<p>The extraction of coalbed methane (CBM) from coal mining-affected areas and goaf areas is an important approach to the coal and CBM co-mining. The application of widely used L-shaped wells has proven challenging in coal mining-affected areas. This study aims to enhance the design and extend the service life of L-shaped wells, thereby boosting their overall efficiency and eliminating the spatiotemporal separation between CBM extraction in mining-affected areas and goaf areas. The sources of CBM in mining-affected areas and goaf areas were analyzed, the gas production effect and the reasons for the low production of three conventional L-shaped wells, first in mining-affected area and then transformed into a goaf area with the coal mining, were discussed. And a novel design methodology, termed “one well, two purposes” was proposed for L-shaped wells, enabling sequential CBM extraction from mining-affected areas followed by goaf areas. It turns out that only one of the three conventional L-shaped wells achieved profitable extraction and therefore the conventional L-shaped well design needs to be improved. A standardized design scheme of the horizontal section of L-shaped wells was proposed. And based on an “O-shaped” ring theory, an “upper three zones” theory and a numerical simulation method, a layer location selection method was proposed for the horizontal section of an L-shaped well in mining-affected areas and goaf areas. The improved L-shaped well design was characterized by a large-diameter two-section wellbore structure, a segmented cementing and discontinuous multi-stage cementing method. And the continuous extraction method of improved L-shaped wells in mining-affected areas and goaf areas was discussed. The optimized design scheme could extend the stable production time span of an L-shaped well and improve its CBM extraction efficiency.</p>