Study On Wellbore Stability Technique Of Daqingzijing Area In Jilin Oil Field

Borehole instability includes well sloughing, formation fracturing and tight hole during drilling and completion. It is one of complicated situations encountered in drilling, which influences the drilling seriously.It is mechanical instability that induces borehole instability. If the stress that acts on shale around wellbore exceeds its intensity, borehole instability will happen. Its main reasons can be summed up as the mechanical factor, chemical factor and engineering technical factor. The last two factors induce borehole instability both by affecting stress distribution around wellbore and material properties of rock.The domestic researchers have made a lot of study on borehole instability for many years to solve it, and some important achievement is got. The achievement catches up with the international level and forms certain characteristics in some aspects. But wellbore instability has not been thoroughly solved for its complexity.Daqingzijing area is where Jilin oil field especially explores in recent years. Borehole instability often takes place during drilling. It severely affects the speed and quality of exploration and development in this area.This study sets up the mechanical model of rock around wellbore with elastic theory of mechanics based on formation properties parameters, determining the range of mud density for drilling in this area. Organic silicon drilling fluid with strong inhibition is also studied. It is low-solid-content and low-density system that has the advantages of polymer drilling fluid and sulfonation drilling fluid. It is effective in preventing well sloughing. This paper studies wellbore instability in mechanical and chemical sides and establishes solid foundation for studying wellbore stability of Jilin oil field.