塔北隆起盐下油气藏井眼缩径研究

Research on Tight Hole of Salt Covered Reservoir in Arched Structure North Tarim Basin

采用Heard非线性蠕变模型作为深井段盐岩蠕变本构方程,并建立含盐膏岩夹层的有限元模型,得到了塔里木羊塔克区块巨厚盐膏层变形及井眼缩径规律。研究表明,由于上覆岩层应力的作用,羊塔克隆起构造盐岩层翘曲段逐渐趋于平缓;在同一盐膏层井段不同井深处井眼蠕变缩径的程度明显不同,顶部和底部盐膏层井眼缩径速率最快,缩径量较大。据此,现场钻井工程师在进行盐膏层井段钻进的时候要特别注意打开盐膏层和钻出盐膏层井段时的钻井液密度控制,优选钻井方案,防止盐岩层井段发生卡钻等井下事故。

Taking Heard nonlinearity creep model as salt rock creep constitutional equation of deep section and forming finite element model of interbed salt formation,the regular pattern of deformation and tight hole of ultra- thick salt formation in block of Yangtake Tarim basin is studied in this paper. The experiment results offer that even in the same salt formation, the degrees of tight hole are various in different depth and the rate of tight hole changes most fastest at the top and bottom section. Therefore, to avoid pipe sticking, controlling density of drilling fluid and optimizing drilling proposal are key elements in drilling operation at salt formation.