bluuebunny/crossref_metadata_2025_split huggingface dataset:
Feasibility of Produced Water Treatment and Reuse – Case Study of a GTL Plant
Authors: Onwusogh U. 
Published: December 2015

Abstract
In a GTL plant located in Qatar, produced water (PW) is considered for treatment and reuse in the existing onsite Effluent Treatment Plant (ETP).
The onsite ETP deploys both conventional and advanced water treatment technologies including flocculation flotation unit, biotreatment, membrane filtration (submerged Ultrafiltration (sUF) and Reverse Osmosis (RO) units), evaporation and crystallization processes, to produce water for reuse within the plant mainly for cooling and power generation among many other uses.
Current PW disposal is in deep wells. PW reuse was considered an economically viable option for the plant due to its quality (TDS &lt; 4000 mg/L).
A test work was conducted to determine the feasibility to route the PW to existing onsite ETP. Firstly, the PW was chemically analysed for key contaminants including hydrocarbons (condensate), heavy metals and naturally occurring elements, Total Dissolved Solids (TDS) etc.
Hydrate inhibitor is normally dosed to the PW during the winter season while Corrosion Inhibitor (CI) is dosed continuously throughout the year. This results in two distinct streams, i.e. a "Winter PW stream" (Stream A) and a "Summer PW stream" (Stream B).
The potential impact of Stream A and Stream B must be evaluated before routing to onsite ETP is considered feasible.
Based on sample analysis (pH, conductivity, COD, TOC, ion chromatography, metals scan, toxicity tests and 28 days COD die-away test), it is known that both Streams A and B have the potential to adversely affect the daily performance of the onsite biotreater, with additional risk of sUF/RO membrane fouling (scaling).
The following have been considered in the study:
Hydraulic load of PW to the onsite ETP Quality of Streams A and B, in terms of Chemical Oxygen Demand TDS which is &lt;4000 mg/L (0.4% wt) Presence of scaling components (Ca, Mg and Ba) Heavy metals in PW
Stream A is considered first for pre-treatment in an onsite Wet Air Oxidation (WAO) unit to destroy hydrate inhibitor, while Stream B will be stored temporarily in a holding tank to ensure complete condensate separation, prior to routing of both pre-treated effluent to the onsite ETP.
Experimental test work conducted over a period of 9 months using two bench bioreactors operated at similar hydraulic and solids residence times as the onsite ETP showed COD levels are reduced to levels that meet the specification for further polishing in downstream UF and RO units. Test work suggests PW (Streams A and B) to be compatible with onsite ETP.
Uncertainties in Fracture Apertures Calculated from Electrical Borehole Images
Authors: Maeso Carlos , Dubourg Isabelle , Quesada Daniel , ElNour Walid Abou 
Published: December 2015

Abstract
Parameters for fracture aperture calculations were calculated for a high-resolution logging-while-drilling (LWD) imaging tool, and the aperture calculation that has been applied to wireline tools was extended to the LWD tool. The causes of uncertainty in calculated apertures were determined and, where possible, their impact was quantified. The uncertainties were investigated for LWD electrical borehole images, but the principles can be applied to their wireline counterparts.
Electrical images of the borehole have been used to quantify fractures since the introduction of imaging tools in the late 1980s. Processing includes the calculation of fracture apertures based on the measured excess current as the tool crosses the fracture. The aperture calculation follows an equation published for wireline tools. In extending the aperture calculation to LWD tools, the tool response was modeled using a 3D finite-element code that accurately represents the tool, borehole, and formation configurations. The modeling covered a series of conditions, including variable standoff between the tool and the formation, different fracture widths and radial extent, multiple background formation resistivities, and different mud properties. In addition, the minimum and maximum apertures that can be calculated using the equation were determined. Field examples are shown from Qatar to illustrate the sources of uncertainty in the calculation. These examples are from data acquired with a high-resolution LWD imaging tool.
Results of this work provide an understanding of the conditions where fracture aperture calculations can be used in confidence and where they should be treated with care. The minimum and maximum extremes vary with the environmental conditions, but it is shown that for more conductive muds, the measurement is sensitive to fractures of a few µm in width. Major factors affecting the confidence of the aperture calculations are the properties of the fluid filling the fractures and the radial extent of the fractures. Uncertainty in the calculated apertures for these factors can be greater than a multiple of two in certain conditions. It is usually possible to recognize where these factors have high uncertainty (e.g., high losses). Other factors generally introduce much smaller uncertainties to the aperture calculation. These include the tool standoff, relative dip of the fracture, image scaling, and fracture spacing. Potential errors for the latter conditions are at a maximum of 30% of the calculated aperture in particular circumstances, but in most conditions the uncertainties are much smaller.
Fracture aperture calculations are widely used within the industry. They are a standard part of processing of many electrical borehole images. The addition of uncertainty guidelines will allow the users to understand where to use the aperture calculations with confidence and where to treat the results with caution.
A Quantum Leap in Borehole Imaging for Formation Evaluation: Deciphering the Photo-Realistic Geology of Abu Dhabi Carbonates in Oil-Based Mud
Authors: AlMutwali O. , Khemissa H. , Alfelasi A. , Dama S. , AlNeaimi A. K. , Ahmed S. N. , Shrivastva C. , Abdulrahim J. , Girinathan S. 
Published: December 2015

