bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fact-Based Energy Education for Non-Technical Students
Authors: Fanchi John R. 
Published: October 2017

Abstract
This paper describes an energy education course that has been designed for the general college student population. The course entitled Energy in Society provides a fact-based analysis of the most prominent energy issues of our time. Consequences of our choices are examined with respect to their effect on the economy, society, and the environment. The pedagogy, course description, and student feedback are provided in this article.
Advancing Electric Submersible Pump Alternative Deployment Technology: An Overview and Case Study
Authors: Roth Brian A. , Xiao J. J. , Windiarto Yhossie , Al-Hadrami Naif , Al-Qahtani Nasser F. , Sarawaq Yahya 
Published: October 2017

Abstract
Traditional electric submersible pump (ESP) systems have drawbacks in terms of installation speed and efficiency. To overcome these obstacles, some alternatively deployed ESP systems, including the one selected, are deployed into the production tubing, subjecting the system to the properties of the produced fluids. A novel rigless-deployed ESP system developed for use in high hydrogen sulfide (H2S)/high chloride production environment is a solution.
An initial step reviewed and ranked competing alternate deployment ESP technologies available in industry along with several new concepts. A new approach to alternate deployment technology was selected. Rigorous testing was conducted to qualify the selected technology and materials for harsh production environments. Testing included a modified NACE TM0175 test due to the processing of the power cable design. Integration testing was performed in a test well to validate the integrity and deployment of the new system prior to field deployment of the rigless-deployed ESP system.
The cable deployed ESP (CD ESP) employs a fit-for-purpose power cable that incorporates an exterior metal jacket, providing strength to deploy ESPs thousands of feet into the well. The TransCoil system's power cable outside diameter is roughly 40% smaller than current 2-3/8-in cable-internal, coiled-tubing (CICT) systems; therefore, it is lighter in weight and reduces tubing pressure losses compared to previous products. Product reliability is enhanced as the power cable is fabricated in a continuous manufacturing and inspection process on a factory floor. The tightly controlled manufacturing process significantly improves the product quality over CT cable systems. The power cable can be fabricated from different metallurgies ranging from carbon steel to nickel allow based on the well requirements. A nickel alloy power cable laboratory qualified to 15% H2S and 150,000 ppm chlorides was field deployed in an onshore well and demonstrated an installation time reduction of nearly 50% over rig-deployed systems.
A power cable rigless-deployed ESP system solves many of the challenges that currently plague the industry including operational efficiency, rapid replacement, and product reliability in wells in harsh environments worldwide. The power cable rigless-deployed ESP system has, in particular, the opportunity to transform ESP replacement in offshore wells.
Nanoparticle-Stabilized Foams for High-Temperature, High-Salinity Oil Reservoirs
Authors: Singh Robin , Mohanty Kishore K. 
Published: October 2017

Abstract
The goal of this work is to develop foams stabilized by a combination of nanoparticles and surfactants for high-temperature, high-salinity reservoirs. Two types of silica nanoparticles (LNP1, LNP2) with different grafted low molecular weight ligands/polymers were used. First, aqueous stability tests of these formulations were performed at high-temperature (80 °C) and high-salinity conditions (8 wt% NaCl and 2 wt% CaCl2). The screened nanoparticles were used in combination with a surfactant. Second, bulk foam tests were performed to evaluate their foaming performance in bulk. Finally, oil displacement experiments were conducted in an in-house, custom-built 2D sand pack with flow visualization. The sand pack had two layers of silica sand — top layer with 40-70 mesh and bottom layer with 100-120 mesh, which resulted in a permeability contrast of 6:1. Water flood with subsequent foam flood was performed. The grafting of low-molecular-weight polymers/ligands on silica nanoparticle surfaces resulted in steric stabilization under high-temperature and high-salinity conditions. In the oil displacement experiments in the layered sand packs, the water flood recoveries were low (~33% OOIP) due to channeling in the top high-permeability region, leaving the bottom low-permeability region completely unswept. Foam flooding with just the surfactant leads to a drastic improvement in sweep efficiency. It resulted in an incremental oil recovery as high as 43.3% OOIP. Different cross-flow behaviors were observed during foam flooding. Significant cross-flow of oil from low-permeability region to high-permeability region was observed for the case of surfactant. Conversely, the LNP2-surfactant blend resulted in no crossflow from the low permeability layer with complete blocking of the high-permeability region due to the formation of in-situ emulsion. Such selective plugging of high-perm channels via nanoparticles with optimum surface coating has significant potential in recovering oil from heterogeneous reservoirs.
Effect of Nanoparticles on Flow Alteration and Saturation during CO2 Injection and Post Flush
Authors: Zhang Xing , Tian Fa-guo , Zhou Hong , Du Hong-ling , Ding Chao , Wang Jing , DiCarlo David A. 
Published: October 2017

