bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microemulsion vs. Surfactant Assisted Gas Recovery in Low Permeability Formations with Water Blockage
Authors: Rostami A. , Nasr-El-Din H. A. 
Published: June 2014

Abstract
Despite all advantages of slickwater fracturing such as low cost, high possibility of creating complex fracture networks, and ease of clean-up, large quantities of water are still left within the reservoir after flowback. Invasion of aqueous fracturing fluids can reduce the relative permeability to gas and thereby cause a water blockage.
Compared to conventional surfactants that lose their activity after contacting just first few inches of formation due to quick adsorption to the rock surface and limited thermal stability, microemulsions with smaller droplet sizes and lower surface tension can penetrate deeper to the formation and will result in significant gas recovery from low permeability formations. Micro-emulsions have shown to be an effective remedy for improving gas relative permeability due to their structure which can pro-vide maximum surface area of contact between surfactant and formation.
Experiments were conducted using outcrop of Bandera sandstone cores to measure the effect of liquid blocking on gas relative permeability. Microemulsion treatment was developed to reduce the damage caused by water and condensate blocking. The chemical treatment alters the wettability of water-wet rocks to less water-wet and increase the gas relative permeability.
The increase in gas relative permeability was quantified by comparing the gas relative permeability before and after treatment. The alteration of wettability after the chemical treatment was evaluated by measuring the contact angles between the solution and rock. Thermal stability tests were conducted using hot rolling cells for temperatures up to 400°F which proved the high stability of microemulsion solutions at HP/HT conditions. Microemulsion solutions showed very good results in gas permea-bility regain, when compared to the other treatment solutions. They can provide excellent fluid cleanup by flowing out of the well to the surface where the entrapped water can be recovered.
Modelling of CO2 and Seawater Injection in Carbonate Reservoirs to Evaluate Inorganic Scaling Risk
Authors: de Souza Ana Paula , Mackay Eric 
Published: June 2014

Abstract
Evaluation of the scaling potential during field appraisal or initial development allows for a better estimation of project costs and reduces uncertainties (e.g. desulphation or scale inhibitor injection, frequency of well workover operations, etc.). When CO2-WAG is injected into a carbonate reservoir, several interactions between the injected fluid, the formation water and the carbonate rock may occur. These interactions may also modify the scaling potential of the produced water. Nevertheless, the prediction of these changes is challenging because it requires complex thermodynamic and kinetic modelling.
The present study outlines a methodology where the geochemical modelling of CO2-WAG injection is used in predicting the scaling potential in carbonate reservoirs. For this, a geochemical simulation was developed, and several cases with different injection strategies were applied to obtain the produced water compositions as a function of time, and to calculate the scaling potential. The recovery method which is least susceptible to inorganic scale deposition in the studied field can be identified. The methodology was applied to data from two Brazilian carbonate fields with different petrophysical and compositional characteristics.
When compared to the standard thermodynamic modelling used to calculate scaling risk, this approach takes account of the impact of the several chemical reactions that occur in situ in the reservoir, and addresses the tendency to overestimate scaling risk when reservoir reactions are not accounted for. A fully quantitative evaluation is not developed in this study since several simplifications were assumed, and many uncertainties exist in the geochemical modelling input parameters (e.g. constants related to reaction kinetics and equilibria). However, the proposed methodology provides a powerful tool for informing project decisions and field injection design. In this study, for example, CO2-WAG injection was found to reduce the risk of precipitation of various scales compared to seawater or Low Sulphate Water (LSW) injection.
Investigating the Effect of Improved Fracture Conductivity on Production Performance of Hydraulic Fractured Wells through Field Case Studies and Numerical Simulations
Authors: Sun Jianlei , Hu Kyle , Wong Joe , Hall Bobby , Schechter David 
Published: June 2014

