渤海X油田无土相水基钻井液室内研究

Laboratory Study on Clay-free Water-based Drilling Fluid in X Oilfield of Bohai Sea

针对渤海X油田存在的黏土分散、软泥岩缩径、起钻遇阻卡、储层段中高孔渗特征等问题,通过优选流变性调节剂、降滤失剂、润滑剂、封堵剂、抑制剂等核心处理剂,形成了一种无土相钻井液,其配方为:海水+0.2%NaOH+0.2%Na_(2)CO_(3)+0.3%PF-VIS+0.3%FA-367+0.6%PAC+2.0%PF-Lube+2%K-HPAM+1.5%超细碳酸钙+1.5%双溶暂堵剂+1%纳米封堵剂JF-1+HCOONa,该钻井液不含膨润土,能有效减少对储层的损害,钻井液滚动回收率在90%以上,且具有良好的热稳定性能及抗岩屑污染能力,形成的封堵层抗压强度在7 MPa以上,因优选HCOONa作加重剂,水基钻井液对WM95S管材腐蚀速率仅为0.0359 mm/a。

In the light of there are some problems in X oilfield of Bohai Sea,such as clay dispersion,soft mud shrinkage,sticking when tripping out,medium and high porosity and permeability in reservoir section.Through the optimization of rheology regulator,fluid loss reducer,lubricant,inhibitor and other main treatment agents,The formula of soilless drilling fluid suitable for Bohai X oilfield is formed,The formula is:Seawater+0.2%NaOH+0.2%Na_(2)CO_(3)+0.3%PF-VIS+0.3%FA-367+0.6%PAC+2.0%PF-Lube+2%K-HPAM+1.5%ultrafine calcium carbonate+1.5%dual solution temporary plugging agent+1%nanoplugging agent JF-1+HCOONa(depending on density),The drilling fluid does not use bentonite to structure,which can effectively reduce the damage to the reservoir,The rolling recovery rate of drilling fluid is over 90%.It has good thermal stability and anti cuttings pollution ability.The compressive strength of the plugging layer is more than 7 MPa,Sodium Sodium formate is selected as weighting agent of drilling fluid,and the corrosion rate of weighted drilling fluid on WM95S pipe is only 0.0359 mm/a.