bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Enhanced Ultrasonic Measurements for Cement and Casing Evaluation
Authors: Morris C. , Sabbagh L. , Wydrinski R. , Hupp J. , van Kuijk R. , Froelich B. 
Published: December 2007

Abstract
The hydraulic isolation of the wellbore casing and cement is critical for the completion of production and injection wells. Zonal isolation prevents the production of fluids from non-completion intervals, contamination of ground water by fluids in the wellbore, and allows conformance control of injected fluids. Current acoustic evaluation techniques may be limited by the acoustic properties of the material behind casing and by the inability to see beyond the cemented region near the casing. A new ultrasonic imaging tool has been developed to address these limitations.
The new imager tool combines the classical pulse-echo technique with a new ultrasonic technique that provides temporally compact echoes arising from propagation along the casing and also reflections at the cement-formation interface. Processing these signals yields unprecedented characterization of the cased-hole environment in terms of the nature and acoustic velocity of the material immediately behind casing, the position of the casing within the borehole, and the geometrical shape of the borehole.5
In order to provide answers to the casing/cement evaluation questions, a field study was performed to evaluate the results provided by both sonic and this new ultrasonic tool in the different cement materials, drilling fluids, and casing sizes. Field examples are presented to illustrate the actual response of the new ultrasonic tool to these various completion environments including wells cemented with conventional and lightweight cement. The results demonstrate enhanced cement evaluation for all cement types and a significant reduction in the uncertainty in making a squeeze or no-squeeze decision. The new cement evaluation tool implements both the traditional pulse-echo technique and the new flexural wave concept. The flexural mode enables deep imaging of the cement sheath up to the cement-formation interface. In addition, the measurement of the borehole geometrical shape makes it possible to evaluation double casing string conditions for potential damage.
Fracturing Previously Bypassed Highly Laminated Tight Gas Sands: A Production Optimization Case Study in South Texas
Authors: Fairhurst D. L. , Semmelbeck M. E. , Reynolds B. W. , Indriati S. , Lewis J. W. , Ellis A. C. , Deupree W. E. , von Plonski J. K. 
Published: December 2007

Abstract
Highly laminated tight gas sand sequences remain prolific targets worldwide and have often been bypassed using standard petrophysical analysis and simple porosity cut-off technique. The problem becomes more acute in marginal tight gas reservoirs. The high cost of hydraulic fracturing increases the need for an effective and useable petrophysical model for an accurate productivity indication of the target interval. The pressure to avoid non-economical completions continues to leave hydrocarbons bypassed. Using recent advances in logging technology and production optimization modeling, the thinly laminated gas bearing permeable sands can be discerned from clay dispersed in silt and sand. A true net height can now be obtained. Through production optimization modeling, it is possible to assess the economic viability of completing and stimulating highly laminated interval. In this paper, we will show a case study from a South Texas tight gas sand field. Several wells were evaluated using micro-resistivity imaging. From this an enhanced high-resolution petrophysical analysis was created. This image-enhanced evaluation of reservoir properties was combined with production modeling. The production performance was simulated for each interval and used for recommendations on completion strategies. Additional pay intervals, normally bypassed, were perforated and hydraulically stimulated. We compared production data from offset wells that used standard petrophysical analysis to the results of the newer wells with the high-resolution analysis. The results indicated that actual field production increased and paid out the increased fracture stimulation cost. Production logs acquired across entire intervals confirmed that portions of the field produced from horizons that were previously bypassed. This process is useful for any highly laminated tight gas sand sequence and is of widespread applicability. Previously bypassed intervals can now be assessed and completed effectively and economically. This process will further add to the reserve base of tight gas.
A New Technique to Determine Horizontal and Vertical Permeabilities from the Time-Delayed Response of a Vertical Interference Test
Authors: Sheng James J. 
Published: December 2007

Abstract
Vertical and horizontal permeabilities are important parameters for designing well completion and predicting well performance. In the past, to determine the permeabilities from a vertical interference test, some investigators proposed correlations or type curves based on simplified point source solutions. However, it is impossible for these correlations or type curves to cover the variety of scenarios found in the real world. In the recent years, people start to use regression analysis to match the responses at the source interval and the observation point. With regression analysis, we face the problem of non-unique solutions. Sometimes, an estimated permeability is outside a reasonable range when analyzing noisy data from real tests.
In a wireline vertical interference test, we perform a drawdown test followed by a buildup test. Because of the delay of response, the pressure at the observation probe continues to drop for some time during the buildup period at the source interval. The maximum pressure drop at the observation probe with regard to the maximum pressure drop in the source interval is time-delayed. Using this time delay and the maximum pressure drop at the observation probe, we developed a new technique to estimate vertical and horizontal permeabilities based on the line source solutions. We have also worked out a novel numerical scheme. The new technique is compared with the previous methods and shows its superiority in accuracy. In addition, our technique can be used in any situation with different test configurations. Application issues in real testing conditions are discussed. Finally, two field tests are analyzed using this technique. Previously, these tests could not be analyzed to determine vertical permeability using published methods because of the poor data quality.
A New Tool To Evaluate the Feasibility of Petroleum Exploration Projects Using a Combination of Deterministic and Probabilistic Methods
Authors: Siddiqui Mohammed , Al-Yateem Karam , Al-Thawadi Abdulla 
Published: December 2007