Abstract
Various analytical and numerical models have been proposed to predict production performance of hydraulic fractured wells and to investigate the effect of fracture geometry and fracture conductivity on well performance. These completion design parameters greatly impact E&P operators' return on investment (ROI). In this study, we conducted numerous field case studies in the Bakken formation to compare production performance of hydraulic fractured wells with different completion designs. Since all wells are located in the same field, the geological difference was considerably minimized. The wells were grouped and analyzed by different completion and stimulation design parameters. Specific grouped categories included percentage of upgraded proppant in the total proppant amount, lateral length, number of stages, etc.
We then simulated post-fracturing production performance of these fractured wells. An advanced meshing technique was developed to honor complex fracture networks with unstructured Voronoi grids. We applied this technique to investigate the characteristics of hydraulic fractures such as fracture conductivity, aperture and permeability distribution on the long-term production of the wells. Core data and well logs were analyzed for reservoir characterization. Several assumptions were made to estimate pumped fracture width, stress-dependent fracture permeability and stimulated reservoir volume. Finally, sensitivity studies were performed to investigate the effect of fracture conductivity on production performance due to superior vs. low-quality proppants.
The objective of this study was to determine if upgrading completion designs to high quality proppant materials would achieve better fracture conductivities and long-term production performance. After all well data was analyzed and the production related parameters were summarized, it was determined that upgrading the completion designs with higher quality proppants provided dramatically improved production rates.
The following unstructured mesh generation algorithms successfully implemented the local grid refinement feature around fractures, which can handle non-orthogonal fractures and more complex fracture geometries. The final simulation runs and sensitivity studies further demonstrated the importance of both stimulated reservoir volume and fracture conductivities. The same long-term production performance was also predicted by using reduced amounts of upgraded proppant with improved fracture conductivities.
Utility of Hybrid Forecasting Models and Diagnostic Plots in Liquid Shales
Authors: Indras Purvi , Lee W. John 
Published: June 2014

Abstract
With the emergence of liquid rich shale (LRS) plays like Eagle Ford and Northern Barnett, the petroleum industry needs a simple, easily applied technique that provides reliable estimates of future production rates in this kind of reservoir. There is no guarantee that methodology that has proved to work in gas reservoirs will necessarily be appropriate in LRS reservoirs. In this work, we found that without corrections of early data, the Stretched Exponential Production Decline (SEPD) model, designed for transient flow, usually produces pessimistic forecasts of future production. The Duong method, another transient model, may be reasonable during long term transient linear flow, but notably optimistic after boundary-dominated flow (BDF) appears. For wells in BDF, the Arps model provides reasonable forecasts, but the Arps model may not be accurate when applied to transient data. A hybrid of early transient and later BDF models proves to be a reasonable solution to the forecasting problem in LRS.
In addition, use of diagnostic plots (like log-log rate-time and log-log rate-material balance time plots) improves confidence in flow regime identification and production forecasting. In some LRS's, BDF is observed within 12 months. In any case, it is essential to identify or to estimate the time to reach BDF and to discontinue use of transient flow models after BDF appears or is expected.
We validated our methodology using "hindcast analysis"; that is, matching the first half of production history to determine model parameters, then forecasting the second half of history and comparing to observed production data.
We also found that application of pressure-corrected rates in decline curve analysis (DCA) may substantially improve the interpretation of data from unconventional oil wells flowing under unstable operating conditions. Fetkovich (hydraulically fractured well) type curve analysis can be added to improve confidence in flow regime identification from diagnostic plots and to estimate the Arps hyperbolic exponent b from the matching b stem on the type curve, which can then be extrapolated to determine estimated ultimate recovery.
Calibrating an Economic Limit Test to Maximize Net Present Value
Authors: Kasriel Ken , Wood David 
Published: June 2014

Abstract
This paper offers a critique of, and suggests an alternative to, commonly used methods – including the method stipulated in the 2011 Guidelines for Application of the Petroleum Resources Management System (hereafter, "PRMS Guidelines"), promulgated by the SPE and others – for calculating the economic limit test ("ELT") for upstream petroleum projects. The ELT determines the assumed project abandonment date.
In particular, the authors fault the PRMS Guidelines-prescribed ELT method because it a) uses a measure of revenue which is often much higher than what Investors actually receive in projects governed by fiscal arrangements such as Production Sharing Contracts ("PSCs"); b) ignores abandonment costs and income tax liabilities, even though these are real and often material cash outflows; and c) appears to ignore the time value of money. These shortcomings can cause the PRMS ELT to assume abandonment dates which result in Net Present Values ("NPVs") of discounted future cash flows which are lower than an Investor could achieve by using a different abandonment date. In such cases, the PRMS approach is tantamount to Investor value destruction.
This paper presents a simple, transparent and mathematically sound alternative ELT calculation method, which considers all Investor NPV-relevant items, including abandonment costs, income taxes, the time value of money, and, in the case of PSCs, actual Contractor cash revenue, to determine which abandonment date maximizes Investor NPV. The method avoids the circularity which can arise when attempting to consider abandonment costs while calculating a future uncertain abandonment date.
The paper compares the results of using the authors' method and the PRMS method in example valuations. These examples show that the authors' method can result in different economic limits/abandonment dates – and thus higher NPVs – than the PRMS method. The authors' underlying Microsoft Excel model accompanies this paper.
The findings are relevant to value-focused investors -- especially those in projects which are governed by PSCs, and/or involve large abandonment liabilities pending in the short-term or long-term -- and to parties who issue or otherwise use PRMS standard valuations.
Impact of Geological and Facility Uncertainties on Strategic Drilling and Facility Decisions
Authors: Erber Alexej , Erber Daniela , Meulengracht Chresten 
Published: June 2014

