bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of Fine Gridding in Full Field Simulation
Authors: Greaser G. R. , Doerr T. C. , Chea C. , Parvez N. 
Published: December 2007

ABSTRACT
A full field 3D simulation study was completed for a large Saudi Arabian oilfield located in the Arabian Gulf. The subject field produced from a highly layered Arab D carbonate reservoir which exhibited a strong water drive. The objective of the study was to determine future platform locations and timing with respect to water encroachment. The large areal extent (13×23 km) and highly layered nature of this reservoir necessitated use of coarse grids in order to obtain a reasonable model size. The coarse grid model was constructed with 86,000 grid cells. Using the coarse model, prediction studies showed an advantage to future platform development with horizontal wells. However, these results were suspect since it was thought that the coarse cell model may not properly model water coning and encroachment around the horizontal wellbores. To improve the modelling of water movement, fine grid numerical simulation techniques were investigated. This paper discusses the use of sector and local grid refinement modelling techniques with commercially available software. Fine grid simulation studies were conducted for a proposed new platform. The fine grid simulation studies showed significantly different results compared with the coarse model predictions. The fine grid simulation results will be discussed, the two fine grid simulation techniques will be compared, and reasons presented why performance differences exist. Performance of the fine grid models on an Unix RISC based workstation is included.
An Advanced Kick Simulator for High Angle and Horizontal Wells - Part II
Authors: Vefring Erlend H. , Wang Zhihua , Rommetveit Rolv , Bach Graham F. 
Published: December 2007

ABSTRACT
This paper presents additional simulation results of gas kicks in high angle and horizontal wells using the advanced kick simulator described in Part I. We place emphasis on the removal of gas bubbles from three potential traps in a horizontal well, i.e., (i) upward inclined section, (ii) local tops in the trajectory, and (iii) washout sections. Operational implications are also discussed based on the simulation results. The critical parameters are noted for operational considerations.
Full scale gas kick experiments in horizontal wells have been performed. We will discuss the experimental set up and test parameters. The test data are being analysed.
Waterflooding in a System of Horizontal Wells. (Analytical Reservoir Model. Offshore Case)
Authors: Bedrikovetsky P. G. , Magarshak T. O. , Shapiro A. A. 
Published: December 2007

ABSTRACT
An approximate analytical method for the simulation of waterflooding in a system of horizontal wells is developed. The method is based on an advanced stream-line concept. The essence of this new method is the exact solution for the 3D two-phase flow problem in the system of coordinates linked with the stream lines under the only assumption of the immobility of stream lines. A software based on this approach was developed for IBM-compatible PC. It allows us multivariant comparative studies of immiscible displacement in systems of horizontal, vertical and slant wells. The simulator has been used in order to optimize geometrical parameters of a regular well system and to predict recovery in conditions of Prirazlomnoye offshore oil field.
Study of the Hydrodynamic Pattern in a Sedimentary Basin Subject to Subsidence
Authors: Jacquin C. , Poulet M.J. 
Published: December 2007

Abstract
The structure of a sedimentary basin is modelized, assuming that this basin is subject to subsidence and has the following characteristics:
shaped like an inverted cone with a circular base having a radius of 300 km, depth in the middle varying from 0 to 3,000 m during an evolution lasting 150 million years and during this evolution, successive deposits of sand and clay strata occurred with gradual expulsion of water from the clay as the result of burial.
This basin structure is used to study the hydrodynamic conditions that have occurred in the different sedimentary strata. The main conclusions of this study are as follows.
Fluid circulations through the clay are quite complex because the direction of flow has usually reversed itself, with this reversal occurring earlier or later following the moment of deposition of clayey material. This leads to an evaluation vs time of the cumulative amounts of water, respectively, running upward (W2) and downward (W2) over a 1 sq cm horizontal surface associated with the clay deposited in a given place at a given moment. The circulation of water through clay causes fluid overpressures compared with the hydrostatic pressure. The vertical distribution and the order of magnitude of these overpressures agree with standard observations made on actual sedimentary basins. The circulation of water through sandy horizons occurs at very low speeds of between about 1 and 10 mm/year, but the volumes of water involved are large (from 10(12) to 10(13) cu m for a period of between 40 and 150 million years).
These results may provide useful indications for studying some of the phenomena governing the formation of petroleum accumulations, i.e., diagnesis and hydrocarbon migration.
Introduction
Hydrocarbon displacement phenomena inside stratigraphic series (primary migration in the source rock and secondary migration in permeable layers where traps are located) cause permeable layers where traps are located) cause the sizable accumulations making up exploitable oil fields. The leading mechanisms assumed to be behind these displacements are displacement of hydrocarbons in a dissolved or emulsion state in water and displacement of continuous oil and gas phases (or possibly oil dissolved in gas) by gravity or aquifer movement.
Relationship Between the Ratio of Formation Exposure Length to Formation Thickness and Ultimate Oil Recovery From Horizontal Wells
Authors: Boukadi F. , Bemani A. 
Published: December 2007

