bluuebunny/crossref_metadata_2025 huggingface dataset:
Proposal of Improved Biomonitoring Standard for Purpose of Microbiologically Influenced Corrosion Risk Assessment
Authors: Lomans Bart P. , de Paula Renato , Geissler Brett , Kuijvenhoven Cor A. , Tsesmetzis Nicolas
Published: April 2016

Microbiologically Influenced Corrosion (MIC) is considered as one of the more notorious corrosion mechanisms as it results in the characteristic pitted-type of corrosion and is therefore often very difficult to predict. Among several environmental parameters, risk for MIC is therefore most often identified based on enumeration of MIC-related microbes (Sulfate Reducing Prokaryotes (SRP), Methanogenic Archaea (MA), etc.). Historically, the enumeration of microbes was performed through use of dilution or Most Probable Number (MPN) series. More recently, however, DNA-based methods like Fluorescent In-Situ Hybridization (FISH), quantitative PCR (qPCR) and metagenomics have been applied. Although these new DNA-based methods are promising, there are also cases where inconsistencies have been experienced. Several case studies showed that qPCR for specific microbial groups such as; SRP, MA, and Nitrate Reducing Prokaryotes (NRP), is unreliable due to the lack of adequate coverage of the target microbial community. As such the claims of DNA-based methods, to be more accurate and indicative, are not always properly met.

The current study proposes an improved biomonitoring standard (data analysis and reporting) that is based on the combination of qPCR (for Total Bacteria and Total Archaea) and single gene (16S rRNA) metagenomic data analysis for the purpose of MIC risk assessment. It also aims to generate ‘calculated numbers’ for oil field relevant microbial groups by combining qPCR counts for Total Prokaryotes and relative abundance (%) of the respectively individual bacterial and archaeal microbial families and genera from single gene (16S rRNA) metagenomic analysis.

The ‘conventional’ qPCR approach (on functional genes) and proposed method are compared through a field case study. In contrast to the ‘conventional’ qPCR approach, the proposed method resulted in reliable, internally consistent and better interpretable results, indicating MIC to be the root cause of a pipeline failure. The proposed biomonitoring standard has been communicated with several biomonitoring service providers that are used by the different oil majors. The proposed biomonitoring standard is aimed to be used as the improved cross-business standard for biomonitoring for the purpose of MIC risk assessment and as such to be implemented in existing NACE standards.
Determination of H2S Partial Pressures and Fugacities in Flowing Streams for a More Accurate Assessment of Integrity Threat in Sour Systems
Authors: Harper Christopher , Taghiyev Kanan , Wilkie Peter , Hall Douglas
Published: April 2016

An Excel-based tool was developed that utilizes cubic equation of state (EOS) and thermodynamic electrolyte chemistry modelling. The software enables operators to assess sour production streams from a reservoir, through production tubing, pipelines and facilities to an export pipeline within a range of temperature and pressure conditions. The tool enables quick and accurate sour-production- stream assessment, improving the operator's understanding of the H2S- related integrity risks to ensure safe and stable production. The tool is designed to support materials of construction suitability reviews and provide input to optimize scavenger applications, using the most at-risk components and/ or locations in the system to determine if wells and facilities are safe to operate under current conditions.

This development represents a unique combination of functionality because it combines three elements to derive accurate partition coefficients across a range of operational conditions and gas/liquid compositions: thermodynamic modelling of water chemistry; equation-of-state hydrocarbon modelling; and the basic physical principles at work in production streams.

The approach is employed to assess the integrity risk posed to system components on Chevrons' Alba field in the North Sea. At the time of the modelling, the asset team planned to bullhead three production wells with base oil because of the significant well integrity concerns resulting from high H2S levels. The ability to quickly determine accurate partial pressure and sulphide partitioning profiles for the three production wells ultimately led to the wells remaining open, and saving the operator from deferring in excess of 3,000 bbl/day of oil production from the at-risk wells.

The modelling results were confirmed by a third-party analysis of sulphide concentrations in three phases in the test separator, indicating that the calculated total sulphide per-unit-volume in the system was correct, and the partial-pressure and three-phase concentration profiles for each well were also correct.

The tool was developed so that non chemists, field personnel, engineers and any other relevant stakeholders can make their own integrity assessments.
Nano-Laminated Alloys for Improved Return on Oilfield Assets
Authors: Paz Orlando , Lomasney Christina , Chaloner-Gill Benjamin , Lomasney Samuel , Yamali Nampetch , Casioppo Daniel , Haley Bart , Hussain Syed M
Published: April 2016

Nano-laminated metallic claddings is an emerging technology that is being used to generate products with material property combinations heretofore not possible. Through a patented electrochemical controlled deposition process, Modumetal produces precisely defined configurations of layered metal alloys that can be applied to a variety of substrates or as near net shape parts. The deposition process can be controlled to produce nano-scale layers with unique interfacial properties resulting in corrosion resistance, elastic modulus, strength, hardness, and fracture toughness combinations uniquely different from conventional material processing.

