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In order to realize the safety, high efficiency and high recovery rate mining of 9-13 m thickness hard coal seam in Jinjitan Coal Mine, the top coal recovery rate and coal wall stability of different cutting heights are analyzed by theoretical analysis and numerical simulation. Based on the corresponding relationship between top coal recovery rate, coal wall stability and cutting height, a super large mining height and small mining and drawing ratio technology which based on mining and supplemented by releasing is proposed. The ZFY21000/35.5/70D two pillar shield hydraulic support with super large mining height is developed. Based on the optimization design of anti impact column and high-efficiency caving mechanism, the problems of easy impact of super high mining height fully mechanized top coal caving face, easy rib spalling of coal wall and easy arching of hard coal are solved. Fully mechanized top coal caving mining with super high mining height and small mining and caving ratio is an effective way to improve recovery rate and realize high yield and high efficiency of extra thick hard coal.

As a representative of emerging unconventional energy, shale gas has the characteristics of large reserves, long production cycle, and environmental protection. However, due to the complex geological characteristics of shale gas reservoirs, the economic development of shale gas reservoirs is difficult. In this paper, on the basis of a full investigation of relevant literature, according to the permeability mechanism of shale gas reservoirs, the productivity of horizontal wells in low-permeability gas reservoirs is studied, and an integrated dynamic simulation model of gas reservoir wellbore is established. And the historical fitting and dynamic forecasting are carried out, and the results are in good agreement with the actual situation.

As the development of each oil field enters the middle and late stage, sand production, wax deposition and the continuous increase of well depth, electric submersible screw pump wells frequently break down, and hidden troubles of equipment can not be found in time, which makes oil wells produce with faults. It increases the wear and tear of equipment, seriously affects the production of oil wells, and causes unnecessary economic losses. Therefore, improving the accuracy of the working condition diagnosis of the electric submersible screw pump production system plays a vital role in improving the overall management level of the electric submersible screw pump well. This can not only enhance the managers’ correct understanding of this kind of oil well system, but also comprehensively monitor the working state of the well. It can find the fault as soon as possible, analyze the cause of the fault, and avoid the accident by adjusting the production parameters, so that the downhole screw pump can work safely, reliably and effectively, and maximize the maintenance free period and economic benefits of the electric submersible screw pump well.

Fire flooding, also known as in-situ combustion technology, is a mining technology that can greatly improve the recovery of heavy oil reservoir. The composition of the output of the fire flooding oil well is very different from that of other heavy oil thermal recovery wells, and shows regular changes with different stages of fire flooding. These changes have a great impact on the efficient lifting of the fire flooding oil well. Numerical simulation can be used to simulate the combustion process of fire flooding and the heat and mass transfer process in the reservoir, so as to simulate the changes of the components of the output with different stages of fire flooding, and provide guidance for the design of fire flooding lifting. The results show that it is feasible to use reservoir numerical simulation software to simulate the production performance and the change of production composition of in-situ combustion oil wells.

The unconsolidated sandstone heavy oil reservoir is dominated by heterogeneous elastic-plastic reservoir with complex structure. The core demand is large in the study of reservoir lithology and physical properties. Although the high-cost freezing and encapsulation processes are used in the process of coring site and indoor processing, they are still easy to damage in the process of extracting cores. Moreover, the physical parameters of ordinary artificial cores are too different from those of producing cores to obtain accurate lithology and physical parameters. So, replacing the production cores with outcrop cores may become an important method to study the physical parameters of reservoirs. In this paper, the micro-velocity displacement method and saturated heavy oil method are used to study the lithology and physical property parameters of outcrop cores. The results show that compared with those of producing cores, the rock mechanics parameters of outcrop cores after high-pressure heavy oil saturation treatment are basically consistent with those of field cores. Therefore, it can be used to replace the core to study the physical parameters of rocks in special cases.

