新型钻井提速工具在龙岗气田软硬交替地层中的成功应用

自21世纪初在四川盆地发现龙岗气田以来，机械钻速低、钻井周期长等问题长期制约着该气田勘探开发的进度和效益。为此，对该气田的钻井地质特点和影响钻井周期的因素进行了系统分析，认识到该气田侏罗系沙溪庙组、自流井组中的砂泥岩软硬交替频繁造成钻头泥包和PDC崩齿，以及上三叠统须家河组定向钻进托压严重是使机械钻速变慢最重要的影响因素。进而提出了不同地层的针对性提速技术方案，即侏罗系采用旋转冲击器带专用PDC钻头钻进，配合钻井液性能调整、钻井参数优化等专项技术措施的应用来预防处理PDC钻头泥包，实现侏罗系快速钻进；在三叠系须家河组的定向钻进井段，采用高速弯涡轮带孕镶金刚石钻头进行高转速低钻压快速钻进，该钻进方式充分利用孕镶金刚石钻头切削齿自锐的特点，以延长钻头使用寿命。最后，在该气田的2口井上进行了现场应用试验，大幅度提高了应用井段的机械钻速、缩短了钻井周期，取得了良好的试验效果。

Application of novel speedup drilling tools in alternate layers of soft and hard rocks in the Longgang Gas Field,Sichuan Basin

〗In the Longgang Gas Field, the progress and benefit of exploration and development are always restricted by low penetration rate and long drilling cycle for a long period since its discovery in the early 21^st century. Therefore, this gas field was systematically investigated in terms of its geologic characteristics and factors influencing drilling cycles. It is indicated that bit balling and PDC teeth breaking occur frequently due to the alternate layers of sandstones and mudstones in Shaximiao Formation and Ziliujing Formation of Jurassic. The reduction of penetration rate is mostly caused by serious backing pressure of directional drilling in Xujiahe Formation. In this paper, therefore, penetration rate improving program is provided specifically for different formations. In Jurassic, PDC bit balling should be avoided by using rotary impactor with special PDC bits, combined with the improvement of drilling fluid properties and the optimization of drilling parameters. At the directional drilling section of Triassic Xujiahe Formation, high-speed turbine with impregnated diamond bits was adopted to realize high-speed drilling with high rotation speed and low weight on bit. In this mode, self-sharpening of impregnated diamond bit cutter is fully exerted, and the service life of bits is prolonged. This program was tested at two wells in Longgang Gas Field and the results were satisfactory. The penetration rate at the program-applying section is greatly increased and drilling cycle is reduced.