Yanjun Li¹, Wandong Zhang¹, Jiang Wu¹, Yuhao Yang¹, Chao Zhang¹, Huanqiang Yang^2,*

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.5, pp. 1237-1248, 2023, DOI:10.32604/fdmp.2022.023147

Abstract Air channeling in the annulus between the casing and the cement sheath and/or between the cement sheath and formation is the main factor affecting the safe operation of natural gas wells at high temperatures and pressures. Prevention of this problem requires, in general, excellent anti-channeling performances of the cement sheath. Three methods to predict such anti-channeling performances are proposed here, which use the weightless pressure of cement slurry, the permeability of cement stone and the volume expansion rate of cement sheath as input parameters. Guided by this approach, the anti-channeling performances of the cement slurry are evaluated by means of… More >

Jike Gao¹, Fawei Li^2,*, Shangjun Liu¹

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.5, pp. 1173-1187, 2023, DOI:10.32604/fdmp.2022.021140

Abstract Composite fabrics based on Polytetrafluoroethylene (PTFE) polymer displays several notable properties. They are waterproof, windproof, permeable to moisture and thermally insulating at the same time. In the present study, PTFE fibers are used as raw material to make fiber membranes. The film is formed by crisscrossing interconnected fiber filaments and the related air permeability: tensile creep characteristics and other properties are tested. The results show that the pore size, thickness, and porosity of the film itself can affect the moisture permeability of the film. The water pressure resistance of the selected fabric is 8.5 kPa, and the moisture permeability is… More >

Sergey Popov¹, Sergey Chernyshov^2,*, Evgeniy Gladkikh²

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.3, pp. 619-634, 2023, DOI:10.32604/fdmp.2022.021936

Abstract During oil and gas fields development, a decrease in reservoir and bottomhole pressure has often a detrimental effect on reservoir properties, especially permeability. This study presents the results of laboratory tests conducted to determine the response of terrigenous reservoir core-sample permeability to changes in the effective stresses and a decrease in the reservoir pressure. The considered samples were exposed for a long time to a constant high effective stress for a more reliable assessment of the viscoplastic deformations. According to these experiments, the decrease of the core samples permeability may reach 21% with a decrease in pressure by 9.5 MPa… More > Graphic Abstract

Wei Chen^1,*, Weijie Shan¹, Yue Liang¹, Frederic Skoczylas²

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.3, pp. 679-696, 2023, DOI:10.32604/fdmp.2022.021249

Abstract This study deals with the analysis of the detrimental effects of a “sulfate attack” on cement mortar for different dry-wet cycles. The mass loss, tensile strength, and gas permeability coefficient were determined and analyzed under different exposure conditions. At the same time, nitrogen adsorption (NAD), scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques were used to analyze the corresponding variations in the microstructure and the corrosion products. The results show that certain properties of the cement mortar evolve differently according to the durations of the dry-wet cycles and that some damage is caused to the mortars in aqueous solution.… More >

Sergey Galkin^1,*, Ian Savitckii¹, Denis Shustov¹, Artyom Kukhtinskii¹, Boris Osovetsky², Alexander Votinov³

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.2, pp. 273-284, 2023, DOI:10.32604/fdmp.2022.021697

Abstract Survey and novel research data are used in the present study to classify/identify the lithological type of Verey age reservoirs’ rocks. It is shown how the use of X-ray tomography can clarify the degree of heterogeneity, porosity and permeability of these rocks. These data are then used to elaborate a model of hydraulic fracturing. The resulting software can take into account the properties of proppant and breakdown fluid, thermal reservoir conditions, oil properties, well design data and even the filtration and elastic-mechanical properties of the rocks. Calculations of hydraulic fracturing crack formation are carried out and the results are compared… More > Graphic Abstract

Chao Zhu¹, Lei Wang¹, Dai Pan¹, Zifei Wang², Tao Wang², Licheng Wang^2,*, Chengjin Ye³

