表开快钻技术在西湖凹陷的应用研究

Study on High Drilling Rate Technique of the Surface in Xihu Sag

随着西湖凹陷油气勘探向深层发展,钻探深度不断增加,在现有套管层次下,需要增加表开钻井深度以缓解下部套管层次钻探压力。表开下部地层岩石可钻性差,机械钻速低,钻井周期长,同时表开最大安全钻深难以确定限制了表开优快钻井技术。针对难题,通过分析地层压力特性与坍塌周期,确定了保持地层稳定与裸眼安全的最大钻深确定方法;通过优化钻具组合、钻井液工艺与钻井参数,提高表开下部地层机械钻速,最终形成了一套适用于西湖凹陷表开快钻技术。现场实践表明,该套技术实现了西湖凹陷表开最大安全钻深的突破,有效提高表开下部地层机械钻速,具有较好的推广价值。

With the development of oil and gas exploration in the Xihu Sag to deep layers,the drilling depth continues to increase.Under the existing casing layers,it is necessary to increase the surface drilling depth to relieve the drilling pressure of the lower layers.With the poor rock drill-ability of the surface drilling,the low mechanical drilling speed,the long drilling cycle,and the difficulty to determine the maximum safe-drilling depth of the surface opening,the surface opening fast drilling technology was limited.To solve the problems,by analyzing the formation pressure characteristics and collapse periods,the determination method of the maximum drilling depth to maintain the stability of the formation and the safety of the open hole was determined;by optimizing the drilling tool assembly,drilling fluid technology and drilling parameters,the mechanical drilling speed of the formation under the surface drilling was increased,and finally a set of surface-opening fast drilling techniques suitable for Xihu Sag have been formed.Field practice shows that this set of technologies has achieved a breakthrough in the maximum safe drilling depth of the surface drilling in the Xihu Sag,effectively increasing the mechanical drilling speed of the lower surface drilling with good promotion value.