Abstract
The Chinarevskoye field in Kazakhstan consists of a significant number of producing gas and oil reservoirs from several stratigraphic zones, with additional discoveries being appraised for commercialty and undiscovered resources being matured for exploration drilling. Process facilities including oil treatment, gas handling, and compression and export facilities were commissioned at the start of commercial production and then more capacity was added recently.
Detailed sub-surface models with risk modeling and uncertainties on and dependencies between geological parameters have been prepared to reflect the geological interpretations. The stochastic results based on Monte Carlo calculations provide distributions of in-place and recoverable resources. Similarly, detailed above-surface activity models with uncertainties on wells and facilities based on the sub-surface models have been prepared to model realistic development scenarios, including both existing and future production given capacity constraints. The stochastic results based on Monte Carlo calculations provide distributions of production profiles, cash flows, and net present values.
Based on these results, the alternative scenarios with exploration, appraisal, development, and production activities have been ranked. The main conclusion is that investments in additional exploration activities and production facilities can be expected to increase the profitability of the Chinarevskoye field, even under the latest Kazakhstan fiscal terms. In addition the optimum exploration well-drilling sequence has been identified.
The technical and economic assessments based on uncertainties and risks that have been ongoing over recent years have resulted in profitable strategic decisions for investments in additional exploration drilling, appraisal programs, and development of facilities for the Chinarevskoye field.
History Matching of Channelized Reservoirs With Vector-Based Level-Set Parameterization
Authors: Ping Jing , Zhang Dongxiao 
Published: June 2014

Summary
For channelized reservoirs with unknown channel distributions, identifying the continuous and sinuous features of channel distributions is crucial for determining their production behaviors. However, traditional history-matching methods are not appropriate because the pixel-based rock-property fields are usually highly non-Gaussian. In this work, a vector-based level-set parameterization technique for channelized reservoirs is presented. We also propose a combination of this parameterization method and a frequently used history-matching approach, the ensemble Kalman filter (EnKF). To properly represent the continuity and sinuosity of its embedded features, the channelized reservoir is parameterized with a vector that consists of level-set function, real radius, and virtual radius on a representing node system. The level-function value indicates the existence of the particular facies; the real radius of a circle in two dimensions or a sphere in three dimensions signifies the size of the facies; and the virtual radius is used to ensure the continuity of the channelized facies. The 2D and 3D examples of channelized reservoirs are set up to demonstrate the capability of the proposed method. It is found that this method is effective to deal with the history-matching problem of channelized reservoirs.
New Analytical Model for Predicting the Unstable Zone Around the Borehole
Authors: Heidarian Mohamad , Jalalifar Hossein , Schaffie Mahin , Jafari Saeed 
Published: June 2014

Summary
In this study, a new analytical model, which is computationally lower in cost than current numerical methods, is presented to calculate the radius of the plastic zone around the borehole in underbalanced drilling (UBD) to prevent borehole instability. With this model, it is also possible to analytically calculate the optimal drilling-mud weight, which is the amount of mud weight with no plastic zone. The presented model is based on the Mouhr-Coulomb failure criterion. The model can be used in both vertical and inclined wells and in poroelastic formations with anisotropic horizontal stresses. Predictions from the model provide a reasonable match to the field data and numerical solution results.
The Evolution of Managed Health Care for the Local Employees of an Oilfield Services Company in Nigeria
Authors: Okorocha Uche , Chukueke Okezie 
Published: June 2014

Abstract
In Nigeria and other Sub-Saharan African countries, public health services are often unavailable or limited. Therefore, access to health care programs for employees and their dependent relatives is an important benefit for employees, especially in the organized private sector. From the employer side, it involves a large amount of administration that must be managed efficiently.
Various approaches have been implemented by an oilfield services company in Nigeria in providing access to health care for its employees and dependents. The health care management of the local employees has evolved through various models to the present model of a fully insured plan managed by four health maintenance organizations. This managed plan has proved very effective in terms of delivery efficiency, administration, and cost optimization.
Practical Implications of Human Rights Due Diligence: Challenges in Demonstrating ‘Respect’ and What it Means for the Assessment and Management of Social and Health Impacts
Authors: Perumalpillai Shahila , Cummins Claire , Phillips Callie 
Published: June 2014

Abstract

Description of the material
Multi-national corporations have endorsed the three pillars of the UN Guiding Principles on Business and Human Rights: the ‘Protect, Respect, Remedy’ framework. The question is what does this mean in practice and how should human rights due diligence be undertaken as described in the Guiding Principles?

