No abstract

In 1D Geomechanics projects, calibration of stress is extremely important in the construction of a valid Mechanical Earth Model (MEM). The minimum horizontal stress data is usually available from LOT (Leak-off test), XLOT (Extended Leak-off test), Open hole stress tests, or cased hole Mini Fall off Test (also called Diagnostic Fracture Injection Test – DFIT). These traditional measurements have a few deficiencies. This paper presents an application to a gas storage field, where stresses are derived from a newer unique approach where the radial variation of acoustic velocity from advanced dipole sonic logging tool is inverted to obtain stress. These derived stresses are then utilized to calibrate the 1D MEM for the gas field. This approach addresses some of the deficiencies of traditional approaches of deriving stress magnitudes. The characteristics of this approach are:Both the minimum horizontal stress (Shmin) and maximum horizontal stress (SHmax) are obtained. Traditional approach provides a value for Shmin only.These measurements are obtained in reservoir zones at multiple depth intervals. Traditional approaches provide a measurement at one depth only.This method is applicable to all formations that are acoustically stress sensitive.This method is relatively more cost effective as compared to traditional approaches where rig time is a premium considering that advanced sonic logs are routinely run for other applications as well. The sonic data was processed to derive a dispersion plot (velocity versus frequency). From this plot, a plot of velocity versus radial distance is derived. As Kirsch equation provides a radial variation of the stress with distance for a hole drilled in a uniform stress field, and variation of stress translates to variation with velocity, a parametric inversion is utilised to derive the stress. In this gas field, no LOT or XLOT were available. However, the advanced dipole sonic logging tool was recorded in a well recently drilled and some of the formations were found to be acoustically stress sensitive as observed from the dispersion plot. Therefore, this inversion technique was applied and Shmin and SHmax were obtained that were extremely useful to calibrate the 1D MEM. This technique is unique in the industry and complements existing methods to obtain stress measurements for 1D MEMs where stress measurements are either not available or expensive to obtain. This method is not widely used. The authors hope that this paper will illustrate how this method was used in this gas field and encourages other users to investigate the application of this method in their fields, when traditional data is limited.

The learning ecosystem is the unified whole formed by education and its surrounding environment, including human elements such as the internal school education system and organization and non-human factors such as the external soft and challenging environment. However, the global COVID-19 outbreak in 2020 has led to large-scale home-based learning among students, which has broken the original ecological balance of learning. The interaction between the four elements of the traditional instructional system cannot explain all the teaching behavior. Based on the research perspective of large-scale home-based learning, this paper proposes to add family and technology into the original teaching system framework to form a new family-school linkage instructional System framework, including school education, family education, online teaching, and other types of education, improve the learning ecosystem and provide new thinking for the education and teaching in the post-epidemic era.

In August 2019, People’s Bank of China launched the reform of Loan Prime Rate (LPR) quotation formation mechanism and then made continuous progress in the order of “new loans first, followed by exiting loans,” dredging the interest rate transmission channel of “policy interest rate, LPR, loan interest rate.” In 2020, Chinese financial institutions have mainly referred to LPR pricing for loans, and the marketization level of loan pricing has significantly improved. This paper analyzed the policy effects transmitted by LPR through constructing a Dynamic Stochastic General Equilibrium (DSGE) decision model, and it was found that the financial market structure, pricing ability of commercial banks, and the degree of LPR application all affected the policy rate transmission effect and had an impulse impact on macroeconomic growth. Based on the above analysis, this paper proposed policy suggestions on the path of interest rate market-oriented reform and coping measures of commercial banks in China.

For exploring the attenuation law of limestone dynamic elastic modulus (DEM) under fatigue cyclic loading, 24 limestone specimens were used to conduct dynamic uniaxial cyclic compressive tests under different loading frequencies and stress amplitudes on MTS Test System. The tests results confirmed that the decrease of DEM goes through three different stages with the increase of cyclic numbers. And, there is no distinct correlation between three-stage evolution rule of DEM and frequencies as well as stress amplitudes. The degeneration of DEM is caused by accumulation of micro-cracks and damage increase in rock specimen. Thus, based on attenuation rule of DEM, a fatigue damage evolution model which can depict the first two stages of limestone fatigue damage development was proposed.