bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pitfalls in the Evaluation of Unconventional Resources
Authors: Haskett William J. , Brown P. Jeffrey 
Published: February 2011

Abstract
There is significant current commitment within the industry to develop and implement methods to assess the prospectivity of Unconventional Resource opportunities. The purpose of this paper is to identify some of the common recurring errors in both numerical evaluation and operational priorities, with specific examples.
Efficient planning and evaluation of Unconventional opportunities is critical due to the low margin, high capital nature of the business. Converting the Conventional exploration and development mindset over to one that places high value on project management and manufacturing efficiency is difficult. Appropriate evaluation and applied operational learning are critical to evaluating decisions that can mitigate downside risk, including the critical post-pilot go/no go decision.
Some Specific trouble points are:
Attempting to model future program results with a single distribution of individual well EUR results-predicting the unpredictable with unwarranted precision. Force fitting a lognormal distribution through datasets that are decidedly non-lognormal, particularly in the outer portions of the probability space. The ‘double whammy’ of prediciting an overpopulation of high volume wells (including unrealistically high recovery wells) and underpopulation of low volume wells results in overestimation of results… often significantly so. Overemphasizing assessment of chance of geologic success, when the key questions to resolve are the chance that the significant risked (pre-pilot) investment will lead to a ‘go’ decision, how often does a particular pilot design correctly predict viability or non-viability-and what the chance is that the entire venture will be an economic success. Failing to recognize the critical success factor-production profile uncertainty – and model this correctly, and develop appropriate prioritized learning objectives for the pilot. Ignoring the impact of business pinch-points, the scarce resource items which when controlled provide profit assurance and distinct competitive advantage.
The failure to link the statistical assessment to operational priorities on project assessment or Play entry relegates business sense to an after-thought. The unfettered, unfocused "drill it and see what happens" approach results in sub-optimal pilots that fail to provide appropriate confidence for critical business decisions, destroys value, and risks loss of competitive advantage in an Unconventional Play.
A New Method for Predicting the Total Vertical Stress Field and Formation Pore Pressures
Authors: Ozan Cem , Brudy Martin , van der Zee Wouter 
Published: February 2011

Abstract
Estimation of formation pore pressure requires the knowledge of the overburden load in an area, which is commonly determined by vertical integration of density data. In fields where the total vertical stresses are significantly affected by topography (e.g., onshore valleys, sub-sea canyons) or lateral density variations (e.g., salt domes), the vertical integration can over- or underestimate total vertical stresses which can lead to over- or underprediction of pore pressures. In this paper, to improve the accuracy of the overburden stress estimations in areas of complex topography and lateral density variations and subsequent the pore pressure predictions, we present a new method to calculate total vertical stresses which utilizes an analytical solution to calculate the contribution of each volume element on the vertical stress field. We also perform finite element analysis for two different geographic cases, quantify the error in pore pressure predictions and compare the results of finite element analysis with those of the proposed method. Moreover, we employ the method proposed in this paper to calculate overburden stresses in two case studies which are developed based on field data.
Our results show that the effect of topography and lateral density variations on the total vertical stress field can result in significant errors in pore pressure predictions if the total vertical stresses are calculated by vertical integration. On the other hand, the total vertical stress calculated by the proposed method are in good agreement with finite element analysis results and the improved method provides a framework to enhance pore pressure predictions.
The proposed method does not require any complex processing of data and calculation times are lower relative to finite element and finite difference analysis. Moreover, the proposed method requires only 3-D density distribution and spatial information about the discrete domain (i.e., dimensions of the volume elements), which are also required for overburden stress estimation using the vertical integration method. In other words, the proposed method improves the pore pressure prediction workflows by refining the overburden calculation algorithm.
Carbon Dioxide Corrosion When Least Expected: Importance of Carbonate Chemistry in Stress Corrosion Cracking on the External Surfaces of Martensitic Stainless Steel Production Tubing and Low-Alloy Carbon Steel Pipeline
Authors: McKennis Jeffrey S. , Bae Nam , Termine Enrico J. 
Published: February 2011

