Numerical simulation of flow field under petroleum drill well of non-simplified PDC drilling bits;

The overall characteristics of flow field are analyzed and various influences of nozzle diameter on the downhole flow field of PDC bits are obtained.

In order to develop the predictable and quantitative research technology, the potential flow theory was used to simulate the bottom?hole crossflow field.

Support technology for goaf left by small coal mine in mine shaft bottom of Shuguang Mine;

The heaving floor forms in the soft rock roadway have been presented by the surveying researches on the drift of the shaft station which in the soft fractured zone in the tectonic stress concentration zone of Guhanshan coal mine,The causes of the heaving floor have been analyzed.

Through the analysis of the field observation and the investigation of the randomness of the railway haulage system of the shaft station, a limited customer M/ M/ 1 queuing model of cradle dumpers in the station is developed and the optimum design of shaft stations is approached.

Stress distribution rules of surrounding rock of shaft station and neighboring caverns before and after mining in Tunliu Colliery of Lu an Group were analyzed by numerical simulation,which provided theoretic foundation for supporting shaft and caverns and provided reference for shaft station design and construction with similar conditions.

Based on the complex geological conditions in Guotun Coal Mine of thick overburden, large inflow of water and high ground stress, this paper proposed some technical problems should be considered in shaft sinking and pit bottom construction and the countermeasures.