bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the Mechanism of Transport and Retention of Nonaqueous Scale-Inhibitor Treatments in Cores Using Novel Tracer Techniques
Authors: Shields R. A. , Sorbie K. S. , Singleton M. A. , Guan H. 
Published: December 2007

Abstract
In recent years, a number of non-aqueous delivery systems for scale inhibitors (SI) have been developed which are designed to be applied as low damage, low watercut or pre-emptive squeeze treatments, e.g. in critical or expensive subsea wells. The mechanisms through which non-aqueous scale inhibitor systems operate is an important technical issue. Only when a good understanding of the transport and retention mechanisms is developed, can this be built into a model for designing such squeeze treatments (such as the SQUEEZE VI model). The experimental work in this paper focused on a specific "oil soluble" version of a standard penta phosphonate inhibitor (DETPMP), which has been described previously in the literature. Several floods have been carried out comparing corresponding non-aqueous and aqueous applications of DETPMP in order to better determine the main features of the transport and retention mechanism of the system. Novel core flood experiments with tracers in both the aqueous and oleic phases have been performed and are reported in this paper. Unique information is generated by designing very detailed flooding cycles and carrying out tracer floods at each stage. Results point to the formation of an immobile "emulsion like" third phase in this system. In order to confirm our proposed mechanism, non-aqueous inhibitor has also been applied at zero residual water saturation (100% oil) to investigate whether or not the tailing effect (or third layer deposition) could be generated without prior oil/water partitioning of the scale inhibitor. For this case, tailing of the brine tracer only was observed. Mass balance showed that there was still considerable retention of scale inhibitor that was ultimately produced during the aqueous post-flush.
The corresponding aqueous inhibitor coreflood showed similar returns to that of the previous non-aqueous experiment and no retardation of either the tracer species or the metal ions in the brine. No formation damage occurred for either phase after the inhibitor was injected. A further control flood (no SI treatment) proved that the brine tracer tailing arose as a direct result of the treatment.
The use of the tracer species in each (water and oil) phase is a genuine innovation, which provides a powerful additional technique for demonstrating the effect of chemical treatments on the flow and the retention of all fluids in the core.
Development of a Nonaqueous Scale-Inhibitor Squeeze Simulator
Authors: Vazquez O. , Mackay E. J. , Sorbie K. S. 
Published: December 2007

Abstract
This paper describes the development and application of a two-phase, multi-component, multi-layer, radial mathematical model capable of simulating aqueous and non-aqueous scale inhibitor squeeze treatments. The model considers the immiscible displacement of oil and water phases along with inhibitor transport in both phases and mass transfer between phases. It can model kinetic and equilibrium adsorption and desorption from either phase. The model has been validated by comparison with analytical solutions, standard conventional single-phase squeeze calculations and multi-phase reservoir simulation calculations.
Example results are presented, along with guidelines for appropriate use of these types of calculation in the design of aqueous and non-aqueous scale inhibitor treatments in wells across a wide range of water cuts.
Semianalytical Model for Reservoirs With Forchheimer's Non-Darcy Flow
Authors: Zeng F. , Zhao G. 
Published: December 2007

Abstract
This paper presents a semi-analytical model to investigate the effect of Forchheimer's non-Darcy flow on the transient pressure behavior of vertical well in an infinite homogeneous reservoir. This model uses the Forchheimer number, defined as the product of the reservoir non-Darcy flow coefficient and a reference rate, to quantify the non-Darcy flow in reservoirs accurately. The traditional non-Darcy skin factor, generally applied to model the non-Darcy flow in reservoirs, is employed to describe the non-Darcy flow across completions only. This study shows that the non-Darcy flow effect may influence the local flow rate profile over a reservoir region of several hundred times the wellbore radius. Therefore, it is not satisfactory to merely use the traditional non-Darcy skin factor to model non-Darcy flow in reservoirs.
Type curves are documented for both drawdown and buildup tests for the first time using the semi-analytical model proposed. It is observed that, when non-Darcy flow in reservoirs and/or across completions are considered, the dimensionless pressure derivative curves of drawdown tests have a wider-transition region with gentler slopes, while those of buildup tests exhibit a shorter transition region with steeper slopes. In the radial flow period, compared to the cases with only non-Darcy flow across completions, the cases with non-Darcy flow in reservoirs for drawdown and buildup tests possess dimensionless pressure derivatives that are moving downwards to approach 0.5 at decreasing rates more gradually and smoothly. In general, the pressure derivatives of drawdown tests are larger than those of buildup tests before they converge to 0.5.
With this model, the skin factor for non-Darcy flow across completions and the dimensionless Forchheimer number for non-Darcy flow in reservoirs can be estimated from a common drawdown or buildup test. Guidelines for interpreting field test data are presented. Several typical cases from the literature are analyzed, and better type curve matches and more reliable results are obtained.
Use of Wavelet Transform in PDG Data Treatment
Authors: Ribeiro P. M. , Pires A. P. , Oliveira E. A. P. , Ferroni J. G. 
Published: December 2007

