Design drilling depth of well Yushen 4 is 3500 meters, well completion depth is 3216.

Study on the suspension technique of tailer cementing in deep and ultra deep wells.;

Research on setting ability for working strings in deep well;

Calculation and analysis of fatigue strength of drill string in deep well;

Test research on ground pressure control for deep mine roadway;

Failure cause and pressure behavior law of soft rock laneway in deep mine;

High strength bolt support technology for gateway with complicated conditions in deep mine;

After many tests of well depth and explosion consumption, we finally adopt the less charge shot array to ensure the high frequency energy of seismic signal propagating sufficiently downward,so we can increase the resolution of seismic explosion.

Based on profit and loss theory, a model on economic reserve boundary of new found proved reserves is built, as w ell as series of corresponding charts, which take consideration of various reser ve types, oil prices, and well depths, are drawn.

In order to meet the requirement of the complicated hydraulics design under different drilling fluid rheological behaviors, a systematic method to calculate the critical well depth according to drilling fluid rheological and flow behaviors is introduced, taking example of the power law fluid.

The application of engineering geology to specific adit digging at deep shaft;

The deformation feature of deep shaft coal roadway is analyzed,and the reason for many kinds of support failures is studied.

,and the problem of vehicle operating in deep shaft is thereon settled.