bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Dynamics of Vertical Pulse Testing in a Slab Reservoir
Authors: Falade Gabriel K. , Brigham William E. 
Published: December 2007

Introduction
Pulse testing, as a practical method of reservoir analysis, was introduced into petroleum engineering literature by Johnson et al. in 1966. Since then, several authors have discussed, expanded on, or applied some of the basic concepts of horizontal pulse testing. Pulse testing as originally formulated by Johnson et al. can provide two pieces of information from which the reservoir transmissibility (T = krh/Î¼) and storage (S = Î¦cth) can be obtained. It does not address itself to the problem of evaluating the in-situ vertical permeability, which is important in reservoir processes where there is appreciable vertical flow.
It has been recognized that vertical interference testing has considerable promise for simultaneous evaluation of the horizontal and vertical permeability; however, no one has considered the use of multipulse tests and the Johnson gradient method for this purpose. This is despite the inherent advantages of multipulse testing over the other techniques.
The objective of this paper is twofold:to examine the behavior of multipulse pressure transients in a vertically pulsed slab reservoir, noting the effect of the finite characteristics of the reservoir, andto generate correlation curves, based on known pressure response characteristics, for interpreting dynamic data from pulse-tested reservoirs.
History Matching of Laboratory Coreflooding Experiments
Authors: Fincham A.E. , Ferreol B. 
Published: December 2007

Abstract
This paper describes a new program (Caropt) which analyses data from dynamic coreflooding experiments and simultaneously estimates relative permeabilities and capillary pressures. Relative permeability curves are parameterised using a new modified form of standard spline interpolation that allows more flexibility in their functional form. Caropt has proven to be both robust and efficient in practice. Examples are given of the application of Caropt to two laboratory coreflooding experiments. The results produced with Caropt show that capillary pressure has a significant effect on the predicted relative permeability curves.
P. 95
Novel Cements Materials for High-Pressure / High-Temperature Wells
Authors: Noik Ch. , Rivereau A. , Vernet Ch. 
Published: December 2007

Abstract
The two primary technical objectives for well cementing are to isolate the producing formation reservoir and to support the casing. The development of deep offshore drilling and HP/HT formulations leads to improve the quality of such operations and needs performant materials.
The present paper focused on new cement composition developed for high temperature wells. Materials is composed with classical Portland cement and silica particles. The original idea of this work is to control and manage with the different component granulometries. At least two types of silica have been used, one is composed of crushed sand particles and the other is silica fume with respectively mean particles size of 30um and 0.1um. Considering the granulometry partition of class G Portland cement, the choice of grain size distribution of silica which partially overlaps the cement one, permitted to adjust the compacity of the powder content system.
Then the water quantity is optimised in relation with the cement primary porosity in order to fill the vacant site between grains and assure the slurry rheology. The consequences on the setting material is to improve the durability and the mechanical strength and decreasing the permeability specially at temperature above 100 C. Good performances were noticed through varying test conditions including: Classical API tests, rheological measurements and durability tests in sea water in the presence of gas.
P. 189
Optimum Offshore Development Schemes Selected with Computer Assistance
Authors: De Ghetto G. , D'Amato M. , Buelli M. , Negri I. , Giacometti L. , Bonuccelli M. , Ferretti C. , Basana R. , Berti D. 
Published: December 2007

Abstract
Reducing the development time to first oil is crucial for oil companies. especially for offshore where, often, large capital commitments are necessary. It is vital to determine the optimum development scheme quickly and efficiently. The process is made more difficult because of the necessity to combine and enhance, often by trial and error, the vast amount of information and data from a variety of sources such as reservoir, drilling, completions, artificial lift, offshore structures. marine operations and project economics. To facilitate this task, we have developed a decision support system that can quickly process all available data from reservoir to export, and determine the technically feasible developments schemes. Project economics are evaluated simultaneously with technical parameters. The system contains a variety of environmental and geographical databases and costs for drilling and completions, offshore structures, marine operations, oil and gas processing, etc. The program determines designs of multiphase pipelines (well and surface), floating vessel requirements, risers and moorings, oil and gas processes. The decision support system evaluates also feasibility development schemes and economics in situations where there is a lack of information such as exploration and appraisal phases.
P. 259
Treating Flow-Rate Uncertainty in Pressure Transient Analysis
Authors: Ovens J.E.V. 
Published: December 2007

