It is a directional drilling technique that is used to change the direction of an existing wellbore. This technique is typically used to sidetrack from an existing wellbore, which means that a new wellbore is drilled from the same wellhead as the existing wellbore. This can be done for a number of reasons, such as to access multiple reservoirs from a single well or to re-enter a well that has been plugged and abandoned.
Principles of Whipstock Drilling
The whipstock is the main component of a whipstock drilling system. It is a wedge-shaped device that is made of steel or another hard material. The whipstock has a sloping face that is designed to deflect the drill bit in the desired direction. The whipstock is anchored in place in the wellbore by cement.
- Setting the whipstock
The first step in whipstock drilling is to set the whipstock in place in the wellbore. This is done by lowering the whipstock into the wellbore and positioning it at the desired depth. The whipstock is then anchored in place by cement. - Initiating the sidetrack
Once the whipstock is in place, the next step is to initiate the sidetrack. This is done by drilling into the whipstock with a directional drilling tool. The directional drilling tool is a specialized tool that is designed to follow the sloping face of the whipstock and deflect the drill bit in the desired direction. - Drilling the sidetrack
After the sidetrack has been initiated, the next step is to drill the sidetrack to the desired depth. This is done using a conventional drilling tool. - Completing the sidetrack
Once the sidetrack has been drilled to the desired depth, the next step is to complete the sidetrack. This may involve running casing, installing a liner, or completing the well.
Advantages and Disadvantages of Whipstock Drilling
Whipstock Drilling technique enables the creation of a sidetrack from an existing wellbore, offering several advantages in various drilling scenarios. However, it also comes with certain drawbacks that need to be considered. Here is a comparison of the advantages and disadvantages of whipstock drilling.
Advantages
Relative simplicity and affordability: Whipstock drilling is a relatively straightforward and cost-effective directional drilling technique compared to more sophisticated methods. The equipment and procedures involved are less complex, requiring less specialized expertise and reducing overall operational costs.
Disadvantages
Directional control challenges: Controlling the precise direction of the sidetrack can be challenging with whipstock drilling, particularly in formations with varying hardness or when drilling through fractured zones. This can lead to deviations from the intended path, potentially resulting in complications or missed targets.