bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of Heavy Oil Emulsion Stability: the Effect of Various Physicochemical Parameters
Authors: Chang Hongli , Saravanan Naresh , Cheng Yaoze , Zhang Yin , Dandekar Abhijit , Patil Shirish 
Published: April 2021

Abstract
The formation of stable heavy oil emulsion, which may upset separation facilities and eventually lead to production impairment, is one of the most common issues encountered in the development of heavy oil reservoirs. This paper investigates the influence of various physicochemical parameters, including water cut, polymer status (sheared/unsheared), polymer concentration, demulsifier type and concentration, and the coexistence of polymer and demulsifiers on the stability of heavy oil emulsion. The viscosity of heavy oil emulsion is also studied at various water cut and polymer concentration. In this study, water-in-heavy oil emulsion was prepared at the water cut of 30% as the blank sample using heavy oil with API gravity of 14.5° and the synthetic brine. The effect of the water cut was investigated by both the bottle test method and multiple light scattering (MLS) method to validate the effectiveness and reliability of the MLS method. The other parameters were studied only through the MLS method. The results showed that the increasing water cut resulted in the decrease of heavy oil emulsion stability and could potentially invert the stable w/o emulsion to loose o/w emulsion at the phase inversion point where the emulsion viscosity peak occurred. Adding polymer, regardless of the polymer status, tended to reduce the stability of heavy oil emulsion, and the unsheared polymer contributed to less emulsion stability. However, the influence of polymer concentration was rather complicated. The emulsion stability decreased as polymer concentration increased, and further increasing polymer concentration enhanced the emulsion stability. A similar trend was also evidenced by emulsion viscosity with increasing polymer concentration. The addition of three oil-soluble emulsion breakers was able to break the heavy oil emulsion efficiently, whereas the water-soluble demulsifier had little demulsification effect. Furthermore, there existed an optimal concentration for the selected oil-soluble demulsifier to achieve the maximum separation. Although polymer itself could intensify the destabilization of heavy oil emulsion, it hindered the destabilization process of the heavy oil emulsion when the oil-soluble demulsifiers were added. This study will provide a comprehensive understanding of the factors affecting heavy oil emulsion stability.
Improved Fluids Characterization Model During Gas Huff-n-Puff EOR Processes in Unconventional Reservoirs
Authors: Yang Gang , Li Xiaoli 
Published: April 2021

Abstract
Despite the great potential of unconventional hydrocarbons, the primary recovery factor from such reservoirs remain low. The gas-injection enhanced oil recovery (EOR) has been proved to be a promising approach by both laboratory and simulation studies. However, the fluid model for characterizing gas and oil in nanoscale pores has not been well understood and developed. Erroneous results can be generated if the bulk fluids model is applied, resulting in a large uncertainty for the numerical simulations. The objective of this work is to propose an improved fluids characterization model tailored for the compositional simulation of gas huff-n-puff in unconventional reservoirs. The Peng-Robinson equation of state (PR EOS) is used as the basic thermodynamic model in this work. Both the attraction parameter and the co-volume parameter in the PR EOS are simultaneously modified for the first time to reflect the effect of molecule-wall interaction and geometric constraints. The collected experimental data are used for validating the model. The newly generated PVT data are imported into the compositional model to numerically simulate the gas huff-n-puff process in the Middle Bakken formation to investigate the influence of modified fluid property on the production and ultimate recovery. The improved fluids characterization model is validated applicable to calculate the confined properties of reservoir fluids. It is demonstrated that the phase envelope of the confined reservoir fluids tends to shrink. At reservoir temperature, the bubble-point pressure of the Middle Bakken oil is reduced by 17.32% with consideration of the confinement effect. Such a significant suppression represents a late occurrence of the gas evaporation, which implies a potentially higher production of the shale oil reservoir. Compositional simulation predicts that the enhanced oil recovery efficiency of CO2 huff-n-puff is unsatisfactory for the specific well in this work, which is also demonstrated in the field pilot test. However, the confinement effect results in a 1.14% elevation of the oil recovery factor in 10 years production. This work not only deepens our understanding of the confinement effect on phase behavior characterization and also shed light on the computation of the thermodynamic properties of hydrocarbons in nanopores. The results also provide practical instructions for the EOR development of unconventional reservoirs.
Effects of Imbibition During Well Shut-In on Ultimate Shale Oil Recovery: A Numerical Study
Authors: Wijaya Nur , Sheng James 
Published: April 2021

