. Subsequent analysis of different well configurations and lifting schemes allows maximizing formation productivity.

The simulation and calibration results are compared to measured well test data. Results from this work shows that if the various petrophysical and fluid properties sources are integrated properly an accurate well productivity model can be achieved. If done early in the field development program, this time / knowledge gain could reduce the risk and maximize the development profitability of new blocks (value of the information1).
Development of an Optimization/Economic Model for Virtual Gas Pipelines
Authors: de Sa Neto A. , Filho V. J. M. F. , Moulin R. G. , Fiuza C.
Published: December 2007

This is the first of a series of papers describing the application of simulation-optimization methods coupled with an economic model to "Virtual Gas Pipelines". Virtual Gas Pipelines consist in transporting compressed (CNG) or liquefied natural gas (LNG) in tanks to remote locations.

In this paper we apply the use of a Virtual Gas Pipeline to a CNG system (compressed natural gas systems). This system is composed by a mother station (compression station with truck upload) with "n" satellite stations (delivery points). The results presented here illustrate the potential in cost-effectiveness that can be made by employing logistics simulation as the foundation for a wide-ranging search for solutions to gas transportation problems.

Two models are developed for a virtual CNG pipelines: a simulation model and an economic model to represent the process of transporting using of trucks. These models are integrated.

A field application case is detailed for CNG for vehicular use (NGV) with many NGV sale stations. Important optimization aspects are discussed such as mother station size, location, gas load distribution, number of loads, truck use and others. Economics aspects are also discussed specially presenting cutoff parameters for determining the application of Virtual Pipelines. Service level efficiency and also business profitability are two key elements of this integrated analysis

This methodology can be adapted for the use of other technologies to a Virtual Gas Pipeline System. These new technologies can be another gas transformation method such as liquefaction (LNG) or another gas transportation system such as shipping (barges).
Advanced Risk Analysis Approach for Optimization of a Water Injection Program -Illustration on a Brazilian Field Case
Authors: Manceau E. , Feraille M. , Zabalza-Mezghani I. , Portella R. C. M. , Reis L. C.
Published: December 2007

This paper presents an advanced risk analysis approach that has been applied on a Brazilian field case to manage and quantify the reservoir uncertainties during production forecasting and production scheme optimization.

The oil field (named PBR) is located offshore Brazil. The PBR reservoir consists of a complex lithology, including mainly turbiditic sandstones interbedded by shales and marls. The workflow of the PBR reservoir modeling from the geostatistical lithofacies model, built using the non-stationary truncated gaussian method, to the flow model (about 24000 active cells) has been implemented in a fully integrated chain. The field was considered in this hypothetical study at its appraisal stage. Main challenge consisted in selecting an optimal water injection scheme to maximize oil production while minimizing water production and maintaining pressure over the 15 years of production, taking into account the overall major sources of uncertainties in the reservoir.

Advanced risk analysis methods were used with the following objectives:

– Determine the impact of the main uncertainties on the field production forecasts versus time and versus geographical locations of production and injection wells – Optimize the water injection phase to maintain pressure over time, while producing maximum oil and minimum water in a 15-years period. – Quantify the impact of main uncontrollable reservoir uncertainties on production forecasts and fluid distribution maps versus time for the optimal water injection program selected in order to identify potential risks with non-drained zones and pressure drops.

At each step, either classical or optimal experimental designs were used to be able to perform an accurate analysis at a minimum cost in terms of reservoir simulation and interpretation.

Results show that this innovative methodology can be successfully applied on complex real cases to quantify the risk associated with the main reservoir uncertainties during production forecasts and to optimize the water injection. In particular, this example illustrates how some innovative interpretation tools can be combined with experimental design methodology to perform advanced risk analysis for reservoir management.
Compositional Modeling of Retrograde Gas-Condensate Reservoirs in Multi-Mechanistic Flow Domains
Authors: Ayala L. F. , Ertekin T. , Adewumi M.
Published: December 2007

