松科2井抗超高温钻井液技术

松科2井是1口部署在松辽盆地的高温科学钻探深井，目的为钻穿白垩纪地层，获取基底陆相沉积记录，预测井底温度超过220℃；四、五开钻沙河子组的泥岩、砂岩混层，火石岭组破碎的凝灰岩、泥岩、煤线的混层，容易发生坍塌现象，防塌措施尤其重要。四、五开属于连续提钻取心钻进，多次起下钻及长时间的裸眼对井壁稳定提出较大挑战；不同钻进工艺具有不同的特点，对钻井液也提出挑战。针对以上难点，研制出了抗高温聚合物钻井液:1.0%钠膨润土+2%凹凸棒土+0.2% KOH+（0.5%~1%）高分子量降滤失剂+1%中分子量降滤失剂+2.5%成膜剂+（2%~4%） SMC+2% FT+3% KCl+2% NaCOOH+3%白油。四开初期对三开的井浆进行评价，结合大量的室内小型转换实验，以原井浆为基础逐步进行转换，以满足钻进要求；五开因处理事故对井浆性能调整较大，事故结束后简化钻井液处理剂种类，逐渐将性能调至稳定状态。在松科2井现场应用时，根据实际情况及时调整，该阶段钻井液高温下流变性好、高温稳定性强，室内评价其抗温能力达到240℃，热滚72 h后性能良好，为顺利完成该阶段钻探工作提供了技术支撑，对提高钻探质量、降低勘探成本起到指导作用。 

Ultra-high Temperature Drilling Fluid Technology of Well Songke-2

The well Songke-2 is a high temperature deep scientific exploration well deployed in the Songliao Basin, its purpose is to penetrate the Cretaceous formations to obtain the records of basal continental deposit. The bottom hole temperature has been predicted to be over 220℃. Measures for preventing borehole wall collapse are especially important in drilling the fourth and fifth intervals since borehole wall collapse has occurred previously in drilling the interbedded mudstone and sandstone in the Shahezi formation, and the broken tuff, mudstone and coal seam in the Huoshiling formation, which were to be penetrated by the fourth and fifth intervals of the well. Continuous coring was to be conducted in the fourth and fifth intervals, and frequent tripping of drill string gave a big challenge to borehole wall stabilization because of long time contact of the open hole with drilling fluid. The adoption of different drilling techniques in turn gave a challenge to drilling fluid. A high temperature polymer drilling fluid has been formulated to deal with these challenges. The composition of the drilling fluid is as follows:1.0% bentonite + 2% attapulgite +0.2%KOH +(0.5%-1.0%) high MW filter loss reducer +1% moderate MW filter loss reducer + 2.5% filming agent + (2%-4%)SMC +2%FT +3%KCl + 2%NaCOOH +3% white oil. At the beginning of the fourth interval, the mud left over from the third interval was evaluated and converted for re-use in the fourth interval based on large amount of pilot tests. In the fifth interval, the property of the mud was greatly modified because of the needs for dealing with downhole troubles. When the downhole troubles were resolved, the mud property was gradually adjusted to a stable state. In field application the mud property was adjusted at all times in accordance with the requirements of drilling operations. The mud had good rheology at high temperatures and good high temperature stability. High temperature resistance of the mud formulation was 240℃ based on laboratory test. The mud property was still satisfactory even after hot rolling for 72℃, providing strong technical support for the success of drilling operation. The drilling fluid technology used in drilling the well Songke-2 is of guiding significance in improving job quality of drilling and reducing exploration cost.