bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of Coiled-Tubing Acidizing Through Real-Time Staged Fluid Tracking
Authors: Zheng A. S. , Bucher R. , Allcorn M. 
Published: December 2007

Abstract
In coiled tubing acidizing, a variety of fluids are pumped through coiled tubing in certain sequence to create the optimized downhole condition to treat the wellbore. Typically, prior to the coiled tubing reaching the target treatment zone, a neutral fluid may be pumped into coiled tubing during running-in-hole (RIH) for circulating purpose. Once at the targeted treatment zone, a pumping schedule (such as pre-flush, treating and post-flush fluids) may be used to treat the wells. During the operations, the coiled tubing operator may also move the coiled tubing (either running-in-hole or pulling-out-of-hole) while staged fluids are being pumped. It is desirable to track the movement of staged fluids inside coiled tubing to optimize the treatment. This paper presents a new technology to track the movement of stage fluids inside coiled tubing. It includes real time surface and downhole measurements, fluid and gas modelings and friction pressure drop calculation along coiled tubing. This new technology allows operators to optimize coiled tubing running speed and surface pumping to create the desired action downhole. The availability of staged fluids information downhole also opens the possibility for real time treatment evaluation. Several field job cases are reviewed to demonstrate the effectiveness of this new technology.
The Use of Finite-Element-Calculated MFL Signals To Study Characterization of Defects in Steel Coiled Tubing
Authors: Breidenthal C. , Larin G. E. , Tipton S. M. , Stanley R. K. 
Published: December 2007

Abstract
A primary consideration with coiled tubing (CT) is that it is consumed by fatigue loading during routine operations. Also, rugged oilfield conditions routinely lead to corrosion and other mechanical surface damage. Since fatigue is a surface phenomenon, the presence of a surface imperfection has a significant influence on fatigue damage mechanisms. This paper describes the study of magnetic flux leakage (MFL) inspection signals caused by surface defects in the form of milled circumferential grooves in steel CT. The focus of the investigation is to identify and estimate the size of surface defects based on characteristic MFL signal features. It is demonstrated that this effort is greatly enhanced by finite element analysis (FEA). The ultimate objective is to accurately extract surface flaw dimensions from conventional MFL signals. These dimensions are used in computer CT life prediction models.
An axisymmetric FEA model is developed and used to calculate leakage flux density solutions for milled circular and rectangular shaped grooves in 1.75" O.D. x 0.156" W.T., 90- ksi CT samples. FEA results are compared to axial and radial MFL signals measured with an experimental inspection unit. Favorable agreement is observed between experimental and FEA data. Furthermore, signal features are correlated with the known slot geometries to identify basic geometry recognition patterns for different circumferential grooves. Signal features reveal qualitative and quantitative trends relative to surface flaw dimensional characteristics.
The need persists to make the operator's string management decision-making process more reliable and automatic with respect to determining fatigue life expectancy. The obstacle here is that due to the inherent inaccuracies in commonly used MFL inspection techniques, there is limited reliable real-time flaw evaluation and characterization capability.
Coiled-Tubing-Deployed Extended-Length Patches Extend Wells’ Production in Prudhoe Bay, Alaska
Authors: Julian J. Y. , Cismoski D. A. , Smart J. C. , Wendt D. D. 
Published: December 2007

Abstract
A non-rig Coiled Tubing Unit (CTU)-deployed tubing patch technique was developed at Prudhoe Bay, Alaska, which provides an inexpensive remediation for wells with production tubing by "A" annulus communication. Extended-length patches (which consist of two retrievable hydraulically set packers spanned by jointed pipe) are a vast improvement over older technology that limited patch length to 35’. Patches of up to 5000’ of 3.5" OD jointed pipe can now be deployed, significantly increasing the viability of repairing a larger percentage of the wells shut in due to loss of tubing integrity.
Extended-length patches are deployed with a crane, a service CTU, and a wellwork platform. The wellwork platform provides adequate clearance for the existing wellhead and workover BOP stack, and protects against arctic conditions of -40 degrees F ambient and -80 degrees F wind chill. The advantages of this system over conventional rig workovers are that there is no need to pull tubing and it has faster mobility and ease of scheduling. Typically, extended- length patches are only 10-20% of the costs to replace tubing with a rig workover.
This paper outlines the results of this work and provides a systematic approach for design and deployment of an extended-length jointed patch. The technique has its greatest application where rig mobilization costs are high, such as offshore, remote, or arctic locations.
Real-Time Depth Measurement with Coiled Tubing Results in Successful Well Recompletion
Authors: Greenaway R. , Coston C. 
Published: December 2007

