中美典型高压页岩气藏钻井提速技术对比与启示

Comparison and implications of ROP improvement technologies in typical high-pressure shale gas reservoirs in America and China

美国Haynesville高压页岩气气藏与中国长宁—威远国家级页岩气示范区下志留统龙马溪组高压页岩气藏的地质、钻井条件最为类似,前者的钻井提速技术思路对于我国页岩气快速钻井也具有重要的参考借鉴意义。为了实现我国页岩气藏的钻井提速,通过对比中国和美国典型高压页岩气藏钻井提速技术,分析探讨了上述两个气藏在钻井提速技术方面的异同点。研究结果表明:①目前美国Haynesville等页岩气藏已将水平段井眼尺寸从215.9 mm缩小到171.5 mm或161.1 mm,单井钻井投资降低超过25%,节能减排优势明显;②美国同行采用的“高效钻头+配套井下提速工具+钻井参数优化软件/装备”的硬研磨性难钻地层系统化钻井提速技术,值得国内重视、借鉴、攻关、应用;③“控压钻井+降密度”钻井技术能够在高压页岩层段钻井提速中起到至关重要的提速应用效果。结论认为,应积极在国内国家级页岩气示范区开展缩小井身结构尺寸及其相关的钻井配套装备、工具、软件的应用探索试验;在目的层段值得持续探索、优化、应用控压钻井技术。

The Haynesville high-pressure shale gas reservoir in America and the high-pressure shale gas reservoir of Lower Silurian Longmaxi Formation in the Changning–Weiyuan national shale gas demonstration area in China are similar in geological and drilling conditions.The technical ideas for improving the rate of penetration(ROP)in the Haynesville high-pressure shale gas reservoir provide an important reference for the fast drilling of shale gas wells in China.In order to realize ROP improvement of shale gas reservoirs in China,this paper compares the ROP improvement technologies used in the typical high-pressure shale gas reservoir in China and in America,and analyzes and discusses the similarities and differences of ROP improvement technologies used in the Haynesville high-pressure shale gas reservoir in America and the high-pressure shale gas reservoir of Lower Silurian Longmaxi Formation in the Changning–Weiyuan national shale gas demonstration area in China.And the following research results were obtained.First,the hole size of the horizontal section in the Haynesville high-pressure shale gas reservoir is currently reduced from 215.9 mm to 171.5 mm or 161.1 mm,the single-well drilling investment is decreased by over 25%,showing an obvious advantage in energy conservation and emission reduction.Second,it is worthywhile for China to pay attention to,refer to,research and apply the ROP improvement technology of"efficient drilling bit+support downhole ROP improvement tool+drilling parameter optimization software/equipment"for high-abrasivity hard-to-drill formations used by American counterparts.Third,the drilling technology of"managed pressure drilling+density reduction"can play an important role in improving the ROP in high-pressure shale intervals.In conclusion,it is necessary to actively carry out exploratory tests on the reduced hole structure size and the application of related support drilling equipment,tool and software in the national shale gas demonstration areas of China,and explore,optimize and apply the managed pressure drilling technology continuously in the target intervals.