Abstract
Shale wells are often shut-in after hydraulic fracturing is finished. Shut-in often lasts for an extended period in the perceived hope to improve the ultimate oil recovery. However, current literature does not show a strong consensus on whether shut-in will improve the ultimate oil recovery. Because of the delayed production, evaluating the benefits of shut-in in improving the ultimate oil recovery is crucial. Otherwise, shut-in would merely delay the production and harm the economic performance.
This paper uses a numerical flow-geomechanical modeling approach to investigate the effect of imbibition on shut-in potentials to improve the ultimate oil recovery. This paper proposes that imbibition is one of the strongly confounding variables that cause the mixed conclusions in the related literature. The investigation methodology involves probabilistic forecasting of three reservoir realization models validated based on the same field production data. Each of the models represents different primary recovery driving mechanism, such as imbibition-dominant and compaction-dominant recovery.
A parametric study is conducted to explore and identify the specific reservoir conditions in which shut-in tends to improve the shale oil recovery. Ten reservoir parameters which affect the imbibition strength are studied under different shut-in durations. Comparison among the three models quantitatively demonstrates that shut-in tends to improve the ultimate oil recovery only if the shale reservoir demonstrates imbibition-dominant recovery. A first-pass economic analysis also suggests that when the shale oil reservoirs demonstrate such an imbibition-dominant recovery, shut-in tends to not only improve the ultimate oil recovery, but also the NPV. A correlation among ultimate oil recovery, flowback efficiency, and NPV also shows that there is no strong relationship between flowback efficiency and ultimate oil recovery. This study is one of the first to emphasize the importance of quantifying the imbibition strength and its contribution in helping recover the shale oil for optimum flowback framework and shale well shut-in design after hydraulic fracturing.
The Behavior of Unconsolidated Rocks in California Waterfloods Under High-Pressure Gradients
Authors: Li Yuanchun , Ershaghi Iraj 
Published: April 2021

Abstract
Most waterfloods in California target sandstone formations that are unconsolidated in nature with high porosities and high permeabilities. These formations are also characterized by high Poisson ratios and low values of Young's Moduli. There has been a concern if, during the waterfloods of these types of formations, fracturing takes place at high-injection gradients.
The influence of various factors on leak-off is studied in detail, indicating that with an increase in rock permeability, the leak-off velocity increases. This study included a comprehensive analysis of the characteristics of such soft formations and their responses to high injection gradients. We show that if the leak-off factors are adjusted to reflect high permeability and proper geomechanical properties, the probability of fracture formation is nil at injection gradients up to 0.9 psi/ft, for unconsolidated rooks. We computed estimated fracture width, fracture height, fracture length and noted for all three calculations, it takes gradients approaching 1psi/ft to note a non-trivial estimated value for these characteristics. This study shows that for unconsolidated formations like those in California targeted for waterfloods, the probability of fracture formation under pressure gradients of 0.9 psi/ft. is nil, and high injectivities can be exercised without the fear of fracture formation.
A Stochastic Method in Investigating Basin-Wide Underlying Distribution Functions of Decline Rate Behavior for Unconventional Resources
Authors: Ashayeri Cyrus , Paul Donald L. 
Published: April 2021

