An efficient correlation for calculating compressibility factor of natural gases

Compressibility factor （z-factor） values of natural gases are necessary in most petroleum engineering calculations.Necessity arises when there are few available experimental data for the required composition,pressure and temperature conditions.One of the most common methods of calculating z-factor values is empirical correlation.Firstly,a new correlation based on the famous Standing-Katz （S-K） Chart is presented to predict z-factor values.The advantage of this correlation is that it is explicit in z and thus does not require an iterative solution as is required by other methods.Secondly,the comparison between new one and other correlations is carried out and the results indicate the superiority of the new correlation over the other correlations used to calculate z-factor.

Application of response surface methodology for optimization of purge gas recycling to an industrial reactor for conversion of CO_2 to methanol

Nowadays, by the increasing attention to environment and high rate of fuel production, recycling of purge gas as reactant to a reactor is highly considered. In this study, it is proposed that the purge gases of methanol production unit, which are approximately15.018 t·h^(-1) in the largest methanol production complexes in the world, can be recycled to the reactor and utilized for increasing the production rate. Purge gas streams contain 63% hydrogen,20% carbon monoxide and carbon dioxide as reactants and 17% nitrogen and methane as inert. The recycling effect of beneficial components on methanol production rate has been investigated in this study. Simulation results show that methanol production enhances by recycling just hydrogen, carbon dioxide and carbon monoxide which is an effective configuration among the others. It is named as Desired Recycle Configuration(DRC) in this study. The optimum fraction of returning purge gas is calculated via one dimensional modeling of process and Response Surface Methodology(RSM) is applied to maximize the methanol flow rate and minimize the carbon dioxide flow rate. Simulation results illustrate that methanol flow rate increases by 0.106% in DRC compared to Conventional Recycle Configuration(CRC) which therefore shows the superiority of applying DRC to CRC.

Synthesis of a PEBAX-1074/ZnO nanocomposite membrane with improved CO_2 separation performance

In this investigation, polymeric nanocomposite membranes（PNMs） were prepared via incorporating zinc oxide（ZnO） into poly（ether-block-amide）(PEBAX-1074) polymer matrix with different loadings. The neat membrane and nanocomposite membranes were prepared via solution casting and solution blending methods, respectively. The fabricated membranes were characterized by field emission scanning electron microscopy（FESEM） to survey cross-sectional morphologies and thermal gravimetric analysis（TGA）to study thermal stability. Fourier transform infrared（FT-IR） and X-ray diffraction（XRD） analyses were also employed to identify variations of the chemical bonds and crystal structure of the membranes, respectively. Permeation of pure gases, CO, CHand Nthrough the prepared neat and nanocomposite membranes was studied at pressures of 3–18 bar and temperature of 25 °C. The obtained results showed that the fabricated nanocomposite membranes exhibit better separation performance compared to the neat PEBAX membrane in terms of both permeability and selectivity. As an example, at temperature of 25 °C and pressure of 3 bar, COpermeability, ideal CO/CHand CO/Nselectivity values for the neat PEBAX membrane are 110.67 Barrer, 11.09 and 50.08, respectively, while those values are 152.27 Barrer,13.52 and 62.15 for PEBAX/ZnO nanocomposite membrane containing 8 wt% ZnO.

Estimating solubility of supercritical H_2S in ionic liquids through a hybrid LSSVM chemical structure model

Development of a predictive tool for H_2S solubility estimation can be very helpful in gas sweetening industry. Experimental databases on H_2 S solubility were rarely available, so as reliable predictive models. Thus, in this study the H_2 S solubility database was established, and then a Least-Squares Support Vector Machine(LSSVM) approach based on the established database is proposed. Group contribution method was also applied to eliminate the model's dependence on experimental data. Accordingly, our proposed LSSVM model can predict H_2 S solubility as a function of temperature, pressure, and 15 different chemical structures of Ionic liquids(ILs). Root Mean Square Error(RMSE) and coefficient of determination(R^2) are 0.0122 and 0.9941, respectively. Moreover, comparison of our model with other existing models showed its reliability for H_2 S solubility in ILs. This can be very useful for engineers dealing with gas sweetening process in different applications of analysis, simulation, and designation.

