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 quadlateral 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.
Several studies in the past have examined the impact of different reservoir
properties on CBM production (Ertekin et al. 1988; Zuber 1998; Katyal et al.
2007), including the effect of secondary (micro-) permeability (Gamson et al.
1993; Mavor and Gunter 2006; Palmer et al. 2006). This paper is dedicated to
examining the impact of different horizontal-well configurations (multilateral)
on the production and recovery in CBM reservoirs.
In this section, a brief background on reservoir-engineering aspects of CBM
production is presented along with details on the reservoir simulator used for
modeling the cases used in this study. Some basic introduction about horizontal
wells and their impact on production behavior is also presented.
© 2008. Society of Petroleum Engineers
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- Original manuscript received:
11 July 2005
- Meeting paper published:
9 October 2005
- Revised manuscript received:
10 July 2008
- Manuscript approved:
2 August 2008
- Version of record:
29 December 2008