A seismic prediction method of reservoir brittleness based on mineral composition and pore structure

The Lucaogou Formation, a typical fine-grained mixed formation in the Jimusaer Sag of the Junggar Basin, exhibits considerable potential for hydrocarbon exploration. Accurate brittle prediction is a crucial factor in determining hydraulic fracturing effectiveness. However, the area features complex lithological characteristics, including carbonate rocks, clastic rocks, volcanic rocks, and gypsum interbeds, along with thin layering and sporadic sweet spots. Traditional prediction methods offer limited resolution and there is an urgent need for a seismic brittle prediction method tailored to this complex geological environment. This paper presents a multi-mineral composition equivalent model for complex lithologies that enables the accurate calculation of Vp and Vs These ratios serve as the foundation for pre-stack elastic parameter predictions, which include Poisson’s ratio and Young’s modulus. By comparing the predicted parameters with well-logging measurements, the prediction accuracy is improved to 82%, with particularly high conformity in intervals characterized by high organic matter and clay content. Additionally, a three-dimensional brittle modeling approach reveals that the brittleness of the reservoir exceeds that of the surrounding rock, showing a gradual improvement in brittleness with increasing burial depth from southeast to northwest. The central area exhibits relatively good brittleness, with a stable, blocky distribution pattern

Evolution of Near-Well Damage Caused by Fluid Injection through Perforations in Wellbores in Low-Permeability Reservoirs: A Case Study in a Shale Oil Reservoir

AbstractDuring the development of shale oil resources, fluid injection is usually involved in the process of hydraulic fracturing. Fluid injection through perforations causes near-well damage, which is closely related to the subsequent initiation and propagation of hydraulic fractures. This study is focused on the characterization of the temporal and spatial evolving patterns for near-well damage induced by fluid injection through perforations in the early stage of hydraulic fracturing. A coupled hydromechanical model is introduced in a case study in a shale oil reservoir in northwestern China. The model considers porous media flow during fluid injection. It also considers elasticity in the rock skeleton before the damage. Once the damage is initiated, a damage factor is employed to quantify the magnitude of injection-induced damage. Results show that damage evolution is highly sensitive to perforation number and injection rate in each individual perforation. Damage propagation is more favorable in the direction of the initial maximum horizontal principal stress. The propagation of damage is drastic at the beginning of fluid injection, while the damage front travels relatively slow afterward. This study provides insights into the near-well damage evolution before main fractures are initiated and can be used as a reference for the optimization of perforation parameters in the hydraulic fracturing design in this shale oil field

Three-Dimensional Modeling of Hydrodynamics and Biokinetics in EGSB Reactor

A three-dimensional model integrating computational fluid dynamics (CFD) and biokinetics was established to model an expanded granular sludge bed (EGSB) reactor in this study. The EGSB reactor treating synthesized municipal wastewater was operated at ambient temperature. The model provided satisfactory modeling results regarding hydrodynamics and biokinetics. The model shows that influent distribution was evenly distributed. In addition, butyrate and propionate degradation rates linearly decreased along the flow direction in the reactor. However, acetate degradation rate increased first and decreased later. VFA degradation rate distributions were different at each reactor cross section. VFA degradation rates near reactor wall were lower than VFA degradation rates at reactor axis. Moreover, a pulse high influent COD concentration had a tiny impact on effluent quality, which indicates that the reactor was stable while treating synthesized wastewater at adopted conditions

Quantitative determination of free volume in Pd40Ni40P20 bulk metallic glass

For a long time, the determination of free volume has been a challenging problem in research on metallic glasses. An approach to determine quantitatively the free volume of metallic glasses from enthalpy measurements and calibration with the equilibrium free volume was developed and validated for as-cast and annealed Pd40Ni40P20 bulk metallic glasses. The free volume change with annealing time is in good agreement with that calculated theoretically from the free volume annihilation kinetics and that deduced from the density measurement results

Integrated anaerobic and algal bioreactors: A promising conceptual alternative approach for conventional sewage treatment

Conventional sewage treatment applying activated sludge processes is energy-intensive and requires great financial input, hampering widespread implementation. The introduction of anaerobic membrane bioreactors (AnMBR) followed by an algal reactor growing species of commercial interest, may present an alternative, contributing to the envisaged resource recovery at sewage treatment plants. AnMBRs can be applied for organic matter removal with energy self-sufficiency, provided that effective membrane fouling management is applied. Haematococcus pluvialis, an algal species with commercial value, can be selected for ammonium and phosphate removal. Theoretical analysis showed that good pollutant removal, positive financial output, as well as a significant reduction in the amount of hazardous activated sludge can be achieved by applying the proposed process, showing interesting advantages over current sewage treatment processes. Microbial contamination to H. pluvialis is a challenge, and technologies for preventing the contamination during continuous sewage treatment need to be applied.Sanitary Engineerin

Nutritional Changes and Early Warning of Moldy Rice under Different Relative Humidity and Storage Temperature

Processed unhusked rice is prone to mildew during storage. In this study, the storage conditions were simulated at temperatures of 20, 30, and 35 °C and a relative humidity of 40%, 60% and 80%, respectively. The water, fatty acid, and total starch content and the peak viscosity, mold colony number, protein secondary structure, and spatial structure of rice were monitored in order to propose the critical point of mildew during storage. In the process of rice from lively to moldy, the water content, fatty acid contents and the peak viscosity were increased. The total starch content decreased and then showed a slow increasing trend, while the microstructure of the powder particles changed from smooth and complete to loosen and hollow. With the increase in storage time, the vibration of the amide Ⅰ band of the rice samples decreased slightly, indicating that the total contents of β-fold, β-turn, α-helix, and random curl of the rice protein also changed. PCA (Principal Component Analysis) analysis showed that rice mildew index was closely related to temperature and humidity during storage. In our investigation, the best and most suitable temperature and relative humidity for rice storge is 20 °C and 40%, respectively. These results suggested that temperature and environmental humidity are vital factors affecting the physicochemical properties and nutrient changes, which provides a theoretical basis for the early warning of rice mildew during storage

Free-Standing Pt–Au Hollow Nanourchins with Enhanced Activity and Stability for Catalytic Methanol Oxidation

Controlling the morphology of Pt–Au bimetal nanostructures can provide a great opportunity to increase their catalytic activity on a Pt mass basis and improve their durability at the same time. In this study, we synthesized Pt-on-Au hollow urchinlike nanoparticles (NPs), which present a structure consisting of a monolayer of small Pt NPs uniformly overgrown on an Au hollow nanourchin (HNU). The Pt–Au HNUs demonstrated an ultrahigh density of sharp tips and uniform coating of 2 nm Pt NPs. This well-controlled bimetal nanostructure exhibited a large electrochemical surface area, more than 2 times higher than that of Pt black, and a relatively high electrocatalytic activity toward the methanol oxidation reaction, more than 3 times greater than the Pt black and Pt/C commercial reference catalysts. Simultaneously, the Pt–Au HNUs showed greatly improved durability because of the small Pt NPs on the surface of Pt–Au HNUs which were effectively stabilized by the Au metal support

Silver nanowires growth via branch fragmentation of electrochemically grown silver dendrites

We have demonstrated a new protocol of synthesizing Ag nanowires via an electrochemical Ostwald ripening (OR) driven branch fragmentation mechanism; the branching rate of the Ag nanowires is significantly decreased by means of an electrodeposition under a strong applied-potential, following a relaxation process