Metan pokładów węgla: zasoby i eksploatacja
Abstract
Coalbed methane: resources and recovery.
A b s t r a c t. Gas produced from coal can be subdivided into three categories: coalbed methane (CBM), coal mine methane (CMM) and abandoned mine methane (AMM). CBM is extracted from virgin coal using wells drilled from the surface. In recent years horizontal drilling is widely used as a primary CBM recovery technique. A pair of wells – a vertical production well intersected by a horizontal multilateral well – is considered the most effective in dewatering a coal reservoir and thus enables maximizing its productivity. Although CBM world resources are huge (100–216 bcm), only a few countries produce coalbed gas commercially. While the US is still the leader, Australia has the fastest CBM production growth. It has been observed that many mature CBM plays reveal highly variable productivity, possibly due to coal heterogeneity. Therefore, CBM reserves/resources should be estimated using probabilistic methods. In spite of its substantial CBM resource potential, Poland has produced only coal mine methane (CMM) whereas significant
efforts of CBM exploration conducted in the 1990s failed to flow gas in commercial quantities due to low permeability. Dart Energy operates a CBM exploration license in the Upper Silesia and has recently finished testing the CBM production pilot using a surface-to-inseam horizontal well with vertical production well intersection. This state-of-the-art CBM completion technology has been used for the first time in Poland and, hopefully, will unlock the sizeable CBM resource of the Upper Silesian Coal Basin.
A b s t r a c t. Gas produced from coal can be subdivided into three categories: coalbed methane (CBM), coal mine methane (CMM) and abandoned mine methane (AMM). CBM is extracted from virgin coal using wells drilled from the surface. In recent years horizontal drilling is widely used as a primary CBM recovery technique. A pair of wells – a vertical production well intersected by a horizontal multilateral well – is considered the most effective in dewatering a coal reservoir and thus enables maximizing its productivity. Although CBM world resources are huge (100–216 bcm), only a few countries produce coalbed gas commercially. While the US is still the leader, Australia has the fastest CBM production growth. It has been observed that many mature CBM plays reveal highly variable productivity, possibly due to coal heterogeneity. Therefore, CBM reserves/resources should be estimated using probabilistic methods. In spite of its substantial CBM resource potential, Poland has produced only coal mine methane (CMM) whereas significant
efforts of CBM exploration conducted in the 1990s failed to flow gas in commercial quantities due to low permeability. Dart Energy operates a CBM exploration license in the Upper Silesia and has recently finished testing the CBM production pilot using a surface-to-inseam horizontal well with vertical production well intersection. This state-of-the-art CBM completion technology has been used for the first time in Poland and, hopefully, will unlock the sizeable CBM resource of the Upper Silesian Coal Basin.