Abstract
In this paper we have presented a new tool to evaluate the feasibility of an exploration and production project. An exploration and production project can be evaluated for feasibility using deterministic methods or probabilistic methods. These two methods vary chiefly in the way they manage uncertainty in the input parameters of the decision model. Deterministic methods neglect the changes in the input parameters with time, but focus on estimating the probabilities of the different outcomes possible at each stage in the decision model. A classical tool of the deterministic method is the decision tree. Probabilistic methods assume that a quantity to be estimated (e.g. reserves) can never be accurately determined. Rather it presents the possible number as a distribution. A typical tool in decsion making using probablitics methods is the Monte Carlo simulation. Each of these two methods, probabalistic and deterministic have thier own advantages and limitations. Our paper discusses combining the benefits of decision trees and Monte Carlo simulation. The new tool combines the simplicity of the deterministic approach and yet takes care of uncertainty in the manner of the probabilistic method. The result obtained by the deterministic method is fed into the probabilistic model as in input. The probability function for each input parameter in the probabilistic method is defined. Other input constraints and limitations are imposed and the model is simulated. The resulting output is analyzed and the associated risk or uncertainty for each output parameter is quantified. The output of the probabilistic model is fed back into the decision tree and the optimum decision is determined. The overall uncertainty in each decision outcome is determined by combining the individual uncertainties. The various options available in the project execution are compared using the new tool and the best project is selected on the basis of the highest return on investment or lowest risk. The advantages of the new tool as compared to using only deterministic or probabilistic methods are also demonstrated.
Protecting Industrial Process Control, Automation, and SCADA Systems From Cyber Threats
Authors: Lowe J. , Lasky J. , Gilbert D. , Sheil K. 
Published: December 2007

Abstract
Industrial process control, automation and SCADA systems are at risk from cyber threats such as hackers, viruses and worms. These mission and safety critical systems are at risk because of the increased use of standard IT technologies such as Windows, TCP/IP, web technologies and wireless. These technologies have introduced security risks into the control and operations environments and need to be managed effectively.
Security incidents in control systems have increased significantly over recent years and hackers are starting to focus on these systems. A recent hacker conference focussed on attacking control systems and used such systems in a hacking competition. Such security incidents could have serious health, safety, environmental and reputation implications. These risks need to be effectively managed. This paper will provide an overview of the risks, summary of recent incident trends and guidance on how to manage these risks.
Organisations reliant on process control, automation and SCADA systems need to review the security protection of their systems and implement effective protection measures and response processes.
This paper highlights recent trends in industrial cyber security incidents oultlines an framework for organizations to manage these risks
These risks are relevant to all organisations which reply on industrial process control, automation and SCADA systems for the safe and reliable operation of their plant. The consequences of security incidents in these systems could have serious health, safety, environmental and reputation implications.
Solid Tubular Expansion in Horizontal Wells
Authors: Pervez T. , Seibi A. C. , Al-Hiddabi S. A. , Al-Jahwari F. K. , Qamar S. Z. , Marketz F. 
Published: December 2007

AbstractThe expansion process subjects a solid tubular to large plastic deformations leading to variations in tubular thickness and length, which may result in premature and unexpected failures under normal operations. Simulation work, laboratory tests, and field trials proved the viability of tubular expansion downhole and field engineers have gained enough knowledge in handling this process. However, tubular expansion in open hole of horizontal sections still presents another challenge to researchers and field engineers due to gravity and drag between the seal and the formation. The present work, therefore, presents simulation results of tubular expansion under various field conditions. In this study a typical tubular size of 57.15 mm outer diameter and 6.35 mm wall thickness is used with two different elastomer seals, 5 mm and 7 mm thick placed at equal spacing of 20 cm. It is found that the drawing force increases as the mandrel angle, expansion ratio, and friction coefficient increase. A typical expansion simulation showed that the drawing force required for expansion using a rotating mandrel is 15% less than that of non-rotating mandrel having same configuration. However, tubular thickness reduction is found to increase by 47% for a rotating mandrel as compared to a non-rotating one, which may affect the post-expansion tubular performance. The tubular wall thickness decreases as the mandrel angle, expansion ratio, and friction coefficient increase.
Detecting and Analysing Fractures in the Subsurface: The Critical Steps in Modeling Fractured Carbonate Reservoir
Authors: Elsaid Mohamed Elhami , Al-Jafri Ghassan M. , Mercado Gary , Sugawara Yuki 
Published: December 2007

