bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling the Effect of External Gas Flux on Reservoir Fluid Distribution
Authors: Montel F. , Bickert J. , Caillet G. , Le Goff C. 
Published: December 2007

Abstract
In some circumstances, particularly in recent mature and permeable petroleum systems, hydrocarbon accumulations are subjected to gas fluxes, which lead to non-conventional fluid distribution.
After their migration into the trap, various forces shape the fluids. Among them, gravity has the most striking effect and has been widely studied. But in many cases, there is evidence for the contribution of other forces like thermal gradients and external mass flux at a geological time-scale. Taking all these phenomena into account to obtain a consistent picture of fluid distribution is an important challenge for the petroleum industry.
There are already a number of tools available for calculating the compositional gradient within a reservoir, including the contribution of gravity and thermal gradient. In many field cases, the actual profile differs from the one calculated. The discrepancies are imputed to other external forces: the mass fluxes at the reservoir boundaries. In this paper, we present the modeling of diffusion fluxes across the reservoir.
Drawing on field examples, the paper provides a methodology for dealing with dynamic reservoir fluid systems and offers petroleum engineers guidelines to avoid many pitfalls during the field evaluation procedure. The model matches the observed compositional gradient and corresponding PVT properties. It allows reliable connectivity assessment in cases where gravitational modeling fails.
The main contributions are a methodology for integrating the geological constraints in the evaluation of fluid distribution in a reservoir and the description of the model, which includes the impact of gravity, thermal gradient and external component fluxes.
Environmental Regulatory Framework in the North Sea: an Update of the Existing and Foreseeable Constraints
Authors: GARLAND Emmanuel 
Published: December 2007

Abstract
Major measures have been taken during the past thee years by the Convention for the protection of the marine environment of the North-East Atlantic (known as OSPAR), a legally binding Convention which came into force in 1998 and plays a key role regarding environmental regulations in the North Sea.
OSPAR adopted in 1999 a "Strategy on Environmental Goals and Management Mechanisms for Offshore Activities", a decision and two recommendations pertaining to the use and discharge of offshore chemicals (in 2000), a decision on organic-phase drilling fluids (also in 2000), a recommendation for the management of produced water (in 2001), in addition to its decision on disposal of disused installations (already adopted in 1998, to be revised in 2003).
Additional measures concerning the measurement of the oily compounds in produced water and the reduction of discharge of aromatic hydrocarbons are currently being discussed amongst OSPAR contracting parties, as well as contaminated drill cuttings piles, and implementation of environmental management systems.
In their Declaration made in Bergen in March 2002, the Ministers of the Environment of the countries bordering the North Sea recalled their desire to have as much of the OSPAR work programme completed by mid 2003, and to see OSPAR addressing new issues such as impact of seismic activities, disused pipelines and cables, use of renewable energy, etc.
The European Community appears to play a key role in addressing and implementing most of the other international legal instruments which affect the North Sea offshore industry.
Feature-Based Geostatistics: An Application to a Submarine Channel Reservoir
Authors: Arpat Burc , Caers Jef , Strebelle Sebastien 
Published: December 2007

Abstract
Characterization of developing submarine channel reservoirs requires geostatistical methods that are capable of reproducing channel facies morphologies. Such deep marine settings are generally characterized utilizing seismic data while in the development phase. Typically, the seismic is analyzed by means of clustering methods to partially interpret facies. Then, facies models are generated using geostatistical simulation methods. Yet, due to the incompatibility between the pixel-based nature of many geostatistical methods and the pattern-catching ability of seismic, making the resulting reservoir models satisfy seismic, geological interpretation and actual well-log / core data is an outstanding challenge. Object-based techniques are not viable for this problem because they are difficult to constrain to well-log data or partially interpreted geobodies. This paper attempts to solve the above problem by proposing a novel geostatistical approach making use of so-called "features". Instead of using single pixels, feature-based geostatistics attempts to work directly on templates of pixels, which represent geologically realistic object pieces, thereby decreasing the dimensionality of the pattern matching problem and promoting geology reproduction. In this sense, feature-based geostatistics is a middle-ground approach between pixel-based and object-based methods. The paper includes a submarine channel case study where the seismic is available and analyzed using a clustering method. A feature-based simulation technique is applied to this data. The method manages to reproduce the facies morphologies desired and conditions to data easily at considerable less CPU demand than either pixel-based or object-based methods.
Representation of Reservoirs Generated by Object-Based Stochastic Simulation in Numeric Flow Modeling
Authors: Pumputis A. , Schiozer D. J. 
Published: December 2007

