| In the ultra-deep wells of the Shunbei Oil and Gas Field in Xinjiang,the drill bit wears a lot,the drilling cycle is long,and the economic cost is high when drilling,which makes bit selection extremely difficult.It is the key to shorten the drilling cycle and reduce the drilling cost by accurately predicting the drillability of the rock and guiding the selection of the drill bit.This paper takes the deep stratum of 4500m-7500 m in the Shunbei area of Xinjiang as the research object.Through theoretical analysis,a mathematical model of rock drillability and rock compressive strength is established,and then a new bit selection is built using the improved ideal point method.Model,and applied this model to field examples.Through the application of 4 wells in the Shunbei Oilfield in Xinjiang,after comparing with adjacent wells,it is found that the rate of penetration can be effectively increased,and the bit selection accuracy rate is 70%,which proves that this method can be a difficult bit selection problem for domestic ultra-deep wells at this stage.Provide an effective theoretical basis.Based on the theory of rock mechanics,this paper focuses on four aspects of research content:1.A mathematical model of rock drillability and compressive strength was established using acoustic time-difference logging data,and a rock mechanics profile diagram was drawn.The establishment of this model accurately predicts the rock drillability of the deep strata in the Shunbei area of Xinjiang and lays a solid foundation for the subsequent research on bit selection.2.Use field drilling data to evaluate rock breaking efficiency with the help of statistical analysis theory.Standard stroke drilling speed is used as the evaluation index of rock breaking efficiency.This indicator eliminates pure drilling time and drilling parameters(weight on bit,speed,row Amount,etc.)on the impact of the drill bit on the rock breaking efficiency.3.The improved ideal point method is used to establish a new method for selecting the drill bit that comprehensively considers the rock mechanics characteristics of the formation,the working conditions of the drill bit,the use effect of the drill bit,and the economic benefit of the drill bit.4.According to the researched rock drillability and the new method of bit selection,field application was carried out.The example application proves that the bit selection method established in this paper is suitable for deep formation in the Shunbei area of Xinjiang,and its rate of penetration and footage have been significantly improved. |
