bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Digital Petrography: Full Thin Section Quantification of Pore Space and Grains
Authors: Buono Antonio , Fullmer Shawn , Luck Kelly , Peterson Keith , king Hubert , More PJ , LeBlanc Stephanie 
Published: March 2019

Abstract
Carbonate reservoirs are often comprised of a heterogeneous pore system within a matrix of variably distributed minerals including anhydrite, dolomite, and calcite. When describing carbonate thin sections, it is routine to assign relative abundance levels to each of these components, which are qualitative to semi-quantitative (e.g. point-counting) and vary greatly depending on the petrographer. Over the past few decades, image analysis has gained wide use among petrographers, however, thin section characterization using this technique has been primarily limited to the pore space due to the difficulty associated with optical recognition beyond the blue-dyed epoxy associated with the pores. Here, we present a new method of computerized object-based image segmentation (Quantitative Digital Petrography: QDP) that relies on a predefined rule set to enable rapid, automated thin section quantification with only minor human interaction. We have developed a novel work flow that automatically isolates the sample on a high-resolution (i.e. &lt;1μm/pixel) scanned thin section, segments the image, and assigns those segments to predefined categories – e.g., pores, cement, grains, etc. Using this technique, statistically relevant numbers of thin sections can be rapidly processed and quality controlled, thereby allowing quantitative data such as MICP, wettability, and surveillance data to be integrated with the petrographic observations for a more complete description of the carbonate rock. Our technique can also incorporate multiple layers, such as cross-polarization, Back Scatter Electron (BSE) imaging, and elemental maps, which allow additional information to be easily integrated with results from QDP. The QDP approach is a significant improvement over previous digital image analysis methods because it 1) does not require binarization, 2) eliminates the subjectivity in assessing abundance levels, 3) requires less hands-on time for the petrographer, and 4) provides a much fuller dataset that can be incorporated across an entire well or field to better address common challenges associated with carbonate reservoir characterization, such as understanding pore type and cement abundance, pore connectivity, grain distribution, and reservoir flow characteristics.
Comparative Analysis of Full-Cycle Cost of Oil and Gas Exploration, Development and Production World-Wide
Authors: Virine Lev , McCoskey Steven 
Published: March 2019

Abstract
Understanding the full-cycle cost of oil and gas exploration, development, and production is critical for petroleum producers and all players in the oil and gas industry. In particular, full-cycle cost assessment is used for corporate planning, acquisitions, operational improvements, project control, and risk management. The challenge is to ensure that full-cycle cost assessment is done accurately and on a consistent basis across different jurisdictions, companies, and geographic areas. Without knowing the full-cycle cost on a consistent basis worldwide, it is impossible to assess capital investment, forecast production from different areas, forecast prices, or assess other factors influencing the world market for oil and gas. This paper discusses the methodology for and the results of full-cycle cost assessment worldwide.
This paper describes a methodology for full-cycle cost assessment that ensures data quality and consistency. It also provides examples of full-cycle cost assessment for major projects worldwide. The results of analysis help to predict long-term pricing trends, determine areas where production will grow or decline, and estimate capital expenditure in the next 10–20 years based on the most recent and most consistent data.
Challenges with Mega-Projects Implementation: Risk Strategies and Opportunities for Growth
Authors: Akimova Irina 
Published: March 2019

Abstract
Russia always plays an important role on iternational energy markets as one of the major oil and gas producers and exporters since the country entered international enrgy market in the middle of the last century. And this role will remain stable at least till the year 2040 according to current forecasts. BP estimates, that Russia will cover around 5% of the global energy demand by the year 2040. Though, Russia has around 17,4% of world gas reserves (OPEC's estimates its even more – around 24,6% due to the different methodology) and only around 6% in world oil reserves, Russia contributes 17,3% to world gas production and 12,2% to world oil production in 2018, according to BP's Statistical Review of World Energy. Developing of enormous gas and oil reserves was extraordinary challenging for the country due to harsh climate conditions, lack of infrastructure, unsufficient financing and need to develop not only fields but the whole remote areas of the country. Though the country was widely ctitised for its dominancy on the European gas market, in this paper it will be outline that developing of the European gas market was of mutual interest of Russia and European Union and both counterpart became beneficiary of it. This paper focuses on challengies with developing enormous gas reserves as Russia has several mega giant gas fields and its experience can be usefull in developing other mega projects around the world.
Improved Carbonate Reservoir Characterization: A Case Study from a Supergiant Field in Southern of Iraq
Authors: Al-Ali Ali , Stephen Karl , Shams Asghar 
Published: March 2019

