大位移评价井利斜572井三开钻井液技术

利津油田沙三段为泥页岩，沙四段为大段砂砾岩夹杂灰质油泥岩，易坍塌，钻时慢。地质资料显示，邻井多次发生井漏、井塌与卡钻；且该井井斜超70°，位移为1911 m，对携岩能力要求高，易形成砂桥，卡钻风险极大。利斜572井采用复合盐强抑制防塌体系，利用KCl的晶格固定作用、NaCl的适度絮凝作用和胺基聚醇的强抑制能力，其加量分别为7%、5%、1%，控制较低的固相、膨润土含量和土相分散度，极大地加快了钻进速度，钻井周期比设计节约了近20 d；优化抗高温降滤失材料配方，复配使用2%乳化石蜡、3%聚醚多元醇、3%超细碳酸钙等具有不同作用原理的封堵材料，维护了井壁稳定；密度执行设计下限为1.15 g/cm3，采用近平衡压力钻井，不但没有漏失，而且最大限度地保护了油气层。电测、旋转井壁取心与下套管均一次成功，平均井径扩大率仅为5.20%，且该井全井零复杂情况、零事故。 

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.