bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrated Leak Detection in Gas Pipelines Using OLGA Simulator and Artificial Neural Networks
Authors: Afebu K. O. , Abbas A. J. , Nasr G. G. , Kadir A. 
Published: November 2015

Abstract
Gas pipeline leakages do not only represent loss of valuable non-renewable resources but also a potential source of environmental pollution and fire disaster, thus making it very important to have a quick and accurate leak awareness scheme in pipeline systems. In a novel approach of providing industry with more reliable, friendly and cost effective technique in handling pipeline leakage especially in countries were pipeline vandalism has been widely reported. This require urgent detection and intervention, the potential of an Artificial Neural Network (ANN) in detecting and locating leaks from everyday flow line measurements was explored in this research paper. Pipeline responses under zero (no) leak condition, and realistic different leak conditions were simulated on a gas pipeline using OLGA simulator. Simulated leaks were seen to be characterized with unique flow rate, velocity, pressure and temperature signatures that were identifiable by the neural network. The network during training was able to learn the correlation between these signatures and the leak parameters and then use the learning in predicting and locating leaks from new signature data. The network predictions showed final RMSE values of 6.14 and 0.977 for the single and multiple leaks model respectively. The correlations between the actual and predicted leak sizes gave R values of 0.95 and 0.60 for the single and multiple leaks respectively while those of the actual and predicted leak locations were 0.97 and 0.96. The system was able to locate 90% of the induced leaks to a distance that is less than 10 m away from the actual leak locations while 62% of the ANN predicted leak sizes differed from the actual value by less than 50% of the actual leak size and the remaining 38% differed by about 65 – 400% the actual sizes. This thus implies that the set has a better precision in predicting leak locations than predicting leak sizes. Based on obtained results, it can be said that with sufficiently large number of measurements, neural networks are of great potential in predicting and locating leaks. Results also showed that leak detectability tends to improve with increasing leak size and increasing distance from the source and the relatively low correlation obtained for the multiple leaks model can be attributed to the partial masking of smaller downstream leaks by larger upstream leaks.These characteristics of leaks are predominant to the countries with cases of vandalism, and could be a potential approach in handling pipe leaks.
The asphaltene risk map recommendation: Asphaltene Risk Estimation on an Offshore Field Utilizing Experimental Results
Authors: Takabayashi Katsumo , Tani Kengo , Arii Hiroaki , Baslaib Mohamed 
Published: November 2015

ABSTRACT
It is widely known that pressure drop and compositional change of reservoir fluid causes asphaltene precipitation. Regarding compositional change, gas injection is believed to be a typical trigger of asphaltene deposition. The injected gases are mixed with reservoir fluid and gradually change the composition in the reservoir as gas front is heading. For such fluids, compositional changes are believed to take place not only near gas injectors but also in a wider area. Thus, asphaltene precipitation risks should be considered on field scale.
This paper demonstrates how to generate "Asphaltene Risk Map on field scale" based on the correlation between Asphaltene Onset Pressure (AOP) and fluid composition. A Middle Eastern offshore oil field which encounters asphaltene problems was selected as an example because the above two key parameters are mainly working in the field for destabilizing asphaltene. For creating risk map, compositions of reservoir fluid near the asphaltene problem wells were calculated from reservoir simulation. The calculated compositions were applied for the asphaltene model with calibrating measured AOP. Various combinations were evaluated on the plots of AOP versus composition to find well-converged correlation.
Eventually, the C1-C19 component was selected to achieve the most reasonable correlation to AOP for this case. According to pressure variation from the correlated AOP, risk ratings were proportionally distributed on the plot. Based on these risk ratings, "Asphaltene Risk Map" was translated from the relationship between C1-C19 component and pressure. The created risk map shows a reasonable tendency to replicate the timing of actual asphaltene precipitation. In addition, two types of asphaltene precipitation mechanism were confirmed on the Risk Map. Namely, higher risk was estimated in two producers; one is located in the gas breakthrough area due to gas cap expansion, and the other is isolated from the gas breakthrough area but is in the vicinity of free gas observed area where compositional change occurs.
This Asphaltene Risk Map is considered useful to optimize gas injection plan, in particular. Time-lapse prediction of asphaltene risk can suggest timing and/or priority to prepare mitigation plan.
Innovative Energy Optimization Program Results in Huge Cost Savings and Sustainability Benefits
Authors: Pushkarna Arun , Elbadiich A. , Motairy M. A. , Abdullah S. , Ali M. , Hendawy M. 
Published: November 2015