A multi-mechanistic flow environment is the result of the combined action of a Darcian flow component (the macroscopic flow of the phase due to pressure gradients) and a Fickian-like or diffusive flow component (diffusive flow due to molecular concentration gradients) taking place in a hydrocarbon reservoir. The present work presents the framework needed for the assessment of the impact of multi-mechanistic flow on systems where complex fluid behavior-such as that of retrograde gas-condensate fluids-requires the implementation of compositional reservoir simulators. Due to the complex fluid behavior nature of gas-condensate fluids, a fully-implicit (IMPISC-type) compositional model is implemented and the model is used for the study of the isothermal depletion of naturally fractured retrograde gas reservoirs. In these systems, especially those tight systems with very low permeability (k < 0.1 md), bulk fluid flow as predicted by Darcy's law might not take place despite the presence of large pressure gradients. The use of an effective diffusion coefficient in the gas phase—which accounts for the combined effect of the different diffusion mechanisms that could take place in a porous medium—and its relative contribution to fluid recovery is discussed. The compositional tracking capabilities of the model are tested and the conditions where Fickian flow can be the major player in recovery predictions and considerably overcome the flow impairment to gas flow posed by the eventual appearance of a condensate barrier—typical of gas-condensate systems—are investigated. Finally, a mapping that defines different domains where multi-mechanistic flow can be expected in compositional simulators of retrograde gas-condensate reservoirs is presented.
Decline-Curve Analysis for Solution-Gas-Drive Reservoirs
Authors: Frederick J. L. , Kelkar M.
Published: December 2007

This paper introduces a new method for analyzing solution-gas production to determine the ultimate recovery of a well or a field. The procedure developed and outlined in this paper requires very little input data and is easily implemented. By modifiying the equations for dimensionless rate and dimensionless cumulative production derived for the single phase model, a new set of equations is developed to approximate the ultimate recovery of a solution-gas well. Using the approximate material balance equation based on numerical results by Vogel1 and the equation for the production rate derived by Fetkovich et al.2,3,4, this new set of dimensionless rate and dimensionless cumulative production equations are derived. Using the relationship between these equations and an iterative calculation procedure, the ultimate recovery for the solution-gas well can be easily determined. All that is needed as input is the producing bottom-hole pressure, the initial pressure, and the oil production data. The method has been validated with twelve simulator cases, six under constant bottom hole pressure production constraint and six under variable bottom hole pressure production constraint. Furthermore, several field cases have been analyzed. The synthetic and field cases validate the procedure. Using the early pseudo-steady state production data in the analysis the results generated by the method are consistent with the actual ultimate recoveries.
Design and Implementation of a Computer-Based Tool for Risk and Impact Assessment of the Environmental Pollution in the Niger Delta Using Simulation Method
Authors: Igbokwe C. M. , Olofinlade A. V. , Ojegbile A. V. , Aroh A. O.
Published: December 2007

This paper presents the design and implementation of risk and impact assessment of a tool that helps quantify and manage uncertainty to aid strategic decision-making over the life of an asset. The dynamic and iterative nature of the tool and the processes involved allows for rapid, quantitative systems analysis of the impact of a wide number of options with their associated uncertainty (risk). The result is a robust method to understand the risks and potential value of the prospective enterprise on an ongoing basis through development, operation, and expansion phases. Implementation of the tool over the entire life cycle of an asset is simulated, discussed and illustrated with two case studies.
Significant Results in Field Trials (Argentina) of an Electronically Controlled Automatic Drilling System
Authors: Fernández M. , Ibáñez D. , Storey G.
Published: December 2007

An Electronically Controlled Automatic Drilling System has shown significant results in improving drilling efficiencies in the Entre Lomas Field located in Neuquen province, Argentina. The new generation of electronic, automatic brake controllers available for land rigs and band brakes delivers increased drilling efficiencies and problem avoidance. An important reduction in total rotating hours has been obtained, by both increasing rates of penetration (ROP) and improving bit life.
Effect of Flue Gas Impurities on the Process of Injection and Storage of CO2 in Depleted Gas Reservoirs
Authors: Nogueira M. C. , Mamora D. D.
Published: December 2007

Our previous coreflood experiments - injecting pure CO2 into carbonate cores - showed that the process is a win-win technology, sequestrating CO2 while recovering a significant amount of hitherto unrecoverable natural gas that could help defray the cost of CO2 sequestration. In this paper, we report our findings on the effect of "impurities" in flue gas - N2, O2, H2O, SO2, NO2, and CO - on the displacement of natural gas during CO2 sequestration. Coreflood experiments were conducted at 1,500 psig and 70°C, in which a flue gas was injected into a carbonate core containing initially methane. Two types of flue gas were injected: dehydrated flue gas with 13.574 mole % CO2 (Gas A), and treated flue gas (N2, O2 and water removed) with 99.433 mole % CO2 (Gas B).

