固定同心式随钻扩孔器防斜打快技术初探

针对传统防斜打快技术限制机械钻速和防斜效果差的缺点，以及先进的自动垂直钻井系统成本高又无法大面积推广的现状，提出了采用固定同心式扩孔器进行边钻边扩来达到防斜打快的效果。其打快原理是：在钻进时，固定同心式扩孔器和领眼钻头形成的阶梯形井底改变了井底岩石的应力状态，使其容易破碎，从而提高机械钻速；领眼钻头可获得足够的机械和水力能量，能提高机械破岩能力及改善清洗井底的效果，从而有利于提高机械钻速。其防斜原理是：扩孔器受到的平衡地层的力克服了钻头偏斜力，使钻头中心线与井底保持垂直；扩孔器与领眼钻头之间的距离很短，使扩孔器下部钻柱弯曲变形十分有限，从而有效限制了钻头偏斜。现场应用表明，采用固定同心式扩孔器随钻扩孔能实现防斜打快的目的，并为防斜打快技术的研究提供了一套全新的思路。

Study on Well Deviation Control and Faster Drilling Technique with Fixed Concentric Reamer

Considering the low ROP and poor deviation control ability of traditional deviation control and faster drilling technique and the high cost and narrow applications of the auto-vertically drilling system, the paper puts forward a new technique which uses the fixed concentric reamer to make deviation control while reaming. Its faster-penetration principles are step-shaped well bottom constructed by fixed concentric reamer and pilot bit makes formations be crushed more easily, and pilot bit can get enough mechanical and hydraulic powers to improve rock penetration capability and hole cleaning effects. Its deviation control principles are that side forces exerted on reamer by formation balances bit deviation force which make bit and hole bottom be vertical, and short interval between reamer and pilot bit restricts bottom pipe buckling, thus effectively limits the drift angle of bit. Field applications show that this unique tool can meet demands for deviation control and faster penetration, and it provides a novel idea for such technique development.