Abstract
Application of the legacy oilbased mud (OBM) borehole images in carbonates has posed challenges due to the limitation of resolution and borehole coverage; often providing too little for textural and sedimentological interpretation, and leaving a lot to be desired for optimal subsurface characterization. A new technology was required in UAE to acquire photorealistic images to decipher the carbonate heterogeneity for optimal characterization.
The Cretaceous carbonates of Abu Dhabi are very complex with varying heterogeneity through different reservoir intervals. To address various drilling challenges and coring requirements, OBM is being used by various operators in different acreages. Formation imaging becomes critical in such wells, where reservoir rocktyping and different enhanced oil recovery feasibility studies are planned. The study well shows the results of a new technology images in comparison with legacy OBM images and core. And, the image data is inverted for advanced processing to prepare standoff images and quantitative resistivity images for high resolution heterogeneity indicator.
The study well penetrates through a shallow marine carbonate setting ranging from shoal grainstone to the shelf setting wackestone and packstone exhibiting a lot of heterogeneity in facies distribution. In fact, a lot of variability was observed in the image logs against the interval of constant porosity observed in petrophysical logs. Stylolites and conductive seams seem to introduce a lot of barriers and baffles; however, stylofractures seem to be breaching the barrier in many intervals as well. The image log data was inverted to prepare the standoff images and quantitative resistivity images to understand the response of open vs. closed fractures; and vuggy/ mouldic porosity. The results were compared with the core photographs for validation of the interpretation. The high resolution heterogeneity indicators derived from the inverted images provided a means of highresolution facies typing; thereby providing electrofacies to be tied to petrophysical response for further reservoir rocktyping. The textural interpretation also helps in understanding the flow behavior. A detailed faciestyping with advanced interpretation is prepared to understand not only the geological characteristics, but also the variations in reservoir properties within seemingly similar facies.
This work presents the first account of interpretation based on a new technology for OBM formation imaging, with innovative inversion techniques. This also serves as a roadmap for carbonate reservoir characterization in Middle East in the wells drilled with OBM. Also, the encouraging results provide a trendsetting example of applications of this new technology.
Relative Permitivity Based Water-Cut Measurment Techniques for Permanent Downhole Applications in Multilateral Horizontal Wells
Authors: Arsalan Muhammad , Ahmad Talha J. , Black Micheal J. , Noui-Mehidi Mohamed N 
Published: December 2015

Abstract
The challanges associated with efficient and reliable permanent downhole water cut measurement in multiphase flow and in multilateral horizontal well environment are described in this paper. The principles of relative permittivity based water-cut meters are explained in detail. A comprehensive analysis of the state-of-the-art relative permittivity based water cut measurement techniques are presented in this paper to evaluate their suitability for permanent downhole deployment. The techniques are compared against a set of requirements suitable for permanent downhole water cut measurement.
Impact of Acid Jetting on Carbonate Stimulation
Authors: Beckham R. E. , Shuchart C. E. , Buechler S. R. 
Published: December 2015