Application/Development
This paper will describe practical examples of how extractive companies are approaching human rights due diligence and explore challenges to ‘know’ and ‘show’ ‘Respect’ for Human Rights. The paper will also consider the extent to which human rights due diligence makes a difference to international approaches to social and health impact assessment through a worked example for the oil and gas industry in Africa.

Results, Observations, and Conclusions
There is a high degree of overlap between the issues addressed through impact assessment done to international best practice standards and those that need to be managed to respect Human Rights. The vulnerability analysis necessary to address international requirements provides an external frame of reference that means issues associated with human rights are taken into account in the assessment of social and health impacts. Nevertheless undertaking ongoing Human Rights due diligence can make a difference: i) a human rights lens on some of these issues reveals different perspectives which mean data collection, mitigation measures and monitoring for the impact assessment process may need to be adapted; ii) impact assessment needs to be a starting point to establishing a dynamic due diligence process – a concept that cannot be fulfilled in a single step. Not only can project or company activity change, but the operating context and stakeholder concerns change; due diligence of human rights requires on-going monitoring of issues through a Human Rights lens. Where an operating context is highly sensitive, specific studies, additional to an impact assessment may be necessary to understand local complexity.

Significance of Subject Matter (Relevance and why it is worth publishing)
Companies increasingly perceive that Human Rights are a risk to business, not only because of links to social licence to operate but also with regard to meeting legal obligations and the expectations of civil society set by the framework of the guiding principles. But given the shifting rights landscape what does demonstrating ‘Respect’ for Human Rights look like? This paper will point to directions for future practical implementation of Human Rights due diligence.
Approaches for Permit Management for Offshore Oil and Gas Development in Frontier Geographies
Authors: Young H.. , van der Westhuizen J.. 
Published: June 2014

Abstract
This paper describes and addresses the most prevalent of the regulatory pitfalls facing new entrants in African countries with emerging offshore exploration industries. These potential pitfalls include issues such as: Lack of defined timeframes and processes;No integrated permitting systems;Numerous regulatory requirements not associated with permits;Difficulties in identifying regulatory requirements; andLack of resources at regulator level.
Drawing on our experience with selected African countries, we then describe and provide practical examples illustrating how these problematic aspects can be addressed and alleviated through the early identification and operationalization of requirements, to create an effective permit management system. Solutions we explore will include the following: Formal aspects such as development of dual systems for permit management and other regulatory requirements; and creating proactive permitting plans and strategizing how to provide integration where none exists (e.g. through alignment with operational timelines to ensure that permitting requirements are fulfilled in time to meet required operational start dates); informal aspects such as establishment of effective relationships with regulators; and utilization of local consultants for the ‘unwritten knowledge’ perspective.
Operating in Ancient Landscapes: Oil Exploration and Archaeology in Arid Environments
Authors: Le Quesne Charles , Peach Mark 
Published: June 2014

Abstract
Recent years have seen an increasing recognition in the oil and gas industry of the need to incorporate cultural heritage as a consideration when assessing the likely impact of operations and production on the environment. This paper presents a recent case study relating to Shell's exploration of the Sirte Basin in central northern Libya during 2007-2009. The approaches taken to establishing the archaeological baseline over such a large and remote area, and the measures used to protect archaeologically significant sites during subsequent seismic surveys provide an example of cultural heritage can be accommodated in oil and gas operations successfully. Key steps in the process were: the collection of desk-based information, the application of remote sensing, selective and targeted ground truthing and the creation of sensitivity mapping which formed the basis for the implementation of a mitigation strategy. It is acknowledged that the techniques used were appropriate to an arid environment and need to be adjusted depending on variations in landscape and culture. However, they do indicate that a systematic and proportionate approach to cultural heritage issues can efficiently be incorporated into oil and gas operations without causing delays. In doing so the IOC adds significant value to their operations within host countries in an area that is often of high public concern.