Drilling a well is the most common way to explore the earth, access underground mineral resources, and geologically store nuclear waste and carbon dioxide. During drilling, the drilling fluid is circulated in the well. It cools the drill bit, transports rock cuttings, prevents wellbore collapse, and balances formation pressure, etc. Lost circulation is a situation where less fluid is returned from the wellbore than is pumped into it. Its economic cost is because of the loss of expensive drilling fluid into the formation and nonproductive time spent on regaining circulation. If untreated, losses may lead to well control issues, poor hole cleaning, pack-offs, and stuck pipe, which seriously affect the normal drilling. With the increasing share of difficult wells (deep-water, deviated, horizontal, high pressure, high temperature, etc.) in the drilling portfolio, lost circulation incidents are more likely than ever to occur. It has been one of the most troublesome drilling problems.
Despite being an old problem, lost circulation has not been well addressed to date. It is even becoming more serious and more difficult to deal with as more extreme conditions are accessed. Lost circulation control is a general term for preventing and curing losses. Both prevention and curing require a good understanding of what causes losses, where they occur, where and how preventive measures and cures may work, and where and why they will not work. To answer these questions, the following scientific issues need to be addressed: 1) multiphase flow in the flow system of drilling assembly-wellbore-formation, 2) geomechanics, rock mechanics, and rock fracture mechanics during fracture initiation and propagation, 3) mechanics of materials and granular mechanics of the sealing zone formed by lost circulation materials physically or chemically, 4) fluid-structure interactions between multiphase fluid and rock. We would like to invite researchers and engineers working in relevant fields to contribute papers that aim to address the above issues. This Research Topic aims to fill the gaps among fundamental theories, applied technologies and field practices, reporting recent innovations and advances related to lost circulation control during drilling and completion in complex formations.
This Research Topic will be dedicated to publishing theoretical, numerical and experimental studies related to lost circulation control during drilling and completion in complex formations. Areas covered by this Research Topic, but are not limited to:
· Prediction of drilling fluid equivalent circulating density and lost circulation pressure.
· Interpretation and diagnosis of thief zone.
· Numerical simulations of drilling fluid or lost circulation material slurry flow in the drilling assembly-wellbore-formation system.
· New theories on mechanisms of lost circulation and lost circulation control based on fluid mechanics, granular mechanics, rock mechanics, fracture mechanics, geomechanics and their interactions.
· New methods and equipment for evaluation of lost circulation and lost circulation control in lab and field.
· New materials (solid and settable), tools, softwares and technologies of lost circulation control.
· Big data analytics, artificial intelligence and expert decision system in lost circulation prediction and control.
Drilling a well is the most common way to explore the earth, access underground mineral resources, and geologically store nuclear waste and carbon dioxide. During drilling, the drilling fluid is circulated in the well. It cools the drill bit, transports rock cuttings, prevents wellbore collapse, and balances formation pressure, etc. Lost circulation is a situation where less fluid is returned from the wellbore than is pumped into it. Its economic cost is because of the loss of expensive drilling fluid into the formation and nonproductive time spent on regaining circulation. If untreated, losses may lead to well control issues, poor hole cleaning, pack-offs, and stuck pipe, which seriously affect the normal drilling. With the increasing share of difficult wells (deep-water, deviated, horizontal, high pressure, high temperature, etc.) in the drilling portfolio, lost circulation incidents are more likely than ever to occur. It has been one of the most troublesome drilling problems.
Despite being an old problem, lost circulation has not been well addressed to date. It is even becoming more serious and more difficult to deal with as more extreme conditions are accessed. Lost circulation control is a general term for preventing and curing losses. Both prevention and curing require a good understanding of what causes losses, where they occur, where and how preventive measures and cures may work, and where and why they will not work. To answer these questions, the following scientific issues need to be addressed: 1) multiphase flow in the flow system of drilling assembly-wellbore-formation, 2) geomechanics, rock mechanics, and rock fracture mechanics during fracture initiation and propagation, 3) mechanics of materials and granular mechanics of the sealing zone formed by lost circulation materials physically or chemically, 4) fluid-structure interactions between multiphase fluid and rock. We would like to invite researchers and engineers working in relevant fields to contribute papers that aim to address the above issues. This Research Topic aims to fill the gaps among fundamental theories, applied technologies and field practices, reporting recent innovations and advances related to lost circulation control during drilling and completion in complex formations.
This Research Topic will be dedicated to publishing theoretical, numerical and experimental studies related to lost circulation control during drilling and completion in complex formations. Areas covered by this Research Topic, but are not limited to:
· Prediction of drilling fluid equivalent circulating density and lost circulation pressure.
· Interpretation and diagnosis of thief zone.
· Numerical simulations of drilling fluid or lost circulation material slurry flow in the drilling assembly-wellbore-formation system.
· New theories on mechanisms of lost circulation and lost circulation control based on fluid mechanics, granular mechanics, rock mechanics, fracture mechanics, geomechanics and their interactions.
· New methods and equipment for evaluation of lost circulation and lost circulation control in lab and field.
· New materials (solid and settable), tools, softwares and technologies of lost circulation control.
· Big data analytics, artificial intelligence and expert decision system in lost circulation prediction and control.
