二氧化碳洗井中相关问题的探讨

Relevant Issues in Carbon Dioxide Well Flushing

二氧化碳洗井方法具有设备简单、用时少,效果好的特点,但随着钻孔深度和孔径加大,井管材料的更新换代,有时也会难以出现壮观的井喷场面,达不到理想的洗井效果,使用范围受到限制的问题。总结多年的洗井经验,依据二氧化碳洗井原理,运用洗井过程中起动压力和用气量的计算公式,进而对洗井深度和影响用气量的因素进行了分析,结果表明:1该方法比较适用于井深300m左右、孔径Φ325mm以内、泥浆相对密度小于1.1g/cm3的新打水井,对大于300m的深井,可采用分层洗井法或压风机引喷法进行洗井。2井喷形成时的二氧化碳气体用量,与瓶内气体的压力、钻杆的下入深度、环空体积、地面管路的长度与直径、钻杆内径、钻井液的密度等成正比,而与水温、气温等成反比;当井的含水层的水柱高度低于70m时,一般不易形成井喷。3二氧化碳洗井适用于井内下入钢管、铸铁管等抗压强度较高的井。对水泥管、塑料管等强度较低的井管则要视情况具体分析。

The method of carbon dioxide well flushing has characteristics of simple equipment, less time used and good effect, But along with drilling depth deepening, diameter increasing, pipe material upgrading, and hard to form spectacular blowout scene quite often, fallen short of perfect well flushing effect, thus scope of application limited. Summarized years of flushing experiences, according to car？bon dioxide flushing principle, using flushing process starting pressure and air consumption computational formulae, and then analyzed factors impacting flushing depth and air consumption, the result has shown：①The method is rather adequate for new drilled deep wa？ter well with depth about 300m, can use layered flushing or air compressor leading blowout to flush.②Carbon dioxide consumption to form blowout is in direct proportion to air pressure in bottle, drill rod setting depth, annular volume, surface pipe length and diameter, rod inside diameter and drilling fluid density;In inverse proportion to water temperature and atmospheric temperature;when height of aquifer water-column under 70m, generally not easy to form blowout.③Carbon dioxide well flushing is adequate to wells set with com？pressive strength higher steel pipe or cast-iron pipe, while to compressive strength lower cement, plastic pipes should be accordingly judged.