In many areas of Qaidam Basin，such as Yingxiongling，Ganchaigou and Xiandong，the shallow strata have poor lithology， loose cementation，fracture development，and frequently-occurred loss-return leakage in the process of drilling，which have seriously restricted the speed of drilling and affected the safety of drilling. This is a regional problem that needs to be solved urgently. Well Chaitan1 is a risk exploratory well located in Xiandong area. Conventional drilling fluid was used for the drilling of the surface section hole with a diameter of 660.4 mm. Leakage during the drilling was huge，and the plugging effect was not satisfactory. Therefore，it no longer possessed conditions to continue with the drilling. By using air-foam drilling technique and selecting the most suitable foaming agent and inhibitor for this well，the problem of frequently-occurred loss-return leakage in shallow strata has been solved，and the drilling cycle has been greatly shortened. By using the technique of sand cleaning-casing running，safe casing running has been realized in the well section with instable borehole and irregular hole diameters. The successful application of air-foam drilling technique in the Φ660.4 mm hole of Well Chaitan1 provides an approach and technical reserve for solving the problems of low pressure and likelihood for leakage and collapse in shallow strata during drilling in Qaidam Basin.

柴达木盆地英雄岭、干柴沟、咸东等多个区域浅表部地层成岩性差、胶结疏松且裂缝发育，钻井过程中失返性漏失 频发，严重制约钻井提速，影响钻井安全，是亟待解决的区域性难题。柴探1井是部署在咸东地区的一口风险探井，一开Φ660.4 mm井眼采用常规钻井液施工期间漏失量巨大，堵漏效果不佳，已不具备继续钻进条件。通过采用空气泡沫钻井技 术，优选该井适用的发泡剂与抑制剂，针对性地解决了浅表层失返性漏失频发难题，钻井周期大幅缩短；采用清砂下套管技 术，实现了井壁失稳、井径不规则井段套管的安全下入。柴探1井Φ660.4 mm井眼空气泡沫钻井技术的成功实施，为柴达木 盆地浅表层钻井低压易漏易垮塌难题提供了解决思路和技术储备。