Abstract
Pressure transient analysis (PTA) relies on the input of information from a variety of sources; pressures from downhole gauges, flow-rates from surface test separators, PVT properties from Lab measurements and geometric properties such as formation height from, for instance, logging. The traditional methods of analysis such as the Horner plot, the Skin plot and even history matching of the full test signal, all try to match the pressure response while implicitly assuming that all the other sources of information have no uncertainty, however, it is almost universally acknowledged that the measurement of flow-rate is possibly the least accurate source of information.
In this paper, this paradox is addressed and a remedy is proposed.
A Monte-Carlo program is used to examine the contribution that uncertainty in flow-rate measurement makes to the overall uncertainty in the estimates of permeability, skin and nonDarcy skin in a multi-rate gas test, using the traditional Horner analysis/ skin plot technique. From this example, it is shown that rate uncertainty completely dominates the errors in output parameters. A new algorithms is outlined for treating rate uncertainty in this type of analysis; the algorithm is based on the problem of fitting a straight line through a set of points where it is known that there are errors in both the dependent and independent variables. Using the Monte-Carlo technique, the paper demonstrates that the new algorithm reduces uncertainty in computed parameters. Finally, an outline is presented as to how the concepts developed above may be applied to the full history matching process.
P. 297
Relations Between Ultrasonic Amplitude and Petrophysical Characteristics
Authors: Chelini V. , Meazza O. , Verhoeff E.K. 
Published: December 2007

Abstract
Empirical evidence suggested that Ultrasonic Amplitude by CBIL tool could be related to formation porosity. A core plug container was designed to investigate this relationship under a variety of controlled conditions. The container holds a number of plugs, radially distributed around the tool transducer. With this experimental setup three different experiments have been carried out. Sandstone, limestone and dolostone samples saturated in water and light hydrocarbon have been used to evaluate the amplitude-porosity relation. The third experimental setup to study the effect of different mud systems on the aforementioned relation has been carried out. The Ultrasonic Amplitude has a distinct linear relation with the core plug porosity for each lithology. The presence of hydrocarbon in pore space increases the CBIL amplitude. The effect of the mud attenuation on the amplitude is independent of the porosity. Measurements of attenuation provide a possible calibration of the amplitude for the downhole environment to the amplitude measured in water. The observed relationships are supported by current theory and model studies. The relation between the CBIL reflection coefficient and plug permeability has also been investigated. The results are applied at downhole acquisitions to evaluate the porosity of the formation using the CBIL amplitude.
P. 307
Tin Fouye Tabankort Gas Field - How Understanding of Abnormal Fracture Propagation and Reservoir Uncertainties Led to Successful Hydraulic Fracturing Operations
Authors: Baylocq Pascal , Sahnoune Abdelkader , Martin Antonio , Sims Michelle 
Published: December 2007

Abstract
Development of the Tin Fouye Tabankort Gas Field, located approximately 600 miles South-Southeast of Algiers, was initiated in 1996 with the simultaneous start-up of surface facilities construction, workovers of existing wells and drilling of new wells, The evaluation of hydraulic fracturing operations was an important step in the formulation of the optimal development strategy for this complex Ordovician age sandstone reservoir. However, production performance and hydraulic fracturing design were uncertain due to large reservoir uncertainties (heterogeneity's, kh, skin, presence of natural fissures, etc.) and doubts about the fracture height growth behaviour.
To overcome these uncertainties, a complete set of measurements were performed including pre and post- hydraulic fracturing well tests, minifracturing on all wells including some bottom-hole pressure recording, temperature logs, and radioactive isotope tracing in both gel and proppant. Analysis of the collected data allowed a better understanding of reservoir characteristics, the influence of natural fissures on fracture design, and fracture growth behaviour. Indeed, results showed that the radioactive shale immediately above the IV-3 reservoir was often not a barrier to fracture growth.
With this knowledge, perforation and hydraulic fracturing strategies were steadily improved to maximize post-job production, and optimize project economics, Results proved to be very successful with the average production increasing by a factor of 5 at significantly reduced drawdown pressures.
P. 361
An Integrated Approach For Evaluating Matrix Stimulation Effectiveness And Improving Future Design In The Gullfaks Field
Authors: Kotlar H.K. , Karlstad S. , Jacobsen S. , Vollen E. 
Published: December 2007