Oil and gas equipment is constantly exposed to corrosive elements that threaten asset longevity and productivity. Corrosion and wear of equipment such as tubulars, downhole artificial lift systems and pumps, leads to production decline over time and ultimately to expensive repairs and operational downtime, all of which negatively impact companies' bottom lines. Until now, the most common fixes to combat pipeline corrosion required a sacrifice of either performance or cost. On one hand, more corrosion-resistant equipment coated with expensive materials like tungsten carbide coatings or high nickel containing steels can be installed at considerable cost. Alternatively, lower-performance materials like carbon steel or organic coatings can be applied, with the understanding that more frequent replacements will be needed. This paper presents a novel class of materials, called nano-laminated alloys that are based on the same conventional materials used today in galvanizing or metal coatings, but configured into nano-laminated structures that deliver significantly higher performance at a price that is competitive with conventional metals and coatings.

Calling on data from field tests carried out in collaboration with Chevron in various onshore fields in the Mid-Continent Region, this paper illustrates how nano-laminated alloys achieve higher performance than traditional alloys at comparable costs. The presentation will include a performance and economics data-rich comparison of nano-laminated alloy coating performance and cost with conventional steels and coatings.

Two case studies are presented for downhole tubulars and downhole plunger lift systems. These case studies represent the conclusions of actual field trials. Results of these case studies review the up-front cost of the nano-laminated product installation, performance comparison both in lab and field trials and return on investment calculation for the nano-laminated products in the field environment.
Corrosion- and Erosion-Resistant Metal Matrix Nanocomposite Coatings for the Oil and Gas Industry
Authors: Monteiro Othon R. , Murugesan Sankaran , Suresh Radhika , Khabashesku Valery N.
Published: April 2016

Ni-based metal-matrix nanocomposite (MMnC) coatings with diamond particles offer an interesting alternative to hard chromium and to conventional electroless Ni coatings, which are used in many components in the Oil and Gas industry. The properties of most value of electroless Ni for the industry are the thickness uniformity, excellent corrosion resistance and abrasion/erosion resistance. In this article we demonstrated that Ni-based MMnCs outperform conventional electroless Ni and hard chromium. Therefore, components manufactured with inexpensive base materials coated with MMnCs should have longer service life, which translates into lower operating cost. In this article we report hardness, erosion and corrosion tests of Ni-based MMnCs, and compare those results with commercially used Ni-B coatings. Ni-B coatings are usually favored over Ni-P in the applications experiencing erosive wear; however they are less resistant than Ni-P to corrosion attack. The results presented here demonstrate that Ni-based MMnC coatings outperform conventional electroless Ni-P and Ni-B, and are expected to outperform hard chromium. The novelty of the Ni-diamond MMnC coatings is in the ability to provide simultaneous corrosion and erosion protection for oil and gas tools and components.
Inhibition Performance of Mild Steel Corrosion in the Presence of Co2, HAc and MEG
Authors: Ikeh Lesor , Enyi G. C , Nasr G. G
Published: April 2016

The formation of hydrate and scale deposition is a major challenge in the petroleum industry. To avoid corrosion and hydrate formation, monoethylene glycol (MEG) is been utilized in the pipeline as an antifreeze and anticorrosion agent. It has been observed that the MEG has to be separated from acetic acid (HAc) and acid gases which enhance corrosion of mild steel in the oilfield environments. HAc and MEG also has an adverse effect of lowering the solubility of mineral salts and causing a higher risk of scale formation.

In this study, the mitigation of corrosion of mild steel in the presence of HAc and MEG in CO2 saturated environment were investigated at 25°C and 80°C using 3.5% wt. NaCl solution in a semi-circulated loop setup. Weight loss and electrochemical measurements using linear polarization resistance (LPR) were used to evaluate the efficiencies of two corrosion inhibitor based chemicals (the phosphate ester and the Olei imidazoline salt) at different concentrations. Test results obtained show that the corrosion inhibitors are found to be very effective in reducing the corrosion of mild steel in the presence of HAc and MEG at different conditions tested. At 25°C and 10ppm of inhibitors, the average corrosion rate decreases from 0.22mm/yr to 0.11mm/yr and from 0.21mm/yr to 0.05mm/yr with 50ppm of both inhibitors. At 80°C, the corrosion rate decreased from 0.20mm/yr to 0.07mm/yr with 10ppm of inhibitors, and from 0.19mm/yr to 0.03mm/yr with 50ppm of inhibitors A and B. The decreased in corrosion rate with the inhibitors shows that the active sites of the steel surface are prevented by the inhibitors absorption which in turn inhibits the absorption of the HAc and CO2 on the mild steel surface.
Review of Typical Challenges in Establishing the Integrity Status of Subsea Pipelines: A Case History
Authors: Marinou Eugenia , de Souza Valdir , Munday Martin
Published: April 2016

An assessment was performed in order to understand better the integrity status of a carbon steel N. Sea pipeline which transports hydrocarbon fluids with a high CO2 content (5.7-6.2 mole%) and H2S (ca. 600 ppm), receiving continuous injection of a combined scale/corrosion inhibitor. The review was triggered by high corrosion rates, with readings up to 0.9 mmpy measured by intrusive topsides corrosion probes coupled with low confidence in the applied corrosion mitigation and management controls.

