bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding Geomechanics in Clastic Sand Formations Proved Critical to the Success of the First Hydraulic Fracturing in the Offshore Clastic Sand Formations Abu Dhabi.
Authors: Aboujmeih H. F. , Al-Mansoori A. M. , Al-Mutwali O. , Al Ameri F. , Kaneko M. , Kuroda S. , Castro Ponce de Leon M. F. , Abbott J. , Akbari A. 
Published: November 2015

Abstract
Hydraulic fracturing is an important technique widely used for to improve well productivity in tight reservoirs and enable economic development. Geomechanical modeling is an important prerequisite required to ensure effective fracture construction and the required contact with the formation. In this paper, we show the first successful hydraulic fracturing in the Offshore Abu Dhabi clastic sand formations in which geomechanical modeling played an essential role in fracture design, completion design and successful execution.
The geomechanical properties and behavior of the clastic sand formations are still largely unknown in the Abu Dhabi region. In other parts of the Arabian Plate this formation is known to be a complex geological environment with high fracture gradients, poorly consolidated intervals, natural fractures and often rock that exhibits poroelastic behavior.
Due to the aforementioned complex geological environment resulting geomechanical attributes, the fracture design and key inputs including the calibrated Mechanical Earth Model (MEM) were essential to the successful design and execution of the first hydraulic fracturing in the Offshore Abu Dhabi clastic sand formations. The lessons learned during this successful design and application is critical for the design of future wells and the development of the UAE clastic sand formations.
The constructed MEM played a key role in successful hydraulic fracturing. Fracture height, length, width, direction, complexity and overall fracture performance are all largely controlled by the formation stresses, stress direction, rock properties and complexity of the rock fabric.
Geomechanical properties in the clastic sand formations in Abu Dhabi offshore were evaluated with less uncertainty by utilizing the advanced MEM. The calibrated MEM was integrated with an advanced fracture design simulator to optimize hydraulic fracture design. Results of the advanced MEM agreed well with fracture diagnostics and temperature surveys.
Work flow in this geomechanical analysis can be applied to hydraulic fracturing in other offshore tight reservoirs with a complex geological environment. Understanding the geomechanical properties of a formation allows engineers to optimize well placement, completion design, perforation placement, charge/gun selection and fracture design for improved well productivity.
Modelling Foam Displacement in Fractured Carbonate Reservoirs
Authors: AlMaqbali A. , Agada S. , Geiger S. , Haugen Å. , Fernø M. A. 
Published: November 2015

Abstract
Foam displacement has been employed in several field pilots which report improvement in mobility control, sweep efficiency, delayed gas breakthrough and EOR. However, foam behavior in highly heterogeneous porous media in general and fractured reservoir in particular is not well understood. Effective application of foam for enhanced oil recovery requires a good understanding of physical displacement processes (e.g. adsorption, foam generation, foam decay) at the laboratory and field scale. This is particularly important for the more complex fractured carbonate reservoirs which host over half of the world's remaining conventional oil reserves.
We investigate the effect of foam displacement in fractured carbonate reservoirs using numerical simulations tuned to experimental data to compare recovery for different injection strategies at different scales. In the experiments, high quality foam was generated by the injection of surfactant solution and N2 gas either in-situ or prior to injection. A mechanistic Lamella Density model was used to simulate core-scale laboratory experiments and history match the unknown foam parameters. We applied our understanding of foam displacement processes at the core scale to a reservoir model at the inter-well scale where additional heterogeneities were encountered. For this model we used a cross section of highly heterogeneous simulation model of a middle Jurassic carbonate ramp that is an analogue to the Arab D formation in Qatar. We used this model to test the effect of foam injection for different injection mechanisms, analyze the displacement processes, and compare the overall sweep and recovery.
Foam injection showed very promising results by diverting the flow from the high permeability fractures to the matrix, allowing for a better sweep efficiency that lead to a noticeable increase in differential pressure. Pre-formed foam yielded a higher recovery (around 78% of OOIP) compared to the in-situ generated foam in the core samples. This might be due to the smooth nature of the fractures leading to fewer snap off sites for foam generation. Varying the foam injection strategies (i.e. pre-formed foam, co-injection, and SAG) resulted in at least a 12% change in recovery compared to conventional water flooding and water-alternating gas injection. Foam quality, foam stability and injection mechanism were all factors that controlled sweep efficiency.
Our results illustrate how the laboratory-scale displacement mechanisms could operate on a larger (i.e. inter-well) scale where additional heterogeneities are encountered and the ratio of viscous to capillary and gravity forces changes. Our simulations also demonstrate that uncertainties in parameterizing foam models using experimental data from core floods translate into considerable uncertainties for predicting recovery at the field-scale. Still, foam can be an effective agent to increase oil recovery in fractured carbonate reservoirs by improving sweep efficiency and reducing gravity override.
A New Solution for the Characterization of Unconventional Shale Resources Based on Analysis of Drill Cuttings
Authors: de Block Merijn , Hofmann Andreas , Rigollet Christophe , Ravestein Johannes , Power Matthew , Haverkort Robert , Slot Bas Bruins , Bonijoly Didier 
Published: November 2015

