Study of distribution of rock mechanics parameter of carbonate rock has an important sense to prevention and decrease drilling accidents. Twenty group outcrops samples of carbonate rock were collected in the Northeast Sichuan

which buried depth of top surface is 3 568-5 983 m. With the help of MTS815.03

RMT150C rock mechanics test system and RSM-SYS5 ultrasonic tester

SEM examination

uniaxial compression test

triaxial compression test

acoustic wave test under confining pressure were carried out. Test results show that (1) carbonate rock is predominantly composed of biological-clastic dolostone and muddy-limestone

the diameters range from 0.01 mm to 0.2 mm; the main pore types are dissolution pore

intraparticle pore and inter-crystalline dissolution pore

porosity ratio range from 2% to12%; (2) spatial distribution characteristics of uniaxial compressive strength is some regularity but triaxial compressive strength has no regularity

be characteristic of chaotic; (3) velocity of longitudinal wave increases with the increasing of confining pressure; the velocity of longitudinal wave changes remarkably under the low confining pressure; and change little under the high confining pressure; the growth rate for dolostone is larger than that of limestone

The relationship between confining pressure and velocity of longitudinal wave is obtained. The results can provide technical parameters for drilling well in deep carbonate formation.