The recovery factor of shale oil is extremely low. CO2 flooding is considered a promising way to improve the recovery factor of shale oil. The pressure gradually increases during the actual injection of CO2. CO2 and oil can go from immiscible to near-miscible and finally to miscible during the whole displacement process. Therefore, a continuous multipressure point displacement experiment (progressive flooding) with nuclear magnetic resonance technology is conducted. The experimental pressure is increased continuously from 0.7 to 11 MPa, which realizes the immiscible flooding change to near-miscible flooding and finally to miscible flooding, simulating the actual continuous displacement process of a reservoir. The results show that from immiscible flooding to near-miscible flooding and finally to miscible flooding, the cumulative oil recovery factor exhibits a step-like growth trend under continuous multipressure point displacement, and the increase in the amplitude of the recovery rate at different displacement states decreases in turn. In addition, the cumulative recovery factor of differently scaled pores shows different bench-type growth trends. When immiscible flooding changes into near-miscible flooding, the oil in the macropores is completely displaced, and the oil recovery of the mesopores increases more than that of the micropores. When converting from near-miscible flooding to miscible flooding, the increase in the amplitude of oil recovery from the micropores is higher than that from the mesopores. Under the conditions of transitioning from immiscible flooding to miscible flooding, CO2 first forms a miscible state with macroporous oil, second with mesopores, and finally with micropores. The research results provide theoretical guidance and reference for the field practice of CO2 flooding.

Large-scale hydraulic fracturing is an essential technical method to achieve effective shale oil and gas development. 1 The complex interaction mechanism between HF and NF needs to be considered in the hydraulic fracturing of shale reservoirs. However, there are a large number of NF, faults, and bedding planes developed in the shale, and the presence of these surfaces of discontinuity significantly affects the geometry of the HF. [2][3][4][5][6][7] At the same time, the injection of high-pressure fluids and the propagation of HF may cause a shear slip in NF in the reservoir that are in a critical stress state. [8][9][10][11][12][13] Therefore, the study of the relationship between hydraulic and natural fracture

This work investigates the electrical characteristics of floating-body and body-contacted SOI devices with Synopsys Sentaurus TCAD simulations. Short channel effects, subthreshold slope, transconductance, DIBL, on and off current are compared and analyzed for floating-body and body-contacted SOI devices, which is useful for device design and optimization. At the same time, the results of TCAD numerical simulation are used to compare the floating body effect characteristics of the two kinds of devices. From the results, the performance of body-contacted SOI devices is better. All the figures in this paper are obtained from TCAD simulation data and results based on 2D device simulation. Circuit and 3D simulations are beyond the scope of this paper, which will be investigate in future work.

Viscosity is an important index to evaluate gas flowability. In this paper, a double-porosity model considering the effect of pressure on gas viscosity was established to study shale gas percolation through reservoir pressure, gas velocity, and bottom hole flowing pressure. The experimental results show that when pressure affects gas viscosity, shale gas viscosity decreases, which increases the percolation velocity and pressure drop velocity of the free state shale gas in matrix and fracture systems. And it is conducive to the desorption of adsorbed shale gas and effectively supplemented the bottom hole flowing pressure with the pressure wave propagation range and velocity increasing, so that the rate of pressure drop at the bottom of the well slows down, which makes the time that bottom hole flowing pressure reaches stability shortened. Therefore, the gas viscosity should be fully considered when studying the reservoir gas percolation.