Abstract
The objective of this work is to characterize the porosity distribution and the types of carbonate facies in the Mishrif reservoir in the West Qurna/1 Oil Field using seismic inversion results, well log data, rock physics model and core data analysis. Identification of the pore system and the spatial distribution of lithology are keys for constructing Mishrif reservoir model, which have a great impact on the development of the most prolific reservoir in the field Mishrif reservoir.
Seismic inversion process is transforming of seismic response into a quantitative elastic properties of the reservoir rocks. It enables the modeling of porosity and lithology distribution in 3D space away from well control. In order to achieve the aim of the work, a step wise approach will be taken. First of all, the vertical distribution of porosity based on well log data and its relationship with elastic properties was undertaken. A model-based seismic inversion guided by rock physic analysis modeling was applied across the high resolution 3-D seismic data, and integrated with core data for validating at Mishrif intervals. The porosity volume was then generated over the entire West Qurna/1 field based on the linear-regression analysis.
The interpretation of seismically derived characterization in the Mishrif reservoir observed a different lateral distribution of acoustic impedance. The results were correlated with computed acoustic impedance log and core analysis data to classify lithofacies of the Mishrif interval. The resulting porosity volume was validated with well log data where good consistency was indicated. By slicing through the porosity volume, it shows a high porosity in many carbonate features with low acoustic impedance which reflect a good reservoir quality (grainstone tidal channel or the accumulation of corals and mounds facies). This observation implied that Mishrif zones displayed a wide range of porosity and lithology fluctuations due to the impact of depositional environment.
The workflow provided insight into the porosity distribution and quantification of its influence on dynamic reservoir behavior. The estimation of the porosity based on seismic data, can increase the reliability of reservoir characteristics through providing a more detailed of porosity distribution in interwell regions. Overall, this study will ultimately lead to improve the development plan of wells in terms of production performance, and economic value of the West Qurna/1 oil field and similar heterogeneous carbonate reservoirs.
Single Station Triaxial Seismic Event Detection, Direction Finding and Polarization Analysis
Authors: Greenhalgh Stewart , Al-Lehyani Ayman , Schmelzbach Cedric , Sollberger David 
Published: March 2019

Abstract
The bearing and elevation (azimuth and inclination) of a seismic event can be estimated directly from measurements at a single triaxial station. There are instances in which the angular resolution secured by triaxial polarization analysis is better than that obtained by beamforming with an extended scalar array. In these situations, one depends totally on understanding the inter-relationships between the triaxial records that make up a seismic wavetrain. There are many approaches to seismic direction finding (SDF). Monte-Carlo techniques of triaxial seismic direction finding seek to maximise signal power by examining the seismic wavefield in many rotated co-ordinate frames. There are variants on this approach, which entail null seeking in an inverse space. Instead of searching all possible directions for the one which best fits the polarization model of a single arrival, it is possible to carry out an eigen-decomposition of the (complex or real) covariance matrix formed from the three-component data. The eigenvector corresponding to the principal eigenvalue yields the polarization direction automatically, with significant savings in computational effort.
Numerical experiments undertaken for different levels of random noise superimposed on a pure mode signal show that there are no significant advantages in using the Monte-Carlo techniques over eigendecompsoition. Confidence measures of event detection may be obtained by examining eigenvalue ratios when using the eigendecompsoition method. A time-domain formulation (covariance or coherency matrix) is preferable to a frequency-domain formulation (cross-spectral matrix) when there are multiple transient events present. The analysis window should be as long as possible (at least half the dominant period of the signal) without causing separate events to interfere.
In practise, the direction-of-arrival estimates deteriorate with increasing levels of random noise, and are generally unacceptable for a SNR of less than 1. Special care is needed to avoid direction errors associated with systematic noise, such as sensor gain misalignment between channels, coupling variations between receiver components, velocity inhomogeneity and anisotropy, the free-surface effect, and multiple event interference.
A Casing Damage Prediction Method Based on Principal Component Analysis and Gradient Boosting Decision Tree Algorithm
Authors: Song Mengxin , Zhou Xiangguang 
Published: March 2019