Abstract
Production decline in several wells in the Gullfaks field in the Norwegian sector of the North Sea has been attributed to various formation damage mechanisms. These include fines migration, scale formation, relative permeability changes after floodwater breakthrough, possible emulsion formation and byproducts of bacteria. To address this decline, many types of treatment operations are employed.
This paper describes how a software program for design of matrix acidizing treatments has been validated for the Gullfaks field. Emphasis has been given to sensitivity analysis of this particular software as a function of variations in critical design parameters. The paper also describes how this program, StimCADE, has been used as an integrated part of a chain of analytical engineering applications, introduces a complete design methodology for possible identification of the damage mechanisms.
The method revolves around analyzing each well's historical production data, immediately before and after a given treatment operation, for changes in reservoir skin using nodal analysis. The actual treatment parameters of the chosen job are input to the StimCADE simulator. The pre-treatment actual and predicted skin values are calibrated to one another by adjusting various input reservoir parameters in either one or both of the nodal analysis and StimCADE programs.
Differences between the post-treatment actual and predicted skin values are interpreted to determine the formation damage mechanism. This improved damage determination is used to design more effective future treatments. The subsequent skin reduction prediction from the StimCADE program is input into nodal analysis to assess the production and thus economic impact of the new design.
Four wells in the Gullfaks field in the Norwegian Sea, operated by Statoil, serve as the basis for a case study. Recommendations are made on how to extend the technique to other similar fields.
P. 413
Downhole Separator Produces Less Water and More Oil
Authors: Verbeek P.H.J. , Smeenk R.G. , Jacobs D. 
Published: December 2007

Abstract
A downhole oil/water separation system is operational since 1997 in the Eldingen field located east of Hannover (Germany). The installation is the first successful demonstration of the downhole separation concept outside North America. The well produces light oil with a high watercut from a consolidated sandstone reservoir. Originally eighty cubic metres of fluids were produced daily with the assistance of a beam pump. The new well completion consists of a hydrocyclone for oil/water separation and of electric submersible pumps for drawdown and for re-injection of the separated water. The downhole separator increases the effective capacity of the flowline thereby debottlenecking the Eldingen production system. By recompleting the well, net oil has increased by a factor of three, whilst net water has decreased threefold. In the first year of operation re-injection of water, separated downhole, didn't cause any damage to matrix permeability, however, an increase of the watercut in the project area is observed.
P. 429
New Applications for Enzymes in Oil and Gas Production
Authors: Harris R. E. , McKay I. D. 
Published: December 2007

Abstract
Historically, enzymes have been used in the oil industry both for improving the characteristics of a range of biopolymers employed in the industry and as breakers for biopolymer gels.
Until recently, the use of enzymes downhole was limited to gel breaking applications where suitable enzymes are used to break down or degrade a specific gel. In this case, the enzyme is used to remove a chemical which is no longer required, such as biopolymers in filter cakes following drilling or in tracing gels after the frac has occurred.
More recently, enzymes have been used to produce useful chemicals in-situ. An enzyme-based method has already been reported which generates organic acids for a variety of acidizing applications such as matrix acidizing, the stimulation of natural fracture networks, damage removal over long horizontal intervals or gel breaking. The generation of acid in-situ following placement of the fluid ensures the even delivery of acid over the whole of the treated zone.
The use of enzymes for generating useful oilfield chemicals has now been extended. Examples in the use of enzymes for the in-situ generation of minerals, gels and resins with potential for use in applications such as water shut off and sand consolidation are now reported.
A Review of Injection Modes and Associated Skin Values for Vertical Wells in High-Permeability Reservoirs
Authors: Lietard Olivier 
Published: December 2007

Abstract
Water injection and stimulation treatments in vertical wells are routine techniques. Injectivity index forecast is however still a problem for many production technologists.
This paper aims at describing the various injection modes a vertical well in a high permeability reservoir experiences when increasing the injection rate. The apparent skin value is derived for each mode and is used to estimate the stabilized injectivity index of the well.
The following injection modes are considered: partial completion matrix flow, damage breakthrough with vertical extension of a forced fracture, radial forced fracture and forced fracture with lateral extension (PKN). Horsepower requirements are calculated in each case. In addition, Step Rate Tests are analytically simulated and discussed.
An actual multi-rate injection test is presented to support the theoretical developments of this paper.
P. 487
Simultaneous Determination of Gas and Liquid Compressibility Factors for Gas Condensates
Authors: Potsch K.T. 
Published: December 2007

Abstract
The compressibility factors for the gas and liquid phases are not directly measurable during a PVT-experiment. Empirical correlations or EOS give just rough estimates. This work presents a method for determining both compressibility factors from volumetric measurements by parameterizing their functional form and finding the coefficients by linear regression. As an alternative an iterative procedure is suggested.
P. 555
Production Forecasting of an Unstable Compacting Chalk Field Using Uncertainty Analysis
Authors: Hegdal T. , Dixon R.T. , Martinsen R. 
Published: December 2007