Abstract
Unexpectedly, numerous stress corrosion cracking failures of production tubing have occurred from the external surface (annular side), rather than from the internal (production side). This problem is encountered frequently in HPHT wells and is termed annular environmentally assisted cracking (AEAC). Studies of these failures have pointed to an incompatibility between the metallurgy of the tubing and the completion/packer fluid placed in the annulus. Simplistic causative factors such as a chloride ion-metal interaction are insufficient to explain the AEAC failure mechanism.
In contradistinction, our research studies on the compatibility of martensitic stainless steel production tubing with a large variety of completion/packer fluids have implicated specific fluid contaminants as key causative factors. Of these contaminants, CO2 and/or its aqueous counterparts (carbonate, bicarbonate or carbonic acid) play a major role. Quite unexpectedly, the presence of bicarbonate/carbonate ion produces cracking in sodium bromide brines, which are often believed to be free of cracking issues.
Similarly, occurrences of stress corrosion cracking on the external surface of pipeline have been reported since the late sixties. In these instances the bicarbonate ion in groundwater has also been assigned a major role.
This paper focuses on the important role of CO2 chemistry in explaining the observed cracking for the two different environments. The unique interactions of CO2 and its basic counter parts HCO3− and CO3−2 with the completion/packer fluid (high salt concentration, divalent cations, etc.) and its relevance to the tubing failures are discussed. Comparison is made to the fluid chemistry responsible for pipeline cracking. Chemical mechanisms to explain the role of bicarbonate/carbonate in the observed tubular cracking are presented.
The study describes the importance of fluid and CO2 chemistry in localized corrosion and stress cracking of diverse metallurgy, advancing our knowledge of the ubiquitous CO2 corrosion issues.
Hydraulic Submersible Pumps: 10 Years Experience on a Heavy-Oil Field in the North Sea
Authors: Mali Gwyn , Morrison Alan , Green Alex , Graham Ronald , Harden William 
Published: February 2011

Abstract
Captain is a heavy oilfield in the North Sea operated by Chevron North Sea Limited, which has utilised Hydraulic Submersible Pumps (HSPs) for over 10 years. To date, the field has developed over 20 subsea wells with HSPs to complement the more established Electrical Submersible Pumps (ESP) technology used on the field's platform wells.
Hydraulic Submersible Pumps are an alternative to Electrical Submersible Pumps that use pressurised water as opposed to electricity for power. The Captain HSPs utilise separated produced water supplied from the surface that is delivered down the annulus to drive turbines on the pumps, where the water is then commingled and produced with the fluid from the reservoir.
The application of HSPs on Captain has realised several benefits through the use of the technology, including: an ability to handle a wide range of flow rates, GORs and water-cuts; good pump run lives; and relatively simple installation in the subsea environment.
This paper shares the operating experiences and presents the lessons learned based on field performance of the HSPs on the Captain Field.
ASP Flooding of Viscous Oils
Authors: Kumar Rahul , Mohanty Kishore K. 
Published: February 2011

Abstract
The goal of the present work is to develop alkaline-surfactant-polymer (ASP) methods to improve recovery of viscous oils. Phase behavior tests of a viscous oil (330 cp) with alkali surfactant formulations was performed to determine conditions for obtaining high solubilization ratio (thus ultra low IFT) and avoid viscous emulsions. The selected alkaline-surfactant system was tested in a sand pack flood. A partially hydrolyzed polyacrylamide polymer was used as a mobility control agent in and behind the surfactant slug. Phase behavior with high solubilization ratios was obtained with a combination of alkali and surfactant at 25°C. Waterflood had an early breakthrough at about 0.3 PV and recovered about 0.61 PV of oil in 3 PV throughput. Injection of tertiary alkaline-surfactant-polymer slug followed by tapered polymer slugs could recover almost 100% of the oil. The pressure drops were reasonable (&lt;2 psi/ft) and depended mainly on the viscosity of the polymer slugs injected.
Comparison of Inflow Performance and Reliability of Open Hole Gravelpacks and Open Hole Stand-Alone Screen Completions
Authors: Burton Bob , Hodge Richard 
Published: February 2011

Abstract
Open Hole Gravelpacks and Open Hole Stand-Alone Screen Completions are used in many high rate oil and gas wells. Selection criteria for determining the applicability of these alternative completion techniques tends to be company specific with proponents of Open Hole Gravelpacks claiming significantly better productivity and reliability than Open Hole Stand-Alone Screens. Review of laboratory and field data in this study shows these claims to be erroneous.
This paper presents results of well productivity studies from field and laboratory data comparing Open Hole Gravelpack and Open Hole Stand-Alone Screen flow performance. Key completion design and installation parameters driving performance for each completion type are indentified and discussed. Field well life and reliability data are also reviewed to show that properly designed and installed open hole completions have reliability statistics similar to those seen in cased hole gravelpacks and frac-packs.
Design criteria using an integrated reservoir characterization, laboratory testing and field installation procedure are provided to allow better selection between Open Hole Gravelpacks and Open Hole StandAlone Screen completions.
Modeling CO2 Injection Including Diffusion in a Fractured-Chalk Experiment
Authors: Alavian S. A. , Whitson C. H. 
Published: February 2011