Abstract
In an environment of high drilling activity and a limited amount of rigs, available alternative completion methods using Wireline or coiled tubing enables a more efficient drilling and completion process. For a successful completion, depth control is critical for the placement of perforating guns and completion hardware. Common practice is to perform the perforating using Wireline, which becomes challenging with wellbore angles over 60 deg.
The use of coiled tubing enables the completion of highly deviated or horizontal wellbores, but depth critical operations performed using coiled tubing historically have presented industry challenges. Using the innovative real time depth measurement (RTDM) tool overcomes the limitations of other down hole depth- correlation methods.
This paper describes the design, planning and execution of a completion in a horizontal well using coiled tubing and a RTDM tool.
Field Trial of QT-16Cr Chrome Coiled Tubing Used as a Workstring on the North Slope, Alaska
Authors: Julian J. Y. , McLellan B. J. , McNerlin B. J. , Martin J. R. , Burke K. W. , Meaux C. 
Published: December 2007

Abstract
QT-16Cr chrome coiled tubing was introduced in 2003, but its use has been limited to velocity strings in corrosive environments. Questions concerning its feasibility as a workstring prompted field testing of a reel of QT-16Cr on the North Slope, Alaska.
Following preliminary laboratory testing, a QT-16Cr reel was deployed in the field and performed a variety of standard coil tubing applications on a daily basis for a three-month field trial. Observations and data were gathered during the field testing to determine operating guidelines, applicability, and limitations of this new coiled tubing technology. The successful field trial indicated QT-16Cr has increased low cycle fatigue life, superior abrasion resistance in chrome completions, and higher resistance to damage in corrosive environments in comparison to standard HS-80 coiled tubing.
This paper documents the testing and results of the lab and field studies. In addition, standard operating procedures for QT-16Cr are described and provide easily implemented guidelines which should work in virtually any area coiled tubing operations are performed. This paper is significant for worldwide coiled tubing operations, especially in areas with high rates of coiled tubing corrosion and where coiled tubing wear is significant due to abrasive tubing tubulars.
Production-System Optimization of Gas Fields Using Hybrid Fuzzy-Genetic Approach
Authors: Park H. -J. , Lim J. -S. , Roh J. , Kang J. M. , Min B. -H. 
Published: December 2007

Abstract
The design of production systems of gas fields has been a difficult task because of the nonlinear nature of optimization problem and the complex interactions between each operational parameter. Conventional methods, which usually are stated in precise mathematical forms, cannot include the uncertainties regarding vague or imprecise information in the objective and constraint functions.
This paper proposes a fuzzy nonlinear programming approach to accommodate these uncertainties and applies to a variety of optimization processes. Specifically, the fuzzy λ -formulation is combined with a hybrid co-evolutionary genetic algorithm for an optimal design of gas production systems. Both the multiple conflicting objective and constraint functions for production systems of gas field are formulated in a feasible fuzzy domain. Then, the genetic algorithm is used as a primary optimization scheme for solving optimum gas production rates of each well and pipeline segment diameters to minimize investment cost with given constraints in order to enhance ultimate recovery.
The synthetic optimization method can find a globally compromise solution and offer a new alternative with significant improvement over the existing conventional techniques. It has been successfully applied to a wide variety of operational problems including well rate allocation and optimal design of pipeline networks. The reliability of the proposed approach is validated by a synthetic practical example yielding more improved results, offering a powerful tool for cost savings in future planning and the optimization of gas production operations.
Tracer-Flow Simulation for Characterization of Naturally Fractured Reservoirs by Streamline Method
Authors: Iino A. , Arihara N. , Waseda U. , Okatsu K. 
Published: December 2007