Abstract
Accurate production forecasting is a critical factor in an oil company's management and decision making. The production forecast forms the basis for long term planning and decision making, investment decisions and to set performance targets for the organization. For the Valhall field, offshore Norway, forecasting has proved to be difficult as a single discrete event, like the failure of a key producer, can reduce annual average production by up to 10%. The current activity level at Valhall is at an all time high, with two drilling rigs occupied with drilling of new production wells, adding up to 12 new, long reach horizontal wells to the production potential yearly. Accurate prediction of drilling time and initial well rates has proved challenging, adding significant uncertainty to the production forecast.
Past years forecasting performance has demonstrated that single most likely' prediction of future production is inadequate for management and planning purposes. Based on this an effort was initiated to improve the forecasting methodology and procedures with special emphasize on handling of uncertainty in Short Term Production Forecasting (STPF). With the STPF being an ongoing effort throughout the year, the preferred methodology should balance the need for using techniques that adequately handle complex relationships while still being efficient and relatively easy to apply in the daily work situation.
A spreadsheet based approach to the problem is described, where the standard parameters that impact the future production of most oil fields are handled, as well as the special challenges faced in predicting the performance of the Valhall field. The proposed methodology shows how a customized spreadsheet and use of commercially available statistical analysis ad-ins allows for traditional deterministic production forecasting, partially probabilistic analysis or fully integrated uncertainty analysis. The resulting forecasts assign probabilities to all outcomes as well as a ranking of the uncertainties in the form of a tornado chart.
The approach is not unique, as some companies are using techniques based on similar concepts. The specific challenges at Valhall adds additional layers of complexity, and requires extensive integration of the various risk elements.
In addition to having an effective forecasting tool, communication and integration of knowledge are seen as key success factors in order to improve the short term production forecasting. The production forecast requires input from several departments and many individuals to ensure that the "company knowledge" is fully reflected. A common language's to communicate uncertainty, and an auditable process to ensure buy-in and consistency is critical for a successful outcome, and is equally important when communicating results. This paper discusses both the development and use of the forecasting tool, and the forecasting process.
P. 149
A New Approach to Gas-Liquid Separation
Authors: Stewart A. C. , Chamberlain N. P. , Irshad M. 
Published: December 2007

Abstract
Effective gas-liquid separation is important not only to ensure that the required export quality is achieved but also to prevent problems in downstream process equipment and compressors. Once the bulk liquid has been knocked out, which can be achieved in many ways, the remaining liquid droplets are separated from by a demisting device. Until recently the main technologies used for this application were reverse-flow cyclones, mesh pads and vane packs. More recently new devices with higher gas-handling have been developed which have enabled potential reduction in the scrubber vessel size. This paper will present some of the recent developments in scrubbing technology which have been aided by the use of computational fluid dynamics.
In addition, this paper will review some of the latest compact separation systems which have also enabled a whole new approach to gas-liquid separation to be considered. There are several new concepts currently under development in which the fluids are degassed upstream of the primary separator. These systems are based on centrifugal and turbine technology and have additional advantages in that they are compact and motion insensitive, hence ideal for floating production facilities
Scale Inhibitor Squeeze Treatments in High-Velocity, High-Calcium Wells
Authors: Fielder Glenn D. 
Published: December 2007

Abstract
Application of scale inhibitors by the formation squeeze technique is a common method for mitigating downhole scale in oil and gas wells. Factors which can adversely affect inhibitor returns include high fluid velocity and high calcium concentrations in the produced water. It has been observed that high calcium levels, particularly at higher temperatures, can suppress inhibitor returns both immediately following the squeeze and thereafter. When coupled with high velocity, wells must be retreated frequently to maintain adequate inhibitor residual concentrations. By increasing inhibitor levels through improved adsorption-desorption properties, squeeze life can be lengthened.
Laboratory data have been reported that polymer/phosphonate combinations can improve both inhibition of calcite and the desorption rate of the phosphonate.1 In the current study, dynamic tube blocking and longer term static scale inhibition tests were conducted against both calcite and barite to evaluate the effectiveness of polymer/phosphonate blends for preventing scale. Flow tests in sandpacks were run to determine dynamic adsorption and desorption characteristics of both polymer and phosphonate from blended formulations. Simultaneous or coadsorption of polymer and phosphonate appeared to be a factor in increasing inhibitor returns.
Data from field squeeze applications show the combination inhibitors provided longer squeeze life compared to phosphonate alone in the presence of calcium concentrations in excess of 10,000 mg/L, at temperatures up to 200F and at near wellbore fluid velocities of 0.01 ft/sec. Field data are presented which are in good agreement with computer modeling results that predict the sensitivity to increased velocity.