Abstract
National Drilling Company has put in place an Energy Management System. The main objective is to ensure an optimum use of energy by trimming waste, better use of natural resources and avoidance of unnecessary operating costs. Additionally the initiative targeted improving environmental performance.
Methods, Procedures, Process:
NDC examined the prevalent practices and energy sources within the company. It then prepared a chart showing the relationship between each energy source thus identifying the largest consumer. This led to the identification of the best improvement opportunity that the company could put in place. Not surprisingly this was the rig engines. Once this was done, the company devised a simple process to monitor and report on the actual energy consumption per site. This was compared with the actual operation at the time of reporting and the correlation between these two parameters identified an opportunity to optimize the deployment of engines. Moreover, with numerous rigs engaged in similar operations a process was put in place to compare between similar rigs and operations. The anomalous use of engines was highlighted and site staff advised against inappropriate use.
Results, Observations, Conclusions:
Although the process was started as an initiative to cut down on diesel consumption (diesel being identified as an energy source in ISO 50001) and conserve energy consumption across the company, the results when compared after one year of operations yielded additional benefits. The overall savings of the company were as follows:
Fuel Savings - Almost 5 million gallons of diesel were saved in the full year.
Cost savings - Over 55 million Dhirams savings were realized
Energy Savings - Almost 700,000 Giga Joules of energy savings were recorded
CO2 Reduction - 50,000 tonnes of reduction in CO2 emissions was recorded for 2014 vis-à-vis 2013.
Other benefits of the project was in reduction of maintenance costs, reduction of lubricating oils for engines, Better utilization of capital assets and a longer life of the engines across the company.
First Principle Models for Emission and Performance Monitoring
Authors: Nielsen Jan Sandvig , Weel Mogens 
Published: November 2015

Abstract
Combustion processes such as gas turbines, furnaces, flares and boilers in the oil and gas industries are significant sources of pollutants that can impair human health and the environment, including sulfur dioxide (SO2), nitrogen oxide (NOx) and carbon monoxide (CO). Further, these sources will have an impact on global climate via its emission of greenhouses gases – primarily carbon dioxide (CO2).
SO2 and NOx, when emitted to the air, react with water and other compounds to produces various forms of acidic compounds and particles, which can remain in the air for days or weeks. Depending on wind direction and speed, these harmfull substances can be spread in wide areas and are not necessarily limited to the country of the emission sources. When the pollutants fall on to earth or water they will have impact on air quality, visibility, acidification, sensitive forest and coastal ecosystems.
SO2 and NOx emissions form fine particles in the atmosphere. Particulate matter is the term used for a mixture of solid particles and liquid droplets found in the air; fine particles (PM2.5) are smaller than 2.5 microns (millionths of a meter) in diameter. The gas fired combustion sources emit particles directly into the air, but their major contribution to particulate matter air pollution is emissions of SO2 and NOx, which are converted into sulfate and nitrate particles in the atmosphere. These particles make up a large part of the fine particle pollution in most parts of the country. It is scientifically well recognized that there is a correlation between elevated fine particulate matter and increased incidence of illness and premature mortality. In addition, NOx and organic volatile compounds forms ozone with the presence of sunlight. This ozone will be present at ground level and is a major part of the smog and is also linked to potential health hazards including respiratory illness.
Borehole Controlled Source Electromagnetic (CSEM) Surveying for Monitoring HC-Saturation in the Bockstedt Oilfield (NW Germany)
Authors: Tietze K. , Ritter O. , Patzer C. , Veeken P. , Verboom B. 
Published: November 2015

