bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Study of Near-Critical Behavior of Gas Condensate Systems
Authors: Shen Pingping , Luo Kai , Zheng Xitan , Li Shi , Dai Zhijian , Liu Henian 
Published: December 2007

Abstract
Much special attention has been devoted in this paper to the near critical phenomena of gas condensate systems, including the critical points, bubble and dew point locus, dynamically optical phenomena, and especially the unusual phase transitions in near critical region.
The experimental measurements are carried out during constant composition expansions in high-pressure PVT cell. The percentage-liquid volumes in near critical region are crossplotted to determine the critical points in pressure-temperature diagram. The reddish-brown color is observed in near critical regimes for the fluids due to the complexities of components.
What most fascinated and surprised us is that unusual phase phenomena are unexpectedly observed in the near-critical region. That is to say, during the constant composition expansion process the retrograde dewpoint phase change occurs twice above the critical temperature, and correspondingly retrograde-dew and normal-bubble point phase changes occur sequentially below critical temperature. In two cases, the first-appeared liquid at the bottom of PVT cell first disappears at the same lower-pressure during different temperature CCE processes. These unusual phenomena occur simultaneously for the same fluid at temperature high up to about 100°C. As far as we know, this is the first report of such an observation in the literature.
Improved Techniques For Logging High-Angle Wells
Authors: Bratovich M.W. 
Published: December 2007

Abstract
High-angle wells are becoming coin inon place, particularly in offshore areas. Because of this, it particularly in offshore areas. Because of this, it has become important to increase the deviation angles at which wells can be conventionally logged. Moreover, firm planning factors are needed to decide whether to try gravity-descent or pump-down tools as the first attempt at logging high-angle holes. This paper describes work which contributes significantly to both objectives. New equipment has been introduced to reduce hole friction, increase tool weight and flexibility, and provide a surface indication of push or pull forces at provide a surface indication of push or pull forces at the tool head. These devices have been extensively field-tested in wells with deviations ranging from 45 to in excess of 70 degrees, in the Gulf of Mexico offshore area. Maximum deviations successfully logged by use of the new equipment were somewhat less than the limits predicted by theoretical and laboratory work, but there predicted by theoretical and laboratory work, but there has been a dramatic improvement in success ratios for logging these high-angle wells.
Examination of the Effect of Generically Different Scale Inhibitor Species (PPCA and DETPMP) on the Adherence and Growth of Barium Sulphate Scale on Metal Surfaces
Authors: Graham G. M. , Boak L. S. , Hobden C. M. 
Published: December 2007

Abstract
One of the major concerns within the oil industry is how to deal with scale formation, whether it is in the wellhead equipment, downhole pipelines or the actual field formation. This is because as the scale forms, it begins to deposit itself on the linings of the pipelines, within the equipment and the pores of the formation. The layers continue to build and eventually there is no passage through for the oil. The most effective way to deal with the problem of oilfield scale formation is the use of scale inhibitors, in order to prevent or delay the scale formation. In many scale performance studies, the emphasis is on determining scale inhibitor species that prevent homogeneous nucleation and growth, rather than examining their impact on their ability to prevent heterogeneous nucleation and growth at the metal surfaces such as the production tubulars themselves. The adhesion and growth of scale on metal surfaces is clearly a much more serious problem than precipitation within the bulk solution.
This paper presents results from an extensive series of "adhesion" experiments that examine the effectiveness of generically different scale inhibitor products at preventing barium sulphate adherence and growth at metal surfaces. Tests have been conducted under ambient conditions and under both laminar and turbulent flow conditions.
Results demonstrate that the presence of scale inhibitor, at levels marginally below their concentration required to completely prevent crystal growth, results in increased surface adhesion. Similar results are recorded for the different inhibitor species examined. Furthermore, the level of surface adherence is shown to be more severe under laminar conditions than for tests conducted under turbulent conditions. The indication is that bulk precipitation is being reduced by the presence of the SI which encourages the more thermodynamically favourable heterogeneous nucleation to occur onto surfaces already present. The SI then continues to prevent bulk nucleation and slow growth continues at the surface in order to reduce the system’s overall supersaturation. Increased surface growth relates to the effectiveness of the SI at preventing bulk nucleation.
Barium Sulfate Scale Inhibition in the Deepwater Cold Temperature Environment
Authors: Yuan M. 
Published: December 2007

