莺歌海盆地高温高压水平气井井控影响因素

Factors influencing the well control of HTHP horizontal wells in the Yingehai Basin

水平井是提高莺歌海盆地区域气井产能的重要手段,该区域的高温高压特点严重制约着钻井井控安全。结合水平井渗流理论和多相流理论,建立了高温高压水平井井控压井模型,以莺歌海盆地的一口井为例,模拟分析了高温高压水平井井控的特点。模拟分析结果表明:水平段长度越长,渗透率越大,溢流量越大;水平井具有更大的井涌允量和更长的关井时间;钻井液密度在该区域高温高压环境下会减小;相同溢流条件下,高温井的井底压力降低更明显;如果使用油基钻井液,溢出气体会溶解到钻井液中,随着向上运移,气体不断析出并且膨胀,导致泥浆池增量在压井后期突然增大。高温高压水平井的井控分析为莺歌海盆地的高效安全开发提供了技术支持。

Horizontal well is an important technology to improve the gas well deliverability in the area of Yinggehai Basin, but its well control safety is seriously restricted by the high temperature and high pressure in this area. In this paper, a well kill model on HTHP (high temperature and high pressure) horizontal wells was built up according to seepage and multiphase flow theories of horizontal wells.And then, a well in the Yinggehai Basin was taken as an example to analyze the well control characteristic of HTHP horizontal wells.It is shown that overflow rate increases with the increasing of horizontal section length and permeability. Horizontal wells are higher inkick tolerance and longer in shut in time. The density of drilling fluid decreases in HTHP environment of this area. When the overflowcondition is the same, the bottom hole pressure of high-temperature wells drops significantly. If oil based drilling fluid is used, the overflowinggas will be dissolved in it. With the upward migration, the gas is evolved continuously and expanded, resulting in sharp increaseof drilling fluid pit increment at the late stage of well kill. The analysis on well control of HTHP horizontal wells in this paper provides the technical support for the safe and efficient development of the Yinggehai Basin.