ABSTRACT
This paper discusses the relationship between the ratio of exposed formation length to oil-bearing formation thickness and ultimate oil recovery from horizontal wells.
Horizontal technology is usually chosen as the best practical solution to improve the ultimate oil recovery and cope with the water and gas coning problems encountered in many oil fields. The intent being to reduce the water production, to minimize the cost of the required treatment of water at surface, and reduce the gas production to limit the consequent energy reduction. Horizontal wells drilled and tested have given confidence to the use of the technique in future operations in different fields in the Middle East and particularly in Oman. Nevertheless, the immediate effects of raised oil output is not to be at the expense of possible lower optimum recoveries. For that reason, numerical sensitivity analyses on reservoir parameters, such as the ratio of exposed formation length to formation thickness at various maximum allowable liquid rates, have been carried out. Recommendations on the water coning horizontal drilling implementations and ways for reducing water coning effects are outlined and thoroughly discussed for various reservoir thicknesses.
Adequate horizontal drilling with a suitable maximum production rate will then be recognized as a fairly better technique for reservoir management.
Geologic Controls On Wettability of Carbonate Reservoirs, Abu Dhabi, U.A.E.
Authors: Marzouk I. , Takezaki H. , Miwa M. 
Published: December 2007

ABSTRACT
Wettability is one of the most important rock properties that controls fluid saturation distribution and fluid flow behavior. It will have significant impact on original oil-in-place, reservoir performance, ultimate oil recovery and accordingly, field economics.
Geologic controls on wettability is a subject of increasing interest, which will lead to better understanding of the origin, distribution and prediction of this important rock property. The Thamama carbonate reservoirs, which are the main producing reservoirs in Abu Dhabi, U.A.E., are the prime target of this paper.
Geological and Petrophysical studies of core samples indicated unique phenomena, which could not be explained by the conventional theory of wettability. For example, review of the "Amott" wettability measurements generally indicated oil wet character in the oil zone, mixed wet in the transition zone and water wet in the water zone. Fresh core resistivity measurement showed variable saturation exponent "n" with changing water saturation of the same sample. Other examples are discussed in this paper.
In order to explain these phenomena, careful examination of geological and petrophysical properties such as pore throat size distribution and petrographie image analysis, were conducted, which confirmed close relation between wettability and rock type especially the pore system. The pore system proposed in this study is based on the pore throat size. Accordingly, the pore system of the Thamama reservoirs is classified into; Macropore throats (more than 4 microns), Mesopore throats (4-0.3 microns) and Micropore throats (less than 0.3 microns). Micropores are always filled with water (Swi). Mesopores are filled with either oil or water depending on the oil column thickness. Macropore are easily filled with oil above the free water level (FWL).
Based on the above observations, a wettability distribution model is proposed and the following new concepts are introduced: True Wettability, represents stabilized condition of grain surfaces in a water/oil system under conditions where oil can contact the rock surfaces. True wettability of the Thamama carbonate reservoirs is considered to be oil wet.Wettability Change, represents the oil accumulation process in a virgin water filled reservoir. Before oil accumulation, wettability was originally water wet, after oil accumulation wettability changed to oil wet if grain surfaces contacted with oil.Apparent Wettability, which is the measured wettability, represents the distribution of oil and water in the different pore spaces. It will depend on micropore throat percent and oil column thickness.
Several geological and petrophysical evidences and examples were discussed in this paper.
Petrophysics and Seismic Wave Technology: Applications in Exploration, Formation Evaluation, and Reservoir Characterization
Authors: Klimentos T. 
Published: December 2007