Abstract
The examination and prevention of casing damage is an important work in oil and gas field development projects. Casing damage will directly influence the production of oil and gas, the effect of water injection and the life cycle of oil, gas and water well. With the number of casing damage wells increasing year by year in each oil field, inspections and precautions of casing damage status have become more and more important during development of the filed. With the development of big data technologies, we can predict the casing damage based on historical and real-time data, and optimize the maintenance intervals of casing.
In this paper, we proposed a casing damage prediction method based on principal component analysis (PCA) and gradient boosting decision tree (GBDT) algorithm. Building a three-nodes Spark big data platform, we tested our proposed method on a dataset in an oil-field in mid-east China. Firstly, based on data analysis and expertise, selected 10 parameters which affect the casing damage most, including casing outside diameter, wall thickness, perforation density etc. Secondly, using PCA to reduce the dimension of parameters. Thirdly, building the algorithm model of casing damage risk assessment by GBDT, training and optimizing the model parameters. Fourthly, using the proposed model for casing damage prediction.
Using precision and AUC(Area Under ROC Curve) to evaluate the proposed method, and compared with traditional methods, including decision tree, logistic regression and Naïve Bayes, the experiment results show that compared with traditional methods, the proposed method gain 86.3% precision and AUC is 1, both higher than traditional methods, which means it has better prediction precision and performance. The proposed method also can apply to predict the probability of a normal well becoming a casing damage well, and finally can provide the decision support for on-site operations. The proposed method using data-driven idea to provide the decision support for oilfield operations, and lay the foundation for the construction of intelligence oilfield.
Influence of Surface Choke on Water Cut and Flow Profile in Horizontal Wellbores Intersecting Fractures and Super-Ks
Authors: Al Sulaiman Ahmed A. , Dimitrios Krinis , Al Shehri Dhafer 
Published: March 2019

Abstract
The surface choke has been utilized in the oil industry to control withdrawal rates per well and to optimize production especially after water breakthrough. However, as found out from this study, applying undue restrictions in horizontal wellbores intersecting high permeability features can have an adverse impact on well performance and unnecessarily lock oil potential.
This paper investigates the effect of surface choke on water cut and flow contribution along horizontal wellbores that encountered natural fractures and high permeability streaks (Super-Ks). The study considered different down-hole completions; open-hole and cased-hole. The investigation was carried out using Multi Phase Flow Meter (MPFM) measurements at different choke sizes in addition to production logs (FSI), wellbore simulation modeling, and real-time data. Instant data monitoring was instrumental in insuring stabilization of sub-surface static pressure while performing many rate tests at different choke sizes. Moreover, it flagged the role of rate stabilization on water cut behavior and rate data quality.
The presence of conductive fractures and Super-Ks substantially influences the flow profile and water cut of horizontal wellbores. These features create high permeability conduits along wellbores such that they dominate production and may cause some matrix sections to contribute little or nothing as observed on FSI profiles. The effect of fractures on production from less permeable sections in the wellbore was investigated at different operating rates using horizontal wellbore simulation modeling.
Both MPFM measurements and FSI logs showed that water cut from horizontal wells, affected by fractures and/or Super-Ks, can decrease if they're flowed at higher rates. Upon reviewing and analyzing data from numerous FSI logs, the study has been able to relate the water cut and surface choking to the well productivity index (PI). Consistently, wells with PI more than twice the averaged matrix PI were found to always perform better at bigger choke sizes. By choke relaxation, the water cut decreased by up to 22% while increasing oil production. Wellbore modeling also suggested that the influence of a fracture on flow contribution from remaining sections in the wellbore can be minimized if the well is operated at higher rates. Restrictive surface chokes were found to disproportionately affect lower permeability sections compared to conductive fractures or Super-Ks which in most cases were invaded by water after water breakthrough. Relaxing these surface chokes allowed more contribution of dry oil from the lower permeability sections, hence the increase in overall oil production and drop in water cut in the affected wells.
Insights into the Impact of Water Salinity on Multiphase Flow at the Pore-Scale in Carbonate Formations
Authors: Abu-Al-Saud Moataz , Esmaeilzadeh Soheil , Tchelepi Hamdi 
Published: March 2019

Abstract
Understanding the effect of injected water salinity is becoming crucial, as it has been shown to have a strong impact on the efficiency of oil recovery process. Various experiments have concluded that carbonate wettability is altered when the water ionic-composition is changed. In this work, a numerical investigation of an oil blob mobilized by water is conducted inside a single pore. The presented model studies the synergy effect of multiphase flow and water salinity at the pore level.
To model the multiphase flow at the pore-scale, the full hydrodynamic Navier-Stokes equations are solved using direct numerical simulation (DNS). The effect of brine ionic-composition is examined through the electric double layer effect. Experimental zeta potential values, published in the literature, of crude oil/water and water/carbonate interfaces have been employed in the model, which capture the water salinity effect.
The simulation results show that the water wetting film surrounding the oil-droplet collapses to an adsorbed nanometer water layer when high salinity water is used. As a result, a large pressure gradient is required to mobilize the oil inside the pore and overcome the attractive surface forces between the oil/water and water/carbonate interfaces. For low-salinity injected water, the carbonate surface becomes more water-wet. The wetting film surrounding the oil blob becomes stable due to the repulsive electric double layer force. Therefore, less energy is required to mobilize the oil blob inside the pore compared to high water salinity. The effect of solid roughness and injected water flow rate are also studied, which show to have a strong impact on the oil displacement efficiency.
The novelty of the numerical method lies in efficiently capturing the nanoscale effect of the electric double layer in pore-scale multiphase flow at the microscale. The simulation results provide fundamental insights on the efficiency of low-salinity waterflooding at the pore level.
Research of Drilling and Completion Technologies for Heavy Oil in Venezuela and Offshore Presalt Hydrocarbons in Brazil
Authors: Fu Jin , Wang Xi , Zhang Shunyuan , Chen Chen 
Published: March 2019

