In the Sichuan Basin,the drilling of complex deep and ultradeep wells is restricted by the casing sequence.Multiple pressure systems are usually encountered in the same open hole section,and narrow safety density wind...In the Sichuan Basin,the drilling of complex deep and ultradeep wells is restricted by the casing sequence.Multiple pressure systems are usually encountered in the same open hole section,and narrow safety density window is observed in vertical strata.The application of managed pressure drilling(MPD)technique which is often used in well drilling ensures the safe and efficient drilling,but it also brings about great challenges to the small-gap liner cementing at the lower part.Therefore,it is of great practical significance to research a cementing technology that can not only satisfy the quality requirement of small gap liner cementing,but also ensure the safe cementing in the strata with narrow safety density window.In this paper,a cementing technology based on precise managed pressure balancing method was proposed by referring to the successful application of MPD technique.According to the cementing design,the hydrostatic column pressure of annulusfluid is under-balanced(slightly lower than the formation pore pressure),and then a precise managed pressure drilling device is adopted to produce back pressure through wellhead restriction or apply wellhead compensation pressure,so that the balanced pore pressure can be reached in the process of cementing via the wellhead pressure and theflow friction offluid in the annulus.After the cementing is completed,a certain compensation pressure is applied to the annulus continuously to prevent annulus channeling during waiting on cement caused by insufficient static pressure and slurry weight loss.After this technology was applied to an ultradeep exploration well in the Sichuan Basin,the qualification rate of borehole cementing quality reached 97%,and the well sections with good cementing quality accounted for 76%.In conclusion,this technology needs no additional equipment,and only by virtue of the MPD equipment,it can achieve safe cementing construction and cementing quality improvement under high displacement efficiency.展开更多
The exploration and development of oil and gas resources in the Sichuan Basin is shifting to the deeper strata.The deep and ultra-deep wells in deep carbonate gas reservoirs are faced with many difficulties,such as mu...The exploration and development of oil and gas resources in the Sichuan Basin is shifting to the deeper strata.The deep and ultra-deep wells in deep carbonate gas reservoirs are faced with many difficulties,such as multiple pressure systems,poor drillability,ultra-high pressure,ultra-high temperature and high sulfur content,which bring great challenges to drilling and completion engineering.In order to ensure the smooth exploration and development of deep carbonate oil and gas resources in the Sichuan Basin,the overall concept of combiningfield practice and technological research is followed.During the 13th Five-Year Plan,a batch of ultra-deep wells(well depth about 8000 m)have been drilled fast and safely(such as Well SYX133 in the Shuangyushi structure),and great progresses have been achieved in the experimental research of the support technologies in drilling and completion of deep and ultra-deep wells.And the achievements are as follows.First,the optimization of non-standard well structure,combined with the application of precisely managed pressure drilling technology and under-pressure plugging technology,lays a foundation for the optimized fast drilling and the safe reaching of geological targets.Second,a high-efficiency customized PDC drill bit is comprehensively optimized,popularized and applied,which effectively improves the average rate of penetration(ROP)in difficult-to-drill formations.Third,the development and application of drillingfluids(e.g.being resistant to high temperature of 200 C and anti-composite brine)and active under-pressure plugging technology effectively reduces downhole complexities while drilling the complex for-mations,such as high temperature and high pressure brine and circulation loss.Fourth,when precisely managed pressure drilling and precisely managed pressure cementing methods are applied in the strata with a narrow density window,multiple pressure systems and pressure sensitivity,the average drilling and completionfluid loss is reduced by more than 90%,and the complexity treatment time is cut down by more than 85%,and the cementing quality pass rate is increased by more than 20%.Fifth,the integrated application of ROP improvement technologies and tools(e.g.air drilling)results in a great reduction of drilling cycle and cost.It is concluded that the experimental research achievements provide basic support for the fast development of natural gas resources in the Anyue Gas Field,Sichuan Basin,and the great discovery of the Permian and Devonian natural gas resources in the northwestern Sichuan Basin.What's more,in order to adapt to the development of the deep natural gas(over 9000 m)in the Sichuan Basin during the 14th Five-Year Plan,it is necessary to speed up researches on drilling and completion tech-nologies in nine aspects,e.g.high-temperature downhole tools and workingfluid.展开更多