Abstract
Since the beginning of the 80´s, more and more Pressure Downhole Gauges (PDG´s) were installed in production and injection wells. The main purpose was well monitoring and evaluation of reservoir performance. This kind of gauge provides a large amount of data, but there are different problems that do not allow their complete use. These problems are related to quantity and quality. Most of the softwares are not able to handle with all the data available in a long recording period, the main objective of the use of PDG´s. Besides that, gauges present noise and strange data (outliers). It becomes necessary to treat the data before its use in the study of reservoir behavior. The concept of wavelet transform was developed about a century ago, but it was during the 80´s that it received practical application. Now it is used in a wide variety of applications, and, especially in data treatment, it presents two main features that make it attractive: smoothing of the signal and retention of the details. In this paper we use the wavelet transform to overcome the main problems and enhance the reliability of the information contained in the data. We tested different wavelets with several decomposition levels against actual and synthetic data. The outliers must be removed before the wavelet analysis in order to enhance its performance. We show that there is no unique "correct" wavelet transform to apply in any flow period. For example, for some datasets the Daubechies 1 wavelet at decomposition level 6 was used for flow periods, and level 3 for build up. It is important to notice that the use of high decomposition levels may cause loss of information, as it is shown in some examples. The wavelet analysis was also used to recognize transients from its ability to enhance the details. This is particularly useful to identify flow rate changes when they have not been reported, for example. Finally, we propose a methodology to treat the data before its use in posterior interpretation.
Enhancing Formation Testing and Sampling Operations Through the Use of Log-Derived High-Resolution Mineral-Based Lithofacies Mapping
Authors: Elshahawi H. , Donaghy E. , Guillory C. , Kear G. R. , Kumar A. , Ardila M. , Williamson D. , Cantwell W. , Briscoe B. 
Published: December 2007

Abstract
Wireline formation testers are being routinely used today in a range of applications that spans pressure and mobility profiling; downhole fluid sampling and downhole fluid analysis; interval pressure transient testing; and micro-stress testing. These tools are able to collect large amount of data at multiple depths thus helping to quantify changes in rock and fluid properties along the wellbore, to define hydraulic flow units, and to understand the reservoir architecture.
A key input into the planning of wireline formation tester operations is an accurate understanding of the subsurface lithology, including subtle reservoir internal baffles and barriers. Not only is it necessary to understand where, in depth, the zones of interest exist, but also their compositions. Log-derived high-resolution mineral-based lithofacies can be used to improve the planning of downhole sampling operations and post-operational analysis. These are computed using borehole spectroscopy and high-resolution micro-resistivity image data. The spectroscopy data is used to classify the rocks into dry-weight mineralogy-based lithofacies based on a specifically designed ternary-diagram classification system. Calibrated high-resolution micro-resistivity image data is integrated with the generated dry-weight mineralogy-based lithofacies to compute a final mineral-based high-resolution set of lithofacies. All the computations can be accomplished on a workstation within a short time. The final lithofacies can be presented as a detailed geological column, or be input, as numerical data, for additional computation and modeling.
These lithofacies can be used to make sampling and pressure point selections. The speed of computation makes them useable for this purpose. The output can be quickly delivered to the decision makers whether in the office or at a remote location. The geological display of the lithofacies makes it readily usable and preferred for choosing sampling locations, whether for pressure or fluids. The inherent mineralogical content combined with the higher resolution bedding directly addresses the need to identify potential zones of interest otherwise indistinguishable. Critical depositional events such as maximum flooding surfaces, condensed sections, reservoir seals such as marl layers and shales, continuous or interbedded, are immediately identifiable with these lithofacies.
The use of log-derived high-resolution mineral-based lithofacies helps place the tool probes and/or packers at optimum formation and depth locations, thereby reducing risk and operating time, easing interpretation, and maximizing data and sample recovery.
Quantification of Carbon Dioxide Using Downhole Wireline Formation Tester Measurements
Authors: Müller N. , Elshahawi H. , Dong C. , Mullins O. C. , Flannery M. , Ardila M. , Weinheber P. , McDade E. Chinn 
Published: December 2007