Abstract
We observed that the mechanism appears to be spontaneous generation of nanoparticle-stabilized droplets of the injected phase, which increases the effective viscosity of that phase. In this paper, we combine water alternating gas and nanoparticles to look into whether the presence of nanoparticles results in more CO2 being trapped, after an additional flood with brine.
This paper concludes two experiments to study the transport behavior of nanoparticles. In the first experiment, CO2 was used to displace 2 wt% NaBr solution in a cylindrical core (diameter 7 cm, length 30 cm) of Boise sandstone (porosity 27.5%, permeability 1D), and then post flush with NaBr solution. For the second experiment, CO2 was used to displace the 2 wt% NaBr and 5 wt% nanoparticles solution in the core, and then post flush with nanoparticles solution. Dynamics of the displacement front and pressure drop across the core were measured in real time with CT scanner and pressure transducers respectively.
Different front dynamics are seen of wetting and nonwetting phases and the stabilizing front is generated by Roof snap-off events. When CO2 displaces brine in which surface treated silica nanoparticles, the initial and residual CO2 saturation are higher than that of the brine without nanoparticles. And the C constant of Land-curve is 2.2 and 2.4 respectively in the nanoparticle case and control case. The results suggest that pre-positioning a dispersion of nanoparticles in the brine will be potential for mobility control in CO2 storage and CO2 EOR, and can eventually be used in engineering CO2 injection protocols.
Introducing engineered nanoparticles into an aquifer or reservoir can potentially control the fluid mobility in CO2 storage and CO2 EOR. This provides an interesting alternative approach for mobility control in CO2 EOR which would work well with WAG processes. Moreover, the same process can increase enhance the residual trapping of CO2 and therefore increase the number of competent formations for secure CO2 storage.
Reservoir Fluid Characterization Procedure for PC-SAFT Equation of State
Authors: Tybjerg Peter , Pedersen Karen S. , Pedersen K. Schou 
Published: October 2017

Abstract
A C7+ characterization procedure reservoir oil mixtures is presented for the PC-SAFT equation of state. The plus fraction of a reservoir fluid composition is split into carbon number fractions and the PNA distribution estimated of each C7+ carbon number fraction. For each component class (P, N, and A) a constant ε parameter is used independent of molecular weight while the parameter m is assumed to increase linearly with molecular weight. The m and ε parameters of the individual component classes are combined into one value, representative of the whole carbon number fraction. To ensure reliable density predictions, the parameter σ is determined to match the density of each carbon number fraction at standard conditions. The procedure has been tested on ten oil compositions originating from the North Sea, Gulf of Mexico, and the Middle East. For those oil mixtures the PC-SAFT equation provides more accurate liquid compressibilities and liquid densities and shows a more correct development in saturation pressure with temperature than the SRK-Peneloux equation. For near critical mixtures, including oil mixtures undergoing gas injection for EOR purposes, the PC-SAFT equation is less suited than a cubic equation. Asphaltenes require lower values of the PC-SAFT m-parameter than non-asphaltene aromatics. Parameter tuning is needed to use the PC-SAFT equation for gas condensate mixtures.
Understanding the Deviation of Horizontal Wolfcamp Well GOR from Type-Curve GOR in the Gas-Condensate Region of the Permian Basin
Authors: Gaurav Abhishek 
Published: October 2017

