Method of and mechanism for acquiring core samples from the sidewall formation of a wellbore

• Main Authors: DERRYL G SCHROEDER, MARCELO F CIVAROLO, JACQUES MAISSA
• Format: Patent
• Language: English
• Published: 04.06.1997
• Edition: 6
• Subjects: EARTH DRILLING; EARTH DRILLING, e.g. DEEP DRILLING; FIXED CONSTRUCTIONS; MINING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS

A method and apparatus for acquiring a plurality of sidewall cores from an earth formation intersected by a wellbore while a coring tool is located downhole. A sidewall coring tool is provided having an internal core receptacle for receiving and storing sidewall cores in serial orientation. The coring tool incorporates a movable bit box providing rotary support and linear coring and retracting movement of a rotary coring bit. A bit box tilting and rotation actuator is incorporated within the coring tool for achieving breaking at the core sample from the formation and for selectively positioning of the bit box and rotary coring bit at a coring position where the bit is oriented in normal relation with the axis of the wellbore and a core ejecting position where the rotary coring bit is positioned in registry with the internal core receptacle for deposit of cores in serially oriented relation therein. Another actuator is provided for accomplishing lateral coring and retracting movement of the rotary coring bit for acquiring a core and for retracting the bit and core within the coring tool. A third actuator is provided within the coring tool for displacing cores from the rotary coring bit into the core receptacle after the rotary coring bit has been positioned in registry with the core receptacle. A mechanism is also provided for locking the coring bit against inadvertent extension during bit box rotation. The sidewall coring mechanism further incorporates a reduction gear transmission permitting slow speed, high torque rotation of the coring bit, which transmission is automatically disengaged when the bit box is rotated from the coring position.