Abstract
The interest for the reservoir characterization through the use of object-based stochastic simulation has increased recently in the petroleum industry, mainly because it is a promising technique for the evaluation of new fields. The objective of this work was to study the representation of object-based stochastic reservoirs in numerical flow simulation and the influence of such a process in the petroleum production forecast. Using data of object-based stochastic simulations of a real petroleum field containing sand rich turbidities reservoirs poorly connected, it was studied the interaction of four different reservoir characterization tools: (1) object-based stochastic simulation, (2) calculation methods of petrophysical properties, (3) upscaling and (4) numeric flow simulations.
Aiming the representation of the real model with the smallest acceptable computational effort, it is shown how the choice of the calculation method of petrophysical data and the upscaling process affect the flow simulation results. It was possible to test the importance of each part of the process, especially the influence of the model heterogeneity and of use of different grids in the flow simulations. Concerning volumes in situ and oil and gas production the effect of the object-based stochastic simulation and of different methods of properties calculation were more important in the final results. Water production was most influenced by the upscaling process.
It is shown the importance of each part of field production prediction process from the reservoir characterization through the flow simulation. The influence of heterogeneity and details about the upscaling process are discussed.
Development of Novel Membrane Efficient Water-Based Drilling Fluids Through Fundamental Understanding of Osmotic Membrane Generation in Shales
Authors: Mody Fersheed K. , Tare Uday A. , Tan Chee P. , Drummond Calum J. , Wu Bailin 
Published: December 2007

Abstract
Wellbore instability in shales is a major problem costing the petroleum industry US$900 million annually, according to conservative estimates. Water-based drilling fluids are being increasingly used to drill through troublesome shale formations. Major drivers for using water-based drilling fluids over oil-based drilling fluids are their cost-effectiveness and greater environmental acceptability. Despite these incentives to use water-based drilling fluids, improper application of such fluids while drilling sensitive shale formations can lead to costly wellbore instability problems. For correct application of water-based drilling fluids, an in-depth understanding of their physico-chemical interaction with the shale formations being drilled is important.
Shale stabilization with water-based drilling fluids can be achieved through a combination of osmotic outflow of pore fluid (chemical potential mechanism) and minimization of mud pressure penetration. Mud pressure penetration can either be prevented by generating an isolation membrane on the borehole wall or be reduced by minimizing hydraulic diffusivity. To help ensure adequate outflow and/or minimize hydraulic diffusivity with water-based drilling fluids, an efficient semi-permeable membrane should be generated within the shale. Several membrane generation mechanisms with varying degrees of effectiveness, depending on shale properties, are described in this paper. Mechanisms described involve chemical reactions between the drilling fluid and shale pore fluid, generation of electrical charges on exposed shale surface to selectively restrict ion movement and modification of clay structure by chemical and mechanical means.
Laboratory experiments on shale samples under realistic downhole conditions exposed to a range of water-based drilling fluids are presented to emphasize the time-dependent nature of membrane generation. The experiments showed that maintenance of shale stability with a new generation of water-based drilling fluids can be achieved through significant increase in membrane efficiencies (greater than 80%) within relatively short exposure times.
A fundamental understanding of the osmotic membrane generation in shales and the application of experimental data have resulted in the development of a new generation of water-based drilling fluids designed to successfully achieve drilling objectives through shale stabilization. Guidelines presented here for drilling of shales should help to significantly reduce shale stability-related non-productive time during drilling.
Effect of Scale Up and Aggregation on the Use of Well Tests to Identify Geological Properties
Authors: Raghavan Rajagopal , Dixon Thomas N. , Thomas Olubusola O. 
Published: December 2007

Abstract
This paper discusses specific issues encountered when pressure tests are analyzed in reservoirs with complex geological properties. These issues relate to questions concerning the methodology of scale up, the degree of aggregation, and the reliability of conventional methods of analysis.
Timing and Distance of Well Interference in Anisotropic Reservoirs
Authors: Chen Her-Yuan , Teufel Lawrance W. 
Published: December 2007

Abstract
This work provides a technique for determining the time and the point at which pressure disturbances originating from two adjacent wells begin to interfere significantly. Reservoir continuity and flow anisotropy due to natural fractures are common issues in tight-gas reservoir. Lacking and accuracy of pressure data makes the interpretation highly uncertain. The developed technique will provide a method to assist the interpretation of well-interference issue and the optimization of well spacing/pattern in tight-gas reservoirs. The technique is based on analytical model and is easy to apply.
The Study of Performance Prediction of Treatment Wells in Low Permeability and Abnormal High Pressure Gas Reservoirs
Authors: Tingxue Jiang , Wu Qi , Wang Xugang , Zhang Fuxiang , Ding Yunhong , Zou Honglan , Fan Yonghong 
Published: December 2007

