The enhanced drilling parameters and custom-designed polycrystalline diamond compact(PDC)bits have greatly improved both rate of penetration(ROP)and footage.Then how to further improve the bit’s ROP and how to deal w...The enhanced drilling parameters and custom-designed polycrystalline diamond compact(PDC)bits have greatly improved both rate of penetration(ROP)and footage.Then how to further improve the bit’s ROP and how to deal with the side effects caused by the enhanced drilling parameters remain a challenge.In this work,the single-cutter rock-cutting tests and full-sized bit drilling tests were conducted to investigate the effects of rock types,drilling parameters,and bit designs on ROP.The results showed that in the easy-to-drill formations,the enhanced drilling parameters had a more pronounced effect on improving the bit’s ROP than the optimizations of bit designs such as changing the cutter shape and size.On the other hand,in the hard-to-drill formations,smaller-sized and shaped PDC cutters combined with high-torque tools offered a promising approach to increase ROP.To further improve ROP and footage,two innovative approaches were introduced:improving the bit durability without compromising ROP to ensure one-trip drilling,and using extended directional nozzles together with enhanced hydraulic parameters.The bit durability was improved by optimizing the cutter shape and diamond materials,which helped complete the single-run footage of 2986 m in the field trial of Shengli Oilfield.It was also found that the extended directional nozzle was less effective under conventional hydraulic parameters,but increased the ROP by 32.1%under enhanced hydraulic parameters because of improving jet impact performance through reduced jet diffusion.The findings provided insights for ROP improvement in the oil and gas drilling operations.展开更多
The ROP(rate of penetration)within the horizontal section of shale gas wells in the Luzhou oil field is low,seriously delaying the exploration and development process.It is proved that reducing mud density mitigates t...The ROP(rate of penetration)within the horizontal section of shale gas wells in the Luzhou oil field is low,seriously delaying the exploration and development process.It is proved that reducing mud density mitigates the bottom-hole differential pressure(ΔP)and increases the ROP during overbalanced drilling.However,wellbore collapse may occur when wellbore pressure is excessively low.It is urgent to ascertain the optimal equilibrium point between improving ROP and maintaining wellbore stability.The safe mud weight window and the lower limit of mud density in the horizontal section of the Luzhou block are predicted using the piecewise fitting method based on conventional logging data.Then,the accuracy of the collapse pressure prediction was verified using the distinct element method(DEM),and the effect of wellbore pressure,in-situ stress,rock cohesion,and natural fracture density on borehole collapse was investigated.Finally,a fitting model ofΔP and ROP of the horizontal section in the Luzhou block is established to predict ROP promotion potential after mud density reduction.The field application of this approach,demonstrated in 8 horizontal wells in the Luzhou block,effectively validates the efficiency of reducing mud density for ROP improvement.This study provides a useful method for simultaneously improving ROP and maintaining wellbore stability and offers significant insights for petroleum engineers in the design of drilling parameters.展开更多
基金supported by Beijing Natural Science Foundation(Grant number:2232060)the Ministry of Industry and Information Technology(Grant number:ZX20240310)National Natural Science Foundation of China(Grant numbers:52574016,52394250,52234002).
文摘The enhanced drilling parameters and custom-designed polycrystalline diamond compact(PDC)bits have greatly improved both rate of penetration(ROP)and footage.Then how to further improve the bit’s ROP and how to deal with the side effects caused by the enhanced drilling parameters remain a challenge.In this work,the single-cutter rock-cutting tests and full-sized bit drilling tests were conducted to investigate the effects of rock types,drilling parameters,and bit designs on ROP.The results showed that in the easy-to-drill formations,the enhanced drilling parameters had a more pronounced effect on improving the bit’s ROP than the optimizations of bit designs such as changing the cutter shape and size.On the other hand,in the hard-to-drill formations,smaller-sized and shaped PDC cutters combined with high-torque tools offered a promising approach to increase ROP.To further improve ROP and footage,two innovative approaches were introduced:improving the bit durability without compromising ROP to ensure one-trip drilling,and using extended directional nozzles together with enhanced hydraulic parameters.The bit durability was improved by optimizing the cutter shape and diamond materials,which helped complete the single-run footage of 2986 m in the field trial of Shengli Oilfield.It was also found that the extended directional nozzle was less effective under conventional hydraulic parameters,but increased the ROP by 32.1%under enhanced hydraulic parameters because of improving jet impact performance through reduced jet diffusion.The findings provided insights for ROP improvement in the oil and gas drilling operations.
基金supported by National Natural Science Foundation of China(No.52074312 and No.52211530097)CNPC Science and Technology Innovation Foundation(2021DQ02-0505).
文摘The ROP(rate of penetration)within the horizontal section of shale gas wells in the Luzhou oil field is low,seriously delaying the exploration and development process.It is proved that reducing mud density mitigates the bottom-hole differential pressure(ΔP)and increases the ROP during overbalanced drilling.However,wellbore collapse may occur when wellbore pressure is excessively low.It is urgent to ascertain the optimal equilibrium point between improving ROP and maintaining wellbore stability.The safe mud weight window and the lower limit of mud density in the horizontal section of the Luzhou block are predicted using the piecewise fitting method based on conventional logging data.Then,the accuracy of the collapse pressure prediction was verified using the distinct element method(DEM),and the effect of wellbore pressure,in-situ stress,rock cohesion,and natural fracture density on borehole collapse was investigated.Finally,a fitting model ofΔP and ROP of the horizontal section in the Luzhou block is established to predict ROP promotion potential after mud density reduction.The field application of this approach,demonstrated in 8 horizontal wells in the Luzhou block,effectively validates the efficiency of reducing mud density for ROP improvement.This study provides a useful method for simultaneously improving ROP and maintaining wellbore stability and offers significant insights for petroleum engineers in the design of drilling parameters.