Abstract
We introduce a new, cost-effective solution for the characterization of unconventional shale resources based on innovative analysis of drill cuttings. This solution was tested successfully on the Toarcian shales of the Couy-1 well, located in the southern Paris Basin, France. Ten samples of cuttings-sized rock fragments from different depths were subjected to several analytical methods to determine geochemical parameters (LECO and Rock Eval), the mineralogy and texture (QEMSCAN), and the mechanical properties (nanoindentation). Based on the results, the Toarcian shales were subdivided into two mineralogically distinct lithostratigraphic intervals. The Upper Toarcian shales consist of siltstone with a matrix of illitic clays, whereas the Lower Toarcian shales consist mainly of calcareous mudstone with a matrix of finely intermixed calcite and clays. The Young's modulus varies between 12.5 and 25.6 GPa and decreases with increasing TOC content. An interval with high TOC content (&gt; 1.9%) is located between depths of 330 and 350 meter in the Lower Toarcian shales, with a maximum TOC content of 7.6%. A basic set of wireline logs was available and subjected to multi-mineral stochastic log interpretation. By calibrating the log interpretation with the results of the analytical methods, the main petrophysical parameters (TOC content, lithology, porosity, saturation) were successfully determined on log scale. This provides a method for upscaling core and drill cuttings measurements to reservoir scale. In addition, nanoindentation data were used to create a synthetic shear sonic log, allowing for calculation of elastic moduli and brittleness logs. The workflow introduced here provides a method for reliable and accurate characterization of unconventional shale resources based on existing data sets, i.e. drill cuttings and basic log sets. The results can be used for assessment of the hydrocarbon potential and identification of the most prospective zones within source-rock intervals.
Strategic Vocational Training for Nationalization
Authors: Jaber Nizam , Hashem Hekmat Bani 
Published: November 2015

Abstract

Objectives
the aim of this paper is to provide a practical model to qualify the National Workforce to meet the increasing demand for skilled workers especially in critical industries such as the oil & gas sector. It builds on the governmental nationalization initiatives and extends human resource development efforts beyond formal education and training to embrace workplace learning as the most effective and efficient approach for competence and capability building.

Method/procedure and process
based on ADNOC standards and guidelines, a model for workplace technical skills development was constructed. ADNOC Code of Practice is integrated with Scottish Vocational Qualifications Standards (SVQs) to ensure achievement of the desired outcomes. The main features of the proposed model include competence – based and structured on the job training (S-OJT). The model makes extensive use of the Scottish Workplace learning and development standards, in particular, facilitation of workplace learning through coaching, assessment of workplace competence and internal verification standard to ensure the quality and effectiveness of workplace learning interventions.

