bluuebunny/crossref_metadata_2025_split huggingface dataset:
Net Pay Cutoff Determination Using In-Situ Permeability Measurements with Advanced Formation Testers
Authors: Harfoushian Jack H. , Suriyanto Olivia 
Published: October 2016

Abstract
For a reservoir rock to be classified as net, a basic requirement is for it to contain sufficient storage capacity (porosity) and demonstrate fluid flow potential (permeability). Most common methodologies in the industry today for applying net pay cutoffs are developed based on petrophysical measurements. This is especially the case in clastic reservoirs, where a simple approach using a porosity-permeability correlation derived from core or logs is often employed.
The ideal approach is where measurements of both porosity and effective permeability are made in situ. It is worth noting that effective permeability can often be quite different from absolute permeability, hence this measurement must be made for the reservoir fluid and not for the invading mud filtrate and taking into account the presence of irreducible water in a water-wet system. By conducting an in-situ permeability measurement, especially in thin layers or heterogeneous zones, the accuracy of net pay cutoff determination is significantly improved.
In-situ permeability can either be inferred from petrophysical evaluation or measured directly with formation testers. Generally equipped with a probe-type device, formation testers can be combined in a drillstring assembly (formation testing while drilling, FTWD) or run on wireline (wireline formation testing, WFT). In either case, other petrophysical logging tools can be combined and measurements made in the same run. One of the challenges in accurately evaluating net pay with petrophysical measurements or single-probe-type formation testers is their inability to resolve or find thin layers. In laminated formations, logging devices with higher vertical resolution are required and formation testers, rather than attempting to communicate with the formation through a single point source, use devices with large surface areas open to flow, which have proven to provide much more representative measurements.
In this paper the benefits of advanced formation testers and the role they play in net pay cutoff determination in challenging environments are presented.
Effect of Near Wellbore Effective Stress on the Performance of Slotted Liner Completions in SAGD Operations
Authors: Fattahpour Vahidoddin , Azadbakht Saman , Mahmoudi Mahdi , Guo Yujia , Nouri Alireza , Leitch Michael 
Published: October 2016

Abstract
In SAGD wells, the gap between the oil sand and the sand control liner closes or collapses over time due to such factors as the oil sand thermal expansion, the melting of bitumen and the ensuing loss of the apparent bonding between the grains. The result is the buildup of effective stresses and the gradual compaction of the oil sands around the liner. Current practices for the sand control design do not account for the effect of time-dependent effective stress variation around the liner on the sand control performance. In this paper, we outline the results of an experimental study on the effect of near-liner effective stress on the performance of slotted liners.
This study builds on existing experimental procedures and investigates fines migration, sand production and clogging tendency of slotted liner coupons in large-scale unconsolidated sand-packs. Sand-packs with controlled properties (grain size distribution, grain shape, and mineralogy) are packed on a multi-slot sand control coupon in a triaxial cell assembly. Varying levels of stress are applied to the sand-packs in directions parallel and perpendicular to the multi-slot coupon. For each stress level, brine is injected into the sand-pack from the top surface of the sample towards the coupon. Test measurements include pressure drops across the sand-pack and the coupon as well as the produced sand/fines mass for each stress level. Post-mortem analysis is performed to measure fines/clay concentration along the sand-pack as a direct measure of fines migration.
Experimental results show that under the subsequent increase in effective stresses, sand-packs experience considerable deformations in directions parallel and perpendicular to the multi-slot coupon; which result in a drastic drop in the porosity and retained permeability. Test results show that the maximum reduction in permeability occurs in the vicinity of the multi-slot coupons due to the fines accumulation and the higher compaction in that region. In comparison to experiments with no confining stress, the application of confining stress results in lower retained permeability in the sand-packs as well as reduced sand production.
This paper presents, for the first time, the effect of near wellbore effective stress on clogging tendency and sand retention characteristics of slotted liner completions. The tests allow the assessment of the adequacy of the use of existing design criteria over the life cycle of the well under variable stress conditions around the liner.
Risk-Based Analysis of Thermal Well Integrity Through Integration of Caprock Geomechanics and Cement Sheath Design
Authors: Glover Ken , Priolo Stefano , Heinricks Cory 
Published: October 2016