Hydraulic fracturing is an economically effective technology developing the glutenite reservoirs, which have far stronger heterogeneity than the conventional sandstone reservoir. According to the field production experience of Shengli Oilfield, horizontal-well fracturing is more likely to develop a complex fractured network, which improves the stimulated volume of reservoir effectively. But the clear mechanism of horizontal-well hydraulic fracture propagation in the glutenite reservoirs is still not obtained, thus it is difficult to effectively carry out the design of fracturing plan. Based on the characteristics of the glutenite reservoirs, a coupled Flow-Stress-Damage (FSD) model of hydraulic fracture propagation is established. The numerical simulation of fracturing expansion in the horizontal well of the glutenite reservoir is conducted. It is shown that a square mesh-like fracture network is developed near the horizontal well in the reservoir with lower stress difference, in which fracture is more prone to propagate along the direction of the minimum principal stress as well. High fracturing fluids injection displacement and high fracturing fluid viscosity lead to the rise of static pressure of the fracture, which results in the rise of fracture complexity, and greater probability to deflect when encountering gravels. As the perforation density increases, the micro-fractures generated at each perforation gather together faster, and the range of the stimulated reservoir is also relatively large. For reservoirs with high gravel content, the complexity of fracture network and the effect of fracture communication are obviously increased, and the range of fracture deflection is relatively large. In the case of the same gravel distribution, the higher the tensile strength of the gravel, the greater fracture tortuosity and diversion was observed. In this paper, a simulation method of horizontal well fracture network propagation in the reservoirs is introduced, and the result provides the theoretical support for fracture network morphology prediction and plan design of hydraulic fracturing in the glutenite reservoir.

The hydraulic fracturing of shale reservoirs is an important topic, and adjusting the fracturing process can enhance fracturing efficiency. To analyze the effect of injection conditions on the fracture network structure and conductivity, numerical simulations and theoretical calculations are carried out based on the construction data, and the variation patterns of the fracture network parameters are determined. During the theory study, a fracture network conductivity model was obtained by combining the fracture network expansion model and the fracture diversion model. Then a numerical model was set up according to the analysis results of monitoring data. The numerical simulation results showed the fracture network structure and proppant distribution under different conditions. Throughout the simulation process, the structural parameters and conductivity of the fracture network can be determined by controlling the injection amount and adjusting the injection method, speed, and sand ratio. Results indicated that the proppant pulse frequency during the injection process was a major factor affecting the structure and conductivity of the fracture network. At the same time, a comparison of the distribution structure of the proppant revealed that although the intermittent injection of the proppant improved the flow channel, the efficiency of fracture utilization can still be improved. [ABSTRACT FROM AUTHOR]

HPAM/PEI gel is a promising material for conformance control in hydrocarbon reservoirs. However, its use in low-permeability reservoirs is limited by the high polymer concentrations present. In this study, the gelation performance of an HPAM/PEI system with HPAM < 2.0 wt.% was systematically investigated. The gelation time for HPAM concentrations ranging from 0.4 to 2.0 wt.% varied from less than 1 h to 23 days, with the highest gel strength identified as grade H. The hydrodynamic radius manifested the primary effect of HPAM on the gelation performance. Branched PEI provided superior gelation performance over linear PEI, and the gelation performance was only affected when the molecular weight of the PEI varied significantly. The optimal number ratio of the PEI-provided imine groups and the HPAM-provided carboxylic acid functional groups was approximately 1.6:1~5:1. Regarding the reservoir conditions, the temperature had a crucial effect on the hydrodynamic radius of HPAM. Salts delayed the gelation process, and the order of ionic influence was Ca2+ > Na+ > K+. The pH controlled the crosslinking reaction, primarily due to the protonation degree of PEI and the hydrolysis degree of HPAM, and the most suitable pH was approximately 10.5. Plugging experiments based on a through-type fracture showed that multi-slug plugging could significantly improve the plugging performance of the system, being favorable for its application in fractured low-permeability reservoirs. [ABSTRACT FROM AUTHOR]