Abstract
One of the flow assurance challenges facing the deepwater oil and gas field development and production is mineral scale control. In a deepwater production system, barium sulfate scale deposition may arise from two causes, namely: a) commingling of injected seawater with connate formation water, and b) temperature cooling from well bottomhole to wellhead and then in a long subsea flowline. The first phenomenon has already been well understood in the offshore oil industry. However, there is very little knowledge in barium sulfate scaling and inhibition mechanisms in a deepwater subsea system, where the fluid temperature can be cooled to a few degrees Celsius. This lack of knowledge is further hampered by the lack of barium sulfate solubility data at the appropriate temperatures.
In this work, barium sulfate solubilities were measured in BaSO4-NaCl-H2O system at 5°C, in which sodium chloride concentrations ranged from 0 to 5 molal in the solutions. This new solubility data is presented in this paper in comparison with the published solubility data for 25°C and 95°C. Significant reduction in barium sulfate solubility from 25°C to 5°C (and even more from 95°C) was noted, which is more pronounced at higher solution ionic strength (NaCl molality). This paper then presents new results from a series of laboratory experiments that investigate the effect of a wide range of temperatures from 95°C to 5°C on barium sulfate scale precipitation and inhibitor efficacy. The inhibitor effectiveness is studied both dependent and independent of barium sulfate scaling tendency change. Both static jar tests and dynamic scale tube-blocking experiments were carried out. It is found that the apparent reduction or loss of inhibitor effectiveness at colder temperatures in a given brine, as seen in the static tests, is mostly due to increased barium sulfate scaling tendency as temperature decreases, while the inhibitor function may have changed little from one temperature to the other. The other interesting finding is that, although the supersaturation of barium sulfate increases considerably as temperature lowers, the kinetic rate of scale precipitation also slows down at colder temperatures. As a result, barium sulfate supersaturation is not the only driving force for it to precipitate, but temperature plays a role as well. This conflict between thermodynamic and kinetic effects of temperature cooling on barium sulfate scaling results in clearly different results between static scale inhibition tests and dynamic tube-blocking tests. That is, in a given brine, a scale inhibitor apparently performs better or equally at a lower temperature than at higher temperature in a flowing system, while apparently performs worse at lower temperatures in a static solution. Also, as far as barium sulfate inhibition is concerned, the two inhibitor chemistries included in this study did not correspond to temperature change or different test methods in exactly the same manner.
Field Experiences with a Combined Acid Stimulation and Scale Inhibition Treatment
Authors: Smith P. S. , Cowie L. G. , Bourne H. M. , Grainger M. , Heath S. M. 
Published: December 2007

Abstract
Calcium carbonate scale impacts oil production in a large number of fields worldwide. This scale is generally managed by acid washing to remove the scale and/or by performing scale inhibition treatments. The methodology adopted is usually cost driven with high cost operations generally selecting scale prevention rather than removal.
Recently reported work 1 showed the potential to integrate scale removal and scale inhibition treatments into a single package, offering clear economic and technical advantages. The combined treatment inherently reduces well intervention costs and well downtime, and protects the value added by the scale removal treatment - by assuring that all of the zones that are stimulated are also inhibited.
Combining acid stimulation chemicals and scale inhibitors is by no means a simple process. Compatibility between the acid, the acid additives and the scale inhibitor presents a significant issue in both live and spent acids. This paper will examine these technical challenges and describes the desired properties of such combined systems. Case histories of recent field trials of combined scale removal and inhibition treatments will be presented, including details of job design, job execution and post-job evaluation. Data demonstrating the scale inhibitor return profile in these treatments will be shown, and lessons learnt from the initial trials will be discussed. Comparative performance data for previous acid treatments will also be presented.
Economy and Technology Balance in Well Life Cycle Management
Authors: Matanovic D. , Gaurina-Medjimurec N. , Rajkovic D. , Kristafor Z. 
Published: December 2007

Abstract
Crucial in well life cycle management is an analysis of technology and economy balance from the beginning (well project) to the end (well abandonment and environment sanitary improvement).
On the basis of over one thousand drilled oil, gas and geothermal wells (since 1950.), on-shore and off shore, over fifty thousand completions and workovers and about five hundred abandoned wells, an overall analysis will be done to state problems and solutions considering the technology to economy balance.
In the paper we will try to point out phases in well life cycle that are of the greatest influence on economy.
Finally, the optimal way of well or entire field abandonment and produced waste management will be discussed from technological and economical standpoint.
Numerical Modeling of Salt Precipitation During Produced Water Reinjection
Authors: Rocha A. A. , Frydman M. , da Fontoura S. A. B. , Rosário F. F. , Bezerra M. C. M. 
Published: December 2007

Abstract
This paper presents a coupled chemical-hydro-mechanical model for the evaluation of the fluid behavior around an injector well taking into account insoluble salt precipitation (barium and strontium sulfate). A salt precipitation model is developed and coupled with the ion transport equation describing the ion movements and reactions through porous media. The finite element method has been used to obtain the solution for the coupling amongst the ion transport, the fluid flow and the mechanical response of the rock. A computer program has been developed to solve this highly nonlinear problem. Results of an experimental test1 carried out in a sand pack with the analysis of the barium sulfate crystal growth was selected as benchmark to test the computer program developed using the methodology described above, showing an excellent agreement between the numerical and the experimental results.
Evolving State of Ecological Risk Assessment at the Former Guadalupe Oil Field, California
Authors: Lundegard P. D. , Garcia G. F. 
Published: December 2007