Abstract
One of the most important issues in reservoir characterization is heterogeneity. Reservoirs are more heterogeneous than researchers have believed in the past. Reservoir heterogeneity can be created by complex sedimentary and diagenetic processes and then modified by a sequence of tectonic changes. The petrophysical and seismic properties of reservoirs may vary significantly from one well to another or even at a distance of a few meters. Therefore, if one could predict such rock property variations in space, it would be very beneficial to reservoir characterization and planning of appraisal and production wells. Moreover, front movement in a water flooding may be monitored by studying the different seismic response between water and hydrocarbon saturated rocks.
In this paper a new method for predicting the spatial variation in rock and fluid properties is presented along with laboratory results and a case study. Various models of porosity, permeability, pore-fluid, and lithology are created to predict the corresponding P- and S- wave velocities and acoustic impedances. The best fit between synthetic seismic and sonic models would indicate the most probable reservoir model.
This method could be useful in (1) Reservoir Characterization: Predicting the spatial variation in rock and fluid properties of a reservoir. This is essential for accurate reservoir characterization and planning of appraisal and production wells; (2) Formation Evaluation: Modeling porosity, permeability and pore-fluids near the wellbore in conventional and horizontal wells; and (3) Seismic Exploration: Direct detection of hydrocarbon bearing rocks in areas for which little subsurface information is available.
Lithological Variability of Electrical Parameters in a Sandstone Sequence
Authors: Amabeoku Maclean O. , Mimoune Kissami , Al-Nufaili Subhi 
Published: December 2007

ABSTRACT
Electrical parameters are the constants in the Archie equation and variants thereof, to calculate water saturation, original oil-in-place, and residual oil saturation from resistivity well logs. The applicability of these parameters in reservoir calculations are, in many cases, reservoir specific. It is, therefore, imperative that determinations of these parameters in the laboratory should be done at conditions that reflect, as closely as possible, those prevailing in the reservoir, with respect to temperature, pressure, and fluids. The formation factor, cementation exponent, and saturation index vary with lithology as well.
The lithofacies identified in this sandstone sequence include clean sandstone, shaly sandstone, and sideritic sandstone. X-ray diffraction analysis shows the mineralogical composition to be clays, ankerite, siderite and quartz.
An experimental program has been conducted to determine these electrical parameters at reservoir conditions using native crude oil on two of the lithofacies identified in the reservoir. This paper discusses results of these measurements. The results are grouped by lithology so that a regime of application can be defined. The importance of this lithological grouping is that different parameter values and lithology flags (or indicators) can be programmed into the water saturation calculation scheme to refine the well log determination of water saturation from Archie-type equations.
Development of a Modified Capillary Pressure J-Function
Authors: El-Khatib Noaman 
Published: December 2007

ABSTRACT
Capillary pressure curves are represented by the equation Pc=a / (Sw-Swi)b. It is shown that for the Leverett J-function to produce a single correlation, the tortuosity, the irreducible water saturation and the saturation exponent b must be the same for the different formations. A modified capillary pressure function J* is introduced that incorporates the tortuosity and irreducible water saturation in its definition. The modified function is correlated with the normalized saturation SD so that all curves will have their vertical asymptotes at a single point SD=0. The modified function represents a significant impro- vement over the original one since it is now sufficient to have the value of the saturation exponent b be the same for two samples to get the same correlation. This was verified by analyzing data from the literature and comparing the two correlations. A modified linear regression by means of weighted least squares method is used to fit the experimental capillary pressure data. Data sets from different sources were analyzed. It was found that a good single correlation can be obtained for samples from the same formation but the correlations were different for different formations.
Factors Affecting Injectivity Decline
Authors: Al-Hamadah A. M. 
Published: December 2007

ABSTRACT
Reservoir pressure support for a large portion of a giant field is maintained by peripheral sea water injection. The temperature of the injected seawater is significantly lower than the reservoir temperature and also lower than the previously injected water obtained from aquifers. Therefore, a decline in injectivity is expected as a result of higher water viscosity due to lower injection water temperature.
This paper presents actual data collected from power water injection wells in two areas of the field, both before and after the start of seawater injection. This data has shown a significant decline in injectivity after conversion to seawater in only one area. The quality of the injected water and other related factors will be reviewed to determine the reasons for this behavior that apparently contradicts what was expected. The paper also discusses the actual effects that cold seawater injection has on pressure falloff behavior.
A New Technique To Analyze Simultaneous Sandface Flow Rate and Pressure Measurments of Gas Wells With Turulence and Damage
Authors: Nashawi I. S. , Al-Mehaideb R. A. 
Published: December 2007

ABSTRACT
Most of the problems associated with conventional gas well tests are related to the nonlinearity of the equations describing real gas flow, the presence of the rate dependent (non-Darcy) skin, and the long shut-in time periods required to collect the data for the analysis in tight reservoirs in which the wellbore storage period can be excessively long.
This paper presents a new pressure buildup technique that reduces the wellbore storage effects, eliminates the long shut-in periods experienced with conventional tests by using afterflow rate and pressure data, and most importantly provides a direct method to estimate non-Darcy skin. The proposed technique uses normalized pseudo-functions to avoid the nonlinearities of the governing equations and involves using two different plots. The formation permeability is obtained from the slope of the first plot. The mechanical and non-Darcy skin factors are obtained respectively from the slope and intercept of the second plot. A field example and two simulated cases are presented to illustrate the application of the new technique.
Calculation of Well Productivity in a Reservoir Simulator (II)
Authors: Chen G. , Tehrani D. H. , Peden J. M. 
Published: December 2007

