bluuebunny/crossref_metadata_2025_split huggingface dataset:
An analytical method for calculating the performance of heterogeneous reservoirs and its use in uncertainty analysis
Authors: Kjønsvik Dagrun , Alvestad Jostein 
Published: April 2008

Abstract
An efficient analytical method for performance calculations in heterogeneous models is developed, under assumptions of a viscous dominated displacement process and unit mobility ratio. The method provides a quantitative measure of the effects of heterogeneities on displacement characteristics and production performance. Results indicate that the method has a potential for ranking a set of geostatistical reservoir model realizations in terms of production performance, thereby providing a basis for selecting realizations for detailed numerical simulations.
Three-phase relative permeability of water-wet, intermediate-wet and oil-wet sandstone
Authors: Baker Lee E. 
Published: April 2008

Abstract
Knowledge of three-phase relative permeability is important to the successful design of many types of improved oil recovery projects. An extensive experimental study was made of three-phase relative permeability in water-wet, intermediate-wet and oil-wet rock. The data obtained in this study are the only complete relative permeability data set for rocks which are not water-wet.
The study confirms the commonly held assumptions about the relative permeability behaviour of wetting and non-wetting phases. Phase saturation and the saturation history (the path by which a particular saturation condition is reached) are major factors in determining relative permeability. In general, the more wetting a phase is, the more nearly the relative permeability of the phase depends only on the saturation of that phase (regardless of saturation history). The relative permeability of the non-wetting phase depends largely (but not entirely) on the saturation of the phase and on the saturation history. The relative permeability surface of an intermediate-wetting phase is affected by the saturations of all phases, particularly when one of the phases is strongly wetting.
Three-dimensional plots of the phase relative permeability surfaces show smooth variation of relative permeability with saturation and with saturation history.
The study provides much new data and guidance for developing and testing theoretical models of three-phase relative permeability. Examples of currently used correlations (Stone’s methods 1 and 2) and a linear interpolation relative permeability correlation are compared to the experimental results.
The role of wettability and spreading in gas injection processes under secondary conditions
Authors: Kalaydjian François , Vizika Olga , Moulu Jean-Claude , Munkerud Per Kristian 
Published: April 2008

Abstract

The objective of this paper is to demonstrate the impact of film continuity on oil recovery by gas injection under secondary conditions, e.g. when water is non-mobile. In this case two films have to be considered: a water film and an oil film. The continuity of the former is insured by the wettability conditions, whereas the continuity and stability of the latter depend on the ability of the oil phase to spread on the water substrate in the presence of a gas phase. This ability is expressed by the spreading coefficient,
S
, defined as a balance of the three interfacial tensions. To study the effect of wettability and spreading on the residual oil saturation obtained by gas flooding and on the capillary pressure and relative permeabilities, centrifuge, displacement and gravity drainage experiments have been performed for various wettability and spreading conditions.

It is shown that both parameters modify the flow characteristics, the residual oil saturation and the recovery kinetics. More specifically, in a water-wet porous medium, the residual oil saturation is found to be higher and the drainage capillary pressure and relative permeabilities lower when measured for a non-spreading oil than for a spreading one. For an oil-wet porous medium the impact of
S
is much less important. However, for the same positive spreading coefficient, although the capillary pressure threshold is almost the same in water-wet and oil-wet porous media, the recovery kinetics are essentially different, due to the different displacement mechanisms.
Gas-oil capillary pressure measurements at reservoir conditions: effect of interfacial tension and connate water saturation
Authors: Longeron Daniel , Kalaydjian François , Bardon Charles 
Published: April 2008

Abstract

This paper describes laboratory equipment and procedures aimed at determining drainage gas-oil capillary pressure functions under reservoir conditions. Two series of capillary drainage tests (porous plate method) were performed with sandstone core samples using binary mixtures of methane/
n
-heptane at different equilibrium pressures, leading to very wide variations in the gas-liquid interfacial tension (IFT) values. Measurements were performed first without connate water (two-phase conditions) and then in the presence of connate water saturation (three-phase conditions). This study has shown that the gas-oil capillary pressures measured at different levels of IFT and without connate water can be transformed into one capillary pressure function,
P
c
/IFT, down to IFT = 3.7 mN/m. Below this value, the capillary pressures measured were significantly lower than those estimated by the Young-Laplace equation. In the presence of connate water, the gas-oil capillary pressures were always higher than the ones measured without water saturation. The difference increased when gas saturation increased and gas-oil IFT decreased. Finally, this paper showed that it is not valid to deduce three-phase capillary pressure from two-phase measurements.
Foam barriers for thin oil rims: gas blockage with hydrocarbon foams
Authors: Dalland Mariann , Hanssen Jan Erik 
Published: April 2008

Abstract

Creation of
in situ
foam barriers to gas flow is a potential way to improve production from wells which suffer gas breakthrough and give high gas-oil ratios. In this paper, new results on gas blockage by foamed liquid hydrocarbons are reported. These foams are applicable in the foam-block process because they can be injected as low-viscous, low-density surfactant solutions which may allow deep penetration near the gas/oil contact. Foam barriers of large radial extent may be created as oil production is resumed by reservoir gas coning through the treated zone.

