An experimental study of imbibition process and fluid distribution in tight oil reservoir under different pressures and temperatures

Tight reservoirs are a major focus of unconventional reservoir development. As a means to improve hydrocarbon recovery from tight reservoirs, imbibition has been received increasing attentions in recent years. This study evaluates how the changes in temperature and pressure affect imbibition through conducting experimental tests under various conditions on samples from the Yan Chang formation, a tight reservoir in Ordos Basin. The fluid distribution is compared before and after imbibition in core samples by nuclear magnetic resonance method. The results show that the imbibition recovery is significantly improved through increasing temperature and pressure. A high temperature facilitates molecular thermal movements, increasing oil-water exchange rate. The core samples are characterized with nano-mesopores, which is followed by nano-macropores, micropores, mesopores, and nano-micropores. Comparative analysis of nuclear magnetic resonance shows that the irreducible water saturation increases after imbibition and is mainly distributed in nano-pores. Increasing pressure increases the amount of residual water in nano pores, with the relatively more significant increase in the amount of residual water in nanomacro-pores compared with other types of pores.Cited as: Liang, Y., Lai, F., Dai, Y., Shi, H., Shi, G. An experimental study of imbibition process and fluid distribution in tight oil reservoir under different pressures and temperatures. Capillarity, 2021, 4(4): 66-75, doi: 10.46690/capi.2021.04.0

A method for analyzing the revolute joint wear of planar multibody systems and its application in unbalance loading working condition

This paper develops an efficient method to describe the evolution of the revolute joint wear during the process of the mechanism movement. In the framework of multibody systems formulation, the prediction method of the revolute joint wear in different motion time interval is established by considering the wear ranges between the pin and the bushing on the basis of the Archard’s wear model. Then a typical non-planar mechanism with unbalancing loads acting on single non-ideal revolute joint is used to illustrate the application of the method. Moreover, the corresponding experimental mechanism is tested to validate the predicting results of the proposed method. The analysis shows that the method proposed is of high efficiency and can guarantee enough predicting accuracy when the predicted wear depth is not big. Therefore, the method is practical to a certain degree in engineering

Polypyrimidine tract binding protein knockdown reverses depression-like behaviors and cognition impairment in mice with lesioned cholinergic neurons

Background and objectivesDepression is a common comorbidity of dementia and may be a risk factor for dementia. Accumulating evidence has suggested that the cholinergic system plays a central role in dementia and depression, and the loss of cholinergic neurons is associated with memory decline in aging and Alzheimer’s patients. A specific loss of cholinergic neurons in the horizontal limb of the diagonal band of Broca (HDB) is correlated with depression and dysfunction of cognition in mice. In this study, we examined the potential regenerative mechanisms of knockdown the RNA-binding protein polypyrimidine tract binding protein (PTB) in reversing depression-like behaviors and cognition impairment in mice with lesioned cholinergic neurons.MethodsWe lesioned cholinergic neurons in mice induced by injection of 192 IgG-saporin into HDB; then, we injected either antisense oligonucleotides or adeno-associated virus-shRNA (GFAP promoter) into the injured area of HDB to deplete PTB followed by a broad range of methodologies including behavioral examinations, Western blot, RT-qPCR and immunofluorescence.ResultsWe found that the conversion of astrocytes to newborn neurons by using antisense oligonucleotides on PTB in vitro, and depletion of PTB using either antisense oligonucleotides or adeno-associated virus-shRNA into the injured area of HDB could specifically transform astrocytes into cholinergic neurons. Meanwhile, knockdown of PTB by both approaches could relieve the depression-like behaviors shown by sucrose preference, forced swimming or tail-suspension tests, and alleviate cognitive impairment such as fear conditioning and novel object recognition in mice with lesioned cholinergic neurons.ConclusionThese findings suggest that supplementing cholinergic neurons after PTB knockdown may be a promising therapeutic strategy to revert depression-like behaviors and cognitive impairment

Growth, Mechanical, Thermal and Spectral Properties of Cr3+∶MgMoO4 Crystal

This paper reports the growth, mechanical, thermal and spectral properties of Cr3+∶MgMoO4 crystals. The Cr3+∶MgMoO4 crystals with dimensions up to 30 mm×18 mm×14 mm were obtained by TSSG method. The absorption cross-sections of 4A2→4T1 and 4A2→4T2 transitions are 12.94×10−20 cm2 at 493 nm and 7.89×10−20 cm2 at 705 nm for E//Ng, respectively. The Cr3+∶MgMoO4 crystal shows broad band emission extending from 750 nm to 1300 nm with peak at about 705 nm. The emission cross-section with FWHM of 188 nm is 119.88×10−20 cm2 at 963 nm for E//Ng. The investigated results showed that the Cr3+∶MgMoO4 crystal may be regarded as a potential tunable laser gain medium

A Complete Developmental Sequence of a Drosophila Neuronal Lineage as Revealed by Twin-Spot MARCM

Labeling every neuron in a lineage in the fruit fly olfactory system reveals that every cell is born with a pre-determined cell fate that is invariant and dependent upon neuron birth orde

Fixed point index approach for solutions of variational inequalities

By using fixed point index approach for multivalued mappings, the existence of nonzero solutions for a class of generalized variational inequalities is studied in reflexive Banach space. One of the mappings concerned here is coercive or monotone and the other is set-contractive or upper semicontinuous

FIXED POINT INDEX APPROACH FOR SOLUTIONS OF VARIATIONAL INEQUALITIES

By using fixed point index approach for multivalued mappings, the existence of nonzero solutions for a class of generalized variational inequalities is studied in reflexive Banach space. One of the mappings concerned here is coercive or monotone and the other is set-contractive or upper semicontinuous

The Viro Method for Construction of Piecewise Algebraic Hypersurfaces

We propose a new method to construct a real piecewise algebraic hypersurface of a given degree with a prescribed smoothness and topology. The method is based on the smooth blending theory and the Viro method for construction of Bernstein-Bézier algebraic hypersurface piece on a simplex

Synthesis of Symmetrical and Unsymmetrical <i>N</i>,<i>N</i>′-Diaryl Guanidines via Copper/<i>N</i>-Methylglycine-Catalyzed Arylation of Guanidine Nitrate

CuI/<i>N</i>-methylglycine-catalyzed coupling reaction of guanidine nitrate with both aryl iodides and bromides takes place at 70–100 °C, affording symmetrical <i>N</i>,<i>N</i>′-diaryl guanidines with good to excellent yields. Unsymmetrical <i>N</i>,<i>N</i>′-diaryl guanidines can be assembled via monoarylation of guanidine nitrate with aryl iodides bearing a strong electron-withdrawing group and subsequent coupling with another aryl iodide