Results/Observations and conclusions
In line with ADNOC competency assurance policy, employees handling HSE critical roles have to know exactly how to do their job properly and be able to rely on the person next to them todo the same. SQA qualifications are designed to ensure that every employee is fully competent and can demonstrate their competence in their normal workplaces to the standard expectations. Integrating SVQs with ADNOCcompetence assurance policy and Code of Practice, will result in developed and well-preparedworkforce that will satisfy the requirements of the international standards as well as UAEPetroleum Industry Sector.

Novel/Additive Information
the unique structure of the presented model as a practical skill acquisition approach spans the trainee to expert knowledge and skills levels. It provides a systematic intervention for implementing vocational training based on experiential and adult learning principles to accelerate workplace learning. This adapted version of SVQs that are specifically tailored to meet ADNOC group demands of highly qualified and ready toparticipate National Workforce. While taking into account the current and future pressing needs for skilled national workforce in the petroleum sector, the model can be implemented in other sectors at the national scale as a supplement to NQA national skill development efforts.
Permeability Estimation from Production Logging for Horizontal Open Hole Drains in Carbonate Reservoir: Myth or Reality?
Authors: Espinoza Irina Baca , Maalouf Christophe Bassem , Al-Jaberi Salem , Ahmed Husnein Shershad , Amer Mohamed Mostafa 
Published: November 2015

Abstract
The estimation of permeability in openhole horizontal drains in carbonate reservoirs poses petrophysical and reservoir engineering challenges. The usual approach relies on the pressure transient analysis (PTA) from well testing data to estimate the average reservoir permeability. The attempt to estimate the permeability from production logging (PLT) usually fails due to many unknown parameters and to complex flow regimes. However, we believe that the average permeability estimated from PTA combined with PLT results can be used to evaluate the distributed permeability across the drain.
In this paper, several approaches for deriving permeability from PLT were evaluated. Considering that PLT is usually performed during early linear flow regime, the Babu and Odeh (1990) equation is used for average permeability estimation. The zonal permeability is calculated proportionally to productivity index (PI) per zone per foot.
In the proposed method, the distributed permeability calculation along the horizontal drain is closer to the average permeability estimated from PTA than other methods, such as core and nuclear magnetic resonance (NMR) permeability index log. Downhole rates and flowing bottom hole pressure are used as reference for history matching. The results from different methods were inconsistent in some zones. A wide range of permeability values were obtained in few zones and could be explained by the presence of fractures.
The paper demonstrates a novel approach of permeability calculation based on PLT data, and could be applicable for previous and upcoming well logging. The method clearly helps to reduce the uncertainties in permeability estimations. The conclusive findings from this study are considered to be a good integration practice that will help to improve reservoir flow characterization and eventually reservoir modeling.
The Interpretation of Permeability Changes During Acid Injection In Carbonates: A New Integrated Methodology
Authors: Qureshi Fahed , Gharbi Oussama , Julien Philippe 
Published: November 2015

