我国页岩气田井工程学习曲线及指标体系研究

Well-engineering learning curves and indicator system for shale gas fields

为了准确预测页岩气田井工程投资,有效控制建井成本,指导油气行业实现页岩气效益开发,以某页岩气田井工程成本为研究对象,分析了学习曲线在国内外的应用情况及影响因素,形成了页岩气田井工程学习曲线,并建立了井工程成本指标体系。研究结果表明:①国内已有的页岩气学习曲线,仅反映了钻井和压裂试气投资随着时间及经验的变化,未反映钻前及配套工程投资随着时间及经验的变化,不适用于含钻井工程、压裂试气工程和钻前及配套工程在内的页岩气田井工程投资预测;②页岩气田井工程成本中压裂及钻井工程分别占总成本的50%和40%左右,其中,压裂工程费用主要受压裂段数影响;③方案设计工程量与实际实施工程量的偏差对钻前及配套工程费用影响较大。结论认为:①新建立的页岩气田井工程学习曲线能有效预测含钻井工程、压裂试气工程和钻前及配套工程在内的页岩气田井工程投资;②在钻井工程费用中,钻井液费用是成本控制的重点和难点;③在设计阶段,应综合考虑各种因素,尽量提高方案设计的准确性。

In order to accurately predict well-engineering investments,effectively control well-construction costs in shale gas fields and realize beneficial development of shale gas,the application of learning curves in China and abroad and their influential factors were investigated by taking the well-engineering cost in one shale gas field as an example.On this ba⁃sis,learning curves of well engineering were formed and the engineering cost indicator system was established for shale gas fields.Results show that(i)since those ready-made learning curves used for shale gas in China only reflect investment changes in drilling and fracturing&gas testing with time and experiences while not mirror the changes in pre-drilling and associated engineering,they are not applicable to predicting the engineering investment to shale gas wells which covers drilling,fracturing&gas testing,and pre-drilling and associated engineering;(ii)fracturing and drilling account for about 50%and 40%in the well-engineering cost in shale gas fields,respectively,in which the fracturing cost is mostly affected by the number of fracturing segments;and(iii)a workload deviation between plan design and engineering exerts a larger ef⁃fect on the cost of pre-drilling and associated engineering.In conclude,the newly-developed learning curves can vividly forecast the engineering investment containing drilling,fracturing&gas testing,pre-drilling and associated engineering;drilling-fluid cost serves as the emphasis and difficulty for cost control in drilling;and all kinds of factor should be taken into account in the design process to maximize the accuracy of plan design.