MEG钻井液页岩抑制性研究  

STUDY ON THE INHIBITIVE CHARACTER OF MEG DRILLING FLUIDS FOR SHALE

作　　者：巨小龙[1] 丁彤伟[2] 王彬[3] 

机构地区：[1]西安石油大学 [2]中国石油大学 [3]北京奥凯立科技发展有限责任公司

出　　处：《钻采工艺》2006年第6期10-12,141,共3页Drilling & Production Technology

基　　金：新疆石油管理局科技攻关项目。

摘　　要：在钻井过程中,由于钻井液滤液的侵入,地层中的粘土矿物发生水化膨胀和水化分散作用,削弱了岩石的力学强度,致使井壁发生失稳。MEG钻井液是一种具有成膜作用的水基钻井液,对页岩具有较好的抑制作用。文中简单阐述了MEG钻井液页岩抑制性机理,分析研究了影响MEG钻井液页岩抑制性的因素,实验验证MEG钻井液的成膜作用。MEG钻井液主要是通过半透膜效应、封堵作用、渗透作用及去水化作用抑制页岩的水化分散和膨胀,当钻井液中MEG浓度足够大时,MEG分子吸附在井壁岩石或钻屑表面上形成一层憎水膜,阻止钻井液滤液向地层或钻屑中渗透。研究表明,MEG浓度大于30%时,其抑制页岩的能力优于浓度为3%的KCl溶液;钻井液中MEG的加量是影响钻井液抑制性的主要因素,并且钻井液中加入无机盐后,无机盐与MEG协同作用使MEG钻井液的页岩抑制能力提高;钻井液中MEG浓度越高,膜效率越好,MEG浓度大于50%时,页岩内水份渗出。During drilling, the wellbore is instable because filtrate invading formation results in rock strength reduction, hydration expansion and dispersion of formation clay. MEG drilling fluids is one of film forming water-base fluids, which can inhibit shale hydration. The paper studied the inhibitive mechanism of MEG drilling fluids for shale, analyzed the factors affecting rejection characteristic of shale and validated the film forming effect of MEG drilling fluids for shale. MEG drilling fluids can control hydration expansion and dispersion of shale by its semi-membrane effect, blocking, percolation and dehydrating effect. The hydrophobic the membrane is formed to prevent filtrate infiltration in formation or bit cuttings by MEG molecules absorbing on the surface of well wall or bit cuttings when MEG concentration is enough high in drilling fluids. The results of experimental research indicate that when the density of MEG is more than 30%, MEG inhibits shale better than that with 3%KCl does. The main factors affecting the inhibitive character are the content of MEG dosage, and after the inorganic salt is added into drilling fluid, the synergic action of inorganic salt and MEG can improve the inhibition of MEG. The concentration of MEG in drilling fluid is higher, the membrane efficiency is better and water in shale is exuded to go into drilling fluid when the MEG concentration in drilling fluid is over 50%.

关 键 词：MEG钻井液 页岩抑制性 半透膜效应 井壁稳定 

分 类 号：TE254.3[石油与天然气工程—油气井工程]