Abstract
Monitoring and predicting the behavior induced by the injection of reactive fluids in carbonates is a common challenge for different applications. More particularly, acid is routinely injected in producers and injector wells within carbonate reservoirs to improve the permeability near the wellbore area. During a typical acid stimulation operation, two parameters are mainly monitored; these are the Bottom Hole Pressure (BHP) and the pumping rate. The objective of this paper is to highlight the importance of local changes on the overall pressure evolution and to provide a new methodology providing better interpretation of pressure-time evolution curves during acid stimulation operations.
First, a series of elevated temperature and pressure acid injection core flooding experiments were conducted. The overall pressure drop across the core samples was monitored classically using two pressure transducers at the inlet and outlet of the samples. In addition five pressure taps were recorded along the samples to be able to monitor the pressure evolution along the cores. Permeability time-evolution was then obtained for different flow rates, acid types and carbonate cores. The carbonate cores were characterized using high resolution pore-scale imaging, MICP and XRD measurements. Then, we complemented our core flooding measurements with values of permeability-changes induced by acid injection found in the literature. A database was formed and was subsequently analyzed.
We show that local changes in permeability can take place without impacting the overall pressure response. The measured permeability change depends on the scale of observation. We identified three main regimes of time-evolution permeability changes. We showed that the permeability is not directly proportional to the wormhole penetration. There is a certain time needed before starting to notice permeability increase. The wormhole breakthrough is characterized by a sharp increase in permeability. A new correlation factor that takes into account the pore size and the injection flow rate was obtained in order to correct for the time evolution permeability readings and take into account the impact of the scale of observations. This correlation was validated on the measurements from literature and from our laboratories. The next step will be to implement this correlation on a field case during acid stimulation operations.
Insights and results of this methodology can be applicable to better monitor other injections of reactive fluids in the areas of EOR and CCS.
Real Time Mitigation of Subsea Spool Instability Due to Uncertain Met-Ocean Data or Other Parameters
Authors: Sarkar Tarun Kumar 
Published: November 2015

Abstract
Instability of subsea riser spools or associated subsea pipeline facilities may arise during installation stage due to combined effect of changes in localized met-ocean data, free riser end not supported by the topside, free spanning seabed and absence of concrete coating in some parts of the riser spool. This paper deals with efficient mitigation of the problem on real-time basis by a new analytical approach. Instability of subsea riser spools or other section of a pipeline, observed during extreme weather condition, needs thorough observation and analysis. It may be difficult to quickly pinpoint the actual cause for the instability amongst a large number of variable parameters present. For example it is not possible to detect potential anomaly in theoretical met-ocean data in a short period as it requires at least six months to one year for validating theoretical met-ocean data by hind-casting with actual measured data. Though theoretical model of met-ocean data normally provides sufficiently accurate basis to proceed with FEED stage design, it may fail to accurately capture some unpredictable cases near islands. The new analytical approach determines additional submerged weight requirement indirectly from stable models observed under extreme weather conditions. Morison's hydrodynamic equations form a good basis to compare the observed response of the stable and unstable facilities. A unique stability response parameter of individual pipeline spools is then computed in a spreadsheet considering pipe OD, wall thickness, spool dimensions, applied concrete weight coating and calculated concrete weight. The result reveals that the response parameters of the stable spools are similar but distinctly different from that of the unstable ones. The additional weight requirements of the unstable facilities are then estimated such that their individual response parameters are aligned with that of the observed stable pipelines. Additional weight requirements are provided on the affected pipeline sections or spools by installing concrete mattresses. The proposed method provides a fast and effective mitigation option to deal with subsea instability issues on real time basis during advanced stage of installation. These safeguards against significant cost and schedule impact
Petrophysical Challenges in Unconventional and Tight Source Rocks, Onshore Abu Dhabi
Authors: Steiner S. , Raina I. , Dasgupta S. , Lewis R. , Monson E. R. , Abu-Snaineh B. A. , Alharthi A. , Lis G. P. , Chertova A. 
Published: November 2015