Abstract
Many wells are drilled with long horizontal completions to maximize their contact with reservoirs. In carbonate reservoirs, such long completions present challenges to the even distribution of acid during matrix stimulation. One approach to addressing these challenges involves bullheading acid through a static limited entry liner engineered to choke back acid flow to the higher permeability and/or lower pressure zones through the sparse placement of small nozzles. While the pressure drop across the nozzles is straightforward to calculate, the interactions between the acid jets created by the nozzles and the carbonate formation are not well understood. Specifically, it is unknown how a high velocity acid jet impinging on a carbonate surface might alter the wormholing efficiency.
To explore the effects of jetting on carbonate dissolution, laboratory experiments jetted hydrochloric acid onto limestone cores at velocities between 100 and 200 feet per second. Consistently, the acid jet formed a substantial bulb-shaped cavity in the face of the rock. Wormholes formed into the rock from this cavity, even at overall flux rates normally too low to generate wormholes. In the absence of acid flux through the core, bulb-shaped cavities formed without wormholes. Low velocity acid jetting did not form cavities. No cavities or wormholes were observed when jetting with only water.
A turbulent jet impinging on a rock will create a localized surface pressure spike near the center of impingement. This pressure spike increases the local flux of acid into the porous rock, and is suspected of initiating the cavity. Once the cavity forms, two mechanisms of carbonate dissolution are active. The first is traditional matrix dissolution, which appears to be enhanced by the increased pressure inside the cavity produced by the kinetic energy of the jet. The second mechanism is surface dissolution, which is accelerated inside the cavity due to turbulent flow along the walls, and results in the enlargement of the cavity throughout the jetting process. Enhancement of the matrix stimulation by the jet is often a benefit. On the other hand, enlargement of the cavity is a disadvantage because it consumes acid that would be better used for wormhole growth into the rock.
Research using both experiments and computational fluid dynamics is ongoing to better quantify the influence of the jet on the two dissolution mechanisms. With such knowledge, it should be possible to better design lower completion liners that exploit the jetting effect for both acid distribution and enhanced stimulation.
An Evolved Approach to Performing Underbalanced Perforating Interventions in Mexico: A Step-Change Improvement in Efficiency, Reliability, and Safety
Authors: Narcizo O. Melo , Aguilar A. Martinez , Mendo A. Rosas , Gordillo J. C. , Ramondenc P. , Burgos R. , Basurto J. R. Cervantes , Rodriguez F. L. 
Published: December 2015

Abstract
An innovative approach to underbalanced perforating in horizontal and highly deviated wells uses a new perforating head specifically developed to leverage the conveyance and real-time telemetry capabilities of coiled tubing (CT) equipped with fiber optics. The results and advantages of this approach have been demonstrated in wells in mature Mexican fields featuring significant reach and pressure limitations.
In recent years, CT equipped with real-time fiber-optic telemetry has been a method of choice to perform interventions in deviated or horizontal wells, as it provides a cost-efficient and flexible alternative to heavier wired CT. In the Mexican fields, this real-time telemetry capability is used to accurately place the guns thanks to downhole casing collar locater and gamma ray tools. The need for pumping fluids to enable detonation, often performed during typical CT perforating operations, is eliminated through the use of a downhole microprocessor-controlled firing head, which is directed by commands sent from surface through the optical fiber.
The result is a nearly instantaneous detonation downhole and positive confirmation provided in real time through an array of sensors in the bottomhole assembly (e.g., accelerometers, pressure, and temperature). The absence of working fluid eliminates any concern of hydraulically loading the well or the need for shut-in, thus significantly reducing the extent of deferred production. It also mitigates uncertainties linked to the influence of downhole conditions on the behavior of working fluids or the potential malfunctions of drop balls. This system is capable of multizone, selective detonation, therefore improving operational flexibility through reduced gun runs. It is also compatible with any other traditional CT service and can easily be combined with a bridge plug setting, a nitrogen lift, or a cleanout within the same run. The approach and its associated workflow enabled a significant reduction in intervention turnaround time by cutting as much as 75% of the time necessary to detonate the guns once the depth has been correlated, while providing fast and clear confirmation of downhole detonation.
This evolved approach not only addresses the conveyance limitations of highly deviated and horizontal wells, it also greatly improves the safety, reliability, and efficiency of underbalanced perforating interventions by leveraging the real-time downhole monitoring and control capabilities of CT with fiber optic telemetry.
Parametric Analysis and Uncertainty Quantification for Flow Assurance
Authors: Twerda Aris , Omrani Pejman Shoeibi 
Published: December 2015

Abstract
Currently, decisions involving a huge amount of money and resources are based on the outcome of simulations. Consequently, an increase in the computational resources has attracted engineers and scientists to increase the complexity of the mathematical models and their numerical algorithms to design or analyze various systems. On the other hand, the transparency of these models has decreased and the sensitivity of the outcome of these simulations on, for instant, certain assumptions or input parameters is often not known a priori.
Furthermore, validation of the models for complex systems in which full scale measurements are limited or even impossible, gives more challenges to the decisions made based on these numerical simulations. Additionally, robust design to consider off-design conditions in a systematic manner is of great importance in oil and gas industry.
Therefore, it would be essential to develop a systematic procedure to quantify the sensitivities and errors associated with each set of simulations in an objective manner. Uncertainty quantification (UQ) could be used as a tool to provide the validity of a performed simulation.
This study describes the current research and opportunities for parametric analysis and uncertainty quantification in the flow assurance such as in performance prediction and validation, risk assessment, decision making and robust design. Additionally, we describe the importance and benefits of probabilistic analysis instead of deterministic analysis. Uncertainty quantification increases the computational expenses and effort of performing deterministic simulations. Therefore, an efficient method to quantify the uncertainties such as probabilistic collocation or surrogate models are required to reduce the computational costs without losing the accuracy of the analysis.
Parametric analysis and uncertainty quantification will give more insights in the validity of simulation data than traditional methods. For instance, using the newly proposed methods will expose the sensitivity of the simulation results to off-design conditions and consequently leads to a systematic decision making based on the probability of an event occurrence. These methods could be used to quantify the most sensitive parameters in the system and the effect of their propagation to the outcome of the model. It is shown that performing non-deterministic analysis in some cases is a necessity.
Mitigating Shale Drilling Problems through Comprehensive Understanding of Shale Formations
Authors: Al-Arfaj Mohammed K. , Abdulraheem Abdulazeez , Sultan Abdullah , Amanullah Md. , Hussein Ibnelwaleed 
Published: December 2015

