Apparatus for stage-cementing an oil well

摘要

An apparatus for use in stage-cementing an oil well in the region of a lost-circulation zone that is proximate an annular space defined by the lower end of an outer casing surrounding an inner casing include a load-bearing annular steel plate of substantial thickness that is positioned on, and maintained stationary relative to the inner casing by supporting and retaining means secured to the inner casing, the outer diameter of the plate being less than the inside diameter of the outer casing so that the plate can be lowered with the inner casing string to the desired location inside of the outer casing and, with a layer of gravel, to provide a seal and support the cement poured into the annulus between the inner and outer casings.

主权项

1. An apparatus for use in stage-cementing a fluid production well in a region of a lost circulation zone that is proximate an annular space defined between a lower end of an outer casing surrounding an inner casing, the inner casing being formed by a cylindrical sidewall having an outer surface, the outer casing being formed by a cylindrical sidewall having an inner surface that has an inside diameter that is greater than the outside diameter of the inner casing, the apparatus comprising:
a load-bearing annular steel plate having an outside diameter and an inside diameter, the outside diameter of the load-bearing annular steel plate being greater than the inside diameter of the load-bearing annular steel plate to form a ring-shaped plate, the inside diameter of the annular steel plate forming a central opening that is greater than the outside diameter of the inner casing, the annular steel plate being immovably positioned on a section of the inner casing relative to a longitudinal axis of the inner casing, the annular steel plate having an upper surface and a lower surface, the upper surface having a continuous annular raised shoulder positioned to continuously surround the central opening, and wherein the outside diameter of the annular steel plate is less than the inside diameter of the outer casing; and an inner casing coupling for joining a pair of adjacent longitudinally aligned casing sections of said inner casing, the inner casing coupling having an outside diameter greater than the outside diameter of the inner casing, the inner casing coupling having an upper surface that is positioned below and supports the lower surface of the annular steel plate.