Abstract
ADCO started its unconventional exploration campaign in 2012 targeting the tight carbonate sequences known as Wasia Group, onshore Abu Dhabi. A front-end loaded data gathering strategy was employed to acquire extensive latest generation logging data tailored for unconventional reservoirs. In a number of wells the entire reservoir section was cored, often up to 800 ft per well, leading to more than 3000 ft of core retrieved to date. ADCO applied unconventional core analysis technologies, such as retort analysis, to generate the optimal core results. Key parameters such as effective porosity, pore size distribution, TOC, source rock maturity, mineral compositions and fluid saturations were determined from logs and core data (where available).
This paper will focus on the petrophysical challenges during the evaluation of the Wasia Group. We will demonstrate that conventional core analysis techniques have only limited applicability, whereas core analysis techniques designed specifically for unconventionals provide more relevant results. A log analysis methodology centered on the application and importance of NMR in unconventional liquid plays is presented. Porosity data measured through retort analysis provide an excellent fit to NMR log-based porosity measurements. Conventional core analysis results generated a poor fit to log porosity, and the resulting values exhibited scatter with a large standard deviation. T2 distribution from NMR log data suggests the presence of large pores with good fluid mobility, which requires confirmation through formation testing or production.
Log data-derived rock typing was performed. It is based on principal component analysis of the reservoir section. Rock classification may help in selecting suitable zones for hydraulic fracture initiation.
Lessons learned from the initial wells for core recovery and analysis techniques are summarized below and have been implemented in later wells: –Preserve part of the core for robust saturation measurements.–Stop acquisition of conventional poro-perm data–Focus on unconventional-specific retort-based techniques for core petrophysics–Focus on pulse decay permeabilities–Use scratch test to aid in core analysis sample selection process, especially for rock mechanics–Add core T1/T2 NMR and MICP to future core analysis programs
The complete integration of core and log data has allowed for a thorough assessment of the unconventional hydrocarbon potential within the ADCO concession.
Managing Sulphur Deposits in MP Sour Flare Headers
Authors: Whateley T. R. , Roquet D. 
Published: November 2015

Abstract
Significant sulphur and iron sulphide deposits were observed throughout the MP Sour flare header within the gas processing plant onshore facility. This deposit was generated through both a slow Claus reaction in the header when SO2 and H2S rich gasses combined and from sulfenic acid reaction with the pipe material. This solid material led to restrictions of up to 80% cross section for some flare sub headers and resulted in potential incapacitation of safety protection systems. Through gamma-scanning, the extent of build up was assessed and through hydro-jetting, several tons of the deposits were removed.
To mitigate future deposit formation, all SO2 rich sources to the MP Sour flare were positively isolated; bursting discs installed upstream of PSVs and spectacle blinds installed in closed position in maintenance vent lines to the MP Sour flare. In addition, purging of the relieving and venting lines with nitrogen following operation in SO2 rich service was mandated through revision of operating manuals. Potential sulfenic acid sources were identified and similarly isolated.
Integrated Formation MicroImager (FMI) and Spectral Noise Logging (SNL) for the Study of Fracturing in Carbonate Reservoirs
Authors: Aslanyan Arthur , Aslanyan Irina , Minakhmetova Roza , Maslennikova Yulia , Karantharath R. , Al Hadhrami Badar , Al Gafri Zaaima 
Published: November 2015

Abstract
Carbonate reservoirs are known to contain considerable hydrocarbon reserves. There are, however, several challenges that may complicate the process of development of this type of reservoirs, such as low porosity and high degree of fracturing and heterogeneity, which, cumulatively, could result in a low oil recovery factor (RF). Optimisation of development process in carbonate fields is impossible without preliminary reservoir studies focused on assessment of their production potential. Such studies include an analysis of complex pore space structure and local system of faults and fractures that may serve both as enhanced reservoir capacity and flow channels. Conventional logging techniques (for example, high-precision temperature logging and spinner surveys) solely used for estimation of reservoir productivity may have a limited scope of application. An integrated approach based on concurrent deployment of Formation MicroImager (FMI) and Spectral Noise Logging Tool (SNL) has considerably improved the interpretation of this scenario.
This paper gives some examples of carbonate reservoir surveys conducted in the wells located in one of the Middle Eastern fields. It has been shown that spectral noise logging data have a high degree of correlation with FMI data resulting from fracturing analysis. The active fracture flow zones have been distinctly outlined by Spectral Noise Logging data and further confirmed by High-Precision Temperature Logging data. The advantages offered by joint application of SNL and FMI techniques for studying carbonate reservoirs have therefore been clearly demonstrated. This approach can be successfully applied for the study of both natural and induced fractures.