It is shown by experiments in a sector model that a hydrocarbon foam of lower density than the reservoir oil, when injected at a low rate to allow gravity segregation, will place itself near the gas-oil contact and, upon production start-up, create an effective barrier to reduce the effect of gas coning. Gas coning in the absence and the presence of foams is investigated and compared.
Effective gas blockage is demonstrated for the first time with hydrocarbon foams at low pressure and at reservoir pressure and temperature. Foam performance is studied in water-wet model porous media at varying temperature and surfactant concentration. Experiments with and without wetting water present show the same performance. A given foamer formulation produced poorer gas-blocking performance in reservoir-condition tests than in low pressure tests. This was found to be related to the loss of solution viscosity as a result of gas dissolving at high pressure. By blending the kerosene solvent with a viscous hydrocarbon liquid such that the viscosity of the high pressure system was matched to that of the low pressure system at the respective foaming conditions, the gas-blocking ability of the high pressure foam was restored to match that of the low pressure system.
Soluble gas injection for waterflood profile modification
Authors: Hazlett Randy Doyle 
Published: April 2008

Abstract
A method involving the addition of water-soluble gas to exploit relative permeability relationships is evaluated for its potential to modify a waterflood profile. In this process, a soluble gas is added to injected water in an amount such that a single-phase aqueous solution enters the formation; however, the bubble point pressure is crossed in the steeply varying pressure profile around an injector. Solution gas alters the relative permeability to water in those zones taking water. Thus, the current water injection profile transports profile modification agent to the zones which need it most. Analytical model results for the radial flow of dissolved gas and subsequent gas evolution indicate that gas saturation is partitioned according to the permeability-porosity ratio. For most cases, this results in beneficial profile modification by three-phase relative permeability effects. Relative permeability reduction by a factor of three is anticipated through the nucleation of a trapped gas saturation. Gas saturations accumulate with time, making the process more beneficial with continued implementation. Though initially this process yields a near-wellbore treatment, prolonged application produces a trapped gas zone deep into the reservoir. Gas evolution away from the injector aids in injectivity maintenance. Increase in microscopic displacement efficiency, in addition to volumetric sweep, is also expected. Nitrogen, methane, and carbon dioxide are screened as potential water-soluble additives.
Performance evaluation and optimization of the Kuparuk hydrocarbon miscible water-alternating-gas flood
Authors: Hallam Richard J. , Ma Tuan D. , Reinbold Eric W. 
Published: April 2008

Abstract
In 1988 a hydrocarbon miscible water-alternating-gas (MWAG) pilot was initiated in the Kuparuk River field, on the North Slope of Alaska. Project decline curve analysis showed a significant response to the MWAG process. The field data alone, however, could not be used to accurately project the ultimate performance of the process. A systematic, integrated approach to reservoir modelling was used to evaluate the MWAG process performance. Finely gridded one dimensional (1D) models were used to evaluate the process mechanisms. Then fine and coarsely layered 2D and 3D compositional models were used to evaluate the process efficiency. The areal effects, including faulting, were then incorporated by using a 3D, coarsely gridded, multi-well, modified black oil (MBO) model. The 3D, site-specific, model was history-matched for the waterflooding period. The miscible flood performance was then predicted using a tuned MBO parameter and compared to the field performance. The 3D MBO model predicted that the ultimate incremental recovery would be 11 0.000000or a 30% HCPV slug. The model indicated that the miscible process can accelerate production of the waterflood reserves. The model was also used to evaluate the effects of total slug size, maturity of the preceding waterflood, and WAG ratio on the process efficiency.
Waterflooding under fracturing conditions: from theoretical modelling to field process
Authors: Niko H. , Ovens J. 
Published: April 2008

