CRITIAL DRILLING TECHNIQUES OF MULTILATERAL HORIZONTAL WELLS USED TO DEVELOP COALBED METHANE RESERVOIRS

Based on the analysis of the geological characteristics of coal bed methane (CBM) reservoirs in China, such as low pressure, low permeability, low saturation, regionally appeared pulverized coal lenses and high heterogeneity, this study concluded herein that to develop CBM reservoir in China with conventional vertical well drilling would be restricted by many geological limitations. In this case of study, multilateral (ML) horizontal well drilling was recommended to increase methane gas production from each well and also improve the gas recovery factor. Combining with the practices of successful six wells drilled in the Qinshui Basin, this study discussed the key procedures of ML horizontal well drilling, including the emphases of geological work, junction of two laterals, well trajectory control and wellbore stability control, etc. This paper points out that ML horizontal well is the best choice for the development of CBM reservoir in China.