Through a comprehensive review of the development status of workover technology of PetroChina Company Limited(PetroChina), this paper presents the connotation of workover operation under the background of the new era,...Through a comprehensive review of the development status of workover technology of PetroChina Company Limited(PetroChina), this paper presents the connotation of workover operation under the background of the new era, the latest progress of workover operation in the respects of equipment, tools, technology and the construction of information and standardization. The gaps between PetroChina and foreign counterpart in workover technology are as follows: the level of automation and intellectualization of tools and equipment is relatively low, the snubbing operation in gas wells characterized by HT/HP and high H2 S is lagged behind;water plugging in the long horizontal wellbore needs to be further developed, coiled tubing and its relevant equipment for ultra-deep well operation has to be optimized;informationization, standardization and big data application of workover operation need to be started. Based on this as well as the development status of workover technology in China and the technical difficulties faced in the future, eight suggestions for future development are put forward:(1) strengthen the dynamic understanding of reservoir and improve the pertinence of workover schemes;(2) develop the general overhaul technology in a systematical way to tackle issues of seriously problematic wells;(3) put more efforts into the research of horizontal well workover operation and develop relevant technology for long horizontal section operation;(4) improve the snubbing technology and extend its applications;(5) expand the capacity of coiled tubing operation and improve the level of special operations;(6) develop automatic workover technology into the field of artificial intelligence;(7) promote clean operation in an all-round way and build green oil and gas fields;(8) perfect the informationization construction to realize the sharing of workover resources.展开更多
Research has been done on an energy-saving type of hydraulic workover rig. This rig can recover and reuse the potential energy which is released by the pipestring when lowered, and the equipped power of this rig is on...Research has been done on an energy-saving type of hydraulic workover rig. This rig can recover and reuse the potential energy which is released by the pipestring when lowered, and the equipped power of this rig is only one third of an ordinary rig. The structure and theory of this rig are introduced. The mathematical model of lowering the pipestring is established and a simulation analysis is conducted. Through simulation some conclusions are obtained： The lighter the pipestring is, the less velocity of lowering the pipestring is; The smaller the throttle valve path area is, the less velocity of lowering the pipestring is; Different air vessel volumes have no evident effect on the pipestring lowering velocity. The actual measure results prove that the simulation results are right. Finally, the energy-saving effect of this rig is proved by the field test results.展开更多
During well-killing operations for the workover of low-pressure gas wells,formation pressure should be balanced so as to guarantee well control safety by preventing natural gas overflow.In this paper,a laboratory eval...During well-killing operations for the workover of low-pressure gas wells,formation pressure should be balanced so as to guarantee well control safety by preventing natural gas overflow.In this paper,a laboratory evaluation was conducted with fuzzy-ball fluids as killing fluids.The results show that,the fuzzy-ball fluid,with a density of 0.5e1.5 g/cm^(3) and a viscosity up to 78,50,000 mPa$s at a low shear rate,realizes controllable performance and forms piston-like plugging slugs of solid-free high structural strength on natural gas wellbore after bonding.During well workover,multiple fluid column pressures were set up by injecting fuzzy-ball fluids with different densities at various rates.Owing to high structural strength of the fluids at a low shear rate,natural gas breaks through only inside the piston-like slug and cannot flow upwards to the ground,so the pathways of natural gas in the wellbore are isolated from the ground surface.Moreover,the fluid can wholly move up and down like a piston-like plug,with the change of formation pressures or the tripping of pipe strings.Like the conventional operations,the production can be restored after the workover,so long as the fluid in wellbore is cleaned by means of gas lift.In a natural gas field in NW China,where the formation pressure coefficient dropped to 0.60e0.82,three wells were fully filled with fuzzy-ball workover fluids for 7 days and another three wells were treated with the piston-like plugs of fuzzy-ball workover fluids for only 3 days.They all presented better technical results.The technology provides a new way for low-pressure gas well workover.展开更多
Force analysis and calculation of workover string in the slanted and horizontal well are the basis of designing and checking string strength, selecting tools and determining operation parameters, which determine the o...Force analysis and calculation of workover string in the slanted and horizontal well are the basis of designing and checking string strength, selecting tools and determining operation parameters, which determine the operation safety and success of engineering accidence treatment. In this paper, by comprehensive consideration of wellbore structure, string assembly, string load and workover operation conditions, the workover string mechanical model has been built under three kinds of working states of lifting, lowering and rotating. The downhole string mechanics has been analyzed and calculated. By field verification, the string assembly, tool selection and operation parameter optimization can be achieved, which can improve the safety and success rates of workover engineering accident treatment.展开更多