Abstract
The paper describes how some of the fundamental rock mechanical, heat and fluid flow aspects, of importance in the process of fracturing of water injection wells, have been used in Shell to build simulation and well testing tools. Examples of application indicate that thermal fractures in highly permeable formations are usually short with negligible influence on sweep efficiency. In tight, thick reservoirs the 3D aspect of fracture modelling becomes very important, particularly that of fracture containment. A field example of a thermal fracture in the North Sea is given, together with a brief account of results of a pilot test on injection under fracturing conditions in the Lekhwair field in Oman, using state-of-the-art fracture monitoring techniques.
Inorganic gels for enhanced oil recovery at high temperature
Authors: Altunina L. K. , Bokserman A. A. , Kuvshinov V. A. , Polkovnikov V. V. 
Published: April 2008

Abstract

A novel physico-chemical EOR method using inorganic gel-forming aluminium salt-carbamide-water (GALCA) systems has been developed. The method is based on the generation of an inorganic gel and CO
2
in reservoirs with high formation temperature. The time needed for gel formation depends on temperature and composition of the mixture used. The gel may be characterized as a thixotropic pseudoplastic solid-like body with a coagulated structure. The gels enhance reservoir homogeneity, modify water injection profile and consequently increase oil production and reduce watercut. In numerous field tests carried out in West Siberia, this method has proven to be both technically and economically effective, as well as ecologically acceptable.
Orbital forcing timescales: an introduction
Authors: House Michael R. 
Published: April 2008

Abstract
A brief review is given of orbital patterns affecting the Earth which may be of use in establishing, for long or short periods, orbital forcing timescales (OFT). The metronomic variations of the Earth-Moon system and of the Earth-Sun orbital patterns produce gravitational and temperature effects which alter the physical environment on the Earth’s surface. These give an interpenetrating effect of forcing cycles ranging from twice daily tides, day-night alternations, various tidal patterns and the annual solar pattern. All of these have been used palaeontologically to give precision to short-term age determination in the past.
It is cycles of the Milankovitch band which are showing promise of enabling new practical timescales to be established for parts of geological time. These depend on changes in the Earth-Sun distance (perihelion and precession cycles of 19 and 23 ka at the present time), changes in the tilt of the Earth’s axis with respect to the Earth’s orbit round the Sun (the obliquity cycles of 41 and 54 ka), and changes in the geometry of the Earth’s orbit around the Sun (eccentricity cycles of 106 and 414 ka). Since the number of days in the year have changed through time; so have the periods of the perihelion and precession cycles. There is increasing evidence that small-scale sedimentary rhythmic couplets, often grouped into bundles, may represent the effect of some of these; often the precessional couplets are grouped into bundles of five or so within the lower eccentricity period. The disentangling of the interpenetrating cycles to produce an OFT is an exciting problem and challenge for palaeobiology and sedimentology. These should enable numerical dates to be given to biostratigraphic and chronostratigraphic timescales and eventually enable many earth processes to be analysed in real time.

26 Ma oscillations related to the Cosmic Year (
c.
260 Ma) have been invoked to explain periodic mass extinctions in the fossil record. But evidence is presented to suggest such extinctions are not, in fact, periodic.
Calibration, analysis and interpretation of depositional cycles in the Early Toarcian of Yorkshire, UK
Authors: Moses Gwyn P. G. 
Published: April 2008

Abstract
The Toarcian of Yorskhire, UK, has been analysed and interpreted in order to determine whether shale-nodule couplets or cycles represent a regular cyclicity, and, if so, what the cyclicity could represent. This was done by calculating rates of deposition by analysing shale laminae and calculating durations of hiatus from rates of growth of nodules which are believed to be formed during hiatuses. This has enabled a new ammonite geochronology to be calculated, giving average zonal durations of 700 ka and subzonal durations close to 300 ka. The cyclicity is not regular enough to represent Milankovitch cycles and a tectonic origin related to pulsed North Sea thermal doming is suggested as an alternative mechanism.
High-resolution palynofacies investigation of Kimmeridgian sedimentary cycles
Authors: Waterhouse Helen K. 
Published: April 2008

Abstract
Palynofacies analysis is used as a tool to investigate in detail the palaeoenvironmental variations through several sedimentary cycles in the Kimmeridge Clay of Kimmeridge Bay, Dorset, UK. Evidence is given of palaeoenvironmental variations within cycles corresponding to those expected for obliquity orbital forcing. In addition, a second cyclical palaeoenvironmental variation, probably precessional forced, is seen in the palynofacies data. Further small-scale variations in palynofacies characteristics, which are not evident in the sedimentology, are also identified and allow cycles to be divided into a number of distinct palaeoenvironmental units. It is proposed that the obliquity cycle had its greatest effects on the marine environment, while the precessional cycle mainly affected the terrestrial environment. The abundance of useful palaeoenvironmental and palaeoclimatic information obtainable through high-resolution sampling in conjunction with a tool such as palynofacies analysis, provides evidence for and information about orbital forcing additional to that of most orbital forcing studies as it allows variations within cycles to be investigated.
Periodicities of carbonate cycles in the Valanginian of the Vocontian Trough: a strong obliquity control
Authors: Giraud F. , Beaufort L. , Cotillon P. 
Published: April 2008

