涌水坑道钻孔岩心上升系数ξ定义及其实践意义

Definition of core-uplift-coefficient ξ in large water kick core holes and its field application

坑道钻孔内涌水给常规小口径取心钻探带来了极大的施工难题。水银洞金矿Ia矿体地下水丰富,坑道钻探施工中,发现孔底岩心可以从孔口冲出。由此提出了坑道涌水钻孔岩心上升系数ξ,其物理意义是岩心在孔底水压和浮力的作用下,克服重力以及与钻杆内壁摩擦力而自动上升的能力,并结合钻孔实际参数,讨论了ξ的实践意义。当ξ≥1时,理论上孔底岩心可以随孔内涌出水从孔内冲出;当ξ<1时,孔底岩心则不能被冲出,只能依靠起大钻取出。通过计算矿层的岩心上升系数,结合实际地层的完整性情况,可以帮助钻探人员控制合适的进尺后割心,使ξ≥1,从而让钻孔内岩心自动从孔底排出。岩心上升系数,可以为提高地表和坑道高压涌水钻孔钻进效率提供理论指导,具有一定的实践意义。

The water kick in tunnel bore holes brings great drilling operation problems to conventional small diameter coring operations.It was found that the core could get out of the hole at high water pressure in the tunnel hole drilling operation to explore the Ia ore body of Shuiyindong Gold Mine.Thus,the core-uplift-coefficientξwas put forward where physically it means that under the action of water pressure and buoyancy at the bottom of the hole,the core overcomes its gravity and the friction force to automatically rise.Its field application was discussed in combination with the actual parameters of bore holes.Whenξis greater than or equal to 1,theoretically the cores at the bottom of the hole can rush out of the hole with the water kick.Whenξis smaller than 1,the cores cannot be flushed out of the hole and drillers should pull out the drilling string to recover the cores.With calculating theξof the ore layer and combining it with the integrity of the actual stratum,the drillers can control the proper drill footage to break off the core so as to make sure theξ≥1,allowing the core in the drill hole to automatically lift up from the bottom of the hole.The core-uplift-coefficientξcan provide not only theoretical guidance for high pressure water kick hole coring in the surface or the tunnel,but also has certain practical significance.