Avoidance of tracking original hole during cased-hole sidetrack

27 January 2018 Hi folks

At a recent DWOP, the team were discussing the planned cased-hole sidetrack.  It will be exiting 9⅝" Q125 casing at approximately 67 degrees inclination. The plan is to 'hold' that inclination for another 1500m (8½" hole)

The milling will be deliberately slow to account for the Q125 casing.  After milling the window, an elongation run is planned to prepare access for the RSS.

The current plan is not to use the milling assembly to drill rathole once the (top) dress mill is outside the casing, so as not to lose directional control.  However, we don't want to be rotating any of the stabilisers of the RSS on the whip-face, so may be obliged to make a separate run with motor, bent sub/housing and rock bit.

It's important not to track the original hole, which is dropping angle.

We'd value any additional considerations that members might have, in particular with regard to avoiding to track the old hole

Many thanks 

Dave.

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