Abstract
The result worked out in laboratory under the condition of in-situ stress indicates that a strong stress sensitivity is usually a main character of low permeability and abnormal high pressure gas reservoirs, i.e., the permeability decreases with the increase of effective stress (the result of decrease of pore pressure), which will cause a reduction of gas wells’ rate in some degree. Therefore, a finite element model is established to simulate above problem. Compared with other models, the model put forward in the paper can take into account the following factors:1)The sensitivity of permeability to effective in-situ stress;2)Non-darcy flow within an artificial fracture;3)Skin factor and erosion depth;4)The fracture conductivity is a function of time, fracture length and effective in-situ stress as well;5)three dimension flow in gas reservoirs, and the state parameters of rock and gas such as density and porosity are functions of pore pressure. After that, a computer program has been worked out by virtue of VISUAL BASIC, and a case study conducted in a gas well of AK1 which is located in TARIM basin, Xinjiang, China.with the simulation result shows a high precision compared with the field data. What's more, the simulation results indicate that: 1)a reduction of a gas well's production rate may decrease up to 10 to 40 percent of its original rate;2)the impact of skin factor is bigger than that of erosion depth;3)a reduction of a gas well's rate may decrease up to 10 to 50 percent of its original value as a result of conductivity damage which is a function of time, fracture length and in-situ stress as well. It should also be noted that the model put forward in the paper can be used to conduct performance prediction of such treatment wells as hydraulic fracturing wells, matrix acidizing wells and acid fracturing wells, so that it has a great significance in improving above wells’ optimal design level and decision making level as well as the production level of overall gas reservoirs, and if it is popularized to field applications, a great benefit may be expected.
Gas Diffusion – Its Impact on a Horizontal HPHT Well
Authors: Bradley Nigel D. , Low Eric , Aas Bjarne , Rommetveit Rolv , Larsen Hans F. 
Published: December 2007

Abstract
If a HPHT well with oil based mud is left undisturbed for a period, eg. when tripping or logging, methane will diffuse from the formation through the mud invaded zone and mud filter cake into the well bore. This can amount to substantial quantities and will occur despite an overbalance of mud hydrostatic pressure existing. Consequences can be potential well control problems when circulation is resumed or pipe is tripped back into the well or degradation of mud properties including loss of weighting material or ‘baryte sag’.
Field Testing of a New Nuclear Magnetic Resonance Logging-While-Drilling Tool
Authors: Morley Jan , Heidler Ralf , Horkowitz Jack , Luong Bruno , Woodburn Charles , Poitzsch Martin , Borbas Tim , Wendt Brett 
Published: December 2007

Abstract
Downhole nuclear magnetic resonance (NMR) measurements are evolving into a powerful formation evaluation tool, providing unique and critical information including formation porosity, pore-size distributions, bound-fluid volume (BFV), free-fluid volume (FFV), permeability, and fluid properties. Obtaining this information while drilling can have a significant impact on drilling and completion decisions. In addition, low rates of penetration common in many drilling environments can be advantageous in improving the NMR measurement statistics.
This paper describes results gained during field tests of a new NMR logging-while-drilling (LWD) tool that has been designed to run in any standard measurement-while-drilling (MWD) bottomhole assembly. The new tool presents no special operational complications in terms of mechanical specifications or wellsite hardware and software, and it has been tested successfully in both real-time and recorded modes in a wide range of formations and drilling conditions. A key consideration in the design of this tool has been to deliver an NMR measurement of wireline quality with a minimum of interference to the drilling process. To this end, the tool is usable in various modes of operation (stabilized, unstabilized, while drilling, while reaming, etc.).
The detrimental effects of tool motion on the NMR measurement are minimized through the hardware design. Motion-effects modeling and log examples address these issues. Having the capability of acquiring data in the conventional T2 mode, this tool offers a familiar interpretation strategy for those users accustomed to evaluating wireline NMR data along with a significant advantage in statistical precision over a T1 acquisition mode.
An Integrated Caliper from Neutron, Density, and Ultrasonic Azimuthal LWD Data
Authors: Ortenzi L. , Evans M. , Maeso C. J. 
Published: December 2007

Abstract
Accurate logging-while-drilling (LWD) borehole caliper data are important for drilling, logging and well completion. A single, accurate LWD caliper can greatly minimize risk and improve quality by bringing critical new information to these applications.
Presently, an LWD azimuthal density porosity tool can provide three different hole-size measurements. In addition to an ultrasonic caliper, a neutron-derived and a density-derived caliper have been recently introduced. Each method has different advantages and limitations that are related to the physics of the measurement and environmental conditions. This paper provides an overview of the ultrasonic caliper, the new neutron- and density-derived calipers and also describes the applicability range of each measurement. A method is also proposed to integrate the different techniques in order to form a single, robust and accurate LWD caliper. Examples of the individual and integrated calipers from an azimuthal density porosity tool are presented.
Estimating Non-Darcy Flow Coefficient from Buildup Test Data With Wellbore Storage
Authors: Spivey J. P. , Brown K. G. , Sawyer W. K. , Frantz J. H. 
Published: December 2007

