Spongy Pores Research Articles

Types and Characteristics of Volcanostratigraphic Boundaries and Their Oil‐Gas Reservoir Significance

AbstractJust like in sedimentary stratigraphy, the volcanostratigraphic boundary is an important factor for constructing volcanostratigraphic framework. The fundamental factor of volcanostratigraphic boundaries is to classify the types and define their characteristics. Based on field investigation and cross‐wells section analysis of Mesozoic volcanostratigraphy in NE China, 5 types of volcanostratigraphic boundaries have been recognized, namely eruptive conformity boundary (ECB), eruptive unconformity boundary (EUB), eruptive interval unconformity boundary (EIUB), tectonic unconformity boundary (TUB) and intrusive contacts boundary (ICB). Except ICB, the unconformity boundaries can be divided into angular unconformity and paraconformity. The time spans and signs of these boundaries are analyzed by using age data of some volcanic fields that have been published. The time spans of ECB and EUB are from several minutes to years. In lava flows, cooling crust is distributed above and below ECB and EUB; in pyroclastic flows, airfalls and lahars, a fine layer below these boundaries has no discernable erosion at every part of the boundary. EUB may be curved or cross curved and jagged. The scale of ECB/EUB is dependent on the scale of lava flow or pyroclastic flows. The time span of EIUB is from decades to thousands of years. There is also weathered crust under EIUB and sedimentary rock beds overlie EIUB. In most instances, weathered crust and thin sedimentary beds are associated with each other laterally. The boundary is a smooth curved plane. The scale of EIUB is dependent on the scale of the volcano or volcano groups. The characteristics of TUB are similar to EIUB's. The time interval of TUB is from tens of thousands to millions of years. The scale of TUB depends on the scale of the basin or volcanic field. Both the lab data and logging data of wells in the Songliao Basin reveal that the porosity is greatly related to the boundaries in the lava flows. There is a high‐porosity belt below ECB, EUB or EIUB, and the porosity decreases when it is apart from the boundary. The high‐porosity belt below ECB and EUB is mainly contributed by primary porosity, such as vesicles. The high‐porosity belt below EIUB is mainly contributed by primary and secondary porosity, such as association of vesicles and spongy pores, so the area near the boundary in lava flows is a very important target for reservoirs.

Synthesis and characterization of novel nanocomposite Chitosan membranes for Ethanol dehydration

Polyacrylonitril (PAN)-supported chitosan (CS) nanocomposite membranes were prepared by cross-linking the CS with 3-aminopropyltriethoxysilane (APTEOS) via sol-gel method. Pervaporative performances of the CS-SiO2/PAN membrane for dehydration of aqueous alcohol solutions were investigated. From SEM cross-sectional images of the membrane, the spongy pores and the finger-like pores were found in cortex and intermediate layer. The PAN microporous substrate and the top layer were about 100 and 7.4 µm thick, respectively. The separation factor and permeation flux of the synthesized CS/PAN and CS-SiO2/PAN membranes indicated that introducing 5% of nanosilica to skin layer of the composite membrane improved its pervaporative properties. At 30℃, a separation factor of 20.03 and 34.25 were achieved for CS/PAN and CS-SiO2/PAN membranes, respectively.

Membrane formation process and mechanism of PVDF-g-PNIPAAm thermo-sensitive membrane

The copolymer of poly (vinylidene fluoride) grafting poly (N-isopropylacrylamide) (PVDF-g-PNIPAAm) was synthesized and its flat sheet membranes were prepared via phase inversion method with N, N-dimethylformamide (DMF) as solvent and ethanol aqueous solutions as coagulation bath. The membrane formation process and mechanism were studied by the phase diagram (thermodynamics) and the ultrasonic time-domain reflectometry (kinetics). The membrane morphology was characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Atom force microscope (AFM). The permeability at different temperature was studied by filtration experiment. The results showed that the coagulation bath composition influenced the membrane formation process and mechanism greatly. When water was used as coagulation bath, instantaneous liquid–liquid demixing dominated the demixing process and resulted in faster membrane-forming speed and typical finger-like macrovoids. With the increase of ethanol content in coagulation bath, the demixing process changed from instantaneous liquid–liquid demixing to delayed liquid–liquid demixing and resulted in slower membrane-forming speed and uniform spongy pores. The special solubility of PNIPAAm in ethanol aqueous solution greatly affected the membrane formation process and the final membrane structure. The permeability and the temperature-sensitivity of PVDF-g-PNIPAAm membrane could be regulated by varying the coagulation bath composition simply.

Effects of the Based Membrane on the Hydrophobicity of Super-hydrophobic PES Membrane and its Structural Properties

Polyethersulphone (PES) was a hydrophobilic material. In order to use the Polyethersulphone (PES) membrane on highly hydrophobic membrane separation process, the PES membrane should be improved its hydrophobicity. In this paper, the super-hydrophobic PES membrane was successfully fabricated via sol-gel method. The chemical composition and the physical micro-structure of fabricated PES membrane surface were analyzed by Fourier-Transform Infrared Spectrometers (FTIR), Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM). The results showed that the PES membrane was super-hydrophobic, and its contact angle was 154°. The super-hydrophobic PES membrane has the low surface energy matters and the micro/nano-meter protuberance on the membrane surface. Those micro/nano-meter protuberances on membrane’s surface contributed for an rms roughness, which was about 350 nm. From the SEM images of the membrane cross-section, the spongy pores and the finger-like pores were found in cortex and intermediate layer, respectively.