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To improve the safety of air flooding, static and dynamic oxidation experiments are conducted to research catalytic low-temperature oxidation (CLTO) technology. The results show that the additives can accelerate the oxygen consumption rate significantly. Saturates and aromatics are converted to resins and asphaltenes during low-temperature oxidation (LTO), and the addition of additives can enhance the changing trend. CLTO technology can accelerate the oxygen consumption and delay the gas breakthrough time. This study can provide guidelines to improve the safety and increase the application of air flooding technology.

The cyclic steam stimulation is an important thermal recovery technique which is used to develop heavy oil reservoirs. However, the development effectiveness is limited in steam huff-puff wells of heavy oil reservoir with edge water because of the sharply increased water cut caused by the incursion of edge water. An experimental device, which can simulate edge water and steam stimulation process, was designed on the basis of steam flooding device to investigate the nitrogen foam anti-edge water-incursion technique. The designed device includes 3 subsystems: reservoir physical simulation subsystem, edge-water simulation subsystem and fluid injection subsystem. The effect factors and application conditions of the technique were investigated, and the results showed that the effect of the technique was influenced by reservoir water-flooded degree, edge water energy and crude oil property significantly. This technique is more suitable for seriously water-flooded reservoirs whose cycle water cut is no less than 80%, and the reservoir edge water energy and heavy oil viscosity should be moderate. As for Henan heavy oil reservoir, the optimum edge water pressure is 4MPa, and the oil viscosity is less than 5000mPa·s at the reservoir temperature (stock tank oil). The optimum injection pattern of the technique is N2 slug – nitrogen foam slug – steam. Pilot tests were conducted based on experimental results. The operation success rate is 100%, the average cycle water cut is reduced by 23%, and the average cycle oil production is increased twice. In view of the test result, this technique is a successful measurement to inhibit the water incursion and enhance the oil recovery of steam huff-puff wells with edge water.

For Unified Power Quality Conditioner (UPQC) adopting traditional hysteresis control method, unstable switching frequency causes great switching loss, and voltage space vector control method leads to a serious interphase interference to three-phase three-wire systems. To solve these problems, a hysteresis tracking control method with constant switching frequency based on voltage space vector is proposed. The hysteresis control method with constant switching frequency changes hysteresis band according to the DC capacitor voltage, supply voltage and differentiation of reference current wave to realize the fixed switching frequency. On this basis, the voltage space vector control method is introduced to change the problem of compensation control into that of how to select the right output voltage vector. So the switching loss is reduced and the problem of interphase interference is solved. At last, the control method proposed in this paper is verified possible and effective by the results of simulation of MATLAB and experiment.

Considering large volume, high cost and low reliability caused by the existence of mechanical sensor in the control system of permanent magnet synchronous motor(PMSM), this paper designed a speed observer instead of mechanical speed sensor based on sliding mode variable structure theory to realize speed sensor-less control of PMSM. Because accurate values of motor voltage and current were needed for sliding mode observer in estimation of rotor position and speed, the SVPWM modulation method was adopted. Simulation and experiments were performed on the basis of system model, and the results indicated that the DTC of PMSM speed sensor-less control based on sliding mode variable structure could significantly reduce the fluctuation of motor torque, flux linkage and current ripple. Besides it had better dynamic and static performance.