bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Semianalytical Model for Simulating Fluid Flow in Naturally Fractured Reservoirs With Nonhomogeneous Vugs and Fractures
Authors: Wu Yonghui , Cheng Linsong , Huang Shijun , Fang Sidong , Jia Pin , Wang Suran 
Published: January 2019

Summary
Carbonate reservoirs comprise fractures, vugs, and cavities. Vugs have a large contribution to reserves of oil and gas, and the fractures provide effective paths for fluid flow in the reservoir. The triple-porosity (TP) model is an effective conceptual method for capturing rock matrix and vugs and the microfractures connecting them. However, these fractures and vugs are always nonhomogeneous. Macrofractures and vugs cannot be handled with a continuum scheme because of their low density and high conductivity.
In this approach, the TP conceptual model is implemented to characterize rock matrix, microvugs, and fractures. To capture the heterogeneity of fractures and vugs, macrofractures and vugs are represented explicitly with the discontinuum model. The boundaries of macrovugs and macrofractures are discretized into several elements. The boundary-element method (BEM) is used to handle flow into macrofractures and vugs. The finite-difference method is applied to handle flow within macrofractures. The flow within macrovugs is assumed to be pseudosteady state.
With a simple discretization of the boundaries of macrovugs and macrofractures, the proposed model is shown to efficiently simulate the behavior of fractured carbonate reservoirs with heterogeneity. The computational accuracy is demonstrated using an analytical model and numerical simulation. On the basis of the proposed model, the effect of the heterogeneity of macrofractures and vugs on pressure-transient behavior is analyzed. The results show that macrofractures and vugs cannot be handled with triple-continuum models analytically. There will be several “dips” on the derivative of the pressure curve if macrovugs are discretely handled. Also, discretely handling the fractures and vugs will make the calculated dimensionless pressure and the derivative pressure lower than those calculated with the triple-continuum models. After increasing the porosity of macrovugs, the pressure and the derivative will go down in the flow regimes dominated by macrovugs. The conductivity of macrofractures has a great impact on almost all the flow regimes except for boundary-dominated flow. Finally, a field case is used to show the application of the proposed semianalytical model.
The novelty of the new model is its ability to model the transient behavior of carbonate reservoirs with nonhomogeneous fractures and vugs. Furthermore, it provides an efficient method for characterizing the heterogeneity of multiscaled fractures and vugs.
A New Fracture-Unit Model and Its Application to a Z-Fold Fracture
Authors: Luo Wanjing , Tang Changfu , Zhou Yingfang 
Published: January 2019

Summary
Following the Cinco-Ley fracture model (Cinco-Ley et al. 1978) and the Luo-Tang wing model (Luo and Tang 2015a), we developed a new fracture-unit model. By coupling the Fredholm integral equation for a fracture with a reservoir equation, we present a new semianalytical method in the Laplace domain, and an example of a Z-fold fracture is then presented to demonstrate the applicability of the fracture-unit model. The effects of fracture conductivity, fracture geometry, and branch length on the transient wellbore pressure are discussed in detail. Our work provides a novel forward model to implement the law of fluid flow in complex fractures.
Numerical Investigation Into the Simultaneous Growth of Two Closely Spaced Fluid-Driven Fractures
Authors: Chen Xiyu , Zhao Jinzhou , Yan Wenyi , Zhang Xi 
Published: January 2019

