Offshore drilling has attracted more attention than ever before due to the increasing worldwide energy demand especially in China. High cost, long drilling cycles, and low rate of penetration （ROP） represent critica...Offshore drilling has attracted more attention than ever before due to the increasing worldwide energy demand especially in China. High cost, long drilling cycles, and low rate of penetration （ROP） represent critical challenges for offshore drilling operations. The hydraulic pulse generator was specifically designed, based on China offshore drilling technologies and parameters, to overcome problems encountered during offshore drilling. Both laboratory and field tests were conducted to collect the characteristics of the hydraulic pulse generator. The relationships between flow rate and pressure amplitude, pressure loss and pulse frequency were obtained, which can be used to optimize operation parameters for hydraulic pulse jet drilling. Meanwhile a bottom hole assembly （BHA） for pulse jet drilling has been designed, combining the hydraulic pulse generator with the conventional BHA, positive displacement motor, and rotary steerable system （RSS） etc. Furthermore, the hydraulic pulse jet technique has been successfully applied in more than 10 offshore wells in China. The depth of the applied wells ranged from 2,000 m to 4,100 m with drilling bit diameters of 311 mm and 216 mm. The field application results showed that hydraulic pulse jet technique was feasible for various bit types and formations, and that ROP could be significantly increased, by more than 25%.展开更多
The maximum internal tangential stress is a critical parameter for the design of the PDC （polycrystalline diamond compact） die that has been widely applied to offshore oil drilling. A new simple equation for the cal...The maximum internal tangential stress is a critical parameter for the design of the PDC （polycrystalline diamond compact） die that has been widely applied to offshore oil drilling. A new simple equation for the calculation of the stress is developed, and verified by the test data from Kingdream Corp. of China, the largest bit Company in China. An opti- mum method for the design of the PDC die is presented and demonstrated in detail, and software for the design and FEM analysis of the die is developed on the basis of the method. This software has been used in oil industry in recent years.展开更多
This paper discusses the development of China's oil exploration & drilling equipment, and it focuses mainly on the domestication, industrialization, and standardization of fixed offshore drilling rigs primaril...This paper discusses the development of China's oil exploration & drilling equipment, and it focuses mainly on the domestication, industrialization, and standardization of fixed offshore drilling rigs primarily constructed by CNOOC. Considering the manufacturing of and application of deepwater drilling equipment in China, the authors put forward suggestions regarding industry policies and the standardization of China's offshore engineering equipment.展开更多
This paper presents a theoretical method and a finite element method to describe wellhead movement and uncemented casing strength in offshore oil and gas wells.Parameters considered in the theoretical method include o...This paper presents a theoretical method and a finite element method to describe wellhead movement and uncemented casing strength in offshore oil and gas wells.Parameters considered in the theoretical method include operating load during drilling and completion and the temperature field,pressure field and the end effect of pressure during gas production.The finite element method for multistring analysis is developed to simulate random contact between casings.The relevant finite element analysis scheme is also presented according to the actual procedures of drilling,completion and gas production.Finally,field cases are presented and analyzed using the proposed methods.These are four offshore wells in the South China Sea.The calculated wellhead growths during gas production are compared with measured values.The results show that the wellhead subsides during drilling and completion and grows up during gas production.The theoretical and finite element solutions for wellhead growth are in good agreement with measured values and the deviations of calculation are within 10％.The maximum von Mises stress on the uncemented intermediate casing occurs during the running of the oil tube.The maximum von Mises stress on the uncemented production casing,calculated with the theoretical method occurs at removing the blow-out-preventer （BOP） while that calculated with the finite element method occurs at gas production.Finite element solutions for von Mises stress are recommended and the uncemented casings of four wells satisfy strength requirements.展开更多
Multilateral wells promise cost savings to oil and fields as they have the potential to reduce overall drilling distances and minimize the number of slots required for the surface facility managing the well.However,dr...Multilateral wells promise cost savings to oil and fields as they have the potential to reduce overall drilling distances and minimize the number of slots required for the surface facility managing the well.However,drilling a multilateral well does not always increase the flow rate when compared to two single-horizontal wells due to competition in production inside the mother-bore.Here,a holistic approach is proposed to find the optimum balance between single and multilateral wells in an offshore oil development.In so doing,the integrated approach finds the highest Net Present Value(NPV)configuration of the field considering drilling,subsurface,production and financial analysis.The model employs stochastic perturbation and Markov Chain Monte-Carlo methods to solve the global maximising-NPV problem.In addition,a combination of Mixed-Integer Linear Programming(MILP),an improved Dijkstra algorithm and a Levenberg-Marquardt optimiser is proposed to solve the rate allocation problem.With the outcome from this analysis,the model suggests the optimum development including number of multilateral and single horizontal wells that would result in the highest NPV.The results demonstrate the potential for modelling to find the optimal use of petroleum facilities and to assist with planning and decision making.展开更多
