Cement Integrity for Life of the Well Perry Beaudoin Les Hendricks Halliburton Energy Services
Why be concerned about Cement Integrity for the life of the well? • Pressure on the annulus side after the well has been cemented and put on production • Annular Gas Flows • Premature water production • Casing collapse
Remedial Options Due to Bond Failure • Monitor document and produce
Remedial Options Due to Bond Failure • Monitor document and produce • Squeeze cement
Remedial Options Due to Bond Failure • Monitor document and produce • Squeeze cement • Abandon the Well
Processes Inducing Changes in Cement Sheath • The Stresses of a Cement Jobs Life • Mechanical shocks from pipe tripping • Expansion of the casing and compression of the cement during pressure testing • Expansion and contraction of the pipe due to cycles in production pressure and temperature • Formation movement
Large Scale Stress TestingConventional Cement • 5 1/2” pipe cemented inside 7 5/8” casing • Inner pipe pressured in stages until cement failure was indicated at 31 Mpa
Conventional Cement • Cement became brittle • Radial cracks formed • Cement bond failed creating a microannulus
Foam Cement is Ductile • No radial cracks • Only slight debonding • Foamed cement deformed and absorbed the expansive energy without failure due to its elastic nature
Foam Cement Foam Cement is a “system” containing cement, additives, foam surfactant, a gas (usually nitrogen), and water.
Lightweight Excellent strength- to-density ratio Improved mud removal Gas migration preventative Expands (compressible) Ductile Stable to crossflows Insulates Stable at high temperatures Flexible system Low permeability Benefits of Foam Cement
Fluid Loss Gas Entry Gas Migration Prevention FlowThrough Unset Cement • Overbalance pressure is lost • Fluid loss (volume) to lower pressure zone • Gas enters wellbore and percolates up annulus
Cement Fluid Cement Sets Cement Hardens Cement Gels Overbalance Pressure Formation Gas Pressure Hydrostatic Pressure Time Hydrostatic Pressure Loss
Foam Cement Cement Fluid Cement Sets Cement Hardens Cement Gels Overbalance Pressure Formation Gas Pressure Hydrostatic Pressure Time
Equipment Required Cement Unit Injection Unit Nitrogen Unit
Summary • Optimum production of hydrocarbons is linked to integrity of cement sheath.
Summary • Life of the Well Cement process has been successfully applied in N.E. British Columbia in over 200 wells to provide superior cement integrity.
Summary • Weak Zone / Loss Circulation • Lightweight foam cement lowered the hydrostatic of cement column.