Abstract
Carbon dioxide (CO2) occurrence in hydrocarbon bearing formations presents a challenge to the valuation and subsequent prospect development of the hydrocarbons. Corrosion is a major concern effecting capital and operational expenditures since the presence of CO2 can cause corrosion failures. Carbon dioxide also denotes an issue for health, safety and the environment (HSE) and is readily absorbed by elastomer seals, weakening the resistance of those seals and compromising the integrity of the fluid samples and the safety of equipment and personnel.
The conventional procedure to evaluate the CO2 content in a hydrocarbon bearing formation is to take fluid samples downhole or on surface during a well test and send the fluids to the laboratory for analysis. Both methods are compromised by the reactive nature of CO2, whose concentration can change significantly by reaction with formation waters, mud filtrates, etc. before reaching an analysis facility. Optimizing the fluid sample acquisition program to match existing fluid complexities is impossible without real-time analysis.
Recently, NIR (near-infrared) spectroscopy has enabled the real time analysis of the CO2 content in downhole fluid samples. This paper describes a new method for using DFA* (Downhole Fluid Analysis) in the real-time determination of the CO2 amount in the MDT* (Modular Dynamic Formation Tester) flow line. Extensive laboratory data from a research grade spectrometer and shop data with the downhole tool support the new methodology. Multiple interpretation algorithms have been developed for CO2 quantification and verified in the laboratory. Several log examples are given Mark of Schlumberger demonstrating successful CO2 detection and subsequent confirmation of the measured concentrations by the laboratory data.
Combining Continuous Fluid Typing, Wireline Formation Tester, and Geochemical Measurements for an Improved Understanding of Reservoir Architecture
Authors: Elshahawi H. , Venkataramanan L. , McKinney D. , Flannery M. , Mullins O. C. , Hashem M. 
Published: December 2007

Abstract
Identifying compartmentalization and understanding reservoir structure are of critical importance to reservoir development. Traditional methods of identifying reservoir compartmentalization such as drillstem tests and extended well tests often become impractical in deep water settings with costs approaching the costs of new wells and emissions becoming increasingly undesirable. Thus, compartments often have to be identified by some other means.
Individually formation pressure measurements, downhole fluid analysis (DFA), and geochemistry are known to provide important information about reservoir architecture. When these powerful methods are systematically combined and applied to datasets, the synergy delivers a much more accurate and robust picture of the reservoir. In this paper, we review a number of case studies in which we have successfully combined continuous fluid facies mapping, pressure gradient measurements, DFA, and geochemistry for reservoir continuity assessment in a diverse range of geological settings including a wide range of field sizes, structural environments, reservoir lithologies, and oil types. Particular emphasis is placed on comparing the strengths and limitations of the different techniques in revealing reservoir architecture, especially vertical permeability barriers. We present a number of unambiguous cases, for which multiple data streams might be viewed as being somewhat redundant. More ambiguous cases, in which the multiple data streams are required to make a robust assessment of key reservoir properties, are also presented.
Expandable Sandface Completions—Design and Performance Review of Single-Zone Applications and Journey to Next-Generation Multizone Systems
Authors: Morgan Quentin , Jones Colin , Macarthur Ally 
Published: December 2007

Abstract
The advent of Expandable Sand Screens (ESS) technology heralded a new era in mechanical downhole sand control by specifically addressing perceived limitations of standalone screens (SAS) and complexities of gravel packs. To date, ESS has been installed in over 400 wells worldwide under a variety of operating conditions, with the majority in single-zone environments.
This paper describes designs aspects and applications engineering behind historical ESS applications, and discloses findings from a recent survey of these installations to derive key performance and reliability indices. A discussion of how these findings have been used to better understand and refine operations envelope for ESS and improve robustness of applications engineering to yield greater system reliability is also included.
The productivity benefits of ESS technology, has been the subject of several authorative papers, with growing body of anecdotal evidence now in the public domain quantifying productivity gains achieved compared with other wells employing variety of other sand control techniques, particularly in open-hole environments.
The drive for maximum well productivity compels many operators to consider openhole completion strategies. However, this has often not been possible through inability to achieve effective zonal isolation. Though ESS has been interfaced successfully with available annular barrier technologies to satisfy this goal in cased hole, technical limitations have constrained use in open hole.
This paper documents therefore an 18-month expandable technology research and development effort that has culminated in the introduction of a wholly new multi-zone Expandable Reservoir Completion (ERC) architecture, where selective isolation or production provides advantage.
This next generation ERC system combines slotted and solid expandable technology to deliver a reservoir completion with a combination of openhole production performance and casedhole functionality. Early results from initial ERC installations are showcased to illustrate system potential.
High-Impact-Resistant Cement Allows Challenging Sidetrack in Abu Dhabi
Authors: El Hassan Hassan , Shagnoubi Mahmoud , Belmahi Abdel , Jarouj Haitham , Voon Eric 
Published: December 2007

