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The diminishing oil resources make the exploration and development of heavy oil reservoirs more and more important. Heavy oil reservoirs need steam stimulation or other thermal development methods; temperature increasing during the thermal recovery process will inevitably affect the reservoir compressive characteristics. In order to study the variation of the compression coefficient of heavy oil reservoirs in the multi-round steam stimulation process, the compression coefficients of the reservoirs after different temperature and pore pressure cycles were tested. The results show that the compression coefficient of heavy oil reservoir decreases with the increase in effective confining pressure and increases with the increase in test temperature; After the temperature and pore pressure cycle, the compression coefficient of the rock is greatly reduced; the decrease in range of compression coefficient of the reservoir after the temperature and pore pressure cycle increases with the increase in the test temperature, and increases with the increase in maximum effective confining pressure. The dynamic variation of the reservoir compression coefficient must be taken into account in the prediction of the production capacity of multi-round steam stimulation.

In this paper, a novel method for respiratory monitoring is presented. The method is based on Trichel pulses (TPs) using a simple field ionization sensor which consists of a needle electrode and a plate electrode. Experiments have been conducted to demonstrate that different respiratory patterns, including normal, ultra-fast, deep breaths, and apnea could be easily monitored in real time by detecting the changes in the TP frequency. The vital capacity could also be assessed by calculating the variation of TP frequency. It is found that the operation principle of the proposed sensor is based on the effects of breath airflow and the atomized water in exhaled air on the TP frequency by changing the ionization process and the dynamics of charged particles in the short gap. The influences of applied voltage and ambient parameters have also been investigated.

Research on the flow low in the slot of the slotted screen used in the unconsolidated sand formation is conducted with computational fluid dynamics method. Research on the erosion and corrosion of the slotted screen is presented with the calculation of flow field and the introduction of erosion model established by the Erosion and Corrosion Research Center of Tula. Moreover, the slot erosion characters and the maximum erosion with different production pressure difference and sand content are given. The result shows that: (1) the maximum value of the flow rate and the erosion appears at the horn mouth of the slotted screen; If the production pressure difference is enlarged, the amount of sand that flows into the inner of the screen will increase and the flow rate of the sand will increase sharply, which worsens the erosion of the screen; (2) the degree of the erosion of the slotted screen grows exponentially with the increase of the production pressure difference and initially increases and then decreases with the increasing of the sand content; the degree of the erosion reaches the peak value when the sand content is ten percent; and (3) the main erosion region is the middle part of the slot, and this region widens with the increasing of production pressure difference. The lower part of the screen is more damaged than the upper part.

The performance of extraordinary magnetoresistance (EMR) depends on the material parameters, hybrid structure design, contacts configuration, and manufacturing technology. In this paper, we pay close attention to the hybrid structure of the EMR device. A semiconductor–metal hybrid model based on the finite element method (FEM) is constructed to study the EMR effect, and the results show good agreement with the experimental data. The analysis of the van der Pauw plate structure indicates that the relationship between the two voltage probe contacts and the different EMR structures is the key factor to the design optimization. Accordingly, we find that the elliptic inclusion configurations improve the performance of the van der Pauw structure of EMR devices within a wide range of applied magnetic field (0–5 T). The bar-type and multibranched inclusion structures are subsequently optimized based on this principle. The new structures show excellent performance; more specifically, the modified multibranched inclusion structure displays a 2-fold increase in the magnetoresistance at 0.1 T and more than 2-order-of-magnitude increase at 5 T when compared with the original structure.

The effects of environmental parameters, e.g., humidity, on the corona discharges in practical applications are important. A two-dimensional (2D) hydrodynamic drift-diffusion model has been used to investigate the effects of humidity on the negative corona Trichel pulses (TPs). The simulations are performed with a conventional needle-to-plate configuration in humid air. It is found that the magnitude of TPs grows gradually with increasing humidity and the frequency of TPs increases with humidity. The movements and formations of charged particles are faster in higher humidity. The numerical results are consistent with the experimental observation.

Wellbore instability is one of the major problems hampering the drilling speed in the Fergana basin. Comprehensive analysis of the geological and engineering data in this area indicates that the Fergana basin is characterized by high in situ stress and plenty of natural fractures, especially in the formations which are rich in bedding structure and have several high-pressure systems. Complex accidents such as wellbore collapse, sticking, well kick and lost circulation happen frequently. Tests and theoretical analysis reveals that the wellbore instability in the Fergana basin was influenced by multiple interactive mechanisms dominated by the instability of the bedding shale. Selecting a proper drilling fluid density and improving the sealing characteristic of the applied drilling fluid is the key to preventing wellbore instability in the Fergana basin. The mechanical mechanism of wellbore instability in the Fergana basin was analysed and a method to determine the proper drilling fluid density was proposed. The research results were successfully used to guide the drilling work of the Jida-4 well; compared with the Jida-3 well, the drilling cycle of the Jida-4 well was reduced by 32%.

In this paper the Trichel pulse regime of corona discharge in airflows is numerically studied with a two-dimensional model. The model is based on the hydrodynamic drift–diffusion approximation, taking into consideration the flow of the air in the discharge gap. Both transverse and longitudinal airflows under different conditions have been investigated. The influences of airflows on the characteristics of the Trichel pulses were clearly observed and analysed. The simulation results proved to be compatible with experimental analysis reported in the literature.

In the process of well completion with mechanical screen to control sand, once the water content of the reservoir increased, the montmorillonite in clay minerals would swell which combined with formation sand has an obvious effect on the plugging of screen pipe in production string. According to the prediction of water production of reservoir, shale expansion instrument was used to establish the relationship between the different water content and swelling properties of montmorillonites and combined with the clogging test of screen under different water content to evaluate the blocking effect of montmorillonite under different water content on the clogging of screen in the process of sand control. It can be found in the experiment that: (1) If the reservoir products water, the expansion height of two kinds of montmorillonites is similar when the water content of oil is less than 10% or more than 20%, the expansion height of montmorillonites is large of which expansion rate can reach to 188% when the water content is between 10 and 20%. (2) Through the simulation experiment of sand control, when the water content is 10 and 30%, the screen blocking is the fastest, and the productivity index per meter is the lowest, the blockage rate is increased by nearly three times when the water content of oil is 0. (3) The influence of concentration ratio of oil and water on the productivity index per meter of metal mesh screen is larger than the swelling of montmorillonites which is mainly reflected in the water content is close to 20–30%. The degree and speed of screen blocking can be reduced by reducing the water content of produced fluid.