Optimization Design Of Drilling Fluid System In Zhangwu Area

Drilling speed in Zhangwu area is slow,drilling cycle is long and complex situation frequently happened, which seriously restrict the exploration and development of oil and gas in this area.In order to improve the drilling speed,this paper combined the research of domestic and foreign literature with the actual drilling situation of the Zhangwu area,proposed to increase drilling speed through optimized the drilling fluid system and drilling tool.The most significant way to improve drilling speed is optimizing the drill assembly, mainly depend on comparing the drill bit and screw usage in different layers,choose a better combination of drill bit and screw for each layer. And this article is mainly through optimization of drilling fluid system to improve the rate of penetration.Drilling fluid increase drilling speed is mainly depends on reducing the unproductive time and downhole complex situation.By the analysis of Zhangwu formation,clay content is high,easy to mud and collapse. Thus prepared three inhibitory better alternative drilling fluid system:potassium ammonium-based polymer drilling fluid system,the oil-in-water drilling fluid system,low density organic salt drilling fluid system.Through the experiment and in combination with the practical drilling situation of ZhangWu region eventually chose the potassium ammonium polymer drilling fluid system.Further optimization of potassium ammonium polymer drilling fluid system,and use of various methods like rolling recovery experiment,linear expansion experiment,rheological experiment,flocculation and filtration experiments to choose the better treating agent.The final optimized potassium ammonium polymer drilling fluid system is:4%Amargosite+5%Na2CO3+0.4%KPAM+1.5%NH4HPAN+3%FT-99+2%HA-Resin+0.5%PB-1.Laboratory experiments and field application shows that the system has excellent performance.Not only has a strong inhibition,also has good rheological properties.It can be effectively reduce non-productive time and be able to reduce the incidence of downhole reaming,etc,save drilling period,reduce the total cost of drilling.