Mechanical Casing Exit Window Locator and Whipstock Alignment System

Abstract

A whipstock assembly for emplacing and orienting a whipstock within a wellbore. The whipstock assembly includes a whipstock, an anchor sub for securing the whipstock within the wellbore and a locating tool which is releasably secured to the whipstock. The locating tool includes a tool body with an inclined contact face and a hook which extends radially outwardly from the tool body. The hook is shaped and sized to engage a lower end of the casing exit window to align and orient the whipstock with the casing exit window.

Description

BACKGROUND OF THE INVENTION1. Field of the Invention[0001]The invention relates generally to devices and methods for steering or diverting subterranean drilling arrangements. More particularly, the invention relates to devices and method for deflecting the drilling direction of a drill string through a borehole wall and into a radial direction away from a main bore.2. Description of the Related Art[0002]To enhance recovery of subterranean oil and gas, it is a common practice to steer or divert a portion of a wellbore away from a substantially vertical main bore and into a horizontal or deviated lateral direction. To do this, it is typical to anchor a whipstock into the vertical wellbore and thereafter mill away a window in the casing of the wellbore. Then the milling tool is removed from the wellbore. A drill string can then be disposed into the wellbore and the drill bit deflected radially by the whipstock to form a lateral bore which extends away from the main vertical wellbore. W...

AI Technical Summary

Benefits of technology

The invention describes a way to place a whipstock in a wellbore that has a casing exit window and a lateral bore. A bottom hole assembly with a whipstock and an anchor is used. A locating tool is attached to the whipstock to help guide it into position. The locating tool has an angled contact face that aligns with the whipstock, and a hook that engages with the lower end of the casing window. The whipstock is then run into the wellbore and set in place. A drilling string can then be run into the wellbore and directed into the lateral bore using the whipstock. This system simplifies the process of installing a whipstock and ensures proper alignment with the casing window.

Problems solved by technology

This operation can be problematic, particularly when running in an anchoring a new whipstock.

Even slight misalignment of the upper end of the whipstock with the lower end of the casing window can result in a subsequently run drilling string becoming hung up or fail to properly enter the lateral bore.

However, the casing profile may be inaccurate or lack sufficient detail to be able to properly place the whipstock.

However, with this technique, it can be difficult to know whether the casing or tubing is located within the lateral leg or the main bore.

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