CMES-Computer Modeling in Engineering & Sciences, Vol.134, No.1, pp. 599-609, 2023, DOI:10.32604/cmes.2022.021052

Abstract In this paper, a model free volt/var control (VVC) algorithm is developed by using deep reinforcement learning (DRL). We transform the VVC problem of distribution networks into the network framework of PPO algorithm, in order to avoid directly solving a large-scale nonlinear optimization problem. We select photovoltaic inverters as agents to adjust system voltage in a distribution network, taking the reactive power output of inverters as action variables. An appropriate reward function is designed to guide the interaction between photovoltaic inverters and the distribution network environment. OPENDSS is used to output system node voltage and network loss. This method realizes… More >

Sheng He¹, Weiqi Leng^2,*, Yuhe Chen¹, Hongchen Li³, Jingpeng Li¹, Zaixing Wu¹, Zizhang Xiao¹

Journal of Renewable Materials, Vol.11, No.1, pp. 321-331, 2023, DOI:10.32604/jrm.2023.022097

Abstract Microwave (MW) drying method was adopted to enhance the liquid permeability of Scots pine lumber. Structure changes were characterized by stereoscope microscope, scanned electron microscope (SEM) and transmission electron microscope (TEM) examination. Pore parameters before and after MW treatment were detected by mercury intrusion porosimetry (MIP) method, and the effect of structure changes on liquid permeability were analyzed. As stereoscope microscope, SEM and TEM examination results shown, macro and micro checks mainly developed at intercellcular of tracheids, intercellular of ray parenchyma and tracheid, while these checks extend main along the radial-longitudinal plane. Pit border destruction, aspirated pits’ orus translocation and… More >

Wenwei Li¹, Xinjie Zhan^2,*, Baotian Wang¹, Jinyu Zuo¹

Journal of Renewable Materials, Vol.11, No.1, pp. 363-378, 2023, DOI:10.32604/jrm.2022.022254

Abstract Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants. Among recent studies, pilot and field tests showed that chemical conditioning combined with vacuum preloading can effectively treat municipal sludge. To further understand the drainage and consolidation characteristics of the conditioning sludge during vacuum preloading, a large deformation nonlinear numerical simulation model based on the equal strain condition was developed to simulate and analyze the pilot and field tests, whereas the simulation results were not satisfactory. The results of the numerical analysis of the pilot test showed that the predicted consolidation degree was greater than… More >

Xuanyu Dong^1,*, Jingyao Yang²

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.1, pp. 175-185, 2023, DOI:10.32604/fdmp.2022.021345

Abstract A new numerical model for low-permeability reservoirs is developed. The model incorporates the nonlinear characteristics of oil-water two-phase flows while taking into account the initiation pressure gradient. Related numerical solutions are obtained using a finite difference method. The correctness of the method is demonstrated using a two-dimensional inhomogeneous low permeability example. Then, the differences in the cumulative oil and water production are investigated for different starting water saturations. It is shown that when the initial water saturation grows, the water content of the block continues to rise and the cumulative oil production gradually decreases. More >

Xiumei Zhong¹, Yuxin Liang^1,2,*, Qian Wang^1,*, Jinlian Ma¹, Shouyun Liang², Yan Wang¹, Xiaowei Xu¹

Journal of Renewable Materials, Vol.10, No.12, pp. 3405-3424, 2022, DOI:10.32604/jrm.2022.021120

Abstract The road subgrade and road surface in collapsible loess area are prone to many engineering diseases such as uneven subgrade settlement, insufficient bearing capacity of soaked foundation, collapse and instability of subgrade side slope due to the special properties of loess. As an environment-friendly, low-cost soil modifier with good adhesion and chelation properties, lignin has been considered to be used in highway subgrade construction. In order to explore the effect of lignin on loess, the compressive and collapsible properties of modified loess with different lignin contents were analyzed based on consolidation compression test. The improvement mechanism of lignin on loess… More >