致密砂岩气藏钻完井关键技术研究进展

 从20世纪70年代开始,美国致密砂岩气藏的广泛开发受到了普遍关注,在致密砂岩气藏钻、完井等方面形成了一系列成熟的先进技术,井型设计从最初的单一直井发展到水平井、丛式水平井,最长水平段超过3000m;布井方式也从单口井钻井转变为工厂化钻井,提高了施工效率;钻井提速采用欠平衡钻井、控压钻井、优质钻井液等技术,实现了长水平段水平井安全、快速钻井;完井技术由常规酸化发展为大型分段压裂技术,改造级数最多超过60级,单井产量提高45%以上,实现了致密砂岩气藏低成本、高效益开发。根据中国致密砂岩气藏储层特征,先后在长庆、吉林等油田进行了丛式水平井工厂化钻井和长水平段加砂分段压裂改造技术的试验应用,钻井最长水平段为2800m,改造级数最多已超过25级,单井成本节约100万元以上,产量是直井的3～10倍,取得了显著的应用效果。这些配套技术的形成推动了中国致密砂岩气藏钻完井技术的进步,对加快中国致密砂岩气藏开发步伐具有重要的指导意义。

Advances in the Key Technologies of Drilling and Completion for Tight Sand-stone Gas Reservoirs

Since 1970s, the wide development of American tight sandstone gas reservoirs have reveived the widespread attention. In the way of driling and completion for the tight sandstone gas reservoirs, a series of mature advanced matching technologies have formed. Well design has witnessed a process of development from the initial single vertical wells to horizontal wells and cluster horizontal wells, and the longest horizontal segment is more than 3000m. The way of well spacing has been changed from single well drilling into the factory drilling to improve the operation efficiency. Many advanced technologies have been utilized for ROP improvement, such as unbalanced drilling, MPD and high quality drilling fluid to realize safe and fast drilling during the long lateral section. Well completion has a development from conventional acidizing technology to large-scale multi-stage fracturing, whose stimulation stage is more than 60, and the individual well production has increased by more than 45%, making low cost and high efficiency come true during the development of tight sandstone gas reservoirs. According to tight sandstone gas reservoir features in China, cluster horizontal wells factory drilling and long horizontal-section with staged fracturing transformative technology have been carried out in Changqing and Jilin Oilfield. The longest horizontal segment is 2800 m, and remoulding stage numbers are more than 25. Single well cost savings are about more than one million yuan, and the output is 3-10 times as the vertical wells. Finally remarkable application results have been achieved. The formation of these supporting technologies gradually improve drilling and completion technologies of the tight sandstone gas reservoirs in China, and it has important guiding significance to accelerating the development pace of tight sandstone gas reservoirs.