基金supported by the National Major Science and Technology Project"Development demonstration project of large-scale carbonae gas fields in the Sichuan Basin-Research and application of large-scale deep carbonate gas reservoir drilling and production technology"(No:2016ZX05052-003)Pet roChina Major Science and Technology Project"Research and application of key technologies for maintaining 30billion cubic meters of natural gas production in Southwest Oil and Gas Field-Research and application ofdrilling,completion,and oil testing technologies for high temperature and high pressure sulfur-bearing deep wells in the Sichuan Basin"(No:2016E-0608)。
文摘In the Sichuan Basin,the drilling of complex deep and ultradeep wells is restricted by the casing sequence.Multiple pressure systems are usually encountered in the same open hole section,and narrow safety density window is observed in vertical strata.The application of managed pressure drilling(MPD)technique which is often used in well drilling ensures the safe and efficient drilling,but it also brings about great challenges to the small-gap liner cementing at the lower part.Therefore,it is of great practical significance to research a cementing technology that can not only satisfy the quality requirement of small gap liner cementing,but also ensure the safe cementing in the strata with narrow safety density window.In this paper,a cementing technology based on precise managed pressure balancing method was proposed by referring to the successful application of MPD technique.According to the cementing design,the hydrostatic column pressure of annulusfluid is under-balanced(slightly lower than the formation pore pressure),and then a precise managed pressure drilling device is adopted to produce back pressure through wellhead restriction or apply wellhead compensation pressure,so that the balanced pore pressure can be reached in the process of cementing via the wellhead pressure and theflow friction offluid in the annulus.After the cementing is completed,a certain compensation pressure is applied to the annulus continuously to prevent annulus channeling during waiting on cement caused by insufficient static pressure and slurry weight loss.After this technology was applied to an ultradeep exploration well in the Sichuan Basin,the qualification rate of borehole cementing quality reached 97%,and the well sections with good cementing quality accounted for 76%.In conclusion,this technology needs no additional equipment,and only by virtue of the MPD equipment,it can achieve safe cementing construction and cementing quality improvement under high displacement efficiency.
基金supported by the National Research Council of Science and Technology Major Project“Sichuan Basin Large-scale Carbonate Cas Fiekd Development Demonstration Project”(No.:2016ZX05052).
文摘The exploration and development of oil and gas resources in the Sichuan Basin is shifting to the deeper strata.The deep and ultra-deep wells in deep carbonate gas reservoirs are faced with many difficulties,such as multiple pressure systems,poor drillability,ultra-high pressure,ultra-high temperature and high sulfur content,which bring great challenges to drilling and completion engineering.In order to ensure the smooth exploration and development of deep carbonate oil and gas resources in the Sichuan Basin,the overall concept of combiningfield practice and technological research is followed.During the 13th Five-Year Plan,a batch of ultra-deep wells(well depth about 8000 m)have been drilled fast and safely(such as Well SYX133 in the Shuangyushi structure),and great progresses have been achieved in the experimental research of the support technologies in drilling and completion of deep and ultra-deep wells.And the achievements are as follows.First,the optimization of non-standard well structure,combined with the application of precisely managed pressure drilling technology and under-pressure plugging technology,lays a foundation for the optimized fast drilling and the safe reaching of geological targets.Second,a high-efficiency customized PDC drill bit is comprehensively optimized,popularized and applied,which effectively improves the average rate of penetration(ROP)in difficult-to-drill formations.Third,the development and application of drillingfluids(e.g.being resistant to high temperature of 200 C and anti-composite brine)and active under-pressure plugging technology effectively reduces downhole complexities while drilling the complex for-mations,such as high temperature and high pressure brine and circulation loss.Fourth,when precisely managed pressure drilling and precisely managed pressure cementing methods are applied in the strata with a narrow density window,multiple pressure systems and pressure sensitivity,the average drilling and completionfluid loss is reduced by more than 90%,and the complexity treatment time is cut down by more than 85%,and the cementing quality pass rate is increased by more than 20%.Fifth,the integrated application of ROP improvement technologies and tools(e.g.air drilling)results in a great reduction of drilling cycle and cost.It is concluded that the experimental research achievements provide basic support for the fast development of natural gas resources in the Anyue Gas Field,Sichuan Basin,and the great discovery of the Permian and Devonian natural gas resources in the northwestern Sichuan Basin.What's more,in order to adapt to the development of the deep natural gas(over 9000 m)in the Sichuan Basin during the 14th Five-Year Plan,it is necessary to speed up researches on drilling and completion tech-nologies in nine aspects,e.g.high-temperature downhole tools and workingfluid.