Abstract
A simulation model for the tracer response analysis in naturally fractured reservoirs was developed by double-continua formulation. Waterflooding in dual-porosity dual-permeability reservoirs is first modeled by the streamline approach. Then flow of the water-soluble tracer described by the coupled convection-dispersion equations is combined. First, 1-dimensional convection-dispersion equation is solved along each streamline in the matrix and fracture systems by ignoring the gravity and transfer terms. The concentrations are mapped onto the grid, and corrected with gravity and transfer.
The model is capable of conducting tracer flow and waterflooding simulation in field-scale dual-porosity dual-permeability systems. It is developed particularly for analyzing multiple-well tracer tests in heterogeneous fractured reservoirs.
The model is validated for homogeneous and heterogeneous permeability distributions comparing with results from Eclipse. Effectiveness of the CFL condition and a TVD scheme to control stability and numerical dispersion are evaluated and analyzed. In the heterogeneous case, the saturation fronts and tracer responses from the model are less smeared than those from Eclipse. The model is also run for validation and sensitivity cases with different dispersivity.
Finally, tracer responses for a multiple injection/production scheme in a realistic reservoir including mega-fractures are simulated. Simulations demonstrate the potential of the streamline approach for characterizing heterogeneity of the fractured distribution, and for identifying flow paths.
Evaluation of heterogeneous fracture developments is critically important for assessing the reservoir performance, and yet remains to be a difficult issue. Tracer flow simulation by the streamline approach is particularly useful to interpret and model fracture-matrix systems in terms of flow properties and anisotropy. The streamline-based model is powerful for analyzing tracer response data with readily available visualization.
Maintaining the Stability of Deviated and Horizontal Wells: Effects of Mechanical, Chemical, and Thermal Phenomena on Well Designs
Authors: Zhang Jianguo , Yu Mengjiao , Al-Bazali T. M. , Ong Seehong , Chenevert M. E. , Sharma M. M. , Clark D. E. 
Published: December 2007

Abstract
Wellbore instability, particularly in shale formations, is regarded as a major challenge in drilling operations. Many factors, such as rock properties, in-situ stresses, chemical interactions between shale and drilling fluids, and thermal effects, should be considered in well trajectory designs and drilling fluid formulations in order to mitigate wellbore instability related problems.
A comprehensive study of wellbore stability in shale formations that takes into account the 3-dimensional earth stresses around the wellbore as well as chemical and thermal effects is presented in this work. The effects of borehole configuration (e.g. inclination and azimuth), rock properties (e.g. strength, Young's modulus, membrane efficiency and permeability), temperature, and drilling fluid properties (e.g. mud density and chemical concentrations) on wellbore stability in shale formations have been investigated.
Results from this study indicate that for low permeability shales, chemical interactions between the shale and water-based fluids play an important role. Not only is the activity of the water important but the diffusion of ions is also a significant factor for saline fluids. Cooling drilling fluids is found to be beneficial in preventing compressive failure. However, decreasing the mud temperature can be detrimental since it reduces the fracturing pressure of the formation, which can result in lost circulation problems. The magnitude of thermal effects depends on shale properties, earth stresses and wellbore orientation and deviation.
Conditions are identified when chemical and thermal effects play a significant role in determining the mud-weight-window when designing drilling programs for horizontal and deviated wells. The results presented in this paper will help in reducing the risks associated with wellbore instability and thereby lowering the overall non-productive times and drilling costs.
Streamline-Based Simulation To Investigate Interwell Connectivity and Tracer Transport in 3D Discrete Fractured Reservoir
Authors: Park C. , Kang J. M. , Jung Y. , Kim S. 
Published: December 2007

Abstract
Heterogeneity and complex intersection patterns make it difficult to characterize a fluid flow on fractured reservoir. Limited information and uncertainty of underground fractures can often produce unreliable results of an interwell connectivity and a tracer trajectory. Previous studies have not been able to analyze an interwell transport taking place in 3D discrete fracture networks since no method was developed for considering plate flow and channeling within the same fracture schemes. Also the conventional streamline simulation as the tool of solute transport, is incapable of extending to 3D discrete one due to meshing problem.
A new streamline simulator with direct quadrilateral mesh generator is developed to determine the interwell connectivity and the main flow path on random discrete fractured reservoir. Quadrilateral grids are generated on polygon-typed fractures by constructing boundary loops automatically. Mass is transported using streamline approach on the unstructured grids. Breakthrough curve has a positively skewed characteristic, which reveals that the solute transport is influenced by not only geological heterogeneity, but pressure distribution and variable apertures. A trajectory of streamlines and a distribution of residence time confirm that the tracer moves selectively along intersecting lines or fracture planes in the direction of decreasing pressure gradient. The new numerical approach using streamline method and automatic quadrilateral meshing algorithm makes the fast analysis of interwell connectivity in relatively realistic manner.
Production of Wet Natural Gas Containing Corrosive Components: Four Case Histories
Authors: Havlik W. , Thayer K. , Oberndorfer M. 
Published: December 2007