Abstract

A high-resolution study of variations in carbonate productivity, quantified by CaCO
3
content and by colour intensity (grey level) for a Valanginian rhythmic succession is presented in the Vocontian Trough. Spectral analysis techniques reveal the presence of strong CaCO
3
cycles linked to cyclic variations in the Earth’s orbit. The results of the analysis suggest that obliquity cycle is the most clearly defined signal whereas the presence of CaCO
3
cycles related to the precession signal is less distinct.

The transition from limestone-dominant alternations in the lower Valanginian to marl-dominant alternations in the upper Valanginian is characterized both by an increase of sedimentation rate and a change from the precession as the dominant forcing in the lower, calcareous part of the Valanginian, to obliquity as the dominant forcing for the upper marly part of the Valanginian.
An orbitally calibrated chronology is presented for the Valanginian based on the identification of the carbonate cycles. The application of band-pass filterings to the original carbonate record allows the extraction of 91 carbonate cycles related to precession and 137 cycles related to obliquity. The proposed duration for the Valanginian stage is 7.04 Ma.
Detailed relationships between platform and pelagic carbonates (Barremian, SE France)
Authors: Quesne Didier , Ferry Serge 
Published: April 2008

Abstract
Field observations suggest that prograding bioclastic wedges of depositional sequences in outer-platform settings correlate with packages of basinal limestone beds thought to represent third-order lowstand systems tracts. The rule is apparently the same for higher-frequency cycles within these sequences, since basinal beds seem to correlate with bioclastic clinoforms while basinal marly interbeds root between clinoforms. If confirmed in other sequences, it would suggest that limestone beds, or bundles of beds, in this basin have the same ‘lowstand’ significance ‘highstand’ vs intervening marls from second- to sixth-order cycles, whatever the source of the carbonate (periplatform oozes or planktonic rain). A major remaining challenge is to understand the mechanisms by which high-frequency sea-level changes, as documented in outer-platform bioclastic wedges, correlate so well with the changes in nannoflora (nannoconus-rich beds vs coccolith-rich marly interbeds) thought to be climatic in the pelagic Vocontian Trough series. Is it glacio-eustasy and how does it work to make the deep-water Cretaceous limestone-marl alternation?
Reservoir geochemistry: methods, applications and opportunities
Authors: Larter S. R. , Aplin A. C. 
Published: April 2008

Abstract
Petroleum reservoirs often contain compositionally heterogeneous petroleum, water and sometimes gas columns which can be interpreted in geologically useful ways. Kilometre-scale lateral compositional heterogeneities in fluid columns suggest petroleum emplacement directions, directions of water flow in biodegraded oilfields and the presence of major barriers to fluid flow within reservoirs. Vertical fluid column heterogeneities on a 10 m scale suggest that reservoirs are vertically compartmentalized. These data can be used as a tool in reservoir description and are thus relevant to many aspects of reservoir appraisal and development. The data supplement those generated by reservoir geologists and engineers, and can be obtained immediately after drilling, at reasonable cost.
Much recent work has focused on polar nitrogen (N) and oxygen (O) containing compounds such as quinolines, carbazoles and phenols. These compounds interact relatively strongly with water, rock minerals and each other, and may significantly influence the viscosity and pressure-volume-temperature (PVT) properties of petroleum, and also reservoir wettability. There are obvious links here between reservoir geochemistry and the more traditional disciplines of petroleum and reservoir engineering which we expect to be exploited in the coming years.

In the absence of phase changes during migration, the composition of reservoired oil reflects the expelled oil plus changes induced by adsorption, especially of polar compounds, onto solid phases or by partitioning into porewaters along secondary migration pathways. The extent of change, as measured by the relative abundances of selected compounds in reservoired oil and associated water, is potentially a direct measure of migration volume and thus of the relative amounts of water, oil and rock on a migration pathway. We present a simplified, equilibrium model which may allow one to assess migration volumes, and use
n
-hexane/benzene ratios of some North Sea oils to suggest that these oils have contacted fewer than one hundred volumes of water on their migration pathways. Future work should aim to quantify the interactions of migrating and reservoired petroleum with rock and water, and should yield a more quantitative assessment of both migration volumes and the controls of reservoir wettability.