Summary
Multistage, multicluster hydraulic fracturing is a widespread method used in the petroleum industry to enhance the hydrocarbon production of low-permeability unconventional reservoirs. The core for fracturing-treatment success is achieving the simultaneous propagation of multiple closely spaced hydraulic fractures to enlarge the fracture surface. To better understand this coupled elasto-hydrodynamics mechanics, a 2D model comprising a combination of a displacement discontinuity method for elasticity and a finite volume method for lubrication is presented in this paper. Furthermore, a universal tip asymptotic solution, reflecting the unique multiscale tip behavior for fluid-driven fractures, is adopted as a propagation criterion to locate the fracture front. Numerical examples are fully implemented to investigate the competition in the growth of two closely spaced fluid-driven fractures at different initial lengths. Parametric studies reveal that the competition between simultaneous and single fracture growth is governed by dimensionless toughness, which represents the energy ratio of fracture-surface creation to fluid viscous dissipation. The simultaneous growth will be promoted when the fluid viscous dissipation is dominant, while, with increasing rock toughness, the tendency for single-fracture growth will increase correspondingly. Numerical results also demonstrate that initial fracture geometric settings play an important role in this competition. A large initial length offset between two fractures will generate preferential growth for the longer fracture, even in the viscosity-dominated regime. Furthermore, this paper provides dimensionless parameters characterizing fracture deflection caused by fracture interaction. The paper concludes by identifying the controlling parameters and their field applications, emphasizing that high injection rate, high fluid viscosity, and small initial fracture-size offset are beneficial to promoting the simultaneous growth at early time, which is important in enhancing reservoir permeability.
Pressure-Transient Behavior of Partially Penetrating Inclined Fractures With a Finite Conductivity
Authors: Teng Bailu , Andy Li Huazhou 
Published: January 2019

Summary
Field studies have shown that, if an inclined fracture has a significant inclination angle from the vertical direction or the fracture has a poor growth along the inclined direction, this fracture probably cannot fully penetrate the formation, resulting in a partially penetrating inclined fracture (PPIF) in these formations. It is necessary for the petroleum industry to conduct a pressure-transient analysis on such fractures to properly understand the major mechanisms governing the oil production from them. In this work, we develop a semianalytical model to characterize the pressure-transient behavior of a finite-conductivity PPIF. We discretize the fracture into small panels, and each of these panels is treated as a plane source. The fluid flow in the fracture system is numerically characterized with a finite-difference method, whereas the fluid flow in the matrix system is analytically characterized on the basis of the Green's-function method. As such, a semianalytical model for characterizing the transient-flow behavior of a PPIF can be readily constructed by coupling the transient flow in the fracture and that in the matrix. With the aid of the proposed model, we conduct a detailed study on the transient-flow behavior of the PPIFs. Our calculation results show that a PPIF with a finite conductivity in a bounded reservoir can exhibit the following flow regimes: wellbore afterflow, fracture radial flow, bilinear flow, inclined-formation linear flow, vertical elliptical flow, vertical pseudoradial flow, inclined pseudoradial flow, horizontal-formation linear flow, horizontal elliptical flow, horizontal pseudoradial flow, and boundary-dominated flow. A negative-slope period can appear on the pressure-derivative curve, which is attributed to a converging flow near the wellbore. Even with a small dimensionless fracture conductivity, a PPIF can exhibit a horizontal-formation linear flow. In addition to PPIFs, the proposed model also can be used to simulate the pressure-transient behavior of fully penetrating vertical fractures (FPVFs), partially penetrating vertical fractures (PPVFs), fully penetrating inclined fractures (FPIFs), and horizontal fractures (HFs).
Experimental Study on the Sliding Friction for Coiled Tubing and High-Pressure Hose in a Cuttings Bed During Microhole-Horizontal-Well Drilling
Authors: Song Xianzhi , Pang Zhaoyu , Xu Zhengming , Li Gensheng , Sun Baojiang , Zhu Zhaopeng , Yang Ruiyue , Lyu Zehao 
Published: January 2019

Summary
Microhole–horizontal–well–drilling technology is a high–efficiency and low–cost technology that has developed rapidly in recent years. However, during microhole–horizontal–well drilling, cuttings deposit easily at the bottom of the wellbore because of gravity and nonrotation of the pipe. The pipe sliding on the cuttings bed will cause extremely serious friction between the pipe and cuttings bed, which is an important limiting factor on the extended length of the microhole horizontal wellbore. Therefore, it is necessary to study the influencing factors and establish a model for evaluating the friction between the pipe and cuttings bed. In this study, laboratory experiments on the sliding friction between pipe and cuttings bed were conducted. By analyzing the comprehensive sliding–friction coefficient (CSFC) between the pipe and cuttings bed, the effects of dimensionless buried depth (0.2 to 1.0) and average cuttings size (0.249 to 2.667 mm) on the CSFC between the pipe and cuttings bed were obtained. CSFC is a function of dimensionless buried depth and relative roughness in the developed model. The results suggest that the sliding–friction resistance between the pipe and cuttings bed increases as the buried depth of pipe increases or the average cuttings size decreases. We propose a model for estimating the CSFC using experimental data and the least–squares method. The predictions show good agreement with the experimental data within suitable ranges of models. This work is expected to provide the basis for predicting the friction resistance between the pipe and cuttings bed.
A Unified Model To Predict Flowing Pressure and Temperature Distributions in Horizontal Wellbores for Different Energized Fracturing Fluids
Authors: Xu Zhengming , Wu Kan , Song Xianzhi , Li Gensheng , Zhu Zhaopeng , Sun Baojiang 
Published: January 2019

