Radial jet drilling(RJD)technology is expected to be a technology for the efficient exploitation of geothermal resources.However,the low rock-breaking efficiency is the major obstacle hindering the development of RJD ...Radial jet drilling(RJD)technology is expected to be a technology for the efficient exploitation of geothermal resources.However,the low rock-breaking efficiency is the major obstacle hindering the development of RJD technology.The flow field characteristics and rock breaking ability of cone-straight abrasive jet,rotary abrasive jet,and straight-rotating mixed abrasive jet are analyzed by numerical simulations and experiments.Results show that the axial velocity of the cone-straight abrasive jet is high,the tangential velocity is basically zero,the radial velocity is also small,and the jet impact area is concentrated in the center.A deep hole with a diameter of only 25 mm is formed when the cone-straight abrasive jet breaks the granite.Due to the presence of the guiding impeller,the rotary abrasive jet basically has no axial velocity and has the highest tangential and radial velocity,so it can break the granite to form a hole with a diameter of about 55 mm and a central bulge.The straight-rotating mixed abrasive jet has a large axial/tangential/radial velocity at the same time,so it can break the granite to form a hole with a diameter of about 52 mm with a low bulge.The results show that the straight-rotating mixed abrasive jet combines the advantages of the cone-straight jet and the rotary jet,and is more suitable for the RJD technology.The research results can provide reference for the development of efficient rock-breaking and hole-forming technology,and promote the development of RJD technology in the field of geothermal development.展开更多
Radial jet drilling(RJD)is one of the emerging hydrocarbon drilling technologies.And,the swirling abrasive waterjet(SAWJ)is expected to drill larger diameter laterals during RJD.Here,the performances and mechanisms of...Radial jet drilling(RJD)is one of the emerging hydrocarbon drilling technologies.And,the swirling abrasive waterjet(SAWJ)is expected to drill larger diameter laterals during RJD.Here,the performances and mechanisms of SAWJ breaking sandstone were studied by laboratory experiments.Results showed that the SAWJ could drill a smooth(surface roughness was 0.043 mm)&large(diameter was in 52.0-73.0 mm)circular hole on sandstone.The hole depth/volume increased as the jetting pressure,abrasive mass concentration and exposure time increased.Conversely,they decreased as the standoff distance increased.The optimal parameter combination under our experimental conditions was 30 MPa,0 mm,12%and 1 min.The SAWJ sandstone breaking mechanism were the erosion of cements,the integrally peeled off and broken of crystal grain.Failure mode of sandstone was mainly the tensile fracture.The key findings will provide guidance for the application of SAWJ in RJD technology.展开更多
基金funded by the National Natural Science Foundation of China(No.52374018)Science Foundation of China University of Petroleum,Beijing(No.2462021YJRC009)。
文摘Radial jet drilling(RJD)technology is expected to be a technology for the efficient exploitation of geothermal resources.However,the low rock-breaking efficiency is the major obstacle hindering the development of RJD technology.The flow field characteristics and rock breaking ability of cone-straight abrasive jet,rotary abrasive jet,and straight-rotating mixed abrasive jet are analyzed by numerical simulations and experiments.Results show that the axial velocity of the cone-straight abrasive jet is high,the tangential velocity is basically zero,the radial velocity is also small,and the jet impact area is concentrated in the center.A deep hole with a diameter of only 25 mm is formed when the cone-straight abrasive jet breaks the granite.Due to the presence of the guiding impeller,the rotary abrasive jet basically has no axial velocity and has the highest tangential and radial velocity,so it can break the granite to form a hole with a diameter of about 55 mm and a central bulge.The straight-rotating mixed abrasive jet has a large axial/tangential/radial velocity at the same time,so it can break the granite to form a hole with a diameter of about 52 mm with a low bulge.The results show that the straight-rotating mixed abrasive jet combines the advantages of the cone-straight jet and the rotary jet,and is more suitable for the RJD technology.The research results can provide reference for the development of efficient rock-breaking and hole-forming technology,and promote the development of RJD technology in the field of geothermal development.
基金funded by National Natural Science Foundation of China-CO_(2) displacement and production increase mechanism in radial horizontal wells of shale oil(No.52374018)the Strategic Cooperation Technology Projects of CNPC and CUPB(NO.ZLZX2020-02)。
文摘Radial jet drilling(RJD)is one of the emerging hydrocarbon drilling technologies.And,the swirling abrasive waterjet(SAWJ)is expected to drill larger diameter laterals during RJD.Here,the performances and mechanisms of SAWJ breaking sandstone were studied by laboratory experiments.Results showed that the SAWJ could drill a smooth(surface roughness was 0.043 mm)&large(diameter was in 52.0-73.0 mm)circular hole on sandstone.The hole depth/volume increased as the jetting pressure,abrasive mass concentration and exposure time increased.Conversely,they decreased as the standoff distance increased.The optimal parameter combination under our experimental conditions was 30 MPa,0 mm,12%and 1 min.The SAWJ sandstone breaking mechanism were the erosion of cements,the integrally peeled off and broken of crystal grain.Failure mode of sandstone was mainly the tensile fracture.The key findings will provide guidance for the application of SAWJ in RJD technology.