The assessment concentrated on the following parameters: flow velocities and wall shear stress rates using field production data; calculation of uninhibited corrosion rates using NORSOK M506; estimation of uninhibited wall loss; review and trending of available corrosion monitoring data; corrosion inhibitor application; review of chemical qualification testing; compliance of inhibitor injection with designated target rate and correlation with the corrosion probe readings; and review of historical production data to ensure that the velocities / shear stress values used for chemical testing were comparable to the flowing regime in place.

The assessment identified that numerous performance metrics were either not in place or not followed up correctly, e.g., inhibitor selection, application, field optimisation and interaction with other chemicals, corrosion monitoring and correlation with inspection data, impact of sand production on inhibitor availability and efficiency, management of change procedures, and issues around internal and third-party communication and interfaces. The latter are of particular significance in operating environments where there are multiple entities involved in operating a system – especially integrity management.

This paper presents a summary of the identified root causes for the observed metal loss spanning a review period of two years; highlights elements of ineffective integrity management practice; and provides a list of pertinent parameters that ought to be assessed so as to obtain a pragmatic understanding of a pipeline's condition, including amendment of applied mitigation measures.
Corrosion in MEG Injection Lines in the Presence of O2 - Experiments and Modelling
Authors: Palencsár Attila , Amri Jamel , Seiersten Marion , Omgba Christian
Published: April 2016

Membrane nitrogen with up to 5 vol% O2 is widely used as blanket gas in the petroleum industry, including as blanket gas on rich and lean MEG tanks. The presence of oxygen, even in low concentrations raises questions with regard to potential corrosion damage in the carbon steel injection line as well as consumption of the dissolved oxygen and residual levels upon entering the pipeline. These aspects constitute the scope of this work.

A series of experiments were carried out with carbon steel specimens exposed to environments similar to service conditions encountered in MEG injection lines, including temperatures between 5 and 65 °C and various levels of alkalinity/acidity. The corrosion processes were monitored by electrochemical measurements. These allowed the empirical determination of a number of parameters governing the corrosion and oxygen consumption reactions. Based on the experimental findings and literature data, a comprehensive finite element model was developed and used for tracking the corrosion rate along an injection line of Lean MEG in the presence of dissolved oxygen under acidic, near-neutral and alkaline conditions. Consumption of dissolved oxygen along the injection line was accounted for via the bulk oxygenation of ferrous iron released during the corrosion process.

The experimental results revealed that the contribution of electrochemical oxygen reduction to the corrosion rates is minute; the oxygen is rather consumed in reaction with ferrous ions in the bulk. The model reproduced the measured corrosion rates well and made it possible to study the consumption of dissolved oxygen as a function of acidity/alkalinity, temperature and residence time. The results showed, for example, that the dissolved oxygen may not get completely depleted in the injection line at high flow rates.

The results presented here, as well as the approach used by the authors can be a useful aid in assessing the risk of corrosion damage in glycol injection lines and pipelines, associated with the presence of oxygen in the lean MEG.
Modulating Hydrofluoric Acid Reactivity and Corrosion Effects of Acidizing Fluids for Different Metallurgies: Titanium, Steel, and Chrome Tubing
Authors: Reyes Garcia Enrique A. , Smith Alyssa LaBlanc , Beuterbaugh Aaron M.
Published: April 2016

Because of increased activity in deepwater and high-pressure/high-temperature (HP/HT) environments, the safe operation of corrosion resistant alloys (CRAs) of different types is important. Reservoirs can be subjected to different flow impairment mechanisms that can require the use of acidizing fluids. Titanium (Ti) alloys can be present in subsea completions and in the casing of geothermal wells, as these are able to withstand ultrahigh-pressure and temperature and corrosive conditions. The need to remove clays or silica fines obstructing fluid flow in deepwater wells and enhanced geothermal systems can pose difficulties to operators if the use of hydrofluoric (HF) acid fluids is necessary. At present, there is no HF-acid fluid compatible with Ti alloys because any contact of HF acid with a Ti alloy will result in its corrosion and dissolution. In this paper, the development of a corrosion inhibitor solution to protect Ti alloys against HF-acid attack is presented.