Abstract
Basin-wide heterogeneity of production in unconventional resources creates additional risk in field development planning. In the past few years, several data-driven models have been developed to increase the accuracy in predicting the recovery from shale gas and tight oil wells. However, many of the machine learning methods with so called "black box" approach provide deterministic results. Therefore, understanding the uncertainty associated with different development scenarios would be difficult to obtain. We have investigated the underlying statistical distribution functions that govern the production rates and decline behavior of unconventional wells. Identification and quantification of these distribution functions provide a strong tool to accurately forecast the cumulative production of a large group of wells in an unconventional basin. By understanding the relationship among geologic characteristics of different sections of the asset, and the impact of varying drilling and completion parameters, capital allocation can be done in a more efficient manner. In this paper, we have identified the statistical distribution parameters of decline behavior is a Power Law model. In doing so, we have used unsupervised clustering techniques to find an optimal number of clusters that enable observing well behaved and identifiable underlying distribution functions. Furthermore, we quantified different types of distribution functions in a trial and error workflow to provide a tool for accurately evaluating the impact of varying geologic parameters on the decline behavior of these wells. Our results show that the leading term (or leading coefficient), which also highly correlates with long term cumulative recovery, demonstrates Gamma distribution, while the power degree (or power coefficient) demonstrate Normal distribution. Peak production rate (maximum average daily rate), terminal rate (rate after switch point), and the time of terminal rate occurrence, all demonstrate Log Normal distribution.
A Practical Study of the Influence of Drill Solids on the Corrosion of Downhole Tubulars When Using Brine Based Drilling Fluids
Authors: Heath Garett , Okesanya Temi , Levey Simon 
Published: April 2021

Abstract
The proliferation of highly concentrated brine drilling fluids systems due to their enhanced performance benefits has instigated a plethora of technical studies on the mechanisms and control of their induced corrosion on downhole drilling tools and tubulars. The majority of these studies often overlook the effect of drill solids on corrosion rates. Therefore, a pragmatic and experimental study was conducted to investigate the effects of various factors on the corrosion rates of downhole tubulars with a streamlined focus on the obscure role of the understudied drill solids; which have not been fully elucidated.
Drill pipe corrosion coupons and drilling fluids/solids obtained from 5 similar wells (located in Grande Prairie, Alberta, Canada) were utilized for experimental analysis. Wells 1 to 4 were on the same pad (surface drilling location) drilling the same formation with the same fluid properties, while the 5th well was on a different pad but drilled the same formation with the same fluid properties to exclude disparity. Industry-standard measurement was carried out on the live used corrosion coupon rings, drilling fluids and solids obtained from these wells to determine selected properties. The total solids content analysis was carried out using an OFITE API (American Petroleum Institute) filter press. Weight loss tests on drill pipe corrosion coupons were used to determine field corrosion rates which were bolstered with the Parr Hastelloy autoclave test in the Laboratory. The oxygen content was monitored using Hach 2100Q dissolved oxygen meter.
Field data, images and experimental results showed that a rapid and minuscule increase of drill solids (as little as 1% v/v) in the active system can impact corrosion rates greater than chemical additives and even oxygen content. It was discovered that low concentration of solids can produce significant damage and a high corrosion potential in non-viscosified fluids thereby making live monitoring of drilling fluids’ properties a priority to mitigate corrosion. This study fills an important technical gap in corrosion study that is indispensable for the optimization of corrosion control in drilling operations. By carrying out a controlled and investigative study backed up with drilling field data and images, the effects of the less understood drill solids have been partially demystified.
Unique Fall Off Signatures for Stage Fracture Characterization, Actual Field Cases
Authors: Ibrahim Ahmed Farid , Ibrahim Mazher , Sinkey Matt , Johnston Thomas , Johnson Wes 
Published: April 2021

