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壳牌勘探开发公司在墨西哥湾(GOM)Auger项目的深水张力腿平台(TLP)上使用控压钻井(MPD)连续实施侧钻小井眼二次开发。利用动态环空压力控制(DAPC)系统成功实施4口侧钻井,消除了井漏和井眼失稳事故。使用MPD能连续提高钻井作业效率,接近先前认为难以达到的油藏目标。由于压力衰竭导致破裂梯度减小,先前认为不能钻达的油层间隙,用MPD却能钻进并且无下套管事故。最近的MPD钻井设计把静态泥浆密度减少到孔隙压力以下,控制有效钻井安全系数。后来的MPD钻井操作中,井底压力给定值变化减少,目标压力窗口之外的额定值消失。Au-ger的油田二次开发需要对钻井设计和MPD设计再次核查。在整个4口MPD侧钻井的作业时间里,实施MPD操作的细节聚焦于工程和操作的改进。
Shell Exploration and Development Corp. has used pressure-controlled drilling (MPD) on a secondary development of a small-bore, side-hole drilling operation on the deep-water tension leg platform (TLP) at the GOM Auger project. The successful implementation of 4-side drilling with the dynamic annular pressure control (DAPC) system eliminated the well leakage and borehole instability. The use of MPD continuously improves drilling efficiency, approaching previously-difficult-to-reach reservoir targets. Due to pressure failure resulting in a decrease in fracture gradient, previously thought to be unable to reach the reservoir gap, MPD was able to drill without casing accident. Recent MPD drilling designs reduce the static mud density below pore pressure to control the effective drilling safety factor. In subsequent MPD drilling operations, the bottom hole pressure setpoint changes decrease, and the target pressure window outside of the nominal value disappears. Second development of Au-ger’s oilfields requires re-verification of drilling design and MPD design. The details of implementing MPD operations throughout the four MPD-side drilling operations focus on engineering and operational improvements.