高效防塌钻井液的研制及在新疆塔河油田的应用

DEVELOPMENT OF COLLAPSE-PREVENTING DRILLING FLUID AND ITS APPLICATION IN TAHE OILFIELD OF XINJIANG AREA

新疆塔河油田三叠系、石炭系地层长期以来存在着严重井塌问题 ,为此 ,用实验方法优选出高效防塌钻井液配方 ,并对其性能进行了研究。结果表明 ,以MAN 10 4 ,KN PAN ,WFT 6 6 6和KCl为主要处理剂的防塌钻井液具有流变性好、滤失量低、泥饼致密等特点。对页岩回收率、膨胀性和毛细管吸入时间的实验研究进一步证实 ,这种钻井液对粘土矿物的水化膨胀和分散具有很强的抑制作用 ,在防塌效果及其他性能方面均明显优于在该地区使用的其他常规钻井液。对该钻井液的防塌作用机理进行了理论分析 ,并在一口重点试验井进行了现场试验 ,取得了理想的防塌效果。与邻井相比 ,三开井段的平均井径扩大率由 14 .6 %下降至 3.14 % ,从而显著提高了钻井效率。

The formulations of a kind of high-performance collapse-preventing drilling fluid for preventing the instability of well bore in the Triassic and Carbonic formations of Tahe Oilfield in Xinjiang area were experimentally optimized. A new-type drilling fluid taking MAN-104, KN-PAN, WFT-666 and KCl as the major additives is characterized by good rheological properties, low filtration loss and non-permeable mud cake. The further measurements of the shale recovery, expansion ratio and capillary suction time confirmed that the new drilling fluid played important roles in inhibiting the hydrated expansion and dispersion of clay mineral in shale. In addition, the new drilling fluid is superior to the conventional drilling fluids in the collapse-preventing effectiveness and other properties. The inhibitive mechanism of this drilling fluid was analyzed theoretically. A satisfactory collapse-preventing effectiveness has been achieved from the field test of a key tested well. Compared with the adjacent well, the enlargement ratio of well bore diameter of the key tested well was reduced from 14.6 percent to 3.14 percent, which indicates that the drilling efficiency has been improved significantly.