OIL WELL SAFETY VALVE APPARATUS AND METHOD

摘要

An oil well control device automatically shuts in a well responsive to the removal of a work string (or other removable structure—ball retarding structure) from the device. The device is placed in the well as a section of the well casing. The device provides a pair of bores, one that aligns with the well bore or well casing, the other being a branch flow line containing a ball structure that will close the well if the drill pipe or drill string is removed. While conducting normal well activity (e.g. drilling, work over or the like) the ball retarder (e.g. work string) prevents entry of the ball structure into the main flow channel.

主权项

1. An oil well safety shut off method, comprising the steps of:
a) providing in a section of well casing having a well bore, a device having a first flow bore of a first diameter aligned generally with the well bore of the casing so that flow through the casing also flows through the first flow bore; b) providing a second flow bore that communicates with the first bore at two spaced apart positions to provide a lower flow entry from the first flow bore and an upper flow discharge into the first flow bore, the second flow bore having a diameter that is at least in part larger in transverse cross section than the first diameter; c) providing an upper ball seat above the upper flow discharge; d) providing a lower ball seat in the second flow bore in between the lower flow entry and the upper flow discharge; e) placing a ball valving member in the second flow bore above the lower seat; f) disallowing entry of the ball valving member into the first flow bore by placing a ball retarding member in the first flow bore, the ball retarding member occupying a position within the first flow bore next to the upper flow discharge; and g) a removal of the ball retarding member enabling the ball valving member to form a seal with the upper ball seat, slowing the flow of fluids upwardly in the first flow bore.