Abstract
The objective of this work is to explain the deviation in GOR/GLR (Gas-Oil-Ratio/Gas-Liquid-Ratio) of hydraulically fractured Wolfcamp horizontal shale well(s) from the type-curve GOR/GLR in the gascondensate region of the Permian Basin.
We relied on the detailed field data reported during the flow-back period of a recently completed well. We identified various aspects of the casing-tubing design, operational changes that were made and any concurrent production disturbance that were noticed. Then we did a thorough literature review of GOR/GLR behavior in gas condensate wells. We identified the key concepts that were applicable to the well in our study. We applied the existing equations for the critical gas rate required to lift liquids in gas wells and highlighted the variation in gas velocity with changing pressure and temperature along the vertical part of the wellbore. Using this approach, we demonstrated the relationship between changing liquid fraction along the vertical part of the wellbore with the changing gas velocity.
A wide range of GOR/GLR was noticed for the well in our study over a period of only a few days of flow- back. The GOR/GLR curves from the nearby producing wolfcamp wells and the PVT diagram available from a nearby wolfcamp well could not explain the observed deviations in GOR/GLR. However, there were some key changes made in the production methodology during the flow-back period. We identified the appropriate mechanisms of multi-phase flow applicable to each operational change during flow back. After identifying the appropriate multi-phase flow back mechanism, we implemented the concept of critical gas velocity (flow-rate) along the wellbore. This enabled us in explaining the GOR/GLRs observed in each operational regime. The corrected GOR/GLR of the well in study aligned with the GOR/GLR of the type-curve of horizontal shale wells obtained from the nearby hydraulically fractured horizontal wells targeting the Wolfcamp in the same formation.
This is a unique study that utilizes the concept of critical flow rate, the different mechanisms of multiphase flow in the production tubing and annulus in identifying the advent of liquid loading. This work assists in explaining the discrepancies observed in the GOR/GLRs in the early production history of horizontal gas wells in gas-condensate regions. In the past, the concept of liquid-loading and the proposed remedies have been applied late in the life of gas wells with small gas rates to explain the abnormaility of the the GOR/GLR. This paper shows that the observed GOR/GLRs on the surface is not solely a function of the PVT diagram. Finally, integrating the learnings from this well with the liquid-loading concepts, we make recommendations for improved completions and flow back methodology for future wolfcamp horizontal gas-condensate wells in the Permian Basin.
Continuous High Frequency Measurement Improves Understanding of High Frequency Torsional Oscillation in North America Land Drilling
Authors: Zhang Z. , Shen Y. , Chen W. , Shi J. , Bonstaff W. , Tang K. , Smith D. L. , Arevalo Y. I. , Jeffryes Benjamin 
Published: October 2017

Abstract
Bit and bottom hole assembly (BHA) rotational speed oscillation is often encountered in North America land drilling applications. One common type of rotational speed oscillation is the well-known stick-slip, with speed variation at a frequency that is close or lower than the fundamental torsional natural frequency of the drillstring (usually less than 1Hz). Another commonly encountered rotational speed oscillation confirmed by the authors' recent studies is the high frequency torsional oscillation (HFTO), with a frequency ranging from 10's to over 100 Hz. This paper will discuss new findings on HFTO.
Most of the commercially available downhole measurement tools have no difficulty picking up the low frequency stick-slip, but lack bandwidth to detect HFTO. Also it is rarely observed from the surface instruments because high frequency torsional wave can be dampened quickly when it is transferred along the drillstring. Hence, HFTO could be misinterpreted as smooth drilling until tool failure or damage occur.
To understand the mechanism of HFTO, a series of downhole tests were conducted in North America land with different BHA setups and applications. An advanced downhole measurement tool was placed in the BHA to continuously record tri-axial acceleration and rotational speed at 1024 Hz sampling rate. After extensive analysis performed on the downhole high frequency data, we present in this paper many interesting findings. HFTO shifts frequency depending on different downhole conditions. There is a strong correlation between the surface parameters (RPM and SWOB) and the occurrence of HFTO. The excitation of HFTO is also related to the formation. 3D transient drilling dynamics simulation confirms the factors that increase the risk of HFTO.
Based on this study, we provide recommendations to downhole measurements for capturing HFTO. With real-time HFTO detection, drilling parameters can be adjusted to reduce the chance of HFTO to avoid premature tool failures. We also provide insights for new tool development to obtain better tool life by eliminating weak spots and perform more robust measurements by selecting better sensor locations, etc. With the help of 3D transient dynamic modeling, we can gain better understanding of HFTO mechanisms through numerical simulation, making it possible to plan the BHA effectively and select drilling parameters to avoid HFTO.
Application of Pin-Point Sand Jet Perforating Annular Fracturing in Multiple Coal Seams Unleashing Clean Energy in Southwest China
Authors: Lee K. K. , Chen J. L. , Liu Y. J. , Li Y. K. , Zeng X. Z. , Zhou B. , Hu G. , Wang S. L. 
Published: October 2017

Abstract
Guizhou Province which located in the southwest China is one of China's least developed but fastest growing provinces, has large reserve potential for Coal Bed Methane (CBM) but yet, the natural gas utilization is among the lowest in China. The exploitation of CBM resources in the province started since early 90's, but no substantial breakthrough has been achieved. Among all the challenges encountered in the attempt to develop the resources, one key challenge is on how to frac stimulate the coal seams effectively. The high coal-rank CBM reservoirs commonly contain low permeability multiple thin coal seams that require frac stimulation to flow. However, conventional blanket-type frac treatment via pumping down casing at high rate has been shown to leave some coal seams untreated and not contributing.
Pin-point fracturing using coiled-tubing allows multiple precisely targeted coal seams to be treated, which can increase gas flow rate and reserve, and significantly shorten time cycle as compare to conventional casing frac method. Three CBM wells in the north-west Guizhou province in China have been pin-point stimulated using coiled-tubing producing gas at an encouraging rate compared with conventional method.
This paper discusses how the pin-point fracturing technique been introduced for the very first time to Guizhou CBM wells, the details of the concept, fracturing process, operational methods, treatment outcome of the field trial, and how the technology could shape the future of CBM exploitation strategy in Guizhou Province.
Recurrent Neural Networks for Permanent Downhole Gauge Data Analysis
Authors: Tian Chuan , Horne Roland N. 
Published: October 2017