Abstract
In petroleum production, the problem of corrosive media attacking metallic structures is almost ubiquitous. Particularly severe environments are encountered in the production and transport of wet natural gas containing corrosive components, such as hydrogen sulphide and carbon dioxide. When exploring new gas fields, it is therefore a prerequisite to take into account the corrosivity of the respective fluids in all stages of the field development, in material selection, field layout, and facilities design. In preparation of the subsequent production phase, reliable corrosion monitoring programmes have to be selected, established, and implemented, as necessary. Furthermore the financial aspects always play an important role thus posing a real challenge for the engineer forced to seek a compromise between economics and design.
This paper gives a comprehensive overview of these considerations regarding four different OMV gas fields, two of them in Austria and two in Pakistan, which were successfully developed and brought on stream between 1967 and 2003. These fields do not only vary in their geographical position, but also in gas compositions, production start, and the location of gas dehydration units.
One major aspect dealt with in each of these cases, was material selection including metallic as well as non-metallic and composite materials. Where the initial decision was made in favour of carbon steel, different methods of corrosion protection, the application of corrosion inhibitors, corrosion monitoring, and intelligent pigging are discussed in the paper.
Comparing the various methods of resolution that have been worked out for all four case histories, experience gained in more than three decades of production and transportation of wet corrosive natural gas is presented.
Furthermore, results of the ongoing corrosion monitoring measurements in operation in the mature gas fields are discussed under the aspect of the remaining facility lifetimes.
Modeling of Stress-Dependent Hydraulic Fracturing in a Dynamic Flow Simulation
Authors: Kaselow A. , Ganzer L. 
Published: December 2007

Abstract
In this work we present a new approach to include the influence of hydraulically induced fractures on the performance of a reservoir. Hydraulic fracturing has become a state-or-the-art completion for all kinds of wells and reservoirs. Especially in the case of low permeable tight gas reservoirs, fracturing is essential for efficient reservoir exploitation. As a result of this, most gas wells are nowadays hydraulically stimulated. However, in the case of low permeable tight gas reservoirs with rather long fractures an appropriate simulation requires a highly-flexible time-dependent adaptive gridding of the model in the vicinity of the created fracture.
Our work is based on a recently proposed simulation method which combines a dual continuum approach with a time-dependent highly flexible gridding method in order to accurately simulate the influence of hydraulic fracturing on well and reservoir performance. We extend this method by treating the process of hydraulic fracturing as a part of the simulation. At any given time during the simulation a hydraulic fracture can be initiated for any desired well. The geometry of the fracture is inferred from a given state of stress, injection rate, and elastic rock properties using the Perkins-Kern-Nordgren model. Once the fracture is created the simulation grid is appropriately adopted.
We have implemented our approach in a commercial reservoir simulator which provides the necessary gridding flexibility and a dual continuum formulation that allows for the definition of locally restricted dual porosity or dual permeability cells. We will show how the accuracy and flexibility of our method enhances the ability to simulate the performance of a reservoir fracture treatment.
From Logs Scale to Reservoir Scale: Upscaling of the Petroelastic Model
Authors: Menezes C. , Gosselin O. 
Published: December 2007

Abstract
Any quantitative workflow, designed to constrain reservoir models to 3D/4D seismic data, must rely on petro-elastic modelling (or PEM), which relates fluid and rock properties to elastic ones.
Various scales must be accounted for: laboratory cores and well logs, geological and seismic grids, fluid flow simulator models. The petro-elastic model is generally a fine-scale model ("pem"), defined and calibrated for each specific case against core and logs data.
Aiming a 4D history matching workflow at the flow model scale, we then need to validate the use of the logs-scale calibrated "pem" at a larger scale, vertically and laterally. In this paper we proposed a methodology to define an upscaled "PEM" (new set of relationships valid at reservoir-scale), by tuning a fine-scale existing "pem", adjusting the most sensitive and relevant parameters, by an optimisation procedure.
Some previous studies already addressed downscaling problems (from reservoir to geological/seismic scale), but no previous work has proposed any solution for an upscaled PEM.
The main results of this study, using real field data, are the following:
■ upscaling is necessary, depending on the degree of static and dynamic heterogeneity; ■ the optimisation procedure is successful in calibrating a fine-scale "pem" to get a reservoir-scale "PEM"; ■ the procedure is sensitive to the Backus averaging parameters, which must be defined carefully; ■ this workflow is performed at wells in this study, but could be extended to reservoir scale, when a fine-scale geological model is available.
Live Well Deployment System
Authors: Evensen M. , Dagestad V. 
Published: December 2007

Abstract
Deployment of long tool strings is often critical for economical intervention in horizontal wells. This is because the extensive exposure to the reservoir produces a corresponding requirement for long perforation and straddle intervals.
A Norwegian operator has faced this challenge to increase recovery from horizontal offshore wells. Deployment of long tool strings into live wells can be a challenging task. When using the down-hole safety valve (DHSV) as the primary well barrier, the operator has only accepted snubbing as conveyance method. Deployment against DHSV on Coil Tubing (CT) and Wireline (WL) has not been accepted in live wells.