Drilling with slotted liner sheathing coiled tubing ( SLSCT) is a new technique for multilateral jetting, which is designed to synchronize the jet drilling and liner tube running in one trip. Its drilling assembly includes dual-pipes, thus the cuttings transport efficiency in a dual-pipe mode needs special analysis. In this study, laboratory experiments were con-ducted to investigate the cuttings transport mechanisms in a dual-pipe system. A Monte Carlo algorithm was proposed to de-termine the amounts of cuttings entering the annulus between the coiled tubing and slotted liner, and it was also used to es-timate the critical pumping rate and drilling rate for the case of cutting blocking. A four-layer model for cuttings transport with the SLSCT multilateral jetting was established, including suspension layer, moving bed layer, stationary layer and cut-ting blocking layer, which exist in the annulus between the coiled tubing and slotted liner. The cuttings carrying capability of a dual-pipe system is higher than that of the conventional coiled tubing drilling due to the smaller flow area thus the high-er annular pumping velocity. Under the experiment conditions of this research, the critical condition for no cutting blocking is that, in the case the slot size smaller than the cutting particle size, the pumping rate is higher than 0. 98 L/s, or the ROP is smaller than 40. 09 km/h, and the wider the slot size, the lower the ROP. In the case of the slot size larger than the cutting particle size, the pumping rate is recommended to be higher than 0. 88 L/s, or the ROP is smaller than 5. 74 km/h.%连续油管带筛管喷射侧钻多分支井钻完井一体化是一种新型的多分支井钻井方法,针对本技术连续油管和筛管所形成的双重管柱,开展岩屑运移试验研究,采用Monte Carlo方法预测岩屑颗粒进入割缝筛管与连续油管之间环空的情况,并计算环空中被岩屑颗粒堵塞的临界参数。结果表明：双重管柱岩屑运移存在悬浮层、跃移层、静止岩屑层以及筛管与连续油管之间的砂堵层。由于具有更小的环空过流面积,双重管柱的岩屑运移能力比常规连续油管钻井高。试验条件下,砂堵层不发生堵塞的临界条件是：当缝宽介于岩屑颗粒之间时,泵排量高于0.98 L/s,或机械钻速小于40.09 km/h,缝宽比岩屑粒径越大,临界机械钻速越小；当缝宽大于岩屑颗粒直径时,泵排量高于0.88 L/s或机械钻速小于5.74 km/h。
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