Abstract
Main objective is to support reservoir monitoring in an EOR production scheme. Enhanced oil recovery calls for efficient monitoring of hydrocarbon saturation changes. In the onshore Bockstedt oil field there exists a substantial difference in resistivity at reservoir level: for initial oil saturation it exceeds 100 Ohmm reducing to 0.6 Ohmm once fully displaced by formation brine. Applicability of the controlled-source electromagnetic method to monitor such resistivity changes is investigated. Targets are Lower Cretaceous shallow marine clastics at approximately 1200 m depth.
Finite difference forward modelling shows CSEM is sensitive to expected resistivity changes, but the effect is difficult to resolve with surface measurements only. Resolution increases significantly if sensors or transmitters are placed in observation wells closer to the reservoir. Behaviour of the vertical electric component (Ez) in shallow boreholes and/or use of complex source configrations look rather promising.
In 2014, a borehole-to-surface CSEM configuration was deployed successfully across the Bockstedt oil field, whereby the current was injected via the metal casing of an abandoned production well. The set-up also allowed conventional magnetotelluric (MT) data acquisition when the transmitter is turned off at night. CSEM response functions are of good quality with high repeatability. Recordings from conventional and new borehole transmitters indicate different current distributions in the subsurface. Results of the tested source configuration are in agreement with predictions by numerical simulations. Preliminary 3D inversion is consistent with previous numeric simulations.
A timelapse CSEM survey is scheduled for 2015, inclusive drilling of a shallow observation well for Ez component monitoring with a new borehole sensor. In parallel, a timelapse workflow for 3D CSEM inversion is developed.
A Multi-disciplinary Integrated Approach To Understand The Potential Of The Najmah-Sargelu Reservoirs Of The Dharif and Abduliyah Fields (West Kuwait)
Authors: Matar Saad , Ray Dipak Singha , Abdulmalik Ameena , Mukherjee Pritish , Perfetti Erwan , Maux Thierry Le 
Published: November 2015

Abstract
The Najmah and Sargelu, two tight carbonate reservoirs of Jurassic age, are oil bearing in the West Kuwait fields Dharif and Abduliyah. Due to their complexity, presence of numerous natural fractures and low matrix porosity and permeability, these reservoirs have been underdeveloped in both fields. A multi-disciplinary integrated study has been performed to thoroughly investigate their potential and design the appropriate future development plans.
This paper shows how the use of the 3D seismic data and the rock typing exercise has been maximized to constrain the derived models and reduce the uncertainties. The main reservoir horizons (top Najmah, top Sargelu and top Dharuma) have first been interpreted using the 3D seismic cube and major faults were picked on vertical seismic section and time slices. A seismic characterization work aimed at enhancing seismic data and better describing both matrix and fractures in between wells was also performed. The seismic fracture characterization study led to a set of seismic fracture index maps detailing the fault/fracture corridor network. The matrix characterization study provided an average shale proportion map in Najmah to guide the shaly facies proportions in the geological model.
From the available well data, mainly core description and classical logs, a detailed sequence stratigraphy and petrophysical interpretations were performed. Electrofacies were then computed at wells before being propagated in 3D in a detailed geological model combining both fields.
Finally analysis of the natural fracture network was made using multiple sources of data: core description for fractures, image logs interpretation, seismic maps, transient well tests, production data … A Discreet Fracture Network (DFN) model was derived and then dynamically calibrated. The equivalent fracture properties (porosity, permeability and fracture spacing) were computed and imported into a dual porosity – single permeability simulation model.
Using the limited production and pressure data in both Dharif and Abduliayh fields, the dynamic models were adjusted to fit the production history: uncertain oil-water contacts depth were modified and small modifications of fractures properties in around one of the well was performed. The calibrated dynamic models were then used to test several development scenarios. Dharif potential, due to the presence of a thin oil column, was shown to be limited. Abduliyah potential, on the other hand, is likely to be greater if the fracture network is proved to be as permeable as in Dharif. If this is confirmed, a development with horizontal producers located at the crest of the structure is likely to be the most suited method.
Innovative Solutions to Overcome Production Constraints
Authors: El Thany Ezzat , Al-Dhaheri Abdulla Mubarak 
Published: November 2015

