景谷凹陷钾盐调查JG-2井饱和氯化镁盐水钻井液技术

Saturated magnesium chloride brine drilling fluid technology for the potassium salt survey Well JG-2 in Jinggu Sag

摘要:

JG-2井位于云南省普洱市景谷傣族彝族自治县凤山镇，构造位置属思茅盆地景谷凹陷，完钻深度1829.44 m。钻遇地层主要为泥岩、砂岩、泥砾岩、石盐岩、钾石盐岩等，泥岩易发生水化膨胀剥落、造成井壁坍塌危害，局部松散砂岩易坍塌掉块，而石盐岩、钾石盐岩易溶蚀形成坍塌超径和盐矿心采取率低等安全和质量隐患。针对JG-2井上述施工难题，进入石膏脉盐岩地层后，采用饱和氯化镁盐水钻井液钻进，圆满地完成了工程钻井与取心任务，解决了钾石盐岩等盐矿心溶蚀、石盐岩粗颗粒不易携带、钻头泥包及松散砂岩坍塌掉块等技术难题，顺利取全盐岩层顶板与底板等岩心，获取了优质的石盐岩、钾石盐岩等盐矿心，全井平均岩（矿）心采取率达97.5%，且未发生溶蚀。本文成功经验可为从事类似钾盐钻探工程提供借鉴和参考。

Abstract:

Well JG-2 is located in Fengshan Town， Jinggu Dai and Yi Autonomous County， Pu’er City， Yunnan Province. The structural location belongs to Jinggu Sag of Simao Basin， and the completion depth is 1829.44m. The lithology of drilling strata are mainly mudstone， sandstone， mud conglomerate， halilith， sylvinite and so on. The mudstone is prone to hydration expansion and spalling， resulting in wellbore collapse hazards. Local loose sandstone is prone to collapse， while halilith and sylvinite are easy to dissolve to form hole enlargement and low salt core recovery rate. In view of the above construction problems， saturated magnesium chloride brine drilling fluid was used when entering the gypsum vein salt formation to successfully complete the engineering drilling and coring tasks. The technical problems such as the dissolution of salt cores such as sylvinite， difficulty to carry coarse particles of salt， bit balling and collapse of loose sandstone were solved. Full salt cores containing the roof and floor part were successfully taken， and high-quality salt cores such as halilith and sylvinite were obtained. The average core recovery rate of the whole well was 97.5% without dissolution. The successful experience of this paper can provide reference for similar potassium salt drilling projects.