超低渗透钻井液在花3-8井的应用

The Application of Ultra-low Filter Loss Drilling Fluid in Well Hua 3-8

海南福山凹陷花场构造的流二段地层含有易垮塌的硬脆性泥岩，裸眼段较长，存在多套地层压力系统，在钻井施工中经常发生大段划眼、井漏等复杂情况。针对该区块的地层情况，在花3—8井流二段采用超低渗透钻井液。该钻井液能在井壁岩石表面形成致密超低渗透封堵薄层，有效封堵不同渗透性地层和地层层理裂缝，阻止钻井液及其滤液进入地层中，有效防止了地层水化膨胀，防止井壁垮塌。现场应用表明，超低渗透钻井液性能稳定，井壁稳定能力强，钻井及完井施工顺利，使该井流二段的井径扩大率比邻井下降了55％，钻井液密度比邻井降低0．08～0．10g／cm^2。

Downhole problems related to formations,such as sloughing brittle shale,long open hole and multi-pressures were frequently encountered in the Liu-er member of the Huachang structure in Fushan,Hainan.These problems always resulted in reaming of the well for lengths and mud losses.To solve these problems,an ultra-low filter loss mud was used to drill the Liu-er member in well Hua 3-8.Shale swelling was inhibited because of the mud cakes formed by the ultra-low filter loss fluid against the invasion of the filtrates into the formation.Filed application showed that the hole enlargement was reduced by 55% and mud density was reduced by 0.08-0.10 g/cm3,compared with offset wells.