Abstract
ADGAS operates three LNG trains of which Train-3 is designed to produce twice the capacity of any one of the other two trains. ADGAS LNG Trains 1&2 process LP Gases and HP Gas from ADMAOPCO, to produce 180 T/Hr of LNG in each train. ADGAS LNG Train-3 processes only HP Gas to produce 384 T/Hr of LNG. Apart from LNG, Propane, Butane, Paraffinic Naphtha and Sulphur are also produced as secondary products. Though the installed capacity of Train-3 was 320 tph, with an initial study and modification the production was increased to 380 tph LNG since its commissioning.
The Impact of Effective Fracture Length versus Effective Fracture Height on Ultimate Recovery in Tight-Gas and Unconventional Reservoirs
Authors: Shaoul J. R. , Park J. , van der Hoorn K. 
Published: November 2015

Abstract
This paper evaluates the effect of different proppant pack cleanup scenarios on welltest analysis results and long-term recovery in tight gas and unconventional reservoirs. Simulated buildups are created in a detailed reservoir simulation model. The simulated buildups are analyzed in a commercial welltest analysis package to obtain an apparent effective propped fracture length, as is common practice in the industry. Two different proppant pack cleanup scenarios are compared, both of which result in a short apparent effective fracture length based on welltest analysis. The effect on long-term recovery for the different cleanup scenarios is then simulated using detailed 3D reservoir simulations, showing that there is a significant difference in recovery, in spite of the comparable welltest analysis results.
In a previous publication (Shaoul et al. 2015), we showed the effect of stress sensitive reservoir permeability on reducing the fracture length estimated from welltest analysis. Now, using detailed 3D reservoir simulations, we simulate welltests with different proppant pack cleanup scenarios, from piston-like flow to complex channeling and analyze them in a welltest package. Welltest analysis estimates effective fracture area, and then calculates length based on an assumed fracture height. When only a portion of the fracture area cleans up, this gives a reduced fracture length. The maximum fracture extent (the furthest distance from the well that the proppant pack has cleaned up, relevant for drainage extent) may be close to the full propped length, while the small effective area calculated from the welltest can actually be caused by a reduced effective fracture height. The impact of this assumption on the buildup analysis and ultimate recovery is examined by simulating two different proppant pack cleanup scenarios.
This work supports field observations that have been made by Barree showing a correlation between ultimate drainage area and fracture size. This work suggests that trying to achieve maximum possible propped length is still important in tight and unconventional reservoirs to maximize long-term recovery and connected gas in place, even when well testing shows a short effective fracture length. Including the effect of effective fracture height, or using more realistic assumptions about proppant pack cleanup, would help to avoid underestimating the actual effective fracture length. Welltests showing short fracture lengths have led some people to reduce treatment volume and increase proppant concentration to achieve higher fracture conductivities. They hope to increase the effective length even while reducing the created propped length. Using more realistic proppant pack cleanup scenarios, we show that this approach may actually be counterproductive in tight gas and unconventional reservoirs, because it reduces ultimate recovery due to a reduced fracture extent.
Recent Technologies for Land Seismic Imaging Over a Complex Near Surface Overburden
Authors: Bouzidi Y. , Vesnaver A. 
Published: November 2015

