A parametric study on the benefits of drilling horizontal and multilateral wells in coalbed methane reservoirs

Recent years have witnessed a renewed interest in development of coalbed methane (CBM) reservoirs. Optimizing CBM production is of interest to many operators. Drilling horizontal and multilateral wells is gaining popularity in many different coalbed reservoirs, with varying results. This study concentrates on variations of horizontal- and multilateral-well configurations and their potential benefits. In this study, horizontal and several multilateral drilling patterns for CBM reservoirs are studied. The reservoir parameters that have been studied include gas content, permeability, and desorption characteristics. Net present value (NPV) has been used as the yard stick for comparing different drilling configurations. Configurations that have been investigated are single-, dual-, tri-, and quad-lateral wells along with fishbone (also known as pinnate) wells. In these configurations, the total length of horizontal wells and the spacing between laterals (SBL) have been studied. It was determined that in the cases that have been studied in this paper (all other circumstances being equal), quadlateral wells are the optimum well configuration.