Implementation of a Petrographical and Petrophysical Workflow Protocol for Studying the Impact of Heterogeneity on the Rock Typing and Reservoir Quality of Reefal Limestone:A Case Study on the Nullipore Carbonates in the Gulf of Suez

This study focuses on the heterogeneity of the middle Miocene syn-rift Belayim nullipore(reefal)marine sequences in the Gulf of Suez and its impacts on reservoir quality.The sequences consist of coralline algal reef limestones with a highly complex dual-porosity system of primary and secondary porosities of widely varying percentages.To achieve a precise mathematical modeling of these reservoir sequences,a workflow protocol was applied to separate these sequences into a number of hydraulic flow units(HFUs)and reservoir rock types(RRTs).This has been achieved by conducting a conventional core analysis on the nullipore marine sequence.To illustrate the heterogeneity of the nullipore reservoir,the Dykstra-Parsons coefficient(V)has been estimated(V=0.91),indicating an extremely heterogeneous reservoir.A slight to high anisotropy(λ_(k))has been assigned for the studied nullipore sequences.A stratigraphic modified Lorenz plot(SMLP)was applied to define the optimum number of HFUs and barriers/baffles in each of the studied wells.Integrating the permeability-porosity,reservoir quality index-normalized porosity index(RQI-NPI)and the RQI-flow zone indicator(RQIFZI)plots,the discrete rock types(DRT)and the R35 techniques enable the discrimination of the reservoir sequences into 4 RRTs/HFUs.The RRT4 packstone samples are characterized by the best reservoir properties(moderate permeability anisotropy,with a good-to-fair reservoir quality index),whereas the RRT1 mudstone samples have the lowest flow and storage capacities,as well as the tightest reservoir quality.

Effect evaluation of shale types on hydrocarbon potential using well logs and crossplot approach,Halewah oilfield,Sab'atayn Basin,Yemen

Log-analysts typically distinguish three types of shale distribution in clastic reservoirs,that is,laminated,dispersed and structural distribution,which tend to influence the effective porosity and permeability of reservoirs.The Alif Member is made up of sandstone interbedded with some shale,with shale dominating on top and at the bottom.In sedimentary formations,the gamma ray log normally reflects the shale content.The gamma ray log and neutron-density porosity crossplot is used to estimate a reservoir's shale volume(Vsh),according to which the Alif Member is divided into three zones.In addition,shale types are recognized by neutron-density porosity crossplot,and the correlation coefficients of gamma ray log-based Vsh and neutron-density porosity-based Vsh are suggested to be reliable.The Vsh and shale types of the three zones are compared against the reservoir's potential to yield hydrocarbons.The major oil intervals mainly concentrate in shaly sand and sandstone zones of dispersed and laminated shale types.The third zone,the lowermost interval,contains pure shale of laminated type and is considered out of reservoir standards in hydrocarbon production due to its excessive shale volume.Quantitative assessment of shale type distribution and Vsh by crossplot approach could not furnish correct information to evaluate massive shale intervals.

Large anisotropic negative thermal expansion in Cu-TDPAT metalorganic framework:A combined in situ X-ray diffraction and DRIFTS study

Cu-TDPAT(H_(6)TDPAT=2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine),a stable nanoporous metal-organic framework with rht topology,has sparked broad interest as an adsorbent for several chemical separation processes.In this work,in situ synchrotron diffraction experiments followed by sequential LeBail refinements reveal that Cu-TDPAT shows unusually large anisotropic negative thermal expansion(NTE).The PASCal crystallography tool,used to analyze the magnitude of the NTE,reveals an average volumetric thermal expansion coefficientαv=-20.3 MK^(-1).This value is significantly higher than the one reported for Cu-BTC(also known as HKUST-1),which contains the same Cu-paddlewheel building unit,αv=-12 MK^(-1).In situ synchrotron single crystal X-ray diffraction and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)were employed to shed light on the NTE mechanism.Using these two methods,we were able to elucidate the three main structural motions that are responsible for the NTE effect.The more pronounced NTE behavior of Cu-TDPAT is attributed to the lower symmetry combined with the more complex ligand structure when compared to Cu-BTC.The knowledge obtained in this work is important for understanding the behavior of the adsorbent under transient variable temperature conditions in fixed adsorption beds.