Different metallurgical specimens (Ti, chrome, carbon (low or high) steel) were exposed to an HF-acid fluid based on a sodium-containing aminopolycarboxylic acid (APCA-Na) chelating agent. The Ti specimens (Grade-1 and -29) underwent delamination or blistering at low temperature (140–250°F), depending on the inhibitor and type of alloy present. An HF acid modulating agent was used to help minimize corrosion and the dissolution of Ti. The steel alloys were tested at 260°F with the HF-acid/APCA-Na fluid, displaying minimal mass loss resulting from corrosion. The main effect observed was surface pitting. While suitable inhibitors exist against HF acid for CRA tubing, there are still limitations, such as in mixtures containing acetic acid, which lead to pitting, complicating the inhibitory process. Temperatures in excess of 100°C limit the exposure time to an HFacid fluid, further convoluting the corrosion protection and inhibitor optimization for multiple alloys. Use of the described HF-acid fluid containing APCA-Na in conjunction with the set of HF acid anti-corrosion agents can facilitate acidizing in wells whose completions contain HF-acid-sensitive alloys, including Ti.
Cost-Conscious Corrosion Control
Authors: Cavallaro Brandon , Clayton Richard , Campos Mario
Published: April 2016

From the summer of 2014 to the summer of 2015, global oil prices declined by nearly 60%. The initial impact of this decline on unconventional assets was to reduce or stop drilling and completion activity, but the lower oil price also had a significant impact on cash flow from existing wells. Operators were able to achieve some reduction in operating expenses through contract renegotiations with suppliers, but cash flow margins from sales of oil and gas from production operations were severely impacted. In fields with higher operating expenses due to corrosive environments, the need to manage costs became even more critical. For example, in onshore fields with highly corrosive reservoir fluids, production chemicals can account for more than 40% of monthly operational expenses. Reducing chemical spend can therefore seem like an easy way to reduce lifting costs. However, a reduction in treatment volume can lead to mechanical integrity issues that are more costly to remediate than to prevent, therefore requiring a strategy to balance cost reduction and mechanical integrity preservation.

A cost-conscious corrosion management strategy was developed and implemented for an onshore, sour-bacteria-laden oil from a shale oil development in south Texas. The strategy addressed treatment cost per barrel produced, the effectiveness of chemical formulations, metallurgies of downhole and surface facility components, and the cost of remediation. This full-spectrum corrosion management approach had a positive financial impact across the field.

Key performance indicators were defined and tracked, and a workflow was implemented to manage the large amounts of data from wells in the field. A lifecycle data management system was employed to not only capture failures, but also facilitate root cause analysis. This afforded the opportunity to design-out repeat failure mechanisms, for example by changing downhole metallurgies. This workflow supported the on-time optimization of chemical pumping rates, which reduced operating costs without ceding equipment integrity. This workflow reduced time spent toiling over corrosion management, thus saving on engineering resources.

Despite a challenging economic environment, corrosion management must be maintained in operational budgets. The example of the successful cost-conscious methodology used in the south Texas field shows that even dramatically reduced budgets can still support the safe, environmentally sustainable operation of an oilfield asset.
Probabilistic Reserves Assessment and Evaluation of Sandstone Reservoir in the Anadarko Basin
Authors: Ampomah W. , Balch R. S. , Chen H.-Y. , Gunda D. , Cather M.
Published: April 2016

This paper presents a field scale reservoir evaluation and uncertainty analysis of hydrocarbon reserves estimation for the Upper Morrow B reservoir of the Farnsworth Unit (FWU), Ochiltree County, Texas. The degree of uncertainty in volumetric reserves estimation for hydrocarbon in place is controlled in larger order by the geological complexity of the reservoir and quality of available geologic data.

Morrow B core and thin sections were examined to determine composition, porosity types, depositional environment and diagenetic history. Composition and porosity types determined from XRD and optical microscopy were compared with results from an ELAN analysis. This information together with additional core, well log, borehole image logs, vertical seismic profiles and 3D surface seismic data were used to characterize and subsequently create a fine scale lithofacies based geocellular model (Ampomah et al., 2016b). The reservoir is classified as a highly heterogeneous.

Probability density functions for input uncertain variables were constructed to estimate probabilistic reserves using first order, parametric and Monte Carlo simulation methods. The relative impact of input variables from these methods were compared and analyzed based on geology, petrophyiscs and engineering knowledge from the FWU to ascertain the applicability of these approaches.

The result for each method is presented with expectation curve and log-probability plot elaborating the likelihood of occurrence as P10, P50, P90 and Mean reserves. A P10-to-P90 ratio and a coefficient of variance were used to analyze the total uncertainty of the reserves estimation. Histograms were used to illustrate the sensitivity of input parameter’s contribution towards the overall uncertainty. Statistical mean reserves from the three methodologies were close to the deterministic calculations. Formation thickness and area were the most uncertain variables and have to be topmost priorities to ensure accuracy in reserves estimation for FWU.

The results from this study show that an analytical procedure such as the parametric method which is easily generated within spreadsheets can be used to replace the "black box" Monte Carlo simulation of estimating hydrocarbon reserves in the oil and gas industry.
Forecasting Production of Shale Volatile Oil Reservoirs Using Simple Models
Authors: Makinde Ibukun , Lee W. John
Published: April 2016

Due to the advent of shale reservoirs as important sources of oil and gas production, there has been a critical need for reliable techniques for forecasting production and estimating reserves from these plays. This work presents the results of a study to determine whether simple decline models can be used to forecast production and estimate reserves of both oil and gas in shale volatile oil reservoirs with reasonable accuracy. We found that hybrid models (i.e., one model such as the Duong model for transient flow coupled with a different model, such as the Arps hyperbolic model with an appropriate value of the parameter "b") are appropriate for forecasting oil production and that it is possible to forecast solution gas production with availability of adequate data.

