Analysis of elastic anisotropy of tight sandstone and the influential factors

Tight sandstone has a certain anisotropy. Using ultrasonic measurements of samples in three different directions and related matched experiments, this study systematically analyzes the pore structure and anisotropy of tight sandstone samples obtained from oil fields and compares results with those of shale. Results firstly show that the anisotropy of tight sandstone is mainly related to the compositional layering and thin interbedding which occur in different sedimentary environments. Tight sandstone has typical transverse isotropic medium characteristics, Young’s modulus increases in different directions with increasing confining pressure, Poisson’s ratio change is not obvious, anisotropic coefficients decrease with increasing effective pressure, and a certain linear relationship exists between ε, γ, and δ. This article finally summarizes anisotropy in different areas, thereby providing a foundation for the use of suitable appraisal models in different regions. This research can be used as an experimental reference for logging evaluation, seismic data interpretation, and fracturing develop of tight sandstones.

在线啤酒分析仪：酒精，真浓，原浓，CO2的在线检测

应用密度／声速方法为酒精度，真浓和原浓的测定提供了一种高精度的测量方法。温度变化对测量结果中压力和发酵度的影响可被很好的补偿。CO2含量的变化会使测量的精确度降低，因此，应该通过CO2在线分析仪测定出啤酒中CO2的含量，然后对结果进行补偿。在线啤酒分析仪还适用于“无醇”啤酒。

Evaluation of Phonon-level Density of UO2 by Molecular Dynamics Simulation

Molecular dynamics calculation of UO2 in a wide temperature range are presented and dis- cussed. The calculated lattice parameters, mean square displacements, and dynamic prop- erty of phonon-level density of the velocity auto-correlation functions for UO2 are provided. The Morelon potential and the Basak potential are employed. It confirms that the cal- culated lattice parameters using the Basak potential are in nearly perfect agreement with the reported values. The models successfully predict mean square displacement and Bredig transition. Furthermore, the phonon-level density of uranium dioxide are discussed. The intensity of phonon-level density increases with temperature, and the properties of UO2 are characterized by large thermal vibrations rather than extensive disorder.

Experimental study on ultrasonic propagation in water-based bentonite slurry

Drilling fluid is a common flushing medium used in pile foundation, geological drilling and petroleum drilling. Study on ultrasonic propagation properties in drilling fluid is of vital importance, not only for developing equipments to non-contact measuring concrete casting level for bored pile, but also for developing equip- ments considering drilling fluid as signal channel. The existence of clay particles makes the ultrasonic propagation and attenuation in drilling fluid much different from pure water. In order to know the relation among ultrasound frequency, slun-y density and depth, a series of laboratory experiments about ultrasound propagation in water-based bentonite slurry were finished. Wavelet method was adopted to process the gained original waves of ultrasonic propagation in slurry, so we knew the velocity and attenuation coefficient of ultrasound propagated in different drilling fluids with different density. The first group experiments shows that with density of drilling fluid increase, ultrasonic velocity will decrease but attenuation coefficient will increase if ultrasonic frequency keep constant. The second group experiments shows that the power of ultrasound will intensify in small bore hole, the attenuation coefficient is much smaller than theoretical value.

Magnetism and Sound Velocities of Iron Carbide （Fe3C） under Pressure

The elastic property and sound velocity of FeaC under high pressure are investigated by using the spin-polarized generalized gradient approximation within density-functional theory. It is found that the magnetic phase transition from the ground ferromagnetic （FM） state to the nonmagnetic （NM） state occurs at ～73 GPa. Based on the predicted Hugoniot of Fe3C, we calculate the sound velocities of FM-Fe3C and NM-Fe3C from elastic constants. Compared with pure iron, NM-FeaC provides a better match of compressional and shear sound velocities with the seismic data of the inner core, supporting carbon as one of the light elements in the inner core.

Effects of chemical,mineralogical,and temperature variations on the density and bulk sound velocity of the bottom lower mantle

In this study, we have modeled the density （p） and bulk sound velocity （V.） profiles of the bottom lower mantle using the experimental thermal equation of state （EoS） parameters of lower-mantle minerals, including bridgmanite, ferropericlase, CaSiO3-perovskite, and post-perovskite. We re-evaluated the literature pressure-volume-temperature relationships of these minerals using a self-consistent pressure scale in order to avoid the long-standing pressure scale problem and to provide more reliable constraints on the thermal EoS parameters. With the obtained thermal EoS parameters, we have constructed the p and V. profiles of the bottom lower mantle in different composition, mineralogy, and temperature models. Our modelling results show that the variations of chemistry, mineralogy, and temperature and AI enrichment at the bottom lower mantle can cause an increase have different seismic signatures from each other. The Fe in p but greatly lower V.. A change in mineralogy needs to be considered with the lateral variation in temperature. The cold slabs will be shown as denser regions compared to the normal mantle because of the combined effect of a lower temperature and the presence of a denser post-perovskite at a shallower depth, whereas the hot regions will have a 1-2% lower p than the normal mantle. V, of both cold slabs and hot regions will he lower than the normal mantle when bridgmanite is the dominant phase in the normal mantle, yet they will be greater once bridgmanite transforms into post-perovskite in the normal mantle. Our modeling also shows that the presence of a （Fe, Al）-enriched bridgmanite thermal pile above the core-mantle boundary will exhibit a seismic signature of enhancedp and V., but a reduced Vs, which is consistent with the observed seismic anomalies in the large-low-shear-velocity-provinces （LLSVPs）. The existence of such a （Fe, A1）-enriched bridgmanite thermal pile thus can help to understand the origin of the LLSVPs. These results provide new insights for the chemical and structure of the deepest lower mantle.