Optimization Design Of PDC Bit For Conglomerate Formation In Mahu Area

There are three sets of conglomerate strata in the Jurassic and Triassic sections of Mahu area.The three sets of conglomerate formations have strong heterogeneity,high rock abrasibility and poor rock drillability.The previous application of roller and conventional PDC bit is not good,which leads to poor drilling effect,long drilling cycle and high drilling cost of the bit in this area,which seriously restricts the oil and gas exploration and development process in Mahu area.Therefore,in order to accelerate the pace of exploration and development in the Mahu area,it is necessary to optimize the design of PDC bit according to the formation nature of conglomerate layer and the damage mechanism of PDC in it,so as to improve its application range.Based on the actual formation properties of the gravel formation,this paper analyzes the main failure modes,damage mechanism and main factors affecting the damage of the PDC bit in the conglomerate layer,and proposes ways to improve the drilling performance of the PDC bit in conglomerate.In this paper,the relationship models of drillability,compressive strength,young’s modulus,internal friction Angle and well logging data of the formation in mahu area are obtained by combining with indoor core experiments,well logging data and well drilling and completion data.In view of the conglomerate formation damage mechanism of the drill bit,this paper lake area formation characteristic analysis,through the optimization design of PDC bit crown section,cloth of comb teeth,tooth structure design,multiple cutting cloth cutter type and parameter optimization,vortex design of force balance,etc.,the optimization design for the diameter of the conglomerate formation at the bottom of the lake area use of 311.2 mm,241.3 mm and 165.1 mm of PDC bit,such as well drilling conglomerate layer and alternating hard and soft non homogeneous formation provides effective ways and methods.Through the use of optimized design of PDC bits in diameter,oblique and horizontal conglomerate formations.The single rigid PDC bit broke through the conglomerate layer at the bottom of Badaoban formation,the single rigid PDC bit broke through the conglomerate interlayer of Karamay formation and the gravel bearing difficult to drill formation of Baikouquan formation,and the footage of the single bit increased by 90% compared with that of last year.The PDC bit in the optimal design of the gravel formation in the horizontal well is combined with the use of the screw to realize "one trip" for a single drill bit in the inclined section.The average drilling speed is increased by 2 times from 1.8m/h to 5.4m/h,and the average footage of a single trip is increased by 3.45 times from 132 m to 588 m.The average drilling speed in the horizontal section increased by 34.8% from 3.05m/h to 4.11m/h,and the average footage in a single run increased by 1.69 times from 151 m to 406 m.The technical achievements have greatly increased the drilling speed,reduced the drilling cost and improved the economic benefits of oil and gas development in Mahu area.