准噶尔盆地达巴松凸起超深井安全快速钻井技术

SAFE AND FAST DRILLING IN ULTRADEEP WELL AT DABASONG UPLIFT,JUNGGAR BASIN

准噶尔盆地达巴松凸起二叠系风城组和石炭系勘探程度低,超深井达探1井完钻井深6226m,井底压力高达125MPa,温度高达150℃。由于近2000m的目的层未钻揭,钻井将面临地层压力系统复杂、深部地层钻速低、风城组盐膏层污染钻井液、长裸眼井壁失稳等难题。需要开展超深井高效钻井的配套技术攻关。包括:利用测井和地震数据精细预测地层压力;分析井筒复杂规律优化井身结构;评价岩石力学特性,优选高效钻头;开展钻井提速工具试验;多元协同和复合盐强化高密度钻井液抑制性及抗污染能力。通过现场试验,达探1井平均机械钻速为3.61m/h,较邻井提高35.5%,钻井周期仅162d,全井复杂事故率为零,创造了准噶尔盆地超深井高效钻井的新纪录。

For Permian Fengcheng Formation and Carboniferous systems of the Dabasong uplift in Junggar Basin the exploration degree is low,in which the ultradeep well Datan 1 was a priority project of Xinjiang oilfield.The well’s TD was 6226 m,the bottom-hole pressure reached 125MPa,and the bottom-hole temperature up to 150℃.Because of nearly 2000m non-drilled target layer,many drilling problems need to be solved,including complex formation pressure system,low drilling speed in many deep formations,drilling fluid pollution in thick Fengcheng salt beds,long open hole wellbore instability etc.Therefore,it is necessary to carry out the ultradeep well drilling technology research,which include how to predict the whole formation pressure precisely by log data and seismic data,to analysis hole complex rules for the well structure optimization,to evaluate rock mechanical properties for optimum bit,to test some new type bits and drilling speed tools,to enhance the inhibition of high density drilling fluid with synergies of KCl and amine,to improve salt tolerance of the under-saturated compound salts drilling fluid,etc.As a result of the field test in Well Datan 1,the average drilling speed was 3.61m/h,35.5%higher than that of adjacent wells,the drilling cycle was only 162 days,the downhole complex accident rate was zero,and some new records of the ultradeep well drilling in Junggar basin have been created.