Abstract
Multistage hydraulic fracturing is the common stimulation technique for shale formations. The treatment design, formation in-situ stress, and reservoir heterogeneity govern the fracture network propagation. Different techniques have been used to evaluate the fracture geometry and the completion efficiency including Chemical Tracers, Microseismic, Fiber Optics, and Production Logs. Most of these methods are post-fracture as well as time and cost intensive processes.
The current study presents the use of fall-off data during and after stage fracturing to characterize producing surface area, permeability, and fracture conductivity. Shut-in data (15-30 minutes) was collected after each stage was completed. The fall-off data was processed first to remove the noise and water hammer effects. Log-Log derivative diagnostic plots were used to define the flow regime and the data were then matched with an analytical model to calculate producing surface area, permeability, and fracture conductivity.
Diagnostic plots showed a unique signature of flow regimes. A long period of a spherical flow regime with negative half-slope was observed as an indication for limited entry flow either vertically or horizontally. A positive half-slope derivative represents a linear flow regime in an infinitely conductive tensile fracture. The quarter-slope derivative was observed in a bilinear flow regime that represents a finite conductivity fracture system. An extended radial flow regime was observed with zero slope derivative which represents a highly shear fractured network around the wellbore. For a long fall-off period, formation recharge may appear with a slope between unit and 1.5 slopes derivative, especially in over-pressured dry gas reservoirs.
Analyzing fall-off data after stages are completed provides a free and real-time investigation method to estimate the fracture geometry and a measure of completion efficiency. Knowing the stage properties allows the reservoir engineer to build a simulation model to forecast the well performance and improve the well spacing.
Flow Physics of Polymer Nanospheres and Diluted Microemulsion in Fractured Carbonate Reservoirs: An Investigation into Enhanced Oil Recovery Mechanisms
Authors: Su Hang , Zhou Fujian , Wang Qing , Yu Fuwei , Dong Rencheng , Xiong Chunming , Li JunJian , Liang Tianbo 
Published: April 2021

SummaryEnhanced oil recovery (EOR) in fractured carbonate reservoirs is challenging because of the heterogeneous and oil-wet nature. In this work, a new application of using polymer nanospheres (PNSs) and diluted microemulsion (DME) is presented to plug fractures and enhance water imbibition to recover oil from the tight, naturally fractured carbonate reservoirs. DME with different electric charges is compared through contact-angle and core-imbibition tests to evaluate their performances on EOR. The cationic DME is chosen because it has the fastest wettability-alteration rate and thus the highest oil recovery rate. Migration and plugging efficiency tests are conducted to identify the screened particle sizes of PNSs for the target reservoir cores. PNSs with a particle size of 300 nm are demonstrated to have the best performance of in-depth propagation before swelling and plugging after swelling within the naturally fractured cores are used in this study. Then coreflooding experiments are conducted to evaluate the EOR performance when PNSs and DME are used together, and results indicate that the oil recovery rate is increased by 24.3 and 44.1% compared to using PNSs or DME alone. In the end, a microfluidic experiment is carried out to reveal how DME works with PNSs.
Exploring soil particle size fraction and spatial redistribution of 137Cs in sloping landscapes with different lynchet height of terracing hedgerows in the remote mountain region, southwestern China
Authors: Zhou Ping , Zhuang Wenhua , Shi Zhonglin 
Published: April 2021

Abstract
Soil erosion is a global environmental problem related to anthropogenic activities, as well as being influenced by natural factors. The sloping cultivated lands, which have serious soil erosion, constitute a major proportion of landscape in the remote mountain region. The traditional soil conservation strategy, referred as certain height of lynchets on the edge of the terracing hedgerows of the sloping lands, plays an effective part in soil and water conservation. A typical sloping landscape with lynchet of terracing hedgerows was chosen in this study. The results showed that fine-grained sediment was deposited in front of the lynchet of terracing hedgerows, especially particle size grouped at < 0.002mm and 0.002-0.02mm. The profiles 137Cs concentration of the lynchet from the upper to the lower sloping landscape showed first increased then decreased trends as the soil depth increased. 137Cs inventory generally increased along the whole sloping landscapes. And the results suggested that the mean 137Cs inventory and erosion rate could be represented by the average value of the middle slope position. The highest value of annual erosion modulus reached to 4917.06 tkm− 2a− 1 on the upper site of the sloping lands. While the annual erosion modulus were synchronous reduced from the upper to the lower of the slope landscape, the erosion rate had the similar trends. Meanwhile, K values of soil erodibility changed from 0.0338 thm2h (hm− 2MJ− 1mm− 1) to 0.0375 thm2h (hm− 2MJ− 1mm− 1) along the slope length. There existed the logarithmic relationship between K value and 137Cs inventory in the correspondent slope position. Therefore, it is useful to study spatial patterns of soil erosion in different slope positions with the different height of lynchet of terracing hedgerows of the whole sloping landscape. Also it is important for implementing soil conservation strategy in the remote mountain region, China.
Phosphated Avocado Seed: A Renewable Biomaterial for Preparing a Flame Retardant Biofiller
Authors: Zuluaga-Parra DAVID , Ramos-deValle L.F , Sanchez Saul , Torres-Lubián J.R. , Rodríguez-Gonzalez J.A. , Borjas-Ramos J.J. , Vázquez-Rodríguez Sofia , Uribe-Calderón J.A. 
Published: April 2021

