EC bit is an expandable and contractable bit a new concept of drilling the boreholes of different radii at different depths and in zone of our choice without changing the size of bit and without tripping operations.

During conventional drilling boreholes of different radii at respective depths are being drilled. In order to drill boreholes of different radii bits of different sizes are manufactured which consumes tremendous amount of material, time and finally the cost. In order to face this challenge here a tool has been proposed which uses single comprehensive bit size to drill complete well. The mechanism of this tool is based on the concept of rack and pinion system. The rotation of gears (pinions) and movement of the racks will help us to drill the borehole of radii of our choice.

With the help of this tool the important advantage is that the drillstring is not changed every time, only one size of drillstring is being used to drill complete well. This revolutionary idea of manufacturing ONLY ONE BIT SIZE will cost the drilling contractor a tremendous reduction in costs of bits. The other advantages include enhance production, reduction in skin damage and control the problem of sand production.


The width of a hole at every depth especially in the payzone is limited using the conventional drilling methods. This is because hole size is limited due to factors like cost of drilling a wide hole, rate of penetration, power requirements, size of BOP required, larger rigs required to handle more power and more weight, hence dramatically escalating the cost of the project.

Having large borehole at every depth or in the payzone is beneficial because it would:

  1. Enhance production

  2. Control the problem of sand production

  3. Accommodate a lot of downhole equipment.

Expandable and Contractable (EC) bit allows us to enlarge the borehole radius up to the order of a few feet selectively in zones we choose.

This is made possible by the EC bit, which uses rack and pinion mechanism (Fig-1) with its unique clockwise and anticlockwise rotation to drill a superwide borehole.

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