Abstract:Slim-hole second spud horizontal well has the advantages of short cycle and save drilling cost but will appear in the process of drilling hole trajectory control difficult, slow rate of penetration and borehole wall collapse and lost circulation problems, according to the above problem of slim-hole horizontal well casing program design, borehole trajectory optimization design, assembly, drilling fluid configuration. The design of well body structure adopts the bottom-up design principle, and the well body structure is determined as second spud horizontal Wells with small holes. The second spud structure can reduce the number of trips and shorten the drilling cycle. In the design of borehole track, the five-stage system of "straight-accret-steady-accret-horizontal" borehole track was adopted, and the steady section was added to make up for the lack of deviation. Rotary steerable drilling technology is used to improve the accuracy of well trajectory control. Finally, polymer drilling fluid was selected to improve wellbore stability. The problems of wellbore trajectory control, slow drilling speed and wellbore stability are solved.