ABSTRACT
Conventional simulators calculate the well productivity using Peaceman's equation[1] for equivalent block radius and the well block pressure. This is generally acceptable for most vertical and horizontal wells. However, no formulation is available for slanted wells. Even for vertical and horizontal wells in which block aspect ratios are far from unity or where the well completion interval is short or the well is located close to a reservoir boundary or other wells, the existing formulations can give erroneous answers. In our previous paperi[2], a novel method was introduced for calculating very accurately the productivity of wells of any deviation (0-90°) fora homogeneous reservoir. In this paper, we present a more general solution for general well position and applicable to multiple wells and heterogeneous reservoirs. A novel method is presented to convert the heterogeneous model to an anisotropic but uniform permeability model before applying the new analytical technique, in conjunction with a numerical simulator. The analytical model developed for this purpose is coupled with a numerical simulator to produce the necessary parameters needs for simulation of well performance in a conventional simulator. The results will have a wide field application for horizontal, vertical and deviated wells.
The Comprehensive Technology of Horizontal Drilling And Development In Shengli Oilfield
Authors: Ye Feiting , Sun Jiancheng , Wang Baoxin , Li Hongwei 
Published: December 2007

ABSTRACT
In the last few years, the horizontal drilling technology in Shengli Oilfield has developed at a rather rapid pace So far, 30 horizontal wells of different types have been completed in various hydrocarbon reservoirs. This paper emphasizes the design and drilling practices in the horizontal exploratory wells and the horizontal development wells of viscous oil gravel reservoirs in Shengli Oilfield. The application and technology of horizontal well to other oil and gas reservoirs are also presented.
Three-Stage Stochastic Modelling Method To Characterize Reservoir With Fluvial Facies
Authors: Wang Jiahua , Zhang Tuanfeng 
Published: December 2007

ABSTRACT
One of purposes of reservoir characterization is to delineate reservoir heterogeneities as truly and effectively as possible. Reservoir heterogeneities are one of main factors to affect recovery ratio. Understanding of reservoir heterogeneities is useful to recognition of effects of barrier layers on fluid flow in reservoir, to clear seeing of spatial distributions of sandbodies and permeability, and to correct evaluation of spatial distribution of residual oil[1].
A number of studies shows that stochastic modelling and stochastic simulation of reservoir with geostastistics is an effective method to evaluate reservoir heterogeneities quantitatively[2][3][4].
Reservoir heterogeneities exist on various observation scales of reservoir, and full into large-scale heterogeneities and micro-scale heterogeneities. Different heterogeneities with different scales restrict and affect each other. More attention has been paid to stochastic modeling of sedimentary facies. The reason is that spatial distribution of sandbodies or geometry of sandbodies is important to control reservoir behaviour, to make development plan, and to estimate reliable recovery ratio of oil and gas [5] [6] [7].
Multi-stage stochastic modelling of reservoir, as an advanced method for reservoir characterization, can show various heterogeneities with different scales, and embody constraint relationships among these heterogeneities. It can make simulation of spatial distribution of sedimentary facies match with simulation of spatial distribution of petrophysical parameters. The process and results with multi-stage stochastic modeling will have more reasonable geological meaning than other stochastic modeling
The systems for reservoir characterization, HERESIM developed by IFP and Geostatistical Center of Paris Mining Institute, and MOHERES developed by Normay State Oil and Norway Computing Center, both have used two-stage stochastic modeling.
This paper proposes a methed for three-stage stochastic modeling of reservoir with fluvial facies. This method consists of three models: stratification plane configuration model, sandbody framework model, and petrophysical parameter distribution modeL A case study, presented in this paper, indicates that this method is especially suitable for fine quantitative description of complex fault block reservoir with fluvial facies.
Predicting and Scanning of Wellbore Trajectory in Horizontal Well Using Advanced Models
Authors: Deli Gao 
Published: December 2007

ABSTRACT
This paper discussed the methods to analyse the bottom hole assembly in horizontal well and gave the non-linear dynamic governing equation of BHA as well as its initial and boundary conditions. A vector model of rock-bit interaction was established. A new concept of the effective drilling force was proposed. Based on the model and concept, some typical anisotropic formations were classified into 12 categories. Their anisotropic drilling characteristics could be presented in the equations and graphs. In a field example, the deflecting performance of a typical downhole motor assembly with the bent housing and two stabilizers in horizontal well was discussed in detail. The adjacent well distance scanning and plotting method and its engineering application were introduced in the last part.