CEMENT PLUGGING SYSTEM Russian patent published in 2008 - IPC E21B33/13 

FIELD: petroleum industry.

SUBSTANCE: invention is referred to the well drilling and workover areas. The system includes nipple with through holes in middle and lower parts, top box, shoe and bottom box located above the shoe. Through holes of the middle part of the nipple are arranged by rows in checkerboard order. Number or rows is calculated from the expression. The shoe is furnished with internal flush hole and tapered outer surface in the lower part provided with blade and made with plug catching baffle for the ball. The shoe has internal groove in the top part with bottom part of the box with development of discharge chamber which is hydraulically connected with the nipple cavity via the holes in the lower part of the nipple. The blade has a L-type cutting, separating it into two parts. Lower surface of the top box and top surface of the bottom box make the annular slot. Lower edge of the lower part holes is located above the annular slot level to the height determined by the condition. Inner surface s of top and bottom boxes and matching outer surface of nipple make annular cavity which is hydraulically connected to the nipple cavity. Outer surface of the nipple above the top row of holes of the middle part has the annular lip, the said annular lip including the element to control opening of the annular slot.

EFFECT: higher quality of cement plugging and improved operational reliability of the system.

1 cl, 3 dwg