Abstract
In Abu Dhabi Offshore areas, the development of Lower Cretaceous fractures carbonate reservoir is a challenge that can be achieved using fracture characterization modelling approach.
Generally, open fractures are part of the main factor controlling the permeability and connectivity of different reservoir flow units within the system; consequently the identification, description and classification of these fractures in such carbonates are essential to effective fracture modelling, formation evaluation, well placement and planning.
Identifying fracture network properties require all available data to be synthesized for such predictive modelling. The first step to establish a reliable predictive model of fractures is to collect the proper data in a consistent and systematic manner from core, image logs, outcrops, rock mechanics and dynamic data including mud losses, flow meter logs, well tests and production data such as gross rates, initial PI and water cut. Since image logs are usually limited in number, it is necessary to use open hole logs to extrapolate findings to wells with no image logs. One of the main steps in fractured reservoir characterization is to interpolate fracture attributes between wells using seismic data.
The next step is to identify the geologic controls (drivers) that have a great impact on the intensity and spatial distribution of fractures such as structure, thickness, lithology, composition and texture, faults and curvature. Nonlinear regression tools are used to rank and correlate the multitude of geological drivers. The selected drivers are used to predict the fracture intensity and generate field scale fracture attribute maps.
The final step in fractured reservoir modelling is to generate a discrete fracture network (DFN) model which determines the number of fractures in each grid block based on the value of the fractures intensity and to output the parameters to a reservoir simulator and compare the simulation results with known well behaviour and field production data.
Strain-Based Design of Tubulars for Extreme Service Wells
Authors: Nowinka J. , Kaiser T. , Lepper B. 
Published: December 2007

Abstract
This paper presents a framework for strain-based design of tubular strings in extreme-temperature or high-pressure high-temperature (HPHT) wells. The relevant concepts are illustrated by examples from analytical and experimental investigation of a casing material considered for use in thermally stimulated wells operated by Shell Canada Limited in Western Canada. Much of this framework is also relevant to other applications where deformation-driven loading mechanisms are present.
Strain-based design utilizes material capacity beyond its elastic range to overcome a number of economic and technical hurdles encountered in conventional load-based designs. It has been used successfully in field applications where plastic deformations occur, e.g. thermal wells and pipelines. However, current industry standards for material selection have their origins in load-based design. More sophisticated material characterization tools are required for strain-based designs, in which post-yield material properties govern much of the system response.
This paper describes application of strain-based concepts to design of casing strings under combined loading where some load components are deformation-controlled. The paper emphasizes the need to address strain localization, high-strain cyclic plastic loading, strain-rate-dependent strength, and associated stress relaxation effects.
Strain-based design is most effective if relevant and reliable post-yield material properties are available. Experimental investigation of a candidate material considered for Shell Canada's thermal wells consisted of a series of custom-designed coupon-scale tests. The tests were conducted to acquire data describing the post-yield material response to monotonic and cyclic loading at temperatures ranging from 20°C to 350°C.
Conclusions of this paper summarize findings of the executed material evaluation program, outline options to minimize strain localization impacts, and provide recommendations for strain-based designs of well completion tubulars. Following these recommendations should result in higher reliability and more cost effective wells in completion programs utilizing strain-based strategies for design of extreme service wells.
Self-Healing Cement—Novel Technology to Achieve Leak-Free Wells
Authors: Cavanagh P. , Johnson C. R. , LeRoy-Delage S. , DeBruijn G. , Cooper I. , Guillot D. , Bulte H. , Dargaud B. 
Published: December 2007