Summary
Energized fracturing fluids, including foams, carbon dioxide (CO2), and nitrogen (N2), are widely used for multistage fracturing in horizontal wells. However, because density, rheology, and thermal properties are sensitive to temperature and pressure, it is important to understand the flow and thermal behaviors of energized fracturing fluids along the wellbore. In this study, a unified steady-state model is developed to simulate the flow and thermal behaviors of different energized fracturing fluids and to investigate the changes of fluid properties from the wellhead to the toe of the horizontal wellbore. The velocity and pressure are calculated using continuity and momentum equations. Temperature profiles of the whole wellbore/formation system are obtained by simultaneously solving energy equations of different thermal regions. Temperature, pressure, and energized-fluid properties are coupled in both depth and radial directions using an iteration scheme. This model is verified against field data from energized-fluid-injection operations. The relative average errors for pressure and temperature are less than 5%. The effects of injection pressure, mass-flow rate, annulus-fluid type, foam quality, and proppant volumetric concentration on pressure and temperature distributions are analyzed. Influence degrees of these operating parameters on the bottomhole pressure (BHP) for different energized fracturing fluids are calculated. The required injection parameters at the surface to achieve designed bottomhole treating parameters for different energized fracturing fluids are compared. The results of this study might help field operators to select the most-suitable energized fluid and further optimize energized-fluid-fracturing treatments.
How Effective Is Carbon Dioxide as an Alternative Fracturing Fluid?
Authors: Li Sanbai , Zhang Dongxiao 
Published: January 2019

Summary
Massive hydraulic fracturing requires an enormous consumption of water and introduces many potential environmental issues. In addition, water-based fluid tends to be trapped in formations, reducing oil/gas-phase relative permeability, and causes clay-mineral swelling, which lowers absolute permeability. Carbon dioxide (CO2) is seen as a promising alternative working fluid that poses no formation-damage risk, and it can stimulate more-complex and extensive fracture networks. However, very little, if any, extant research has quantitatively analyzed the effectiveness of CO2 fracturing, except for some qualitative fracturing experiments that are based on acoustic emissions. In this study, we systematically examine water and CO2 fracturing, and compare their performance on the basis of a rigorously coupled geomechanics and a fluid-heat-flow model. Parameters investigated include fluid viscosity, compressibility, in-situ stress, and rock permeability, illustrating how they affect breakdown pressure (BP) and leakoff, as well as fracturing effectiveness. It is found that (1) CO2 has the potential to lower BP, benefiting the propagation of fractures; (2) water fracturing tends to create wider and longer tensile fractures compared with CO2 fracturing, thereby facilitating proppant transport and placement; (3) CO2 fracturing could dramatically enhance the complexity of artificial fracture networks even under high-stress-anisotropy conditions; (4) thickened CO2 tends to generate simpler fracture networks than does supercritical CO2 (SC-CO2), but still more-complex fracture networks than fresh water; and (5) the alternative fracturing scheme (i.e., SC-CO2 fracturing followed by thickened-CO2 fracturing) can readily create complex fracture networks and carry proppant to keep hydraulic fractures open. This study reveals that, for intact reservoirs, water-based fracturing can achieve better fracturing performance than CO2 fracturing; however, for naturally fractured reservoirs, CO2 fracturing can constitute an effective way to stimulate tight/shale oil/gas reservoirs, thereby improving oil/gas production.
Multiple-line Chemotherapy and Tyrosine Kinase Inhibitor Treatment in Patients with Advanced Lung Cancer
Authors: Zhang Hua , Yang Jie , Deng Yan-ming , Zhao Ning , Liang Jian-miao , Yang Shuang , Zhang Shun-da , Feng Wei-neng 
Published: January 2019

Aim:
To analyse the clinical outcomes of patients with lung cancer treated with first and
multiple-line chemotherapy and tyrosine kinase inhibitor (TKI).

