Sigra can design a directional drilling programme. This ability stems back from work in the 1990’s which involved underground directional drilling studies and the first surface to in-seam well in Australia. This developed with further studies into the behaviour of tool joints under axial load, torsion and bending and internal pressure. All of this work was undertaken as a project for the Australian Coal Industry Research Program.
Currently Sigra has three key capabilities in this area supported by in house software which has the following functions.
Sigra can model the location of a borehole using information from total depth and angular information from a survey tool.
Torque and Drag Modelling
This models all the forces on a drill string in a borehole with a defined path. Because it is a stiff string model the bending moments and shears within the drill pipe and their interaction with the borehole wall are fully taken into account. It is suitable to model all directional drilling systems whether rotary, rotary steerable or mud motor. The inputs to the model are:
- Borehole trajectory
- Borehole size
- Drill pipe type
- Coefficient of friction between the drill pipe and the borehole wall
- Movement direction – rotation, sliding in, pulling out
- Bit loading. The outputs are:
- Hook load
- Total load within all sections of drill string – axial, bending and shear
- Ratio of stress: failure stress within the drill string
The software can be used to analyse old holes, predict for new holes or be linked to a drilling operation in real time so as to derive full information on the state of stress within the drill string while drilling.
Bottom Hole Assembly Build Characteristics
Sigra has developed software which can rapidly determine the angular build characteristics of a bottom hole assembly (BHA) from drilling information. This takes hole survey and drilling rate information and analyses it to create a model of how the assembly will respond. It can be used to analyse previously drilled holes or in real time mode on the drill rig to learn behaviour of the BHA in a particular formation as it drills.