摘要
塔中油田志留系储层的平均孔隙度为8.25%~10.04%,平均渗透率为7.118×10-3~52.628×10-3μm2,属于特低渗储层,加上储层中存在微裂缝、构造缝和收缩缝,为固相颗粒和液相侵入提供了通道,固体很容易对储层造成伤害。通过室内研究优选出了弱凝胶无固相保护油气层钻井液。该钻井液具有独特的流变性,表观粘度低、动塑比高、低剪切速率粘度高、切力与时间无依赖性、即使在140℃下也具有良好的悬浮携砂能力、润滑性和抑制性,渗透率恢复值最高达97.5%。现场应用表明,无固相弱凝胶钻井液性能稳定,能够快速形成低渗透性泥饼,阻止外来流体的侵入,利于油气层保护,岩屑代表性好,荧光级别低,容易清洗,满足录井需要,并具有除H2S效果,维护简单,高温稳定性好,抗温可达140℃,能够满足井深为6450 m的超深井钻井施工的需要。
Reservoirs in the Silurian formation of Tazhong oilfield are of extremely low permeability,with an average porosity of 8.25%~10.04% and permeability of 7.118×10^(-3) to 52.628×10^(-3)μm^2;Furthermore,micro fractures,structure fractures and shrinking fractures exist in the formation,providing communications for solids and liquids to enter and thus causing formation damages.Solid free weak gelling drilling fluid was optimized based on laboratory study,which exhibits such advantages as unique rheology,low aPPArent viscosity,high dynamic to plastic ratio,high shearing viscosity,good cutting transportation,lubrication and inhibition capabilities even in 140 ℃,and permeability recovery as high as 97.5%.Field applications showed that it has stable performance,and low permeable filtrate cake can be quickly formed to prevent the invasion of foreign fluid;the returned cuttings has low fluorescence grade and is easy to wash,and represents the true formation drilled.Meanwhile,this drilling fluid system can be used to remove H_2S,it is easy to maintain and has high temperature tolerance as high as 140 ℃,thus can be used in ultra-deep well drilling as deep as 6450 m.
出处
《钻井液与完井液》
CAS
北大核心
2005年第5期35-37,共3页
Drilling Fluid & Completion Fluid
关键词
无固相钻井液
弱凝胶
防止地层损害
抗高温
特低渗储层
solid free drilling fluid
weak gelling
formation damage
high temperature resistance
extremely low permeability formation.