Abstract
The cellulose and starch present in the avocado seed can be chemically modified to obtain biofillers with fire retarding characteristics. The resulting composites could be used as substitute of the corresponding halogenated composites. For this, the avocado seed was first washed, dehydrated and pulverized, and thereafter, chemically modified with phosphoric acid in the presence of urea. This was studied using infrared spectroscopy, nuclear magnetic resonance and X-Ray photoelectron spectroscopy, in order to determine the resulting chemical structure and confirm the presence of the proposed functional groups. In addition, scanning electron microscopy and elemental analysis were used, respectively, to establish the resulting morphological changes, as well as the elements present on the surface of the modified material. Thermogravimetric analysis was also carried out in order to establish the thermal stability of the material and predict the effect on the flame retardancy due to the mentioned chemical modification. Further tests established that the obtained modified structure and morphology of the avocado seed was highly dependent on the method used to dehydrate the pulverized avocado seed. It was also determined that chemical modification greatly increased the thermal stability of the avocado seed in air atmosphere. The flame-retardant effect of the modified avocado seed was assessed in polyethylene/ethylene-vinyl-acetate (PE/EVA) composites via cone calorimeter tests. These results showed that the modified avocado seed decreased the peak of the heat release rate (pHRR) by 50% and the total heat released (THR) by 15%. This phosphated avocado seed could be a good option as a renewable biofiller for polymer composites with enhanced flame-retardant properties.
Response of Population Canopy Color Gradation Skewed Distribution Parameters of the RGB model to Micrometeorology Environment in Begonia Fimbristipula Hance
Authors: Zhang Pei , chen zhengmeng , Wang Fuzheng , Wang Rong , Bao Tingting , Xie Xiaoping , Zhang Renzu , An Ziyue , Liu Chunwei , jiang haidong 
Published: April 2021

Abstract

Background: The high quality and efficient production of greenhouse vegetation depend on the micrometeorology environmental adjusting such as the system warming, illumination supplement. In order to improve the quantity, quality and efficiency of greenhouse vegetation, it is necessary to figure out the relationship between the crop growth conditions and environmental meteorological factors, which could give constructive suggestions for precise control of greenhouse environment and reducing the running cost. The parameters from the color information of plant canopy reflect the internal physiological conditions, thus, RGB model has been widely used in the color analysis of digital pictures of leaves.Results: The color scale for single leaf, single plant, and the populate canopy of Begonia Fimbristipula Hance (BFH) photographs are all have a skewed cumulative distribution histograms. The color gradation skewness-distribution (CGSD) parameters of the RGB model were increased from 4 to 20 after the skewness analysis, which greatly expanded the canopy leaf color information and could simultaneously describe the depth and distribution characteristics of canopy color. The 20 CGSD parameters were sensitive to the micrometeorology factors, especially to the radiation and temperature accumulation. The multiple regression models of mean, median, mode and kurtosis parameters to microclimate factors were established, and the spatial models of skewness parameters were optimized.Conclusions: The models constructed based on the color gradation skewness-distribution (CGSD) parameters of the RGB model, can well explain the response of canopy color to microclimate factors and can be used to monitor the variation of plant canopy color under different micrometeorology.