Abstract
An algorithm has been developed for computing the pressure response for a well with constant wellbore storage and non-Darcy skin factor across the completion. The algorithm has been used to generate type curves for drawdown and buildup tests. The buildup pressure derivative response for a well with non-Darcy flow across the completion exhibits a much steeper slope during the transition out of wellbore storage than that of a well with constant skin.
No reservoir model with constant wellbore storage and skin can reproduce this steep derivative. Thus, if it is present in a buildup test, the well is experiencing either decreasing wellbore storage or decreasing skin factor, or both.
With the new type curves, under favorable conditions, both Darcy and non-Darcy skin components may be estimated from a single buildup test following constant rate production. The new algorithm may also be used to model a test sequence comprising multiple flow and buildup periods.
Reverse Like-Kind Exchanges for Oil and Gas Transactions Enter a New Era: New IRS Procedures Add Needed Flexibility
Authors: Brown C. D. , Brown A. J. , Phillips R. C. 
Published: December 2007

Abstract
Oil and gas transactions frequently result in sizable capital gains taxes that have a negative impact upon profitability. The Internal Revenue Code, Section 1031, has long provided a method to defer the tax by using a deferred like -kind exchange process, whereby a property must be sold before the "target" can be bought.
Last year, the IRS endorsed and published the reverse like-kind exchange procedures, which allow companies to purchase properties before selling others. This paper explains both procedures and provides examples for utilizing one or both to provide companies with the maximum rate of return from their acquisitions and divestitures. Key elements of the like-kind exchange procedures are identified to assist operators and help them avoid costly oversights that can cause a like -kind exchange to be ruled ineligible.
Would You Know a Good Decision if You Saw One?
Authors: Bratvold R. B. , Begg S. H. , Campbell J. M. 
Published: December 2007

Abstract
Ever since the early publication by Grayson,1 we have seen an increasing interest in decision-analysis in the oil and gas industry. There have been numerous studies and publications discussing methods and models for rational decision-making. Given the inherent limitations of intuition and heuristics, one might expect decision-makers to be delighted with the more consistent approach provided by rational decision-making techniques. Modern decision models can help process large amounts of information without losing valuable pieces. They never suffer from distraction, fatigue, boredom or random error. They are consistent, week after week.
Yet, in spite of these obvious advantages, people treat these with a nearly instinctive distaste. They are particularly resistant to the idea that simple models can validly make such subjective evaluations. For some, that resistance may stem simply from unfamiliarity with the statistics and probability involved. Many more, however, subscribe to the widespread assumption that human judgment is more discerning than a model. They are reluctant to believe that simple mathematical calculations can match the complexity of the human mind. "Take away an ordinary person's illusions," says Dr. Relling in Henrik Ibsen's Villanden, "and you take away happiness at the same time."
A particularly interesting aspect of human judgment and decision-making are the traps we unknowingly step into. Many decision-makers believe that intuition, repeated experience and their general intelligence will see them through. Unfortunately, as will be discussed in the paper, intuition and repetition are unreliable teachers at best.
Fluvial Channel Parameter Estimation Constrained to Static, Production, and 4D Seismic Data
Authors: Phan Vinh , Horne Roland N. 
Published: December 2007

Abstract
This paper proposes a subcell technique for modeling geometry and spatial distribution of channels in a fluvial reservoir by history matching of production and 4-D seismic data while constraining to well log and 3-D seismic information. The method developed here is capable of processing any number of geological objects with arbitrary geometric shapes and results in a fast and feasible inversion. The application of the proposed technique is presented in this work through several two- and three-dimensional examples in a two-phase water-oil case. The results of this work also show that the ntegration of production and 4-D seismic data can give us a better understanding of the reservoir geology and geophysics.
Introduction to a Method to Obtain Formation Pressure by Pressure Build-Up Curves and Some Characteristics of Formation Pressure in Multi-Zone Heterogeneous Reservoirs of Daqing Oil Field
Authors: Wang Demin , Sun Yingjie , Tang Xuping , Wang Gang 
Published: December 2007

Abstract
This paper introduces the theoretical basis, derivation of the formulas and actual procedures of a method to obtain formation pressure by pressure build-up curves. The formation pressure can be average pressure in the drainage area, average pressure at the boundary, pressure when there are faults near the well, pressure for closed boundary conditions and water drive (with different injection – production ratios). This method is quite versatile, accurate and simple in procedure. Daqing Oil Field has used this method for more than 40 years to calculate formation pressure more than 1 million times.
Daqing Oil Field is very heterogeneous, has multi-zones and the zones are not very continuous between wells. The characteristics of formation pressure of this type of reservoir are quite different from that of homogeneous single-zone reservoirs. Field data and history curves are shown to point out the special characteristics of formation pressure of this type of reservoir.