Abstract:During the drilling process in the covering layer of Zhumadian area in Henan Province, drilling encountered the Quaternary clay layer, the sandy mudstone, the loose sandstone and mudstone interbedded with uneven thickness, difficult drilling wall protection, and prone to accidents such as block jamming, hole collapse and burial, taking core difficultly. Based on the geological and stratigraphic conditions and the drilling construction data within the area, the dual-polymer anti-collapse drilling fluid was used. Through the on-site application of the dual-polymer anti-collapse drilling fluid, the stability of the hole wall was good during the drilling process in the long open hole well section, without any incidents of falling or collapsing. The core monitor rate met the geological design requirements with reducing the depth of casing insertion and saving construction costs.