Abstract
There is a very large number of wells worldwide that leak or have sustained casing pressure (SCP). In Central Europe and the Middle East there are hundreds of wells with reports of trapped pressure that cannot be bled off. In the US and Canada there are thousands of wells leaking to surface, which may or may not be discharged to the atmosphere. Furthermore, 25% of all wells in the Gulf of Mexico have measurable sustained casing pressure. Additionally, remedial work fixing issues relating to cement failure has been estimated to be more than $50M a year in the US alone.
Throughout the lifecycle of a well, planned cycle or operational changes can contribute to unknown damage to the cement sheath integrity that is hard to identify or locate, including the generation of a microannulus. Within flow paths, hydrocarbons can either migrate to surface, or become trapped below the wellhead leading to pressure build-up. Typical events occur during cementing, while perforating or stimulating, throughout the subsequent production, and even after abandonment. These can easily create this loss of cement integrity.
This paper describes a novel isolation system that is activated only when a cement integrity problem occurs. The system will automatically and rapidly form a complete hydraulic barrier by swelling in the presence of hydrocarbon flow. Once activated, it will seal the damaged zone, and will even be able to be activated again, should further damage occur again during production or abandonment. The system has properties equivalent to conventional cement systems, and requires no modifications to standard surface equipment.
High pressure static and dynamic laboratory tests highlight the ability of the system to rapidly shut off gas flows within 30 minutes. Field tests have also highlighted the robustness of the system, with a number of wells currently using the system remaining leak-free.
More Ultradeepwater Drilling Problems
Authors: Shaughnessy John , Daugherty William , Graff Rick , Durkee Todd 
Published: December 2007

Abstract
A 1999 SPE/IADC paper (52782) identified and documented solutions to a number of drilling problems encountered in Ultra-deepwater drilling. Since that time the industry has pushed the water depth record beyond 10,000' of water and drilling depths below 32,000'. A number of new problems have occurred in the last 8 years that have been caused by mechanical failures (equipment stressed to its limits) or human error. In the Gulf of Mexico recent drilling has encountered problems drilling salt and tar that the industry had not previously experienced. Three operators active in deepwater GOM have collaborated on this paper to document problems under the assumption that understanding what can go wrong is the best way to avoid problems.
Adjoint-Based Well-Placement Optimization Under Production Constraints
Authors: Handels M. , Zandvliet M. J. , Brouwer D. R. , Jansen J. D. 
Published: December 2007

Abstract
Determining the optimal location of wells with the aid of an automated search algorithm can significantly increase a project's Net Present Value (NPV) as modeled in a reservoir simulator. This paper has two main contributions: first to determine the effect of production constraints on optimal well locations, and second to determine optimal well locations using a gradient-based optimization method. Our approach is based on the concept of surrounding the wells whose locations have to be optimized by so-called pseudo-wells. These pseudo-wells produce or inject at a very low rate, and thus have a negligible influence on the overall flow throughout the reservoir. The gradients of NPV over the lifespan of the reservoir with respect to flow rates in pseudo-wells are computed using an adjoint model. These are subsequently used to approximate ‘improving directions’, i.e. directions in which to move the wells to achieve an increased NPV, based on which improving well positions can be determined. The main advantage over previous approaches, such as finite difference or stochastic perturbation methods, is that the method computes improving directions for all wells in only one forward and one backward (adjoint) simulation. The process is repeated until no further improvements are obtained. The method is illustrated by two waterflooding examples. In the first the location of a single injector is optimized to maximize NPV. Starting from four different initial injector locations the algorithm converges to four similar local optima. The second example involves optimization of the locations of 9 producers and 4 injectors. Starting from two different initial well configurations we obtain nearly the same (local) optimum.
Further Development, Field Testing, and Application of the Wellbore Strengthening Technique for Drilling Operations
Authors: Fuh Giin-Fa , Beardmore Dave , Morita Nobuo 
Published: December 2007

Abstract
The currently popular concept and practice on "Wellbore Strengthening" for drilling applications was originated in part from our earlier SPE papers on "A New Approach to Preventing Lost Circulation While Drilling"1 and "Theory of Lost Circulation Pressure".2 Based on our theory and earlier test results, a significant increase in formation fracture resistance could be achieved due to fracture sealing or plugging mechanism induced by a particle "screen-out" effect resulting from the drilling fluid loaded with an adequate amount of narrowly-sized granular materials. We have shown in both our laboratory and field tests that such an increase in formation fracture resistance is particularly valuable in helping the following well operations: 1) drill through depleted zones without losing fluid even when a much higher mud weight (than the normal fracture gradient) is used; 2) strengthen the weaker formations that usually require additional casing strings for protection; 3) avoid lost circulation during cementing operations as the strengthening operation also improves the strength of the cement sheath; and 4) drill high-angle well sections with high mud weights that would normally not be possible due to low formation fracture gradients, etc.
We have recently conducted several Wellbore Strengthening treatments using a special type of lost circulation material, in terms of particle size range and loading density, for increased formation fracture resistance (or increased apparent fracture gradient) during normal drilling operations. A wide variety of wellbore problems encountered have been addressed by this technique. Using several field case examples, this paper will provide a review and discussion of the theory, potential, and limits of the wellbore strengthening technique. Lessons learned from our field treatments will also be discussed along with precautions for optimum drilling applications.