Main results of our study to-date are as follows. First, during displacement of methane, the dispersion coefficient increases with concentration of the "impurities". Gas A exhibits the largest dispersion coefficients, 0.18 - 0.25 cm2/min, compared to 0.13 - 0.15 cm2/min for Gas B, and 0.15 cm2/min for pure CO2. Second, for all cases, recovery of methane at breakthrough is relatively high, ranging from 86% OGIP for pure CO2, 74-90% OGIP for Gas B, and 79-81% for Gas A. Lastly, injection of Gas A would sequester the least amount of CO2 as it contains about 80 mole % nitrogen. From the view point of sequestration, Gas A would be least desirable (though the cheapest separation process). Gas B (flue gas with N2, O2 and water removed) appears to be the most desirable as separation cost would probably be cheaper than that for pure CO2 while natural gas recovery are similar in both cases.
Interface Management for Subsea Sand Control Completion
Authors: Crumrine T. , Nelson R. , Cordeiro C. , Loudermilk M. , Malbrel C. A.
Published: December 2007

Poor interface management can lead to time overruns and negatively impact the relationship between time, cost, scope, quality, and resources.The trend of streamlined organizations with reduced staffing often requires companies to rely on mul-tiple parties to complete a project.Even with the trend of streamlining, deepwater operators are challenging themselves to drill more complex wellbore architectures, and subsea sand control completions are becoming increasingly intricate.The development of such wells poses particular risks due to the completion complexity and requires a high degree of interface management to ensure operational success.

Interface management (IM) problems lead to scope creep in which the balance between project scope, time, cost, quality, and resources is upset.The objective of this paper is to pro-vide a roadmap in dealing with interface management issues early on in the project life cycle, so that potential problems can be mitigated and scope creep can be eliminated. The goal is to help provide a fit for purpose and high quality completion system delivered on time and within budget.

The objective is accomplished by first investigating Interface management, and second using proven project management techniques to solve common problems associated with poor IM.Third, three subsea sand control completion cases are reviewed in which proper IM was used to provide successful project results.An additional case review provides insight on IM outside of the oil and gas industry.Finally, an IM "road-map" is provided to assist the reader in developing their own IM philosophy.While the scope is limited to sand control completion systems, the IM techniques presented can be ap-plied to all aspects of the industry.
Well Succeeded Examples of Mature Waterflood Project Revitalization
Authors: Dõria M. A. F. S. , da Silva A. W. , Franco C. A. C. , do S. M. S Batista M. , De C. J. A. M.
Published: December 2007

Carmópolis, Siririzinho and Riachuelo oil fields, located onshore Northeast region of Brazil, were discovered in the sixties and quickly put into primary production. Waterflooding followed in the seventies, trying to restore reservoir pressure and well productivity.

For more than twenty years, oil production in these fields was maintainned under infill drilling and addition of new areas to the waterflood projects. Since production has reached its technical and profitable limits, oil rates has reversed to a deep decline.

A strategic IOR project conducted by PETROBRAS focused on improving waterflooding efficiency in Carmópolis field, led to significant changes on the management of that field and Siririzinho and Riachuelo fields as well, and supported the revitalization process of these fields.

The results were not only a total reversion but also an increasing in oil production profile that was declining for more than ten years. This work presents the results of the revitalization program in the mature waterflooding projects of Carmópolis, Siririzinho and Riachuelo fields, showing the importance and influence of each decision made during the project implementations.
A Case Study of Value Generation with Intelligent Well Technology in a High Productivity, Thin Oil Rim Reservoir
Authors: Elmsallati S. M. , Davies D. R. , Erlandsen S. M.
Published: December 2007

The Application of Intelligent (or Smart) Well Completion Technology (IWT) has not progressed as rapidly as originally expected. This is partly due to management's lack of confidence that the "added value" is sufficient to justify the extra investment. This concern can be addressed by publication of well-documented examples of IWT delivering value.

This paper describes the detrmination of the "added IWT value" from maximising oil production, within allowable gas constraints, for the Norwegian NH-field that produces from a thin oil-rim using high productivity, horizontal-wells. The well drawdown is similar, or lower, than the frictional pressure drop along the completion length. This generates a skewed production profile along the length of the completion; the bulk of the oil production - and early gas and water break-through - occurring at the heel of the well. This is further accentuated by the presence of a tilted, high-permeability sand that connects the heel of the well to the gas cap. A further complication is that the bubble point is close to the initial reservoir pressure (in fact at the gas-oil-contact, the saturation pressure and the reservoir pressure are identical) and 34% of the total Hydrocarbon Liquid is associated condensate in the gas cap.

This paper not only shows how the "added IWT value" was derived, but also the: Development of a well-performance management philosophy,Optimisation of the conventional well using a sector of the full-field model,Insertion of a detailed, Intelligent Well (I-well) completion model within this model,Development of an I-well design and operation philosophy,Illustration of the advantages, disadvantages and utility for well optimisation of available keywords within commercial simulation packages.

Finally, understanding how the I-well Completion "adds value" allows the development of guidelines for the choice of candidate wells in this type of reservoir where IWT is capable of delivering value.