Abstract
In order to develop an inhibitive water-based mud capable of mitigating the adverse effects of shale-mud interactions, it is important to characterize the shale sample in terms of its geological structure, mineralogical composition, reactivity potential, etc. Further, the shale-mud interactions should be studied through a series of experimental tests such as swelling, dispersion and inhibition durability.
This paper presents the results of characterization and testing of one of the studied shale samples with X-ray diffraction, micro-CT, ultrasonic rock mechanics testing, capillary suction time and cation exchange capacity. The paper also shows how petrophysics data of shale formations can be utilized to improve and optimize drilling practices in order to achieve the ultimate goal of enhanced wellbore stability. Depending on clay content, different shale formations have different responses when exposed to drilling fluids. It is therefore very important to characterize the shale formation to develop the appropriate drilling fluid.
The tested shale sample was found to be a silica-rich shale with a small percentage of clay minerals, mainly kaolinite. Characterization scheme included also Micro-CT where the images revealed the heterogeniety and fractures in the internal matrix. Dynamic elastic moduli were determined using ultrasonic rock mechanics testing. A cation exchange capacity (CEC) value of 2.5 meq and capillary suction time (CST) value of 42.6 seconds indicated low tendency of the shale rock to both swelling and dispersion.
An Experimental Study of Water Production Mitigation and Improved Acid Diversion during Acid Injection in Heterogeneous Carbonates
Authors: Ali Nour El Cheikh , Al-Sammaraie Mohammed , Goedeke Stefan , Benquet Jean-Claude , Aubry Eric , Julien Philippe , Gharbi Oussama 
Published: December 2015

Abstract
A well-designed acid stimulation treatment is a rapid well intervention operation that can lead to long-trim economical benefits. In carbonates, the main challenge is to better design acid stimulation treatments in order to meet the two main characteristics of carbonate reservoirs which are high water production and a wide range of heterogeneities. Acid diversion is one of the key factors for a proper distribution of acid which determines the success of these treatments, especially in heterogeneous carbonate formations.
In this study, we aim at producing novel solutions in order to reduce water production and enhance zonal coverage through effective diversion. The ultimate goal is to validate a single pumping sequence that combines water mitigation, diversion and acid injection. In order to achieve this, we rely on an integrated R&D approach combining single core and dual core experimental setups. The advantage of the dual core setup is to investigate different permeability contrasts, different saturations configurations and to experimentally validate wormholing in heterogeneous carbonates. In fact, in carbonate effective diversion happens when acid is flowing in the low permeability area at sufficient velocity. An easy way to validate this is through parallel core flooding.
We performed a series of high pressure and temperature single and dual core flooding experiments over a range of different carbonate samples having different permeability and porosities. The injection took place at 90 °C and 250 bars. We assessed the efficiency of polymer adsorption by measuring permeability during, before and after polymer injection. Computed Tomography scans were used in order to validate our conclusions. We showed that, adsorption of polymer in carbonates is possible but needs careful design.
We experimentally investigated acid diversion in high permeability contrasts (matrix-fissures) through core flooding. This is another novelty in this study. Finally, the combined pumping sequences were experimentally assessed. We validated diversion in carbonates and identified the optimum injection rates required for such applications. An optimum configuration of permeability contrasts and saturations exists for a combined pumping sequence.
The experimental results and observations are translated into a series of guidelines and procedures which are directly applicable to acid stimulation field operations. The areas of future required research in applied fluid-rock interactions will be highlighted.
General Parallel Reservoir Simulation
Authors: Beckner B. L. , Haugen K. B. , Maliassov S. , Dyadechko V , Wiegand K. D. 
Published: December 2015

Abstract
Faster reservoir simulation turnaround time continues to be a major industry priority. Simultaneously, model sizes are reaching a billion cells and the recovery mechanisms and reservoir management processes to be modeled are rapidly changing and are becoming computationally more expensive. A new reservoir modeling solution has been developed to quickly solve these largest and most complex modeling studies within ExxonMobil.