Abstract
The process of sidetracking an existing borehole with a balance cement plug has historically been time consuming and problematic for the drilling industry. The formations in the Middle East are classified as some of the most competent formations in the industry. These formations present its own challenges when attempting to sidetrack because of changes in the drilling trajectory. Historically, the operator has faced problems sidetracking in the Shilaif formations, where longer drilling time and/or numerous cement plugs are required to achieve this objective. These requirements lead to an increased in drilling costs.
Traditionally, a conventional cement system with a high compressive strength is used for sidetracking purposes. However, these cement systems have low resistance to impact and shock and hence will fail through rupture when placed across the competent formations. An optimized particle sized distribution cement system, combined with engineered metallic micro ribbon technology has allowed the sidetracking to be achieved efficiently.
The technology improves the durability and the resistance of the cement to load bearing capacity and fracture propagation. Further laboratary testing comparisons have confirmed the enhanced mechanical properties of this cement system. As a rule of thumb, the industry relied on the rate of penetration (ROP) as an indicator of how good a cement plug is for sidetracking purposes. It is believed that the lower the ROP is, the easier the sidetrack can be achieved.
As the technology is "tougher" than the formations, the drilling bottom hole assembly (BHA) can be deflected/ sidetracked efficiently and drilling operations resumed, in a shorter period of time compared to using conventional cement systems.
An Innovative Inert Material To Cure the Losses in the Brent Depleted Reservoirs— North Sea Case Histories
Authors: Shuttleworth Nigel , Frederiks Kees , DerPlas Klaas Van , McCraith Steve , Taoutaou Salim 
Published: December 2007

Abstract
Drilling in the Brent field began to experience severe lost circulation problems after the start of depressurisation in 1998. The losses occurred in the reservoir sections, which were penetrated by extended reach and near-horizontal wells. In contrast, wells drilled before the onset of depressurisation experienced few losses.
The lost circulation problems resulted from a narrowing of the drilling operating window as reservoir depletion gradually reduced the fracture gradient. Numerous interbedded reservoir shales, which were subseismic in thickness, required a minimum mud weight to maintain stability, especially in the subhorizontal sections. Problems became acute when the fracture gradient was reduced to a level below the equivalent circulating density (ECD) required to successfully drill the shales.
The rate of decline in the fracture gradient was much lower than would have been predicted from conventional geomechanics estimation, and this extended the duration of the Brent drilling programme during depressurisation. Drilling and cementing the Brent reservoir with no losses has proven very difficult in the past 2 years.
This paper will describe the lost circulation problems when drilling and cementing the Brent reservoir and the new approach used during cementing to cure losses without adding constraints to the offshore operation.
A New Neural Network Approach to Reservoir Permeability Estimation from Well Logs
Authors: Lim Jong-Se , Park Hui-June , Kim Jungwhan 
Published: December 2007

AbstractReservoir permeability is one of the most important properties of oil and gas fields for reservoir characterization. In un-cored intervals or wells, reservoir description and evaluation methods using well log data represent a significant technical as well as economic advantage because well logs can provide a continuous record over the entire well where coring is impossible. Permeability determination from well logs in heterogeneous formation has a difficult and complex problem to solve by conventional statistical methods. Recently artificial neural networks (ANNs) have been successfully used to solve many of complex problems in reservoir permeability estimation. However, the applications of the neural network to mapping complex nonlinear relationship have revealed a number of unsolved technical limitations despite of the high versatility. This paper proposes a group method of data handling (GMDH) based on polynomial neural network (PNN) for permeability prediction from well logs to alleviate limitations of the conventional neural network approach. The PNN evolutionally synthesizes network size, connectivity, processing element types, and coefficients for globally optimized structure through training. This self-organizing approach automatically presents internal relationships among data in the polynomial forms, and enhances data approximation and explanation capabilities of resulting data-based learning models. This technique is demonstrated with an application to the well data in offshore Korea. The comparative study with conventional neural networks reveals that the proposed model gives a relatively positive performance although the prediction accuracy of the PNN model is affected by errors in measurement data. The PNN is a practical and powerful tool for predicting reservoir permeability of a heterogeneous formation utilizing well logs.