不倒翁式偏心防斜钻具的设计

Design of a tumbler eccentric and deviation-controlled drilling tool

目前所使用的各种钻具主要是靠钻具本身的重力来产生降斜力,在井斜角很小时,降斜力一般很小,在某些区块钻井时不能满足防斜要求。据此,设计了一种不倒翁式偏心防斜钻具。该钻具有1段钻铤,钻铤的两端各有1个偏心稳定器,钻铤外表面有一半圆形的偏心块,在钻铤和偏心块之间有轴承结构。利用不倒翁原理,当井斜超过一定值时,偏心块会在重力作用下自动停留在井眼低边,这样就可以将此处的钻柱顶到井眼的高边上去,从而产生一个很大的降斜力,使井斜得以有效控制。

As for the currently-used drilling tools, the drop-off force is produced mainly by the gravity of the tools. When the deviation angle is very small, generally the drop-off force is very small too, and this can not meet the need of hole-deviation control during the drilling in some blocks. Therefore a tumbler eccentric deviation-controlled drilling tool is designed. In the drilling tool, there is a collar, and two eccentric stabilizers are respectively fixed on its both ends and a half-round eccentric block is located on its surface, and a bearing is placed between the collar and the eccentric block. Based on the principle of tumbler, when the deviation angle exceeds certain value, the eccentric block will automatically stop at the low side of wellbore under the gravity force, and the drillstring here is pushed to the high side of the wellbore, thus a high drop-off force is produced to control the deviation.