Abstract
The integrity of thermal in situ wells is a function of the distinct yet inter-related processes that control the integrity of the reservoir caprock and of the wells themselves. Our objective was to bridge the scale gap between reservoir caprock integrity analysis and thermal well cement sheath design, and in so doing, improve the risk analysis of cement sheath integrity.
At the well pad scale, a coupled finite element geomechanical model was used to predict the evolution of thermal and mechanical stresses in the caprock due to thermal in situ operations. The geomechanical models were populated with data from public domain reports from northeastern Alberta thermal in situ projects. These model results were then used to constrain a risk-based analysis of the multiple potential failure mechanisms at the wellbore scale that can compromise cement sheath integrity of thermal wells. Common thermal well and cement blend properties were used to then analyze the probability and magnitude of cement sheath damage during thermal injection operations.
Although integrity may be predicted within the caprock for a given operational practice, the integrity of the cement sheath was shown to be less certain. Several factors contributed to this uncertainty. Firstly, the selection of caprock material and plasticity models for caprock stress analysis has significant implications for the risk of cement sheath damage. Secondly, the statistical distribution of caprock mechanical properties is typically quite broad through the overburden and caprock intervals, meaning that average zone mechanical properties may not be sufficient to model and design cement sheath integrity. Thirdly, it is necessary to adequately constrain our knowledge of the initial state of stress within the cement sheath after placement, and before steam injection. Our results show that these three factors can be adequately constrained to reduce well integrity uncertainty through the integration of geomechanical caprock integrity analyses and cement sheath integrity analyses.
In this study we combine relatively time-consuming coupled finite element method analyses with rapid semi-analytical system response curve methods for cement sheath integrity. In so doing, we quantify the impact of the uncertainties present in caprock modeling and in the constitutive modeling of thermal cement blends on a risk-based evaluation of cement design requirements.
Injector Design Optimisation for SAGD Conformance and Cost
Authors: Kaiser T. M. , Taubner S. P. 
Published: October 2016

Abstract
The "Soaker Hose" concept for SAGD injectors has long been a topic of interest for oil sands development, but few field trials have been attempted to date. The primary interest in this type of design is its potential to produce more uniform injection distributions, but other more elaborate solutions have garnered interest from the industry. Another, less prominent feature of the soaker hose concept is its potential for reducing well completion cost. In the current economic climate, the need for controlling cost has become paramount, which could make this design concept a subject of renewed interest for the industry.
The basic premise of the soaker hose concept is to deliberately increase the radial flow resistance through the liner so that it dominates the overall flow resistance relative to the axial flow resistance in the wellbore, with a consequent reduction in radial flow variation. Some examples exploring the concept have been reported (e.g. Stalder, 2012). The performance interpretation is a product of the assumptions made to estimate the radial flow distribution, in particular the ideal formation conditions into which injection occurs. Modelling developments focused specifically on the SAGD process can shed new light on completion performance and provide more rigorous bases for optimizing completions that account for factors beyond wellbore hydraulics, including variances in drilling and reservoir performance.
This paper presents results of SAGD modelling for various injector completion designs to quantify the potential for optimizing the recovery process. The Mechanistic SAGD Model incorporates coupled injector/producer wellbore hydraulics with essential reservoir flow models to simulate SAGD conformance. It uses reservoir performance as input for directly calculating the liquid level distribution produced by the injector/producer completion configuration in the specific reservoir context. In this set of case studies, some variations on the soaker hose theme are included, and completion options for addressing examples of non-ideal reservoirs through reservoir-specific optimization of the injector design are considered. The cost saving potential for the various completion options is also discussed.
A Novel Failure Mangement Framework for SAGD Well Integrity
Authors: Irani Mazda , Hamuli Christian 
Published: October 2016

