Patent ID: 7735550

Claim:
A throttle unit for a dump bailer used in blocking a water out zone in a production well, comprising: a hollow outer barrel having an upper end and a lower end, the upper end serving as a joining end including a joining structure, and the lower end serving as a releasing end and including an annular conical surface formed inside the outer barrel between the joining end and the releasing end; and a hollow inner barrel connected to and received in the joining end of the outer barrel, the inner barrel having an upper end and a contacting section, the upper end including a connecting section connectable to the dump bailer and a lower end including an engaging section engageable with the joining structure of the outer barrel, and the contacting section being provided on an annular wall with a plurality of spaced through holes and extending downward from the lower end of the inner barrel by a predetermined length, and having a bottom shaped into a conical guiding surface corresponding to the annular conical surface in the outer barrel, wherein the inner barrel is height adjustably received in the joining end of the outer barrel, so that a size-adjustable flowing space is defined between the conical guiding surface at the bottom of the contacting section and the annular conical surface in the outer barrel by adjusting an amount of overlap between the joining structure of the outer barrel and the connecting section of the inner barrel to create the flowing space between the annular conical surface and the conical guiding surface, to release a fluid through the flowing space and the releasing end of the outer barrel.