Patients & Methods:
The present study included a total of 89 patients of whom lung cancer was
histologically confirmed between July 2016 and September 2017. Patients’ demographics,
chemotherapy/TKI treatment details and clinical outcomes were retrieved. The progression-free
survivals (PFS) after first-line and multiple-line treatments were evaluated using Kaplan-Meier
analysis with log-rank test. Risk factors for progressive disease (PD) were identified using Cox
multivariate regression model.

Results:
A total of 50 males and 39 females were enrolled. About 90% of the tumors were
histologically classified as adenocarcinoma, and 77/89 cases (86.5%) were at TNM stage IV. The
median PFS for the first-line treatment was 6.17 months. After first-line treatment, more favourable
PFS was observed in patients who had prior surgery of lung cancer (P = 0.002). Multivariate analysis
showed that patients who had received no prior surgical treatment for lung cancer were at higher risk
of PD (OR, 4.311; 95% CI, 1.836 to 10.120; P = 0.0008). Besides, in patients with driver mutations,
those who received no TKI treatment were under higher risk of PD compared to those who had been
treated with TKI (OR, 4.876; 95% CI, 1.877 to 12.666; P = 0.0011). The median PFS for the
multiple-line treatment was 24.67 months. After multiple-line treatments, favourable PFS was
associated with tumor histological types of adenocarcinoma (P = 0.041), genetic lesions at exon 19
of EGFR (P = 0.001) and fourth-line treatment (P = 0.001). Risk factors for PD after multiple-line
treatments were no prior surgery for lung cancer (OR, 3.335; 95% CI, 1.158 to 9.605; P = 0.0256),
no TKI use in multiple-line treatment (OR, 10.095; 95% CI, 2.405 to 42.378; P = 0.0016), and being
treated by first-line treatment alone (OR, 30.421; 95% CI, 4.813 to 192.269; P = 0.0003).

Conclusion:
The present study demonstrated the benefits of TKI in patients with advanced lung
cancer, providing insights into the refinement of the management strategy.
Analysis of Four Types of Leukemia Using Gene Ontology Term and Kyoto Encyclopedia of Genes and Genomes Pathway Enrichment Scores
Authors: Lu Jing , Zhang YuHang , Wang ShaoPeng , Bi Yi , Huang Tao , Luo Xiaomin , Cai Yu-Dong 
Published: January 2019

Aim and Objective:
Leukemia is the second common blood cancer after lymphoma, and
its incidence rate has an increasing trend in recent years. Leukemia can be classified into four types:
acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic
leukemia (CLL), and chronic myelogenous leukemia (CML). More than forty drugs are applicable to
different types of leukemia based on the discrepant pathogenesis. Therefore, the identification of
specific drug-targeted biological processes and pathways is helpful to determinate the underlying
pathogenesis among such four types of leukemia.

Methods:
In this study, the gene ontology (GO) terms and Kyoto Encyclopedia of Genes and
Genomes (KEGG) pathways that were highly related to drugs for leukemia were investigated for the
first time. The enrichment scores for associated GO terms and KEGG pathways were calculated to
evaluate the drugs and leukemia. The feature selection method, minimum redundancy maximum
relevance (mRMR), was used to analyze and identify important GO terms and KEGG pathways.

Results:
Twenty Go terms and two KEGG pathways with high scores have all been confirmed to
effectively distinguish four types of leukemia.

Conclusion:
This analysis may provide a useful tool for the discrepant pathogenesis and drug design
of different types of leukemia.
Design, Synthesis and Anticancer Activity of New Thiazole-Tetrazole or Triazole Hybrid Glycosides Targeting CDK-2 via Structure-Based Virtual Screening
Authors: Kassem Asmaa F. , Abbas Eman M. H. , El-Kady Dina S. , Awad Hanem M. , El-Sayed Wael A. 
Published: January 2019