Abstract
The former Guadalupe Oil Field, in the central California coastal region, is the location of past and ongoing efforts to assess ecological risk. While there are a number of chemicals of concern, the main focus of the risk assessment is a crude oil thinning agent, known as diluent. Approximately 8 million gallons of diluent were accidentally spilled within the 3000 acre property during its 45 year history of use. The risk assessment must consider the hundreds of plant and animal species, both terrestrial and aquatic, that inhabit the site and its neighboring properties. Among these plants and animals are at least 40 threatened and endangered species.
The first efforts to evaluate ecological risk at the site were initiated during a Natural Resource Damages (NRD) lawsuit. These efforts focused on developing a case for biological injury and establishing a basis for financial damages. Since settlement of the NRD lawsuit in 1998, risk assessment has focused on providing input to decision-makers so that objective remediation goals can be established. This paper reviews the status of the ecological risk assessment, its role in site decision-making, and specific technical challenges that have been encountered.
Laboratory Testing of High-Pressure Coiled-Tubing Drilling System
Authors: Cohen J. H. , Maurer W. C. , Leitko C. C. , Gwilliam W. J. 
Published: December 2007

Abstract
A new high-pressure coiled-tubing (CT) drilling system has been developed with support from the DOE that drills 2 to 3 times faster than conventional CT motors. Downhole motors have been developed that utilize diamond thrust bearings, titanium flexshafts, high-pressure rotor/stator sections and other advanced features that allow these motors to operate at high pressures. Laboratory tests have been conducted using the high-pressure system to cut 1 to 2 inch deep helical slots in wellbore walls to remove formation damage (patent pending) and to drill cement out of drillpipe at rates up to 1,400 ft/hr compared to 60 ft/hr for conventional motors. This jet-drilling system can also be used to remove barite scale from tubing, to clean slotted liners, to ream holes at high rates, and to under-ream when drilling with casing. The high-pressure system will be field tested and commercialized during the next phase of this DOE project.
Optimization of Decision Tree and Simulation Portfolios: A Comparison
Authors: Erdogan M. , Mudford B. , Chenoweth G. , Holeywell R. , Jakubson J. 
Published: December 2007

Abstract
This paper compares the results of carrying out portfolio analysis and optimization of a collection of exploration projects that have been modelled using both decision tree and stochastic simulation approaches. The collection of exploration projects comprises the opportunity set for the portfolio. In the decision tree approach, selecting a few scenarios from the full distribution and assigning probabilities to those scenarios approximates the range of possible project outcomes. In contrast to the decision tree method, stochastic simulation proceeds by assigning probability distributions to key input variables. In a single iteration of the simulation each of these variables is randomly sampled, with allowances for dependencies, in order to calculate cash flow and economic parameters such as net present value. This process is repeated many times for each exploration project to produce a distribution of economic outcomes. Earlier studies have shown the difficulty of adequately characterizing projects with large uncertainty using the decision tree approach. In this paper we take the comparison between decision tree and simulation methodologies to the next stage by looking at the effect on portfolio selection of the differing evaluation methodologies.
The portfolio analysis is carried out using the optimization methodology pioneered by Markowitz to estimate the combination of projects, which produces the maximum NPV for a given level of risk. Comparison of the project selections made for the decision tree and stochastic simulation portfolios shows significant differences between the project selections required to produce an efficient portfolio for the two different evaluation methodologies. This result implies that, even if a decision tree model could be constructed which adequately characterized the uncertainty in a project, the optimization of a collection of projects modelled using decision trees may not yield an efficient portfolio if the full range of uncertainty were to be considered.
Probabilistic Prospect Evaluation With Spreadsheets
Authors: Hooper H. T. 
Published: December 2007

