Research And Design Technology QK18-1 Preferred Oil PDC Drill Bit

With the development of design and manufacturing technology for PDC bit, PDC bit has become one of the most widely-used bits. When drilling the soft to medium hard formations, PDC bit has the feature of high drilling speed, long life and the fewer times of trip which can bring very significant economic benefits. For some special formations, conventional PDC bit cannot meet the requirements of safety and efficiency, so the design of personalized bit is needed in order to better adapt to different formations. Take the broken formations as an example, the block in the well often leads to conventional PDC bits to be stuck. More seriously, the tooth or the blade may drop during the drilling operation. Another example, when drilling the formation containing gravel, conventional PDC bit is likely to occur the following problems:the beat of bit, the break of composite sheet, the abrasion of bit, the low drilling speed, the short life of bit and so on. Therefore, the design of personalize PDC bit for the particular formation to improve the ROP has great significance in theory and application.According to the logging data of QK18-1oil field, this paper firstly established relational model of strata compressive strength, shear strength, hardness, drillability. and logging parameters (SDT, density, resistivity) to obtain the parameters of formation rock mechanics and the profile of drillability, abrasivity which can provide the basis for the optimization of bit and the design of personalized bit. Gray correlative method is used to establish the relationship between the drill models and the parameters of formation rock mechanics, drillability, abrasivity. Based on this method, the bits for different layers and different hole sizes were optimized. According to the parameters of formation rock mechanics, the bit’s crown structure and the arrangement of teeth were redesigned. By simulating bottomhole flowing feature, the hydraulic structure of PDC bit were optimized which can reduce the ball up. Based on the optimization of bit and the design of personalized bit. the new bit was tested in the field and the working condition in2013and that before2013were compared. On the basis of the results, the drilling parameters and the bits for different lays were recommended.In QK18-1oil field, BEST TS1951SS PDC bits were recommended in Φ311.15mm borehole, and the corresponding drilling parameters:WOB60-80kN, rotate speed70r/min-90r/min,discharge rate60L/s, pump pressure15～18MPa; Chuanke CKS605PDC bits were recommended in Φ215.9mm borehole, and the corresponding drilling parameters:WOB60-80kN,rotate speed40r/min～60r/min, discharge rate30L/s, pump pressure of16～19MPa.