The solid weighting material in a high-density workover fluid is prone to static sag.Existing experi mental methods cannot predict the parameters of the settling stability of workover fluids at high tem perature and h...The solid weighting material in a high-density workover fluid is prone to static sag.Existing experi mental methods cannot predict the parameters of the settling stability of workover fluids at high tem perature and high pressure(HTHP).Therefore,in this study,static settlement experiments were carried out using a novel experimental setup.The experimental setup enables the measurement of the density profile of heavy workover fluids at HTHP.A multi-parameter correlation equation between the sag factor and particle diameter,particle density,base fluid density,workover fluid density and rheological pa rameters,aging time,temperature,and pressure was obtained using dimensional analysis and multi variate nonlinear regression methods.The results reveal that the settlement stability of the workover f luid decreases with the increase in temperature and pressure.Based on the multi-parameter correlation,the predicted and the measured values were compared and verified.The error between the predicted value and the measured value was within 5%.The average prediction error was 1.68%,and the maximum prediction error was 3.8%.These results reveal that the model proposed in this study can effectively predict the static sedimentation stability of the solid weighted Polysulfonate workover fluids.Further more,the proposed correlation can guide the properties adjustment of the workover fluids to achieve the required sag stability.This work provides a new approach to predict and control the sag stability of the solid weighted workover fluids.展开更多
This paper summarizes the important progress in the field of oil and gas production engineering during the"Thirteenth Five-Year Plan"period of China,analyzes the challenges faced by the current oil and gas p...This paper summarizes the important progress in the field of oil and gas production engineering during the"Thirteenth Five-Year Plan"period of China,analyzes the challenges faced by the current oil and gas production engineering in terms of technological adaptability,digital construction,energy-saving and emission reduction,and points out the future development direction.During the"Thirteenth Five-Year Plan"period,series of important progresses have been made in five major technologies,including separated-layer injection,artificial lift,reservoir stimulation,gas well de-watering,and workover,which provide key technical support for continuous potential tapping of mature oilfields and profitable production of new oilfields.Under the current complex international political and economic situation,oil and gas production engineering is facing severe challenges in three aspects:technical difficulty increases in oil and gas production,insignificant improvements in digital transformation,and lack of core technical support for energy-saving and emission reduction.This paper establishes three major strategic directions and implementation paths,including oil stabilization and gas enhancement,digital transformation,and green and low-carbon development.Five key research areas are listed including fine separated-layer injection technology,high efficiency artificial lift technology,fine reservoir stimulation technology,long term gas well de-watering technology and intelligent workover technology,so as to provide engineering technical support for the transformation,upgrading and high-quality development of China’s oil and gas industry.展开更多
This paper gives an overview of recent development of the marine well containment system (MWCS) after BP Macondo subsea well blowout occurred on April 20,2010 in the Gulf of Mexico. Capping stack,a hard-ware utilized ...This paper gives an overview of recent development of the marine well containment system (MWCS) after BP Macondo subsea well blowout occurred on April 20,2010 in the Gulf of Mexico. Capping stack,a hard-ware utilized to contain blowout well at or near the wellhead is the center piece of MWCS. Accessibility to the dedicated capping stacks is gradually becoming a pre-requirement to obtain the permit for offshore drilling/workover, and the industry for manufacturing,maintenance,transportation and operation of the capping stack is in the making.展开更多
基金Supported by the National Science and Technology Major Project(2016ZX05010,2016ZX05023).
文摘Through a comprehensive review of the development status of workover technology of PetroChina Company Limited(PetroChina), this paper presents the connotation of workover operation under the background of the new era, the latest progress of workover operation in the respects of equipment, tools, technology and the construction of information and standardization. The gaps between PetroChina and foreign counterpart in workover technology are as follows: the level of automation and intellectualization of tools and equipment is relatively low, the snubbing operation in gas wells characterized by HT/HP and high H2 S is lagged behind;water plugging in the long horizontal wellbore needs to be further developed, coiled tubing and its relevant equipment for ultra-deep well operation has to be optimized;informationization, standardization and big data application of workover operation need to be started. Based on this as well as the development status of workover technology in China and the technical difficulties faced in the future, eight suggestions for future development are put forward:(1) strengthen the dynamic understanding of reservoir and improve the pertinence of workover schemes;(2) develop the general overhaul technology in a systematical way to tackle issues of seriously problematic wells;(3) put more efforts into the research of horizontal well workover operation and develop relevant technology for long horizontal section operation;(4) improve the snubbing technology and extend its applications;(5) expand the capacity of coiled tubing operation and improve the level of special operations;(6) develop automatic workover technology into the field of artificial intelligence;(7) promote clean operation in an all-round way and build green oil and gas fields;(8) perfect the informationization construction to realize the sharing of workover resources.
文摘Research has been done on an energy-saving type of hydraulic workover rig. This rig can recover and reuse the potential energy which is released by the pipestring when lowered, and the equipped power of this rig is only one third of an ordinary rig. The structure and theory of this rig are introduced. The mathematical model of lowering the pipestring is established and a simulation analysis is conducted. Through simulation some conclusions are obtained： The lighter the pipestring is, the less velocity of lowering the pipestring is; The smaller the throttle valve path area is, the less velocity of lowering the pipestring is; Different air vessel volumes have no evident effect on the pipestring lowering velocity. The actual measure results prove that the simulation results are right. Finally, the energy-saving effect of this rig is proved by the field test results.