Abstract
Bow-tie approach was originally implemented for safety management system. The theory behind the bow-tie approach can be found in the Swiss cheese model by British psychologist James T. Reason (1990). The bow-tie has become popular as a structured method to assess risk where a qualitative approach is not possible or desirable. Bow-tie method can accommodate multiple outcomes and simultaneous multiple failure events. Bow-tie method avoids repeating the barrier analysis which is the old version of bow-tie method for multiple scenarios. In another word bow-tie method assimilates an accident scenario to a sequence of events, and barriers are mitigating the event results.
Although Bow-tie method has been used in many industries, it is an unknown technique in oil and gas. The features attributes to bow-tie diagram are mostly designed for failures which are not attributed to location as depth or timing as operation versus abandonment timing. Due to these down sides the failure management diagram (FMD) is suggested which handles these challenges with bow-tie diagram. In this method the incidents causing the well shut-in or regulatory actions is presented as incidents and failures which yield to these incidents such as buckled casing of micro-annulus in cement which is not treated as failure events and things which may cause these failure events are called hazards.
In this study the framework of FMD is presented for different well elements (i.e., casing, cement, and liner) during different stage of its life. Also the risk assessment analysis using fuzzy sets theory and Dempster-Shafer theory (DST) is discussed and results are discussed for different well elements.
Impact of Installation Loads on Thermal Service Performance of Slotted Liners
Authors: Chartier Mark A. , Yung Victor Y. 
Published: October 2016

Abstract
Slotted liner is a widely used sand control technology for completion of thermal wells. During installation, liners are subjected to tensile and compressive loads generated by string weight and wellbore drag and to bending when run through curved wellbores. Additionally, torque is often applied to "break" friction, reducing axial drag and extending reach. These conditions lead to combined loading of liners with simultaneous axial, bending, and torsional loads.
Combined loading that exceeds the elastic capacity of the liner during installation can alter the structural capacity of the liner and reduce its ability to withstand subsequent operational loads. In particular, permanent deformation of liner struts during installation can create weak zones that trigger localization of deformations and liner failure under thermal service loading conditions (i.e. constrained thermal expansion). Further, the presence of ‘residual’ torque from installation can trigger and exacerbate the tendency of the liner struts to buckle.
This paper describes an evaluation of the impact of installation loading on subsequent thermal service structural performance. Specifically, the relationships between both plastic twist and residual torque from installation loads and the critical strain capacity of the slotted liner under constrained thermal expansion are examined. Results demonstrate that a slotted liner can tolerate some plastic twist during installation without a significant impact on slot width or subsequent thermal service performance. However, large plastic twist or residual torque from installation can bias the liner to fail in torsional buckling during thermal service. The results further show that both the plastic twist applied during installation and the residual torque remaining after installation that can be tolerated varies between slotted liner configurations.
Prior published work considered slotted liner installation limits and thermal operating limits separately. This paper advances industry understanding of slotted liner by examining the impact of installation loads on subsequent thermal service performance. Further, the methods demonstrated in this paper can support installation procedures by providing a basis for determining the maximum torque that can be applied to liner.
Reflections on Overall Heat Transfer Coefficient with Application to Thermal Well Design
Authors: Ichim A. C. , Teodoriu C. 
Published: October 2016

Abstract
Drilling high quality wells requires the use of high-performance drilling muds that can support and protect the wellbore during the drilling process. Drilling mud will create an internal and external filter cake to protect the well during drilling. Although the external filter cake is usually removed before or during cementing jobs, the internal filter cake remains in the near-wellbore formation throughout the life of the well. As thermal well design relies on maximizing the heat delivered to the reservoir, minimizing heat losses to top formations while also protecting casing and cement layers is mandatory.
A literature review shows that the effects of temperature on drilling fluids or cements have been intensively investigated. For example, high temperature generates a decrease of rheological properties of drilling muds, as well as increasing fluid loss. When heat transfer estimations are required, the drilling mud properties are not important, unless a thick filter cake is considered.
This is why laboratory investigations on filter cake thermal capacity and conduction, together with theoretical estimations of the effect of filter cake on the wellbore heat transfer process make the subject of this paper. For this, the overall heat transfer coefficient has been revisited and additional effects of cement layers and filter cake have been incorporated. The results show that conventional water base muds can reduce the heat transfer from and to the wellbore. Two mud samples have been tested and an increase of the thermal conductivity with temperature is observed. Adding barite to the drilling mud will increase the thermal diffusivity of the filter cake. The thermal diffusivity of the drilling mud is higher than that of its produced filter cake, but can change the heat distribution in the well and the cement temperature levels. Such effects, together with cement layer conductivity and size are usually neglected in conventional heat transfer models and a reassessment of conventional models while considering such parameters is presented in this work.
Application of Modern Geological Technologies to Well Construction – Using Seismic for Geosteering
Authors: Karpov V. B. , Yurkina T. A. , Ishimov I. A. , Zhirov A. V. , Sadykhov S. D. 
Published: October 2016

