Optimization of Coalbed Methane Well Type Based on Osculating Value Method

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 account: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 optimize 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 horizontal 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 horizontal well,perforated and fractured vertical well,V-shape horizontal well.