Abstract
This paper presents a modeling study of CO2 injection in chalk core based on laboratory data reported by Darvish et al. (2006). The experiment consisted of a vertically-oriented 60-cm long chalk outcrop core initially saturated with live reservoir oil at 130 ºC and 300 bar. After saturating the core with the oil mixture by displacement a small fracture volume surrounding the core was created by heating the solid Wood's metal that originally filled the volume between the core and core holder. Then CO2 was injected for 22 days. The experiment was performed at a pressure above the minimum miscibility pressure (MMP) as defined by a traditional 1D multi-contact displacement process (MMPlD).
Our modeling study was conducted with a compositional reservoir simulator. The 2D r-z model used fine grid for the core matrix and surrounding fracture. The match of reported production data gave a high degree of confidence in the model. Also, produced mass fractions of components measured periodically during the experiment were matched. The compositional data fit was sensitive to the modeling of diffusion and the EOS model fit to depletion and swelling test data which included oil and gas mixtures with a clear definition of a critical transition.
Our study indicates that gravitational drainage affected the recovery process for CO2 injection in the Darvish experiment, but also mass transfer by vaporization, condensation, and molecular diffusion.
The injection of CO2 in North Sea fractured chalk reservoirs is of keen interest, as a secondary and tertiary recovery process (e.g. in Ekofisk and Valhall). Proper modeling of experimentals such as the Darvish tests is not only a step to understand local (microscopic and matrix-fracture interaction) recovery phenomena, but also as an important step in model upscaling for pilot and full-field projects.
Assessing Reservoir Connectivity through Biomarker and Bulk Compositional Gradient Analysis
Authors: Pomerantz A. E. , Cañas J. A. , Peters K. E. , Mullins O. C. , Koerner K. R. , Auman J. B. , Curry D. J. 
Published: February 2011

Abstract
Reservoir connectivity is among the most important risk factors in deepwater environments and cannot always be identified by traditional techniques such as pressure surveys, petrophysical logs, and geochemical fingerprints. Here we describe a workflow in which reservoir connectivity is assessed through a combination of traditional techniques, compositional gradient analysis, and geochemical evalution of reservoir history. That workflow is demonstrated in a case study in which compositional gradients are detected by optical spectroscopy (which provides a precise measurement of asphaltene content) and viscosity measurements. These gradients are interpreted in the context of the modified Yen model, which characterizes different aggregatation states of asphaltenes and can be used to predict the magnitude of asphaltene content gradients in condensates, black oils, and heavy oils. Additionally, fluid composition is studied with two sophisticated laboratory techniques: comprehensive twodimensional gas chromatography, which measures the detailed composition of the nonpolar fraction of petroleum, and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, which measures the detailed composition of the polar fraction of petroleum. These complentary techniques provide a detailed picture of the composition of almost the entire crude oil, enabling confident biomarker identification and analysis. In this case study, a series of 25-norhopanes and mildly altered normal and isoprenoid alkanes were detected, suggesting the reservoir has experienced multiple charges and contains a mixture of oils biodegraded to different extents. Compositional gradients and interpreted reservoir history are consistent with a connected reservoir in which the observed viscosity variation originates from gravitational segregation of asphaltene nanoaggregates in a crude oil with high asphaltene concentration resulting from a biodegraded charge. This combination of traditional techniques, analysis of compositional gradients delineated by optical spectroscopy, and sophisticated laboratory measurements allows connectivity to be assessed with greater confidence than otherwise attainable during exploration and appraisal.
Building Effective Training Models for Today’s Global Challenges
Authors: Fiffick William S. , Kenner Claude W. , Susko David 
Published: February 2011

Abstract
In today's global business, the ability to effectively train and develop the people we need is vital to our success. New training technologies do broaden our reach, but technology alone is seldom sufficient to achieve our goals. Too many times "learning technology" is deployed as a "solution" rather than as a component of a learning strategy. Therefore, developing a learning strategy is key. Taking that strategy, and building the appropriate training models, helps enhance the ability to effectively develop the Human Capital we need.
In some cases, a single development model may be sufficient. But to be successful globally one must consider: language, location, culture, economics and a host of other issues.
So we begin by asking questions. Do we have accurate competency models? What motivates our people to learn? Who makes up our audience? (Are we just training our employees, or are there other "partners" in need of training?) How do we sustain our training and development programs? How can we ensure better consistency in our programs? How do we support learning globally? What role should "learning technology" play in these efforts? How do we ensure local training standards are still in place? How should we measure our progress?
Asking and answering these kinds of questions helps build the models needed. These queries can help us engage minds from the Executive ranks, Management, Operations personnel, Engineering & Technology, as well as, Human Resources and more. We can then build more effective models by ensuring the best ideas are brought into the fold.
The following is a case study detailing how a leading global organization is building effective training models. Although the main focus is on the processes employed, best practices, and lessons learned are examined and discussed.
Kinematic Hardening Characterization: Applications to Solid Expandable Tubulars
Authors: Durivault J. , Bernard J. , Desdoit E. , Bureau-Bayart A.-S. , Villani A. 
Published: February 2011

