Drilling Fluid Technology for Drilling Third Interval of Extended Reach Appraisal Well Lixie572

drilled in Lijin block (Shengli Oilfield) penetrate two formation members, the shale Sasan member and the sandy conglomerate Sasi member interbedded with calcareous mud stone. These two members are easy to collapse and hard to drill. Geological data show that wells drilled nearby have experienced many times of mud losses, borehole wall collapse and pipe sticking. The well Lixie572 has well angle of at least 70° and horizontal displacement of 1911 m, requiring that drilling fluid should have good drill cutting carrying capacity, or the drill tools will got stuck by settled cuttings. A drilling fluid formulated KCl, NaCl and amino polyol was used to drill this well. KCl was used to inhibit shale formations by clay lattice fixation and NaCl to inhibit shale formations by flocculation. The amino polyol has strong shale inhibitive capacity. The drilling fluid had low solids and bentonite content throughout the drilling operation, and clay dispersion was kept at low level. The ROP was greatly increased, and total drilling time was saved by 20 d. Using high temperature filtration control agents and other sealing agents such as emulsified paraffin, polyether polyol and ultra-fine calcium carbonate, the borehole wall was maintained stable. Near-balanced drilling was adopted in the drilling process; the density of the mud was maintained at the lower limit of the designed values. In doing so, mud losses were avoided and the reservoir was protected from being damaged. Wireline logging, rotary side coring and casing running were all performed successfully at the first try. Average percent hole washout was only 5.20%, and there were no downhole troubles and no downhole accidents ever happened.