Directional Drilling Flashcards
What is a relief well?
A well drilled to intercept another well that is gone out of control with HC burning or overflowing.
Why is it important to drills directional well when faced with a salt dome structure?
Drilling mud will dissolve the salt enlarging the hole, although there are alternatives, a directional well would be cheaper.
Explain directional drilling.
Is a form of drilling that intentionally deviates to achieve a desired objective.
What 2 types of directional wells are there?
J type, is a well deviated to a certain inclination and then maintained to target.
S type, a well deviated to certain inclination from vertical to a certain length and then brought back to vertical.
Name 2 rig parameters that are important in directional wells.
- rotary torque
- pump pressure
Why is it important to know dips of the formation while drilling directional wells?
Helps the driller plan for trajectory better, will know what to expect at every point in the wellbore. Uses the data to plan rotations and slides more effectively.
What benefit does a directional driller have in knowing offset well data?
Driller can know when to anticipate problems and what solution to use to fix the problem. Another benefit, knowing which drill bits to use to optimize performance.
Having several nearby wells on a pad creates what problem for the directional driller?
Colliding with other wells.
When reading a travelling cylinder plot, where is the subject well located on the plot?
The subject well is always at the centre of the plot.
When a survey is taken, does it provide a reading at the bit or a distance away from the bit? What must the driller do to plan for the next course of action?
The survey is completed about a 15m distance behind the bit. The driller must update his model and takes necessary action to keep the well on plan.
What problem is inherent in all survey tools? What Is the source of this problem?
There is a degree of error from the mathematical model of calculations but also from the down hole changes in the magnetic field.
What survey tool only provides inclination?
Totco is the simplest and most common.
What is required as part of the drill string for the survey tools to be able to measure azimuth without interference?
A non-magnetic drill collar or drill pipe.
Which survey tool is not affected by magnetic interference?
A gyro tool due to the difference in the principle of measurement.
What tool is referenced as the benchmark in surveying?
A gyro tool due to its accuracy in measurement.