Abstract
Located in south of Eastern Venezuela Basin, Orinoco Oilfield is an onshore heavy oil field in South America. The heavy oil is known for its high content of acids, heavy metals and asphaltenes with a viscosity of 1000-10000mPa·s. According to the reserve report released by PDVSA by the end of 2016, JUNIN Block that is situated in east of Orinoco Oilfield has an OOIP of 178*108bbl.
Data of drilled wells and distances between offset horizontal intervals in Orinoco were both studied to improve ultimate production rates. 3-dimension borehole trajectories were designed and the most effective anti-collision measures were taken.
After optimziation 8-12 horizontal wells are distributed on one pad. As the horizontal interval extends, the stable production time is prolonged and the accumulative production per well improves. However, the recovery rate stops increasing when the horizontal interval is over 1600m in JUNIN Block. Economically a large space between offset horizontal intervals results in fewer wells and lower costs, but a smaller space contributes to a higher production efficiency per well. If the space exceeds 600m, the accumulative production rate increases much more slightly. A three-dimension well trajectory consists of a vertical interval, an angle building interval, an angle holding interval, an angle building & direction changing interval, a direction turning interval as well as an absolute horizontal interval.
Since Petrobras developed the first ever offshore deep reservoir (Lula) by scale in 2006, Brazil has been conducting a progressive campaign targeting hydrocarbons buried under deep water, which contributes to discovery of Lula, Carioca, Jupiter, Buzios, Libra and other giant presalt reservoirs in Santos Basin after Campos Basin, where there are 9 oil fields ranking among the top 20 offshore oil fields in terms of OOIP. By June 2017 over 160×104bbl oil and gas were produced per day in deep water of Santos Basin, taking up 57.1% of the total yield of Campos and Satos.
Creep deformation of ultra-thick salt beds, severe loss of limestones, poor drillability of formations and insufficiency of deep water drilling equipment all make drilling and completion challenges more complicated. Mud systems and casing programs are optimized to conquer creep of salt and formation of hydrates due to low downhole temperature. Turbines + impregnated bits are deployed to improve drilling efficiency of siliceous carbonates (Lagoa Feia A Group). Precise control of ECD and efficient LCMs solved engineering challenges caused by narrow density windows (Lagoa Feia B Group and Lagoa Feia C Group).
Dynamic Response of Side-Mounted Guns and Assessment of the Potential Damage Risk to Sensitive Tools
Authors: Craddock G. G. , Rios Federico , Burky Thomas , Rodgers John , Serra Marco , Khairy Tamer 
Published: March 2019

Abstract
Side-mounted gun strings present a unique challenge for predictive perforation modeling tools because of their asymmetric geometry. To fully capture the dynamic response of the side-mounted system and more accurately predict the response of any gun system in general, it is important to fully capture the three-dimensional (3D) effects of model geometry and detonation-induced loading.
This work details the modeling approach developed for a side-mounted gun system that enables the full geometry to be simulated so that accurate predictions of stresses and displacements could be made; these predictions are necessary for evaluating the damage potential to sensitive tools in the string, It is important to allow operation designers to optimize gun spacing and provide string flexibility to help ensure it can withstand downhole conditions without affecting performance.
The simulation methodology was calibrated against previous test measurements, where loads and accelerations were captured during surface testing of a gun string. A detailed model was developed for the planned operation, and simulations were performed to predict the dynamic response of the wellbore fluid and tool string. Multiple damage sensitivities were identified for particular tools, and model results were extracted to evaluate 1) pressure dynamic loading on the tool, 2) displacement levels where movement is expected, and 3) dynamic loading of the tool. These results were provided to the developers of the sensitive tool to help assess potential damage risks.
For each case, predictions were compared to previous test results and operation experience to develop a risk evaluation for the planned operation. Further, results were used to make adjustments to the operation to help optimize performance; comparison plots are presented for the different configurations evaluated. This overall process provided confidence to the operators that the operation would be performed successfully with no damage to the sensitive tool.