Abstract
This paper discusses an enhanced method to predict expandable tubular performance such as collapse and connection sealability. It presents the implementation of the hardening characterization into FEA. The enhanced modelling was then applied to study specific applications, i.e. post-expansion collapse and loads cycles on expanded threaded connections.
The hardening induced by the cone (or any other solid expansion process) creates anisotropy and deeply modifies the grade properties: the tensile-compression tests and first fatigue cycles enable to characterize the material state vs. the rate of deformation. The tests highlight the Bauschinger effect in the material after plastic deformation. Since the material state after hardening depends on the deformation path, and that this memory effect is not accounted for in standard finite element analysis (FEA) models, a parametric model of kinematic hardening has been developed to match the mechanical tests observations for each grade. The integration of hardening effects on the expanded material properties improves significantly the FEA modelling results. It is one of the main causes of the post-expansion collapse pressure decrease, as illustrated by the FEA results using the enhanced hardening law that matches closely test results of expanded pipe collapse. Significant variations in the FEA results on expandable connections during post expansion cycle loads were observed.
The understanding of hardening effect on material properties is the key to design and improve the expandable tubular products (casing, connections). The material knowledge after expansion and the enhanced material FEA modelling allow predicting accurately the behaviour and performances of expandable tubular products used in expandable tubular applications.
Core Tests for Relative Permeability of Unconventional Gas Reservoirs
Authors: Dacy John M. 
Published: February 2011

Abstract
A combination of up to seven or more core tests provides a practical approach to krg and krw function definition even when absolute permeability is at the sub-microdarcy level. The method is designed to provide data needed to define function parameters required by traditional engineering equations for relative permeability. This is accomplished with cores by determining end point specific permeabilities, end point non-wetting phase trapping capacity, critical gas saturation, and a small but sufficient number of effective gas permeabilities to define both drainage and imbibition krg as functions of water saturation. Assessment of the krw function is handled variously and is described. This combination-method is used because traditional core tests involving somewhat continuous displacement are invalid or not practical when cores have absolute permeability approaching a microdarcy and lower.
Conventional analysis of gas shale and tight gas sand cores provides a snap-shot of reservoir permeability. The more complete view of flow capacity needed by engineers and petrophysicists comes with the availability of gas-water relative permeability. Measured relative permeability data are used for reservoir simulation, production forecasting, interpretation of formation damage, and to develop detailed reservoir permeability versus depth profiles.
Sample and test conditions are described. Data for several tight gas sand and gas shale cores are presented along with the required data integration steps to combine the separate test results and to generate relative permeability functions of water saturation. Results show these unconventional rocks can be characterized with well-known relative permeability equations and that traditional rock-property logic can be followed during data integration.
The significance of this work lies in presentation of a novel yet practical solution for acquiring rock curves from unconventional rocks. It is believed to represent the first treatment of core tests for krg hysteresis in tight gas sands and of core-based development of relative permeability functions in gas shales.
Scaleup Methodology for Chemical Flooding
Authors: Veedu Faiz Koyassan , Delshad Mojdeh , Pope Gary A. 
Published: February 2011

Abstract
Accurate simulation of chemical flooding requires a detailed understanding of numerous complex mechanisms and model parameters where grid size has a substantial impact upon results. In this paper we show the effect of grid size on parameters such as phase behavior, interfacial tension, surfactant dilution and salinity gradient for chemical flooding of a very heterogeneous oil reservoir. The effective propagation of the surfactant slug in the reservoir is of paramount importance and the salinity gradient is a key factor in ensuring the process effectiveness. The larger the gridblock size, the greater the surfactant dilution, which in turn erroneously reduces the effectiveness of the process indicated with low simulated oil recoveries. We show that the salinity gradient is not adequately captured by coarse grid simulations of heterogeneous reservoirs and this leads to performance predictions with lower recovery compared to fine grid simulations. Due to the highly coupled, nonlinear interactions of the many chemical and physical processes involved in chemical flooding, it is better to use fine-grid simulations rather than coarse grids with upscaled physical properties whenever feasible. However, the upscaling methodology for chemical flooding presented in this paper accounts approximately for some of the more important effects, as demonstrated by comparison of fine grid and coarse grid results and is very different than the way other enhanced oil recovery methods are upscaled. This is a step towards making better performance predictions of chemical flooding for large field projects where it is not currently feasible to perform the large number of simulations required to properly consider different designs, optimization, risk and uncertainty using fine-grid simulations.