Abstract
This multidisciplinary study is dedicated to an integrated approach to formation evaluation while drilling. The article focuses on the important issue of mitigating risks associated with the design and construction of horizontal wells.
This work summarizes practical experience of logging while drilling (LWD) methods, results of well site cuttings analysis and points up the need to use seismic data in the field development stage for horizontal well planning and geosteering while drilling.
The analysis was conducted using data from two fields located on the Frolov NGO territory. Their geology is characterized by low gross thicknesses, thin interbeddings of sandstone and siltstone, high compartmentalization, low permeability, presence of zones with poor reservoir properties and block structure of the fields.
Development of comlex reserves required a detailed geological model of the reservoir indicating high risk zones where faults meet. When drilling through thin formations it is critical to ensure accurate wellbore placement with the geological structure in mind in order not to exit the reservoir.
The article shows the potential of using advanced methods and technologies enabling optimum wellbore placement within the oil reservoir. This approach will be of interest to specialists in horizontal wells design and construction. The integrated approach to drilling and minimizing risks of reservoir exit can be applied to any field being developed.
Stimulation Treatment Analysis and Improvement in Mangystau Region, Kazakhstan
Authors: Dmitriy Abdrazakov , Bolyspayev Nurlan 
Published: October 2016

Abstract
One of the main factors affecting the type of stimulation treatment in carbonates is reservoir properties. Acid fracturing effectiveness, in terms of economics and production increase, could be potentially more beneficial than matrix acidizing in case of low permeability of the stimulated reservoir due to creation of additional surface of fluid influx at the fracture faces. Matrix acidizing, on the other hand, makes more sense than hydraulic fracturing for the reservoirs where existing natural fractures and vugs have created conductivity similar to the expected conductivity of acid-etched hydraulic fractures.
However, if the reservoir has average permeability and is neither tight nor extremely fractured, it is a subject for additional studies on which type of treatment to choose. Mature and newly discovered oil fields within Triassic carbonates in Mangystau region, Kazakhstan, are examples of such reservoirs. The matrix acidizing and acid fracturing treatments have been actively exploited in the region, but no previous studies have been performed for Triassic carbonates in Mangystau regarding important questions about the comparative efficiency of the acid fracturing versus matrix acidizing treatments and the influence of reservoir parameters on expected treatment type and efficiency.
This paper considers post-stimulation production trends as a tool for evaluation of stimulation treatment effectiveness and suggests empirically derived conclusions for choosing the relevant stimulation strategy. The paper covers the analysis of 21 matrix acidizing and acid fracturing jobs performed in the Triassic carbonates of Mangystau region.
Acute respiratory failure and tracheal stenosis following aspiration of activated charcoal
Authors: Mahli Ahmet , Inan Gozde , Coskun Demet 
Published: October 2016

SummaryGastric decontamination with orally administered activated charcoal is a common treatment for many poisonings. However drug ingestion may result in loss of protective airway reflexes and aspiration of activated charcoal in these patients presents an important complication. Although activated charcoal is thought to be an inert substance it may cause damage to the respiratory tract if aspirated. We report a case of acute respiratory failure and pulmonary damage that resulted in tracheal stenosis following accidental aspiration of activated charcoal.
A surprise finding on laryngoscopy: large asymptomatic vallecular
Authors: Jack James Martin , Sloan Chris , Paul Mark , Henderson Karen 
Published: October 2016

SummaryWe present the unexpected discovery of a previously asymptomatic vallecular cyst that was found during laryngoscopy. We describe pre‐operative assessment of the patient, the immediate and subsequent management of the cyst, and follow up. This case report highlights the limitations of commonly used bedside airway assessments, the need for immediate access to a difficult intubation trolley and the potential benefits of airway imaging pre‐induction. We discuss the contemporaneous decisions made and review the literature related to vallecular cysts.
Ultrasound guided cricothyroidotomy for retrograde intubation in a patient with critical airway obstruction
Authors: Stallard Michael , Irvine Donald , Ball David R 
Published: October 2016

SummaryWe report successful use of ultrasonic identification of the cricothyroid membrane to permit awake retrograde tracheal intubation in a patient with a critically obstructed airway, impalpable neck anatomy and tracheal deviation.