CHINESE CONTINENTAL SCIENTIFIC DRILLING PROJECT

Drilling engineering

    To drill a 5000m deep continuously cored scientific borehole in hard crystalline rock means a strong challenge to drilling technique and at the same time a good opportunity for its development. Following advance drilling methods and technologies are to be adopted:

         Diamond wireline coring
Diamond coring system driven by down the hole motor
Hyro-hammer drilling
Automatical controlled vertical drilling

     ZJ-70D electric rig used in this project is the newest product of China’s drilling equipment industry. This rig will be driven with the electric power of the public network. Its rated depth capacity is 7000m.

 Basic borehole parameters

         Borehole depth: 5000m
Coring diameter: 6 ¹/₈ in (156mm)
Percentage of Core drilling: 100%
Formation conditions: gneiss, eclogites, amphibolite，schist and so on. Estimated temperature gradient: 2.5 degree/100m.

 Drilling strategy

Double hole drilling concept: Pilot hole and Main hole

Hybridized drilling (petroleum drilling/geo-drilling) technology: A high speed top-drive system and a diamond wireline coring system will be added onto a petroleum rotary rig.

In this project, diamond coring bits with different crown profiles and structures and manufacture with different methods will be used.