摘要
以四川某高含H2S气体的气井井身结构及钻井工况为基础,针对高含H2S气井溢流时的特点,考虑H2S在水中的溶解度,建立溢流期间环空各相流体的质量和动量守恒方程,并用有限差分法对方程进行求解。结果表明:H2S在井底的溶解度远大于CH4的,在距井口约360 m开始大量析出;H2S的含量越高,气体在上升过程中密度变化越大,气体开始剧烈膨胀的位置越接近井口;井底侵入气体量相同的情况下,H2S的含量越高,气体的膨胀倍数越大,泥浆池增量也越大,同时,刚开始气侵时H2S含量越高气相的体积分数越小,而到达井口后H2S的含量越高气相的体积分数越大,导致溢流检测的难度和井控的危险程度增加;高含H2S气井溢流时井底压力的下降值、泥浆池增量、关井套压小于纯烃类的,不能反映真实的气侵程度,而且随着时间的增加情况会更严重;高含H2S气侵时压井过程中套压值与纯烃类的相差不大,因此可以在井口施加一定的压力,抑制H2S气体的膨胀,减缓井喷事故的发生。
Based on hole structure and drilling behavior of a gas well which has a high content of H2S gas in Sichuan,the conservation of mass equations and momentum equations were established considering overflow characteristics of high content of H2S gas kick and H2S solubility in water.And the equations were computed by using finite difference approach.The results show that the solubility of H2S is greater than that of CH4 at bottom hole,and H2S begins to separate at about 360 m away from wellhead.With the content of H2S increasing,the density change range increases during the gas going up,and the position of the gas dramatic expansion is close to the wellhead.When the gas kick volume is same at the bottom,the higher content of H2S,the greater gas expansion factor and pit gain,at the same time,the smaller gas volume fraction at the beginning,but greater when they reach wellhead,which increases the difficulty of gas kick detection and the danger of well control.The descent of bottom hole pressure,pit gain and shut-in casing pressure is smaller than that of pure hydrocarbon when high content of H2S gas kick happens,which can t truly reflect gas kick and the situation is getting worse with time.The casing pressure of high content of H2S gas kick during killing well has little difference to pure hydrocarbon,so applying certain pressure to wellhead can inhibit the expansion of H2S and slow down the blowout accidents.
出处
《中国石油大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2012年第1期73-79,共7页
Journal of China University of Petroleum(Edition of Natural Science)
基金
国家自然科学基金项目(51034007
51104172)
山东省自然科学基金项目(ZR2010EL010)
山东省博士后创新项目(200903107)
关键词
气井
气侵
H2S
环空多相流
溢流
natural gas wells
gas kick
H2S
multiphase flow in annular
overflow
