胜科1井三开钻遇软泥岩钻井液技术

Drilling Fluid Technology for Gumbo Shale Drilling: A Case History in the Third Section of Well Shengke-1

胜科1井是一口超深重点科学探井，目的为证实胜利油田渤海湾盆地深层生油的可能性。在该井三开（2931～4155m）钻进过程中，分别钻遇盐膏层、盐岩层、软泥岩、膏质泥岩、砂岩等多套层系并在3套盐膏层中钻遇软泥岩，使工程变得复杂，钻井液性能起伏较大。在现场施工中，围绕着解决如何提高钻井液在高密度下对土相的污染容限，以及如何在高固相情况下调整好钻井液的流态问题，成功地运用了多聚物复合盐欠饱和钻井液体系，很好地解决了多层系、多压力地层特点带来的钻井难题，顺利地钻穿沙四段，为盐下段的施工打下了良好的基础。介绍了软泥岩段的电测结果。对3000～4200m井段软泥岩的蠕变速率进行了研究，得出了不同井深处、不同钻井液密度下的井眼蠕变速率，以及保证不同井深处软泥岩地层蠕变速率小于0．8mm／h所需的钻井液密度。

Well Shengke-1 is an ultra deep exploration well aimed at determining the potential of oil generation in the deep formations in Bohai gulf basin in Shengli Oilfield.Drilling operation in the third section(2931-4155 m) found salt and gypsum,salt rock,gumbo shale,mudstone with gypsum,and sandstone,which made the drilling very difficult and drilling fluid properties uncontrollable.Analyses of the downhole problems showed that attention should be paid to the clay tolerance and the rheology control of the high density mud.An under-saturated saltwater polymer mud was chosen to drill the well,and the Shasiduan Formation was successfully drilled.The creep property of the gumbo shale from 3000 to 4200 m under different mud densities was obtained based on the analyses of the shales.Mud densities under which the creep speed of the gumbo is less than 0.8 mm/h were also calculated.