文摘During well-killing operations for the workover of low-pressure gas wells,formation pressure should be balanced so as to guarantee well control safety by preventing natural gas overflow.In this paper,a laboratory evaluation was conducted with fuzzy-ball fluids as killing fluids.The results show that,the fuzzy-ball fluid,with a density of 0.5e1.5 g/cm^(3) and a viscosity up to 78,50,000 mPa$s at a low shear rate,realizes controllable performance and forms piston-like plugging slugs of solid-free high structural strength on natural gas wellbore after bonding.During well workover,multiple fluid column pressures were set up by injecting fuzzy-ball fluids with different densities at various rates.Owing to high structural strength of the fluids at a low shear rate,natural gas breaks through only inside the piston-like slug and cannot flow upwards to the ground,so the pathways of natural gas in the wellbore are isolated from the ground surface.Moreover,the fluid can wholly move up and down like a piston-like plug,with the change of formation pressures or the tripping of pipe strings.Like the conventional operations,the production can be restored after the workover,so long as the fluid in wellbore is cleaned by means of gas lift.In a natural gas field in NW China,where the formation pressure coefficient dropped to 0.60e0.82,three wells were fully filled with fuzzy-ball workover fluids for 7 days and another three wells were treated with the piston-like plugs of fuzzy-ball workover fluids for only 3 days.They all presented better technical results.The technology provides a new way for low-pressure gas well workover.
文摘Force analysis and calculation of workover string in the slanted and horizontal well are the basis of designing and checking string strength, selecting tools and determining operation parameters, which determine the operation safety and success of engineering accidence treatment. In this paper, by comprehensive consideration of wellbore structure, string assembly, string load and workover operation conditions, the workover string mechanical model has been built under three kinds of working states of lifting, lowering and rotating. The downhole string mechanics has been analyzed and calculated. By field verification, the string assembly, tool selection and operation parameter optimization can be achieved, which can improve the safety and success rates of workover engineering accident treatment.
基金financed by the Natural Science Foundation of Sichuan Province (No. 2024 NSFSC0204).
文摘The solid weighting material in a high-density workover fluid is prone to static sag.Existing experi mental methods cannot predict the parameters of the settling stability of workover fluids at high tem perature and high pressure(HTHP).Therefore,in this study,static settlement experiments were carried out using a novel experimental setup.The experimental setup enables the measurement of the density profile of heavy workover fluids at HTHP.A multi-parameter correlation equation between the sag factor and particle diameter,particle density,base fluid density,workover fluid density and rheological pa rameters,aging time,temperature,and pressure was obtained using dimensional analysis and multi variate nonlinear regression methods.The results reveal that the settlement stability of the workover f luid decreases with the increase in temperature and pressure.Based on the multi-parameter correlation,the predicted and the measured values were compared and verified.The error between the predicted value and the measured value was within 5%.The average prediction error was 1.68%,and the maximum prediction error was 3.8%.These results reveal that the model proposed in this study can effectively predict the static sedimentation stability of the solid weighted Polysulfonate workover fluids.Further more,the proposed correlation can guide the properties adjustment of the workover fluids to achieve the required sag stability.This work provides a new approach to predict and control the sag stability of the solid weighted workover fluids.
基金Supported by the Basic Science Center Project of National Natural Science Foundation of China(72088101)National Natural Science Funded Project(52074345)CNPC Scientific Research and Technology Development Project(2020D-5001-21)。
文摘This paper summarizes the important progress in the field of oil and gas production engineering during the"Thirteenth Five-Year Plan"period of China,analyzes the challenges faced by the current oil and gas production engineering in terms of technological adaptability,digital construction,energy-saving and emission reduction,and points out the future development direction.During the"Thirteenth Five-Year Plan"period,series of important progresses have been made in five major technologies,including separated-layer injection,artificial lift,reservoir stimulation,gas well de-watering,and workover,which provide key technical support for continuous potential tapping of mature oilfields and profitable production of new oilfields.Under the current complex international political and economic situation,oil and gas production engineering is facing severe challenges in three aspects:technical difficulty increases in oil and gas production,insignificant improvements in digital transformation,and lack of core technical support for energy-saving and emission reduction.This paper establishes three major strategic directions and implementation paths,including oil stabilization and gas enhancement,digital transformation,and green and low-carbon development.Five key research areas are listed including fine separated-layer injection technology,high efficiency artificial lift technology,fine reservoir stimulation technology,long term gas well de-watering technology and intelligent workover technology,so as to provide engineering technical support for the transformation,upgrading and high-quality development of China’s oil and gas industry.
文摘This paper gives an overview of recent development of the marine well containment system (MWCS) after BP Macondo subsea well blowout occurred on April 20,2010 in the Gulf of Mexico. Capping stack,a hard-ware utilized to contain blowout well at or near the wellhead is the center piece of MWCS. Accessibility to the dedicated capping stacks is gradually becoming a pre-requirement to obtain the permit for offshore drilling/workover, and the industry for manufacturing,maintenance,transportation and operation of the capping stack is in the making.
