密切值法在煤层气井井型优选中的应用研究

Optimization of Coalbed Methane Well Type Based on Osculating Value Method

针对目前常用的多目标决策方法多存在缺点的现状,进行了密切值法在煤层气井井型优选中的应用研究。对国内外煤层气井常用的射孔压裂直井、U形水平井、V形水平井和羽状水平井4种井型,以数值模拟为手段,利用Eclipse软件进行了产能预测,并在此基础上进行了经济评价,然后综合考虑累计产气量、净现值、投资回收期、内部收益率和钻井风险系数等5项评价指标,应用密切值法优选了延川南区块煤层气井井型。产能预测和经济评价结果表明,该区块羽状水平井优势明显,15年累计产气量达5.058×108 m3,高于其他井型;净现值1.21亿元,是其他井型的5～11倍;投资回收期3.96年,约为其他井型的1/3;内部收益率0.28,约为其他井型的2倍。据此进行密切值法评价,结果显示该区块4种井型方案从优到劣的排序为羽状水平井、U形水平井、射孔压裂直井和V形水平井。

In view of the deficiencies in multi-objective decision methods, the application of osculating value method in CBM well type optimization was investigated. Focusing on the commonly used well types at home and abroad： perforated and fractured vertical well, U-shape horizontal well, V-shape horizontal well,and pinnate horizontal well, Eclipse software was employed to predict CBM production of every well type in this paper. Meanwhile economic evaluation taking five evaluation indexes into comprehensive ac- count：accumulated gas production, net present value, invest recovery period, internal rate of return and risk coefficient in the process of CBM well drilling,was conducted. Osculating value method was used to opti- mize CBM well types for Yanchuannan Block for the first time. The research results showed that pinnate horizontal well had obvious advantages in developing CBM, with the cumulative production in 15 years of 505.8 million cubic meters which was higher than other well types;net present value of the pinnate hori- zontal well was 121 million RMB,which was 5-11 times other well types;investment recovery period was 3.96 years,which was about 1/3 of other well types; internal rate of return was 0.28, which was about 2 times of other well types. Osculating value method evaluation results showed that the four well types schemes of this block in the order of descending superiority were pinnate horizontal well, U-shape horizon- tal well, perforated and fractured vertical well, V-shape horizontal well.