完善采气工艺 提高卫79-9井采收率

Perfecting Gas Production Technology to Enhance Gas Recovery in Well Wei-79-9

东濮凹陷户部寨气田卫 79- 9井因储层低渗致密、单井控制储量小、生产压降快、自然产能低、生产受地层产水影响较大 ,稳产基础薄弱。针对该井生产特征 ,在开发初中期 ,先后应用和完善了合理工作制度自喷带水采气 ,泡沫排水采气和间歇气举排水采气工艺 ,应用这些工艺 ,使压降储量采出程度达 6 5 .8%。气井进入开发后期 ,产能进一步降低 ,带水能力显著下降 ,泡沫排水及间歇气举已无法使气井正常生产。通过对该井生产特征祥细诊断 ,明确了后期工艺措施效果变差的原因是参数选择不合理、气举参数没有达到雾流稳定带液最小气量。计算结果表明要使该井井筒下部流体由段塞流变成雾流 ,气举井口初始产气量 (启动气量 )必须大于 46 830m3/d ,维持该井连续带液生产 ,井口产气量必须稳定在 2 712 5m3/d以上。优化气举参数后 ,采出程度提高了 9% 。

The steady production fundament of well Wei-79-9 in Hubuzhai gas field in Dongpu Sag is frail because of reservoir's being densified with low permeability, a little reserves controlled by single well, rapid production pressure drop, low natural productivity and a large influence of formation water on producing, etc. In light of these production characters mentioned above, some reasonable working systems as water-carrying flowing gas production, drainage gas recovery by foam and that by intermittent gas lift were applied and improved early or late in the primary-middle production stage. During this period, the recovery percent of the reserves estimated by pressure decline method was up to 65.8% by use of these techniques. In the late production stage, because the productivity of the gas well has been further dropping and its water-carrying capacity decreases obviously, the gas well can't be normally put into production by applying the techniques as drainage gas recovery by foam and that by intermittent ga s lift. Through analyzing the production behaviours of the well in detail, it is found that unreasonable parameter election, i.e. the gas lift parameters of forming the minimum gas production for mist flow steadily carrying liquid were not obtained, is the reason for causing the later stimulation treatment effectiveness to be worsened. The calculation result indicates that the primary wellhead gas production (starting gas flow) of > 46830 m3/d is necessary to make the fluid in the lower part of the wellbore be changed from slug flow into mist flow; and the wellhead gas production must be steadied at more than 27125 m3/d to maintain a successive liquid-carrying production in the well. The recovery percent increased by 9% after optimizing gas-lift parameters, which shows a considerable economic return has been obtained.