Abstract
Conventional methods used to steer the BHA when drilling with air are primitive and time consuming. Usually, a single shot survey tool is the most convenient option for steering the BHA.1 Survey tools, however, are not designed for the harsh environment. Consequently, they are prone to early failure in this application. To improve reliability and drilling efficiency in air and gas drilling, the Modular Magnetic Tool (MMT) was developed. The MMT employs a rugged steering tool with a wet-connect system. This MMT/Wet Connect System allows orientation of the drilling motor in a particular direction while still allowing drilling straight ahead with drill string rotation.
The steering tool was specially designed to handle the high shock and vibration when drilling with air and gas. It provides continuous surface readout of drift angle and azimuth of the hole as well as tool face orientation while drilling ahead.
The wet-connect system allows the wireline to be run through the drill string from the top of the Kelly. Connection of the wireline employs a male end (rocket) that sits in a special sub in the drill string. A female end stabs onto it whenever it is desirable to orient or survey. The female end can be tripped out of hole inside the Kelly, either to make a connection or to allow rotation of the drillstring. This configuration minimizes both down time and damage to the wireline that could be critical when drilling in certain formations.
This paper discusses system design and performance, and presents case studies of wells drilled utilizing this system.
