Fine extraction is a practice in coalbed methane management by using
extraction data for obtaining a high yield. When extracting coalbed methane on
ground, mining coal leads to a decrease in strata energy, and a fast falling in
case pressure, which needs fine extraction to secure ground extraction for a
stable production. This paper, based on a case study on Xiandao-1 well in
Shiquan coal mine, studies its structure, buried depth and strata pressure, and
compares its geology with surrounding basin of coalbed methane, analyzes its
fracturing features and conducts fine extraction management, providing
references for later mass ground extraction. Five steps are planned, setting up
objective of daily production up to 400 cubic meters over 30 days,
understanding its occurrence and under-pressured features, conducting
extraction gas-water evolution characters, planning “balanced water production stage (no gas
release), controlling well bottom fluid pressure stage, stably increasing
production stage, and declining stage”, controlling well bottom pressure to
balance strata pressure and then to determine critical releasing pressure and
water point, releasing point, gas releasing point and stably producing point.
Emergency measures are also prepared through three groups in managing the
process, site group, research group and decision group. A real-time response
and linked decision-making strategy bring a daily gas production from 100, 200,
400, 600 and up to 1 041 cubic meters in two months. Fine extraction management
is the key means for such an achievement. Mass ground gas extraction requires
planning, emergency measures and flowchart, which are vital technical
guarantees to ensure a good production.