Permanent whipstock
AssigneeBaker Hughes Incorporated
InventorsJohn P. Davis, Gerald D. Lynde, Mark H. Lee, Arthur G. Alexander
Life of this patent
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Abstract
This invention relates to a permanent whipstock assembly which uses camming pivot arms to secure the whipstock at the desired location within a cased wellbore. Camming pivot arms are pivotally attached to the downhole end of a whipstock housing and are further attached to a slip pad. Intentionally induced relative movement of the slip pad and the whipstock housing causes the camming pivot arms to pivot in such a manner that slip pad housing 4 and slip pad 5 are forced away from each other and cammed into the cased borehole. The invention relates specifically to a device that is particularly adapted to be lowered through a small diameter and later to be activated and set in a much larger casing or hole diameter.
Claims34
A permanent whipstock assembly comprising:
- a) an elongated whipstock housing including a whipstock and a slip pad housing;
- b) a plurality of pivot arms pivotally connected to said slip pad housing;
- c) a slip pad pivotally connected to at least one of said plurality of pivot arms;
- and
- d) a setting assembly connected to said slip pad for drawing said slip pad uphole to set said plurality of pivot arms thus biasing said slip pad, said slip pad housing and said whipstock against a casing in a wellbore wherein the permanent whipstock is located, whereby said whipstock assembly is permanently secured within said wellbore.
A shear block assembly for use with a camming whipstock assembly comprising a lower shear block and an upper shear block said lower shear block being shearably fastened by a fastening arrangement to said upper shear block said shear block assembly being disposed within an opening defined by said whipstock.
A method of setting a permanent whipstock at a preselected position within a cased borehole comprising the steps of:
- a) running in a permanent whipstock assembly, including a slip pad housing having at least one camming pivot arm attached to the slip pad housing, a slip pad attached to the at least one pivot arm, the slip pad being attached on an uphole end to a downhole end of a lower setting bar, an uphole end of said setting bar being attached to a lower shear block, said lower shear block being shearably fastened by a fastening arrangement to an upper shear block which is connected to an upper setting bar;
- b) generating a tensile force within the assembly sufficient to shear a shear pin in the lower shear block so that a setting assembly begins to rotate the at least one pivot arm, thus moving the slip pad further from the slip pad housing and increasing the diametrical dimension of the whipstock assembly in the region of the slip pad housing and slip pad, so that the dimension is equivalent to an inner diameter of the cased borehole so that the at least one pivot arm is set;
- c) increasing tensile force upon the assembly until the fastening arrangement fastening the upper shear block and the lower shear block shears.
Dependencies are inferred from the claim text.