To establish the "truth case" for comparison, we simulated production with four different reservoir fluids using a commercial compositional reservoir simulator. We tested a variety of hybrid and simple DCA models on simulated data (and later on field data) with a work flow that included identifying flow regimes with diagnostic plots for each fluid sample. We analyzed 0.5 to 3 years of production history to estimate model parameters for forecasting future production. Also, we forecasted gas production using a technique similar to one recently presented in the literature.

Lengthy transition periods between transient linear flow and boundary dominated flow (BDF) were observed on the diagnostic plots. This is presumably due to multi-phase flow effects, as this transition period is typically much shorter in single-phase shale reservoirs. As in single-phase flow, the Arps decline model proved to be good for forecasting in the BDF regime. For transient flow, we examined the Duong model (which includes transient linear flow as a special case) and YM-SEPD (modified form of Stretched Exponential Production Decline model). In some cases, we applied the Arps model for both the transition period and BDF regimes (with different b values). We concluded that hybrid DCA models are more appropriate for multi-phase flow analysis than simple DCA models. In most of the cases, the hybrid YM-SEPD and Arps models led to more accurate oil production forecasts than other alternatives. Our analyses of solution gas forecasts indicated that solution gas production forecasting is possible but there is still need for more research in this area.
Production Forecasting in Shale Volatile Oil Reservoirs
Authors: Makinde Ibukun , Lee W. John
Published: April 2016

While there has been a steady increase in production from shale plays in recent years, recovery factors are still relatively low when compared to conventional formations. To improve on the existing technology and production from unconventional plays, a better understanding of reservoir fluid properties and phase behavior are vital. Understanding the dynamic behavior of reservoir fluids and the reliable prediction of reservoir performance in unconventional formations like shale are quite difficult. Reservoir simulation is an important tool that makes this easier and the type of reservoir simulation model used is a significant factor in this process.

This paper focuses on performance analyses of shale volatile oil reservoirs using black-oil and compositional simulation models. The performance analyses were done using single-phase (oil) and two-phase (oil and gas) black-oil simulations, as well as compositional simulations. The three approaches were compared in this paper. While black-oil simulations are easier, more accessible to the user and less time-consuming compared to compositional simulations, we assume that results are not as accurate as with compositional simulations. Nonetheless, how accurate are black-oil simulation results compared to compositional simulation results? Can the results be trusted to a reasonable extent? We have attempted to answer these questions and many others in this paper. The answers are vital because we cannot afford to use easier and less time-consuming methods at the expense of jeopardizing the accuracy of results of production forecasts.

Results show that the two-phase black-oil simulations are different and probably more accurate than single-phase black-oil simulations. As we have no field data to support our assumption for now, our opinion is based solely on the impact of the gas phase (for two-phase flow) on production performance. Also, the effects of fluid composition on cumulative oil production and oil rates were analyzed using compositional and two-phase black-oil simulations. Results from compositional simulations were different and presumably more accurate than two-phase black-oil simulations. This hypothesis is based on the fact that compositional simulation includes more of the physics that we assume are important in modeling reservoir fluids. Therefore, for thorough analysis of fluid composition effects and improved production forecasts (especially for reservoir fluids like volatile oils in shale formations), compositional simulations are necessary in most cases. We believe the compositional simulation will provide the most accurate forecasts, two-phase black-oil simulation will be the next most accurate, followed by single-phase black-oil simulation. However, this list is in inverse order of ease-of-use, so the simpler approaches are well worth considering to see whether they might be adequate. Finally, in this paper, the impacts of fluid sampling errors on cumulative oil production and oil rates were examined and found to have substantial effects on production forecasts.
What Factors Control Shale Gas Production Decline Trend: A Comprehensive Analysis and Investigation
Authors: Wang HanYi
Published: April 2016

One of the biggest practical problems with the optimization of shale gas stimulation design is estimating post-fracture production rate, production decline, and ultimate recovery. Without a realistic prediction of the production decline trend resulting from a given completion and reservoir properties, it is impossible to evaluate the economic viability of producing natural gas from shale plays.

Traditionally, decline curve analysis (DCA) is commonly used to predict gas production and its decline trend to determine the estimated ultimate recovery (EUR), but its analysis cannot be used to analyze what factors influence the production decline trend due to lack of underlying support of physics, which make it difficult to guide completion designs or optimize field development.