Abstract
This case history describes the creation of a spreadsheet-based, Monte-Carlo economic model for exploration prospects. Looking at "probabilistic economics" instead of "probabilistic reserves" allows decision-makers a better understanding of the potential outcomes associated with a prospect. Although commercial software exists for such analyses, creating this spreadsheet model proved more efficient in this case through the utilization of spreadsheet algorithms already in place. The simulation model is now used routinely in-house for individual prospect analysis and is considered a viable alternative to the commercial packages.
A probabilistic reserve distribution can be generated using uncertainty distributions for volumetric input parameters and then sampling the input distributions through Monte Carlo simulation. After sampling the input distributions and calculating the corresponding reserves many times, a probabilistic distribution of reserves is created. Often in rank exploration prospects, a given reserve size is not a unique solution to the volumetric equation. Different reserve scenarios, e.g. combinations of lateral extent and recovery per acre, may yield the same reserve size but may differ in capital requirements by an order of magnitude or more. In these cases especially, it is appropriate to consider not only the range of reserve outcomes resulting from the full range of possible scenarios, but also the range of corresponding economic outcomes for the many possible scenarios. Meanwhile every single realization within the range of outcomes must be realistic. Furthermore, by calculating economics stochastically, other probabilistic methods such as mean reverting price models may be incorporated.
The spreadsheet economic model was used because it provides a significant advantage where evaluation time is limited. For the evaluation described in this paper, the analysis of exploration prospects was accomplished within a very short time frame. As the prospects were in remote locations outside of the Lower 48 and estimation of capital expenditures and production taxes was complicated, a spreadsheet program provided the desired degree of flexibility. The model was created quickly since spreadsheet algorithms already existed to calculate reserves, capital, production taxes, mean reverting price forecasts, and AFIT economics.
This paper describes how five existing spreadsheet algorithms were integrated to develop a robust Monte Carlo economic model for exploratory prospect evaluations. Emphasis is placed on the advantages of using the spreadsheet platform to establish dependencies between variables and to facilitate customization of the model.
Subsurface Appraisal: The Road From Reservoir Uncertainty to Better Economics
Authors: Demirmen Ferruh 
Published: December 2007

Abstract
Subsurface or field appraisal is an activity aimed at reducing reservoir uncertainty. For optimal results from appraisal, it is necessary to have a clear understanding of appraisal, to distinguish between two types of appraisal, and to use a decision tool that ties reservoir uncertainty to potential economic consequences in the event of development. The tool proposed is "value of information" (VOI), which provides a consistent, auditable criterion for decision-making. In the case of optimization appraisal, VOI enables an analysis of the economic merits of a series of development scenarios with and without appraisal information. The probability distribution of the underlying uncertainty, e.g. reserves, is a key ingredient. A truly cross-disciplinary effort is called for. The ultimate goal in appraisal is to reduce economic risk with regard to field development.
Residual Hydrocarbon Saturations in the Maui Field
Authors: Verbruggen M. H. W. , Adams S. J. 
Published: December 2007

Abstract
Residual gas and oil saturations and relative permeabilities have been quantified in the Maui Field. Additional Special Core Analysis (SCAL) laboratory data was acquired using decane/brine and oil/brine centrifuge experiments. Such measurements are considered most representative of water influx into gas and oil reservoirs respectively. In the case of oil, ageing of the samples to restore wettability is shown to be essential. Relative permeability curves were obtained by history matching the raw experimental production data via numerical simulation. This process corrects for experimental artefacts and limitations, resulting in a significant reduction in residual hydrocarbon saturations compared to typical analytical interpretations. A correlation using a form originally proposed by Land has been used to relate the residual hydrocarbon saturations to the initial water saturations. In-situ field measurements of hydrocarbon saturations using pulsed neutron logs in water-flooded zones are shown to support the SCAL data.
The work described represents the state-of-the-art in quantification of residual hydrocarbons. In particular, the combination of the sampling methodology, the experiment design, the advanced numerical interpretation and the in-situ measurements is material previously unpublished in technical literature. The results are significant in that they show lower residual saturations than commonly expected, while adding to the limited published data on residual hydrocarbons. Use of lower residual hydrocarbon saturations together with the appropriate relative permeabilities in reservoir simulation has resulted in improved reservoir history matches and has had a positive influence on Maui Field reserves. Application of these state-of-the-art techniques to other water-drive fields is likely to have a similar impact.
West Seno Field Development: the First Deepwater Field in Indonesia
Authors: MacArthur J. , Inaray J. , Setiawan Y. , Terry A. , Palar S. , Darmono S. 
Published: December 2007

Abstract
West Seno Field is located in deepwater offshore East Kalimantan, Indonesia. The field was discovered in August 1998 and after appraisal drillings, the field was deemed commercial. Efforts are underway now for a target initial production in fourth-quarter 2002. The Seno anticlinal structure is an elongate, 4-way dipping closure, about 70 square kilometers in area. A total of 205 ft of oil was found by the discovery well, West Seno-2. Subsequent well tests (DST) confirmed the producibility of the hydrocarbon-bearing sand. The field lies in 2400 to 3200 ft of water hence upon production, this will be the first producing deepwater field in Indonesia. Two Tension Leg Platforms (TLP) with one Floating Production Unit (FPU) and supporting pipelines are envisaged to handle oil and gas production with the peak rates estimated to be 60 MBOPD and 150 MMCFD respectively. A blue print to develop this field has been approved by the Indonesia government. The plan of development lists in the expenditures and the infrastructures required to bring in this 280-MMBOE field to production. This paper is the summary of the plan of development.