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四川某坝址,属中生代侏罗纪重庆群地层,岩性为砂岩夹软弱粘土岩。为了取好岩样及了解粘土岩是否有泥化现象,我们在坝址中主要剖面上的几个钻孔,全孔采用了无泵钻进方法,取样效果较好,特别在软弱岩层中岩心获得率高,基本上能保证质量。现将在钻进中的几点作法和体会叙述于下: 一、无泵钻具 1.单弹子无泵钻具(见图1):适用于可钻性3～4级的粘土岩类地层。其特点是:管路较粗(φ1(1/4)~(11)),活动钻具时,能使冲洗液畅通,岩心不易烧死。 2.双弹子无泵钻具(见图2):适用于可钻性5～6级的砂岩及粉砂岩地层。其特点是:(冂巳)次钻进完毕后,可洗孔投卡料,把岩心卡取上来。二、操作方 法
A dam site in Sichuan Province is a member of the Mesozoic Jurassic Group in Chongqing. Its lithology is sandstone clamped soft clay rock. In order to obtain the rock samples and understand whether the clay rocks are muddy, we have several holes drilled in the main section of the dam site. The whole hole adopts the non-pump drilling method, and the sampling effect is good. Especially in the soft rock layers, Get high, basically to ensure quality. Now drilling in a few practices and experiences described in the following: First, non-pump drilling 1. Single-pin pump-free drilling (see Figure 1): applicable to drillability of 3 to 4 clay rock strata . Its features are: the pipeline is thick (φ1 (1/4) ~ (11)), the activities of drilling tools, make the flushing fluid flow, the core is not easy to burn. 2. Double-pinch pump-free drilling (see Figure 2): applicable to drill 5 to 6 sandstone and siltstone formation. Its features are: (冂 巳) After the second drilling, washable hole vote expected to take the core card. Second, the operation method