In this article, we presented a unified shale gas reservoir model, which incorporates real gas transport, nano-flow mechanisms and geomechanics into fractured shale system. This model is used to predict shale gas production under different reservoir scenarios and investigate what factors control its decline trend. The results and analysis presented in the article provide us a better understanding of gas production and decline mechanisms in a shale gas well with certain conditions of the reservoir characteristics. More in-depth knowledge regarding the effects of factors controlling the behavior of the gas production can help us develop more reliable models to forecast shale gas decline trend and ultimate recovery. This article also reveals that some commonly hold beliefs may sound reasonable to infer production decline trend, but may not be true in a coupled reservoir system in reality.
Estimation of Unconventional Well Recoveries and Economics from Tranient Flow Data
Authors: Seidle J. P. , O'Connor L. S.
Published: April 2016

Accurate forecasts of future production and the associated economics for conventional wells are possible with Arps decline curves as these wells attain boundary-dominated flow (BDF) relatively quickly. Unconventional wells completed in low permeability formations can require several years (and several annual evaluations) to reach boundary-dominated flow, often making Arps based production forecasts for these wells unreliable. Application of methods based on production history, such as rate-transient analysis (RTA), may provide reasonable production forecasts but require wellhead or bottomhole pressures in addition to production rates. In contrast, data available for estimation of proved reserves for unconventional wells routinely includes only rate data from transient flow, limiting the utility of both the Arps and most RTA methods. This study addresses the ability of three models which require only production data, the modified Arps, Duong, and stretched exponential decline model (SEDM) methods, to fill this gap by using time-slice data (6 months, 1 year, 3 years) from long-lived unconventional wells. Accuracy of these models in predicting future well performance and the resulting economics based on constant prices and constant operating expenses, and the ability of these reserves estimates to meet the SEC requirement that proved reserves should remain constant or increase over time are considered.
How Corporate-Level Economics Enable Expected Value Thinking
Authors: Adejumo A. , Queen S. , Gama B. , Germain O. R.
Published: April 2016

Decisions made every day at the asset level affect corporate-level profitability, and oftentimes, this big-picture impact is not obvious to those on the front lines. How can exploration and production (E&P) organizations enable frontline managers to make decisions for a particular field within the larger context of the larger corporate portfolio?

A view of the corporate portfolio shows how oil and gas (O&G) assets come together to drive or diminish value. The E&P industry was originally structured in siloed multidisciplinary teams, and this has resulted in inherently suboptimal overall performance for O&G assets. Projects run behind schedule and over budget, reserves are frequently downgraded after final investment decisions, and value winds up destroyed. Juxtaposed with the huge capital expenditure (CAPEX) required to meet long-term global hydrocarbon demand, an increasing need exists to leverage technology and integrate people, processes, and platforms to produce better results.

This paper discusses the decision dynamics of E&P organizations within the context of the lifecycle of a hydrocarbon asset, identifies the weak links in this decision-making process, and suggests ways of achieving a more collaborative process for making value-added decisions. It demonstrates, using a case study of an exploration project and an acquisition target, how organizations can build resilient portfolios by continuously calibrating to rapidly changing technical and market conditions, thus, unlocking "option value" and achieving balance between risks and rewards.

This paper seeks to trigger a new way of thinking in how organizations could leverage an integrated platform to solve the disconnect between underlying technical risks resident in engineering and execution models and the economic risks inherent to the market and its models.

Much like how the integration of point engineering models significantly advanced the utility of the digital oilfield in the early 2000s, the coupling of petrotechnical, operational, and economic models will unlock a new, greater level of upstream optimization. This paper uniquely shows how possible this integration is today and helps progress the adoption of expected value thinking in the industry. Additionally, the paper introduces the effective use of a cloud-enabled integrated solution to evaluate prospects in a timely manner with minimal information and less resources, thereby, delivering results in mere minutes that would have previously taken a team of professionals several months to achieve.
Data Mining and Analysis - Eagle Ford Formation, South Texas
Authors: Romero Dario H. , Poston Steve W.
Published: April 2016

The paper applies commonly available public information to outline well behavior for productive trend modeling within a chosen area of the Eagle Ford shale in South Texas. Public records are often thought to contain qualitatively insufficient information to provide a reasonable analysis of well and producing character trend characteristics. They –Public records- contain both static and dynamic well data. Static information consists of completion histories, locations, deviations surveys, core analyses, and well property maps while oil, gas and water production records comprise dynamic records. Too often, this freely available information is not utilized for regional studies because pressure, porosity, permeability profiles are not included in these files. More descriptive data are usually only available in individual company well files. This means for most cases, rate – time data represent the only information available to the public.

The study of monthly production records involving multiple ownership properties can highlight regions of no additional interest but also can highlight areas of potential additional economic value. Property value could be increased by well cleanouts, workovers, and re-fracturing or new drill locations to increase recovery from these high productivity areas. In any case, a seemingly intractable data problem could be reduced to a rather straightforward procedure by the study of well records.

Cumulative production, remaining reserves or initial production rate estimates plotted on available property maps could highlight areas for further review or in the majority of cases exhausted areas of no additional interest.

