Drill String Design CalculationsDrilling Bit and provide sufficient torsional and tensile strength to withstand the vigorous and dynamic conditions of drilling. The drill string should also withstand burst and collapse pressure loads and be designed to minimize hole stability problems.
There are many factors that must be considered in the drill string design such as:
- Total depth
- Hole size
- Mud weight
- Over pull
- Bottom Hole Assembly
- Hole angle
- Pipe weights and grades
- Corrosive environment
- Ability to fish tools out of hole
Introduction To Drill String Design:To full understand the steps for the drill string design calculations, you will have to get in details on the drill string components including the design of drill pipes specification and drill pipes tool joints selection.
Drill String Design Calculations Steps
Drill Pipes Selection
Maximum Over Pullcheck the maximum over pull you can apply to drill string without drill pipes failure. It is easy to be done just remember don't exceed 80% of drill pipes yield strength.
Drill Pipes Collapse Pressurecalculate the effective drill pipes collapse pressure.
Drill Pipes Burst Pressure.check the used drill pipes burst pressure.
Tool joint Torsional Strength
Assume that the produced torque during drilling the well proceeds the make up torque of drill pipes tool joints or the torsional strength of drill pipes, then what will happen. So checking tool joints torsional strength and drill pipes torsional strength is important during the drill string design calculations.
Drill Collars Size SelectionOn which basis you are going to use bigger or smaller Drill collar. Next step to select the proper drill collar size for your drill string design.
Weight On Bit (WOB) Calculations
Heavy Weight Drill pipes
The Final step on Drill String designThe final step in vertical hole drill string design calculations is to select the proper Bottom hole Assembly according to many aspects. Go in deep details on Bottom Hole Assembly Components, Types, Behavior
Directional Drilling String Design for Deviated wells to have more details.
Drill String Design for High Angle and Horizontal Wellbores
The objectives of drill string design in horizontal wells are:
- Provide adequate weight on bit without buckling the drill pipe or heavy weight drill pipe.
- Ensure that the components in the drilling assembly are not subjected to mechanical loads that exceeds their design limitation