Mr. Erik Milito - The House Committee on Natural Resources ...

76 API STANDARD 65-2
Critical Well Design Parameters
<strong>The</strong> condition of the wellbore affects the ability to successfully isolate a potential flow zone. <strong>The</strong>se well conditions, whether
induced or naturally occurring, should be considered in the cement design and placement.
Pore/Fracture
Pressure
Simulations
Close-tolerance
and Other Flow
Restriction
Considerations
TOC
Hole Diameter
Deviation, Dogleg
Severity
Trapped Annular
Pressure
Lost Circulation
Mechanical Barrier
Rathole
Wellbore fluid hydraulics (ECD) modeling shall be performed in well sections containing a potential flow
zone in order to assess pore pressure and fracture gradient limits.
In order to best facilitate the installation of a cement barrier element, centralizer placement, ECD and fluid
displacement simulations shall be performed.
Within the constraints imposed by hydraulic, operational, logistical or well architecture limitations, the
results of these simulations shall be considered during the cementing design and execution.
ECD pressure calculations shall include any flow restrictions, particularly those of significant length and
small cross-sectional area, such as liner overlaps, liner top packers, liner hangers, tieback sleeves, casing
connections and drill pipe tool joints.
<strong>The</strong> planned TOC shall cover the shallowest potential flow zone.
Is hole enlargement minimized sufficiently to allow for adequate centralization
Is the wellbore trajectory sufficiently smooth to allow for running casing and adequate centralization
Has the risk of trapped annular pressure in designing the TOC been assessed and mitigated for subsea
wellheads
Is there a plan for mitigating lost circulation
Has the use of mechanical barriers (e.g. liner top packers, ECPs) been evaluated and included in the well
design if warranted
Has the rathole length been minimized or filled with drilling fluid with a density greater than the cement
density