基金financial support from the Program for New Century Excellent Talents in University (No. NCET-12-0971)
文摘Offshore drilling has attracted more attention than ever before due to the increasing worldwide energy demand especially in China. High cost, long drilling cycles, and low rate of penetration （ROP） represent critical challenges for offshore drilling operations. The hydraulic pulse generator was specifically designed, based on China offshore drilling technologies and parameters, to overcome problems encountered during offshore drilling. Both laboratory and field tests were conducted to collect the characteristics of the hydraulic pulse generator. The relationships between flow rate and pressure amplitude, pressure loss and pulse frequency were obtained, which can be used to optimize operation parameters for hydraulic pulse jet drilling. Meanwhile a bottom hole assembly （BHA） for pulse jet drilling has been designed, combining the hydraulic pulse generator with the conventional BHA, positive displacement motor, and rotary steerable system （RSS） etc. Furthermore, the hydraulic pulse jet technique has been successfully applied in more than 10 offshore wells in China. The depth of the applied wells ranged from 2,000 m to 4,100 m with drilling bit diameters of 311 mm and 216 mm. The field application results showed that hydraulic pulse jet technique was feasible for various bit types and formations, and that ROP could be significantly increased, by more than 25%.
文摘The maximum internal tangential stress is a critical parameter for the design of the PDC （polycrystalline diamond compact） die that has been widely applied to offshore oil drilling. A new simple equation for the calculation of the stress is developed, and verified by the test data from Kingdream Corp. of China, the largest bit Company in China. An opti- mum method for the design of the PDC die is presented and demonstrated in detail, and software for the design and FEM analysis of the die is developed on the basis of the method. This software has been used in oil industry in recent years.
文摘This paper discusses the development of China's oil exploration & drilling equipment, and it focuses mainly on the domestication, industrialization, and standardization of fixed offshore drilling rigs primarily constructed by CNOOC. Considering the manufacturing of and application of deepwater drilling equipment in China, the authors put forward suggestions regarding industry policies and the standardization of China's offshore engineering equipment.
基金financial support from the National Key Sci-Tech Major Special Item(No.2011ZX05026-001)Program for Changjiang Scholars and Innovative Research Team in University(IRT1086)
文摘This paper presents a theoretical method and a finite element method to describe wellhead movement and uncemented casing strength in offshore oil and gas wells.Parameters considered in the theoretical method include operating load during drilling and completion and the temperature field,pressure field and the end effect of pressure during gas production.The finite element method for multistring analysis is developed to simulate random contact between casings.The relevant finite element analysis scheme is also presented according to the actual procedures of drilling,completion and gas production.Finally,field cases are presented and analyzed using the proposed methods.These are four offshore wells in the South China Sea.The calculated wellhead growths during gas production are compared with measured values.The results show that the wellhead subsides during drilling and completion and grows up during gas production.The theoretical and finite element solutions for wellhead growth are in good agreement with measured values and the deviations of calculation are within 10％.The maximum von Mises stress on the uncemented intermediate casing occurs during the running of the oil tube.The maximum von Mises stress on the uncemented production casing,calculated with the theoretical method occurs at removing the blow-out-preventer （BOP） while that calculated with the finite element method occurs at gas production.Finite element solutions for von Mises stress are recommended and the uncemented casings of four wells satisfy strength requirements.
文摘Multilateral wells promise cost savings to oil and fields as they have the potential to reduce overall drilling distances and minimize the number of slots required for the surface facility managing the well.However,drilling a multilateral well does not always increase the flow rate when compared to two single-horizontal wells due to competition in production inside the mother-bore.Here,a holistic approach is proposed to find the optimum balance between single and multilateral wells in an offshore oil development.In so doing,the integrated approach finds the highest Net Present Value(NPV)configuration of the field considering drilling,subsurface,production and financial analysis.The model employs stochastic perturbation and Markov Chain Monte-Carlo methods to solve the global maximising-NPV problem.In addition,a combination of Mixed-Integer Linear Programming(MILP),an improved Dijkstra algorithm and a Levenberg-Marquardt optimiser is proposed to solve the rate allocation problem.With the outcome from this analysis,the model suggests the optimum development including number of multilateral and single horizontal wells that would result in the highest NPV.The results demonstrate the potential for modelling to find the optimal use of petroleum facilities and to assist with planning and decision making.
