Simulation of penetration rate of air percussion drilling bit;

Experimental investigation in transmission ratio and penetration rate of cone bits;

It has long been held that the penetration rate of PDC bits is lower than roller bits during air drilling.

In view of many problems faced by drilling in the lower stratum in Xujiaweizi region, such as complex geologic structures, high grade value of rock drillability, low drilling rate, slow footage, and long drilling cycle, it is urgent to correctly predict the grade value of rock drillability which will provide powerful references for a better drilling plan in reasonable way.

Although the drilling rate is related to the structure of the bit, property of the drilling fluid, drilling parameter as well as make-up of string and so on, the theory and practice indicates that the formation factor is the main factor in affecting drilling rate, which not only affects drilling rate directly, but also restrains the influence of drilling parameter on drilling rate.

The mechanical drilling rate relates closely to drilling bit structure,drilling fluid property,drilling parameters and drilling tool constitution,but according to theory and practice formation factor is still the one that impacts the drilling rate most.

There are many problems when drilling in the complex stratum formation in Xujiahe,Sichuan province,such as low rate of penetration,borehole collapse,high accident frequency,short bit life,and so on.