Missan油田盐膏层钻井技术

The Research and Application of Safe Controlled Drilling in Evaporite Salt Layer of Missan Oilfield

Missan油田盐膏层含有高压盐水层,钻井液密度窗口窄,受其影响,钻井过程中出现了井漏、溢流、井眼缩径等多种复杂情况和事故。为解决这些问题,根据盐膏层蠕变速率和地层破裂压力确定了钻井液密度范围,选用复合有机盐钻井液体系,并进行了抗钙侵、沉降稳定性试验,使用具有井壁修整和倒划眼功能的钻具组合,采用双级固井技术且制定了固井防漏措施。经过现场应用,达到了防止漏失、压稳高压盐水、抑制地层蠕变的目的,固井质量合格,钻井工期从平均100.4d缩短至15.5d。这些技术对策有效解决了窄钻井液密度窗口条件下高压盐水对盐膏层钻井造成的困难,为同类地层钻井提供了经验。

The evaporite salt layer can make borehole close in the effect of creep,which often leads to tight hole and pipe sticking.The deviation angle has an important impact on creep rate when drilling directional wells in the evaporite salt layer.This paper analyzes the creep property of the vaporite salt layers of the given oilfield,the creep constitutive model is given,the creep parameters are given by mud density and caliper log data.The geologic condition of the salt layer is considered,Numerical calculation of the salt layer creep carried out by Lagrange method.The effect of deviation angle on drilling in the salt layer is analyzed,the conclusion is that drilling in maximal earth stress,the creep rate increases with the increasing of the deviation angle,the safe mud density also increases,the high deviation angle in directional well is much more risky.It makes great contribution for the optimizing deviation angle,designing well track and reducing the troubles when drilling directional wells are drilled in the salt layer.