Abstract
The rich information contained in permanent downhole gauge (PDG) data has drawn attention from researchers. Previous work has demonstrated feature-based machine learning to be promising for PDG data analysis. The recent rise of deep learning was powered by techniques including recurrent neural networks (RNNs), which have been shown useful for processing sequential information. In this work, we explored how RNN can be utilized to analyze PDG data for better reservoir characterization and modeling, by examining two specific RNN structures: nonlinear autoregressive exogenous model (NARX) and standard RNN.
RNN is a special type of artificial neural network designed for sequential data processing. Unlike a nonrecurrent neural network, the hidden layers in RNN take memories of previous computations (e.g. hidden layers or outputs computed in previous time) into account. In that way, the information contained in the measurements prior to a certain time can be used to model the response at that time, i.e. the convolutional effects are modeled by the recurrent structure of the RNN. Another favorable property of RNN is that it requires no assumptions on physics in advance. Both the inputs and outputs come directly from the raw measurements, and no handcrafted features need to be extracted from the forward physics model. Compared with feature-based machine learning, RNN is more powerful for the modeling where the forward model has not been determined.
In this work, RNN was first tested on a series of synthetic and real flow rate-pressure datasets. The patterns learned by RNN from those data helped correctly identify the reservoir model and forecast the reservoir performance. RNN was also applied on temperature transient data, to demonstrate its advantage over feature-based machine learning with no assumptions on the physics model. The study also showed that RNN has the noise tolerance and computational efficiency that make it a promising candidate to analyze PDG data in practice.
The Development of a Coupled Geomechanics and Reservoir Simulator Using a Staggered Grid Finite Difference Approach
Authors: Gao C. , Gray K. E. 
Published: October 2017

Abstract
For a stress-sensitive reservoir, the constant rock compressibility term used in a conventional reservoir simulator (CRS), does not account for change of porosity and permeability. This paper develops a coupled geomechanics and reservoir simulator (CGRS) which accounts for changes in porosity and permeability related to deformation.
The simulator in this paper adopts a staggered grid finite difference method for fluid flow and displacements. Displacements and pore pressures are placed at centers of faces and grid blocks, which increases numerical accuracy. Four types of nonlinear, coupled equations (porosity, permeability, displacements, and pressure equations) have been derived for use in CGRS. The Newton-Raphson method requires solving all the unknowns simultaneously, a computationally intensive procedure. An alternative is to use the Macro Gauss-Seidel method, which divides a huge nonlinear matrix into several smaller matrices, thus speeding up computations.
Solutions from CGRS have been validated using two analytical solutions: a one dimensional consolidated reservoir and an idealized reservoir. This validated simulator is used to simulate a 3D reservoir with multiple vertical and horizontal wells. The comparison between CRS and CGRS shows that pressure depletes faster in CRS as compared to CGRS. CGRS results in higher bottom-hole pressure for a constant rate well. Constant rate wells yield a result of 1 to 1.26 times higher bottom-hole pressure than CRS. This shows that neglecting geomechanics effects in CRS can lead to an under prediction of reservoir/bottom hole pressures and production rates. Another powerful function of CGRS is the output of 3D displacements, which cannot be predicted by CRS. After producing for 1000 days, the maximum vertical displacement reaches 0.34 ft. (0.085% of reservoir thickness). Maximum displacements in the x and y directions (lateral displacements) are 4 × 10-4 ft. and 0.015 ft., both of which are smaller than vertical displacement because of fixed lateral boundary conditions.
Unlike traditional iterative coupled (IC) methods, fluid flow and geomechanics share the same mesh, which solves the problem of numerical instability in two discretization methods used in traditional IC. Also, the change of volumetric strain with respect to time (usually neglected in traditional IC) has been included in the fluid flow equation to better characterize the effects of solids movement on fluid flow. The Macro Gauss-Seidel method was adopted to increase computation efficiency of the simulations. The simulator introduced in this paper has its own data structure for geomechanics analysis which can be incorporated in single-phase, two-phase, three-phase or compositional reservoir simulators.