Background & Objective:The target tetrazole glycosides were synthesized by construction of ring system by cycloaddition reaction of benzothiazole-linked nitrile derivative and sodium azide followed by N-glycosylation process and deprotection.Methods:The triazole glycosides were prepared by applying click approach involving dipolar cycloaddition of benzothiazole possessing alkyne functionality and different glycosyl azides. The products incorporating acyclic analogs of sugar moieties were synthesized through alkylation using acyclic oxygenated halides.Results:The anticancer activity was studied against human breast adenocarcinoma cells (MCF-7) and human normal Retina pigmented epithelium cells (RPE-1). High activities were revealed by three compounds with IC50 values 11.9-16.5 µM compared to doxorubicin (18.6 µM) in addition to other four derivatives with good inhibition activities.Conclusion:Enzyme docking investigation was performed into cyclin-dependent kinase 2 (CDK2); a potential target for cancer medication. Compounds which have possessed highest activities revealed good fitting inside the binding site of the protein molecular surface and showed minimum binding energy.
Selective Anti-proliferative Activity of Indole Alkaloids from Rhazya stricta Decne Leaves
Authors: Abdul-Hameed Zainab H. , Alarif Walied M. , Omer Abdulkader M.S. , El Omri Abdelfatteh , Ayyad Seif-Eldin N. , Badria Farid A. , Neamatallah Thikryat , Bawakid Nahed O. 
Published: January 2019

:
Rhazya stricta is a rich indole alkaloid medicinal plant species, that is used in traditional
medicine particularly in Middle East countries to treat inflammations, diabetes, rheumatism, and skin
disorders. The alkaloid plant extract of R. stricta was fractionated on aluminum oxide column and further
purified by different chromatographic methods. The chemical structures of the isolated compounds
were elucidated by interpretation of their 1D and 2D NMR, IR, UV and MS spectral data. The potential
antitumor effect was examined against three cancer cell lines; HCT-116-colon cancer, PC-3-prostate
cancer and HepG2-liver cancer as well as a control cell line (Vero) using MTT assay. Two new indole
alkaloids, identified as 16-epi-stemmadenine-N-oxide (1) and stemmadenine-N-methyl (2), along with
the known indole alkaloid 20-epi-antirhine (3) were isolated from the leaves of Rhazya stricta. Compound
2, stemmadenine-N-methyl exhibited a reasonable selectivity index and a broad anticancer effect
against the examined cell lines with IC50 35.0±0.7, 35.0±0.6, 40.0±0.7and 79.0±1.0 μM, respectively.
Furthermore, the effect of stemmadenine-N-methyl was evaluated on cell migration using woundhealing
assay. It significantly hindered cell migration and delayed-wound healing. 16-epistemmadenine-
N-oxide and stemmadenine-N-methyl are new indole alkaloids isolated from the leaves
of Rhazya stricta, of which stemmadenine-N-methyl selectively inhibited the proliferation of three different
cancer cell lines. In addition, it prevented cell migration and delayed wound-healing. Further
studies are required to confirm the mechanism by which this promising alkaloid exhibits its antitumor
activity.
Highly Efficient Michael Reactions of Nitroolefins by Grinding Means
Authors: Cui Dong-Xiao , Li Yue-Dan , Zhu Jun-Chao , Jia Yan-Yan , Wen Ai-Dong , Wang Ping-An 
Published: January 2019

Aim and Objective:
The direct β-functionalization of trans-β-nitroolefins by Michael reaction is regarded
as an efficient way to provide precursors for β-functional amines. However, Michael additions by grinding
means with solvent-free conditons are rarely reported. We have developed facile access to
β-functional nitroalkanes by grinding means under solvent-free conditions.

Materials and Methods:
From commercially available materials including ethyl 2-nitroacetate, alkyl
2-cyanoacetates and malononitrile, the grinding reactions between these above-mentioned activated methylenecompounds
and various trans-β-nitroolefins were performed at room temperature and solvent-free conditions.

Results:
A highly efficient direct Michael reaction of nitroolefins by simple grinding means has been
developed. Various trans-nitrostyrenes were easily converted into corresponding β-functional nitroalkanes in
excellent yields within 5~10 min (up to 36 examples).

Conclusion:
Herein, we have developed a simple and efficient way to β-functional nitroalkanes through
Michael reactions by grinding means. The grinding Michael reaction is fast, clean and stable and these Michael
adducts could be easily converted into the other amino compounds served as building blocks in organic
synthesis.