应用成像测井确定川西须家河组漏层及漏失性质

Location and Property Determination of Loss Zone with Electric Imaging Log

川西须家河组在钻探过程中经常发生井漏。该储集层具有低孔隙度、低渗透率特征,属于裂缝性致密碎屑岩储层,在一定压力下,造成了钻井液沿天然裂缝渗透;具有异常压力特征,在钻开致密异常压力地层时产生诱导裂缝而发生井漏。根据钻井液漏失现象在成像测井图像上的特征,提出了应用成像测井技术确定川西须家河组漏层及漏失性质的方法。通过2口井的成像测井实例分析,说明了成像测井技术可以为钻井泥浆配制、钻井施工与防漏与堵漏方案制定提供可靠、直观的依据。

Reservoirs of Xujiahe formation in west Sichuan are classified as fractured tight clastic reservoir characterized by low porosity and low permeability. Circulation loss often happens while drilling to the Xujiahe formation Considered are tow kinds of circulation loss zone, one is the zone where certain mud pressure pushes drilling fluid leaking off along natural fracture and dissorlution pore, the other is that leaking off along stress-induced fracture produced by ahnormal pressure as the tight clastic reseroir is drilled. These two loss zones have their own characters in conventional and electric imaging logging. Based on these properties, proposed is a method applying electric-imaging logging to determine loss zone and its properties in Xujiahe Formation. By cases of 2 wells shown is that electric-imaging logging can provide dependable and intuitional bases in preparation of drilling fluid, operation of drilling, and establishment of scheme on leak protection and sealing.