摘要
对某油田3口典型井遇阻井段的综合情况进行分析,发现这3口井出现的套管强度问题都有一个共同的特点,即在钻完盐膏层并固井以后,如下部地层为稳定地层就需要降低钻井液密度,当密度下降到一个值后,套管出现弹性变形,造成钻头难以通过,因此,套管内钻井液密度的下降过程也将对套管变形产生影响。通过建立管内压力变化速率对套管应力影响的有限元分析模型,并对其进行分析研究,结果表明:当压力变化速率越快时,套管代表单元上的应力增大速率也越快,且最大值也越大;降低管内压力变化速率可以有效降低套管中的应力值,也即延长密度置换时间有利于套管抗挤,防止套管变形。
Based on the analysis about comprehensive situations of drill pipe blocking interval of three typical wellsin an oil field,a common characteristic of casing strength problem in three wells has been found that after salt andgypsum layers are drilled and cemented,there is a need for reducing the density of drilling fluid to drill the understable strata,when the density decreases to a certain value the elastic deformation of the casing occurs,leading tosome difficulties for the bit to pass through the casing. Consequently,it is necessary to consider the influence of thedrilling fluid density decrease on the casing deformation. The finite element analysis model of the inner pressurevariation rate of the casing influencing on the casing is established and some relevant analytical research by themodel is presented in the paper. Results show that the stress increasing rate of the representative unit is faster alongwith the quicker variation rate of the pressure and the maximum value of that is bigger,reducing the variation rate ofthe inner pressure can effectively reduce the stress value of the casing. That is to say,prolonging the time of densityreplacement benefits casing strength and preventing casing deformation.
出处
《西南石油大学学报（自然科学版）》
CAS
CSCD
北大核心
2011年第6期105-108,209,共4页
Journal of Southwest Petroleum University(Science & Technology Edition)
关键词
管内压力变化速率
钻井液密度
数值模拟
套管强度
蠕变地层
inner pressure variation rate
drilling fluid density
numerical simulation
casing strength
creep formation