Transforming production data is only the first step of the process, a comprehensive interpretation of the results must follow. Property and maps obtained from public records provide a basis for plotting production trends for a particular well set. Analysis of well tickets coupled with the oil, gas and water production history supply considerable insight into interpreting a well history since erratic production changes are numerous in the Eagle Ford trend.

Recovery estimates can only be determined after the data are plotted and studied to select the proper production segment to analyze. Selection of transient and boundary dominated segments is of paramount importance for interpreting Eagle Ford wells. Smoothing techniques such as material balance time and normalized production can be applied if necessary. The "goodness" of the fracture system can be estimated from the transient portion of the curve while estimated reserves from the boundary side. Of course, the process will not apply if discrete systems cannot be identified. These results are plotted on a property maps and interpreted.

A particular area within the south Texas area is identified and each well subjected to the data mining process. The result of this study should help identify maturely developed areas and highlights areas of interest.
A Strategy for Low Cost Development of Incremental Oil in Legacy Reservoirs
Authors: Attanasi Emil D.
Published: April 2016

The precipitous decline in oil prices during 2015 has forced operators to search for ways to develop low-cost and low-risk oil reserves. This study examines strategies to low cost development of legacy reservoirs, particularly those which have already implemented a carbon dioxide enhanced oil recovery (CO2 EOR) program. Initially the study examines the occurrence and nature of the distribution of the oil resources that are targets for miscible and near-miscible CO2 EOR programs. The analysis then examines determinants of technical recovery through the analysis of representative clastic and carbonate reservoirs. The economic analysis focusses on delineating the dominant components of investment and operational costs. The concluding sections describe options to maximize the value of assets that the operator of such a legacy reservoir may have that include incremental expansion within the same producing zone and to producing zones that are laterally or stratigraphically near main producing zones. The analysis identified the CO2 recycle plant as the dominant investment cost item and purchased CO2 and liquids management as a dominant operational cost items. Strategies to utilize recycle plants for processing CO2 from multiple producing zones and multiple reservoir units can significantly reduce costs. Industrial sources for CO2 should be investigated as a possibly less costly way of meeting EOR requirements. Implementation of tapered water alternating gas injection schemes can partially mitigate increases in fluid lifting costs.
Operating EOR Projects: The Experience of an Independent Energy Company
Authors: Covey F. D. , Craig F. F.
Published: April 2016

A major producer of natural gas and natural gas liquids, Mitchell Energy Corporation also produces 5,200 barrels per day of crude oil and condensate, 15 percent due to secondary (waterflood) operations and 16 percent due to tertiary (enhanced) operations.

This presentation examines Mitchell's Enhanced Oil Recovery (EOR) philosophy and commitment and the role EOR plays in Corporate operations. Manpower size and capabilities are discussed, along with Corporate efforts to keep personnel technically up-to-date in the rapidly changing EOR environment. The independent's advantages and limitations with regard to EOR operations are highlighted by describing the development chronology of Mitchell's Alvord South (Caddo) Unit, a full-field carbone miscible flood located near Fort Worth, Texas. The impact of Corporate innovations, such as development of a patented carbon dioxide tracer system and the application of hand-held computers to data gathering and reporting, as well as the impact of industry-wide events, such as the end of the DOE's Tertiary Front-end Recoupment Program and the 1986 collapse of oil prices, are continuing to play a major role in the technical and economic outcome of the Alvord South (Caddo) project. Mitchell's view of the EOR potential for independents under current conditions is also reviewed.
Comparison of Phosphorus Fertilization Diagnostic Methods of Potato in Mollisols
Authors: Zamuner E. C. , Lloveras J. , Echeverria H.
Published: April 2016

The aim of this research was to provide tools for the profitable and environmentally friendly P fertilization of potato (Solanum tuberosum L.) crops. The objectives were: (i) to examine the relationships between the available soil phosphorus index (Pav), as determined by Bray1, Mehlich 3, Olsen, and CaCl2 in Mollisols, and potato yields and (ii) to identify the P fertilization rates required to obtain the maximum agronomic yields, considering the environmental risk of P loss. The study was conducted from 2005 to 2014 in soils with a wide range of initial available P levels (8.6–50.0 mg kg−1 Bray1; from a depth of 0 to 20 cm in which irrigated potato crops fertilized with P were cultivated. The linear‐plateau, quadratic‐plateau, and Cate–Nelson models were used to analyze crop responses to P and to determine the phosphorus threshold (Pt) required to identify soils with positive responses to P fertilization. The Pt was 32 mg kg−1 for Bray1 and Mehlich 3, 11 mg kg−1 for Olsen and 2.8 mg kg−1 for CaCl2. Recommended P rates were defined based on the initial soil Pav index, the quantity of P removed by the crop for a specific yield, the P required to increase the initial soil P to the Pt, and the environmental Pt. Soil Bray1 determined postharvest confirmed that the P fertilizer recommendation was appropriate in Mollisols soils.

Core Ideas

The relationships between potato yield responses and available soil P were examined.

