山西沁水盆地柿庄北区块3#煤层注入埋藏CO2提高煤层气采收率试验和评价

对沁水盆地南部柿庄北区块进行了深煤层注入地质和工程评价,认为柿庄北区块适合进行深煤层注入CO2开采煤层气技术的应用;通过SX-001井的微型先导性试验,对SX-001井的注入前后产气量与产水量、气体成分变化和井底压力变化规律进行了总结。通过现场试验,注入CO2后SX-001井的产气量是注入前的2.45倍;在小于煤岩破裂压力的条件下,每天注入20 t的CO2能够实现顺利注入,并且压力上升速度较慢;注入CO2后,煤岩发生膨胀,局部煤层的渗透率降低,排采一段时间后恢复;在目的煤层中注入的CO2的影响范围内,烃类气体总的置换效率达到14.18 cm3/g。该试验成果证明柿庄北区块通过注入CO2开采煤层气实现了CO2的埋藏,提高了煤层气井的采收率。

Test of and evaluation on elevation of coalbed methane recovery ratio by injecting and burying CO2 for 3# coal seam of north section of Shizhuang, Qingshui Basin, Shanxi

By conducting geological and engineering evaluation on deep coalbed methane injection in North Section, Shizhuang, South Qingshui Basin, methane extraction technology by deep coalbed injection of CO2 is thought applicable for north block, Shizhuang. By miniature and pilot test for SX 001 well, change rules of gas production, water production, gas composition and well bottom pressure of the SX 001 well before and after injection are summarized. The gas production after injection is 2.45 times of that before injection as shown by on site test. Under pressure lower than rupturing pressure for coal seam, 20 of CO2 can be injected smoothly daily with slow elevation of pressure. After injection of CO2, the coal rock swells and the local coal seam get less penetration ratio, which recovers after extraction for a period of time. The total replacement ratio of hydrocarbon gas reaches 14.18 cm3/g within the scope influenced by CO2 injection in the target coal seam. The test result proves that extraction of coalbed methane by CO2 injection can realize burial of CO2 and elevation of recovery ratio for the coalbed methane well.