Research On The Anti-sloughing And Leak-proof Drilling Fluid System Of Horizontal Well In Haituozi Area

Because of the small drawdown pressure of horizontal well and large drainage area, the horizontal well production has been the major oil recovery technique to exploit new oilfield and enhance oil recovery. Meanwhile it can control the ascending rate of water percentage to increase the liquid producing capacity. So the horizontal well production has gained more and more application in exploiting low permeability reservoir.This paper develops an anti-sloughing and leak-proof drilling fluid of horizontal well in Haituozi area. This drilling fluid system can solve many difficulties in the process of horizontal well drilling. In order to drill horizontal well smoothly and improve oil well production, we first analyze the clay mineral of Nenjiang group, Yaojia group, Qingshan group and Quantou group in Haituozi area. Then do the physicochemical performance analysis and study borehole wall stability. Finally we draw a conclusion that upside of Haituozi area is moderate hydrate expansion layer as the result of high content montmorillonite. The lower-middle side is friable hard mud shale formation as the result of high amount andreattite and fractures. In this layer, the clay mineral easily disperses when contacting with water. And drilling fluid will enter the inner side of formation along the microcrack and form thick hydrated film to produce large hydrating repulsion force. Thus the formation will collapse easily. It’s weak/moderate expansion and moderate/strong dispersion formation. The Haituozi area forms a stability profile of borehole wall. It provides systematic basic datas to study the anti-sloughing and leak-proof drilling fluid system. Achieve the goal that safely and fast drill the horizontal well and effectively save the drilling cost. Besides improve single well production and exploitation effect.