The available soil P threshold was determined with the Bray1, Mehlich 3, Olsen, and CaCl2 tests.

The P rate required to maximize the potato yield while avoiding environmental pollution was defined based on empirical information.
Enhancing Speaking Ability of EFL Students through Debate and Peer Assessment
Authors: Fauzan Umar
Published: April 2016

The objective of the study was to implement the debate technique and peer assessment to improve the third semester student’s speaking ability. This study employed classroom action research and it was done in two cycles.  There were four meetings in each cycle; three meetings was for the implementation of debate in the teaching of speaking and one meeting was for conducting speaking test. The instruments used to collect the data were: (1) observation checklist, (2) field-note, (3) score sheet, and (4) questionnaire. The result of the research showed that the criteria of success had been reached in cycle 2. There were two aspects determined as the success criteria; score improvement and classroom atmosphere. The result of speaking test showed that the students had made some progress, the average scores raised from 60 in pre-test, 69 in cycle 1 and 75 in cycle 2. These scores indicated that there is an increasing ability from being ‘fair’ to being ‘good’. The classroom atmospheres were also increasing positively. The result shows that the students gradually could express their thought and opinions in debate practice. This activity encouraged the students’ creativity to explore the language, since they were asked to develop their arguments from certain motions. The motions were made familiar to them so that they found it easy to speak on the topics. By practicing speaking in the debate practice, they improved their fluency as well as their confidence.
Fourth branch of arch of aorta and its clinical implication
Authors: Gitte Rashmi N , Ganji Chenna Reddy , Salve Vishal M
Published: April 2016

In human beings the most common branching pattern of the aortic arch was its division into three great vessels ie the brachiocephalic trunk, left common carotid artery and the subclavian artery. The vertebral arteries arise from the superior aspect of the first part of the subclavian artery. In present case, a left vertebral artery arose from the aortic arch as fourth branch was found. The diameter of left vertebral artery at its origin was 6 mm as compared to the right vertebral artery, which has diameter of 3.5 mm at its origin. In this case left sixth dorsal intersegmental artery might have persisted as first part of vertebral artery hence left vertebral artery arising from arch of aorta. Knowledge of the variations in branching pattern of the aortic arch is important in the diagnosis of intracranial aneurysm after subarachnoid haemorrhage.J. Biomed. Sci. 2015, 2(3):21-23.
Apprentissages collectifs et activités de conception
Authors: Hatchuel Armand
Published: April 2016

Les approches cognitives peuvent aider au renouvellement des paradigmes gestionnaires. Elles peuvent en particulier conduire à réenvisager et approfondir l'analyse des processus d'apprentissage collectifs. Ainsi permettent-elles, comme le montre l'auteur, notamment en distinguant systèmes d'aide à la décision et systèmes d'aide à la conception, de s'interroger sur des évolutions à venir, telles que l'émergence d'une « nouvelle ingénierie de la conception » et la multiplication d'expériences d'« autonomies ».
Vers une ingénierie de la recherche en sciences de gestion
Authors: Chanal Valérie , Lesca Humbert , Martinet Alain-Charles
Published: April 2016

Quelles modalités permettent qu'une recherche en gestion soit à la fois directement utile dans l'entreprise et génératrice de connaissances scientifiques nouvelles ? La « recherche ingénierique » – où le chercheur devient un « ingénieur organisationnel » qui conçoit un outil, le met en place dans l'entreprise et l'évalue avec les utilisateurs – se propose d'atteindre ce double objectif, montrent les auteurs en s'appuyant sur plusieurs exemples de recherches récentes ayant conduit à des applications pratiques. Un plaidoyer, aussi, pour la démarche constructiviste et les approches prenant en compte la complexité des processus en matière de gestion.
The Best of Times, the Worst of Times: Angela Merkel, the Grand Coalition, and “Majority Rule” in Germany
Authors: Mushaben Joyce Marie
Published: April 2016

Angela Merkel has not only been repeatedly ranked “the world’s most powerful
woman;” she is also the only German chancellor since 1949 to have successfully
led her party to a “normal” victory after a full term heading a grand
coalition from 2005-2009. Merkel’s ability to lead has been shaped by the
dynamics of coalition politics, proportional representation, and German federalism.
Perceived as a more successful leader under an exceptional grand
coalition than under a typical CDU/CSU-FDP constellation, Merkel provides a
one-woman-laboratory for comparing the impact of different coalition modes
on the chancellor’s powers and limitations on her ability to rule. The study
offers a two-level analysis, comparing Merkel’s performance atop a “gender
balanced” Grand Coalition (2005-2009) with Hans- Georg Kiesinger’s maledominated
Grand Coalition (1966-1969). It then contrasts leadership dilemmas
confronting Merkel during her first term with those arising during her
second chancellorship, 2009-2013. It urges scholars to “bring the institutions
back in” when considering the skills female leaders must evince in order to
manage divergent coalition types: grand coalition configurations may, in turn,
require men to adopt leadership behaviors usually ascribed to women in
order to prove effective cross-party managers.