Abstract
Removing signal distortions due to near surface complexities is the key challenge for land seismic data imaging. In the Middle East, where several major oil fields are located onshore, these complexities require developing new technologies: as extreme shallow velocity variations occur occasionally elsewhere, not enough research and development has been carried out to fully compensate them so far. In addition, the common recording geometry for deep targets produces a near-surface information gap (Vesnaver 2005). In this paper we review recent advances and some ongoing research that address this problem, with applications to real cases in the Arabian Peninsula.
The first technique reviewed is the inversion of the vibrator plate controller data, normally available in the Vibroseis seismic records, but rarely used for improving the Earth imaging. We show that it helps removing high-frequency spatial distortions due to local soil anomalies. As recording this data is part of standard field operations, its use comes almost for free, as the related processing is not heavy in terms of computing power.
A second cost-effective approach is the integration of seismic and satellite imagery. The resolution commercially available for Earth images in various electromagnetic bands is fitting the normal bin size adopted in 3D seismic surveys, e.g., 25×25 m. Thus, correlating the soil properties in terms of back-scattered radiation with physical properties as P-wave velocities or Q factor, allows improving the resolution of the shallowest layer in our Earth model. As this layer – (the so-called weathering) – is normally the most heterogeneous, improving its estimate allows removing better the related distortion for imaging the possible underlying oil and gas reservoirs.
Sensitivity Analysis of Unstructured Meshing Parameters on Production Forecast of Hydraulically Fractured Horizontal Wells
Authors: Sun Jianlei , Schechter David , Huang Chung-Kan 
Published: November 2015

Abstract
In the context of multi-stage hydraulically fractured horizontal wells, unstructured grids such as PEBI (perpendicular bisector) grids or Voronoi grids have been widely applied to generate simulation meshes for fracture networks. In previous work we developed a robust optimization-based 2D meshing algorithms to handle non-orthogonal, low-angle intersections of extensively-clustered fractures with non-uniform aperture distributions. However, vertically extruded 2.5D PEBI grids become necessary with more wells being drilled into dipping layers. Besides, it is necessary to provide practical application suggestions for choosing an unstructured mesh to accurately resolve flow regimes of production.
In this work we extended 2D PEBI workflow to 2.5D, and then validated it against two models: (a) a synthetic model with one horizontal well and 120 orthogonal intersected hydraulic fractures built by Tar-tan grid and (b) a field-scale model with three horizontal wells and 120 non-orthogonal intersected hydraulic fractures in a slightly dipping reservoir created by a commercial software plug-in. For the synthetic model, we simulated production performance at a constant bottom-hole flowing pressure up to 20 years. For the field-scale model, we first performed history matching and then predicted production at a constant rate up to 20 years. We compared pressure diffusion front, bottom-hole flowing pressure as well as CPU performance.
Reasonably good matches between PEBI grids and other grids are observed in both pressure diffusion front and production behavior. Sensitivity analysis suggests that refinement around the fractures has modest impact to early time production while background density has dominant impact to the late time production. Background grid type and grid orientation have less influence as long as they have the same grid density. Less number of 2.5D PEBI cells can be achieved by removing unnecessary refinement around fractures, increasing reservoir background size and reservoir background size ratio, replacing unstructured background grids with structured grids, and reducing the complexity of the fracture networks without loss of the accuracy and therefore result in much favorable CPU performance. The existence of opened natural fractures was evaluated to simulate the out-of-zone production. The results suggest that effective drainage area can be significantly greater with the synergy of the natural fractures.
This study is the first to apply unstructured grids to simulate multiple horizontal wells with irregular hydraulic fractures. Besides, this paper provides detailed discussions of implementation algorithms as well as comparisons between 2.5D PEBI and LGR based grids in the context of fracture modeling. And most importantly, this study answers the question regarding how to choose an appropriate 2.5D PEBI mesh to yield both accurate results and good CPU performance.