Primary funding is provided by The SPE Foundation through member donations The SPE Foundation through member donations and a contribution from Offshore Europe The Society is grateful to those companies that allow their The Society is grateful to those companies that allow their professionals to serve as lecturers Additional s pport pro ided b AIME Additional support provided by AIME Society of Petroleum Engineers Distinguished Lecturer Program www.spe.org/dl
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The SPE Foundation through member donationsThe SPE ... · Fluids Program-Type of treatment: *Pills Data Collected *Continuous-Handling WSM-Fluid property management-Monitoring tools
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Primary funding is provided by
The SPE Foundation through member donationsThe SPE Foundation through member donations and a contribution from Offshore Europe
The Society is grateful to those companies that allow theirThe Society is grateful to those companies that allow their professionals to serve as lecturers
Additional s pport pro ided b AIMEAdditional support provided by AIME
Society of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl
How to Stabilize and Strengthen the Wellbore during Drilling OperationsWellbore during Drilling Operations
Dr Fred GrowcockDr. Fred Growcock
Society of Petroleum EngineersSociety of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl
Presentation Outline
The Lost Circulation Problem
Strategy for Managing Lost Circulation
Wellbore StrengtheningWellbore Strengthening
Wellbore Stress Enhancement
Application Strategies on the Rig
Case HistoryCase History
Summary
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The Lost Circulation Problem: High-Risk Operations
eigh
t
Stable Wellbore
Fractured Wellbore
Pressure Gradient / Mud Density
Wei
ght
Mud
We Stable Wellbore
Collapsed Wellbore
Weak zone (depleted)
Frac Gradient
Mud
Mud
W
Well Inclination0 30 60 90
Deviated Wellbores
( p )Weight
Pore Pressure
Depleted ZonesDepleted Zones
Deep Water
The Lost Circulation Problem
• Estimated industry cost in the Gulf of Mexico:$1 billion/yr. Worldwide: ~ $ 2 to 4 billion/yr. y y
• On average, 10-20% of the total cost of drilling anHTHP well is expended on mud losses (U.S.Department of Energy)Department of Energy).
• No consistent approach to manage lost circulation.• Nearly 200 products offered by 50 drilling fluidNearly 200 products offered by 50 drilling fluid
companies to control lost circulation.
A comprehensive Lost Circulation mitigation and prevention program is required. g
Ti V l P d ( )Time or Volume Pumped (constant pump rate)
Fracture Closure Stress
• High-fluid-loss treatment for existing fractures
A li d hi h fl id l ill h l d• Applied as high-fluid-loss pills or whole mudtreatment (Drill-n-Stress)
• Pill may be water-based in a non-aqueoussystem
• May follow with cross-linked polymer plugs orcement
Fracture Closure Stress
As existing fracture is widened, particles are forced deep within the fracture.
Liquid leaks from the slurrythrough the fracture walls or tip.
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Fracture Closure Stress
As the slurry deliquifies, it consolidates.
The residual solid plug supports the fracture and isolates the tipisolates the tip.
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Hoop Stress Enhancement
• Wellbore is pre-fractured and sealed to preventsubsequent fracturing
• Mathematical models are used to design the : calculate the required fracture width and particle size q pdistribution of
• is added at moderate concentration whileis added at moderate concentration whiledrilling (involves solids control management):Continuous addition is much more effective than pillsp
• The formation is pressured every stand to build hoopstress or ECD is raised to desired levelstress, or ECD is raised to desired level
Hoop Stress Enhancement
As fracture is widened, large particles are forced inand wedged in the fracture mouth to create bridge
Smaller particles come in behind the bridgeand seal the openingg
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Hoop Stress Enhancement
Trapped fluid filtersthrough permeable walls of fracture
The pressure drops and compressive p p pforces are transferred to WSM
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Hoop Stress Enhancement Application Cycle
Suitability of Treatment Data CollectionModeling of FractureCreation and Fillingg
Output:-Fracture dimensions-Formulation of LossPrevention MaterialLessons Learned
Si ed Marble- Sized Marble- Granular Synthetic Carbons
Case History – Deepwater Gulf of Mexico
No losses in 2900 ft sand section above salt No losses in 7500 ft salt section, screened upNo losses in 9200 ft sand section below salt (where majority of losses occurred in offset wells)(where majority of losses occurred in offset wells)
Savings• Total cost for the WSM ~ $ 0 7 MM Previous mud• Total cost for the WSM ~ $ 0.7 MM. Previous mud
losses ~ $ 2.7 MM. Net savings ~ $ 2.0 MM on materials alone.
• On subsequent 4 wells, similar net savings of ~ $ 2.0 MM on materials alone.
The 4-tier strategy for managing lost circulationSummary
must be an integral part of well planning
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