Synthesis,characterization and application of ZnO-Ag as a nanophotocatalyst for organic compounds degradation,mechanism and economic study

The current work deals with ZnO-Ag nanocomposites（in the wide range of x in the Zn1-x O-Ag x chemical composition） synthesized using microwave assisted solution combustion method.The structural, morphological and optical properties of the samples were characterized by XRD（X-ray diffraction）, FTIR（Fourier transform infrared spectrometry）, SEM（scanning electron microscopy technique）, EDX（energy dispersive X-ray spectrum）, ICP（inductively coupled plasma technique）, TEM（transmission electron microscopy）, BET（Brunauer–Emmett–Teller method）, UV–Vis（ultraviolet–visible spectrophotometer） and photoluminescence spectrophotometer. The photocatalytic activity of the ZnO-Ag was investigated by photo-degradation of Acid Blue 113（AB 113） under UV illumination in a semi-batch reactor. This experiment showed that ZnO-Ag has much more excellent photocatalytic properties than ZnO synthesized by the same method. The enhanced photocatalytic activity was due to the decrease in recombination of photogenerated electron-holes. The results showed the improvement of ZnO photocatalytic activity and there is an optimum amount of Ag（3.5 mol%） that needs to be doped with ZnO.The effect of operating parameters such as p H, catalyst dose and dye concentration were investigated. The reaction byproducts were identified by LC/MS（liquid chromatography/mass spectrometry） analysis and a pathway was proposed as well. Kinetic studies indicated that the decolorization process follows the first order kinetics. Also, the degradation percentage of AB113 was determined using a total organic carbon（TOC） analyzer. Additionally, cost analysis of the process, the mechanism and the role of Ag were discussed.

Will the future of shale reservoirs lie in CO2 geological sequestration?

CO2 geological sequestration in a depleted shale gas reservoir is a promising method to address the global energy crisis as well as to reduce greenhouse gas emissions. Though improvements have been achieved by many researchers, the carbon sequestration and enhanced gas recovery(CS-EGR) in shale formations is still in a preliminary stage. The current research status of CO2 sequestration in shale gas reservoirs with potential EGR is systematically and critically addressed in the paper. In addition, some original findings are also presented in this paper. This paper will shed light on the technology development that addresses the dual problem of energy crisis and environmental degradation.

Effect of TiO2 loading on the morphology and CO2/CH4 separation performance of PEBAX-based membranes

Membranes have attracted much attention as economical methods for industrial chemical processes. The effects of the titanium dioxide nanoparticle load on the morphology and CO2/CH4 separation performance of poly (ether-block-amide)(PEBAX-1657) mixed matrix membranes (MMMs) were investigated from pressures of 3-12 bar and temperatures of 30℃-60℃. The PEBAX membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, atomic force microscopy and tensile strength analysis. The incorporation of TiO2 nanoparticles into the polymeric MMMs improved the CO2/CH4 gas separation performance (both the permeability and selectivity) of the membranes. The CO2 permeability and ideal CO2/CH4 selectivity values of the nanocomposite membrane loaded with 8 wt-% TiO2 were 172.32 Barrer and 24.79, respectively whereas those of the neat membrane were 129.87 Barrer and 21.39, respectively.

Erratum to: Large anisotropic negative thermal expansion in Cu-TDPAT metalorganic framework: A combined in situ X-ray diffraction and DRIFTS study

Erratum to Nano Research 2021,14(2):404410 htts://doi.org/10.1007/s12274-020-2792-y The title of Ref.[19]in References in page 6 was unfortunately wrong,instead of Dry post-combustion CO_(2) capture:The effect of ligand properties on the eficiency of M-BTTri family of frameworks.

Unconventional resource's production under desorption-induced effects

Thousands of horizontal wells are drilled into the shale formations across the U.S.and hydrocarbon production is substantially increased during past years.This fact is accredited to advances obtained in hydraulic fracturing and pad drilling technologies.The contribution of shale rock surface desorption to production is widely accepted and confirmed by laboratory and field evidences.Nevertheless,the subsequent changes in porosity and permeability due to desorption combined with hydraulic fracture closures caused by increased net effective rock stress state,have not been captured in current shale modeling and simulation.Hence,it is essential to investigate the effects of induced permeability,porosity,and stress by desorption on ultimate hydrocarbon recovery.We have developed a numerical model to study the effect of changes in porosity,permeability and compaction on four major U.S.shale formations considering their Langmuir isotherm desorption behavior.These resources include;Marcellus,New Albany,Barnett and Haynesville Shales.First,we introduced a model that is a physical transport of single-phase gas flow in shale porous rock.Later,the governing equations are implemented into a one-dimensional numerical model and solved using a fully implicit solution method.It is found that the natural gas production is substantially affected by desorption-induced porosity/permeability changes and geomechancis.This paper provides valuable insights into accurate modeling of unconventional reservoirs that is more significant when an even small correction to the future production prediction can enormously contribute to the U.S.economy.