In deepwater drilling, a small margin usually exists betweenformation integrity and pore pressure. Accurate determinationof the formation integrity at casing shoes is paramount todrilling an interval without losing returns. Non-aqueous fluidis often the fluid of choice for deepwater environments, andcold temperatures in the riser result in higher drilling fluidviscosity and gel strengths along with pressure andtemperature effects on fluid density. These effects on fluidproperties can induce inaccuracies in the interpretation ofsurface collected data when determining the fracture initiationpressure (FIP) during a formation integrity test (FIT).Downhole pressure technology can be used to more accuratelydetermine fracture initiation during a FIT by measuring thetrue bottomhole pressure at the formation, thereby eliminatingthe effects of mud gel strength and varying mud weight in themud column. The comprehensive pressure data, however, isstored in downhole memory and can only be accessed upontool recovery or wireline data link. Neither of these optionsare economically attractive in the deepwater cost environment.However, limited downhole pressure data can be transmittedback to the surface once circulation is re-initiated. This paperpresents a field useable method which makes use of limitedreal-time downhole pressure data to correct interpretation ofsurface collected data. This method has been compared toover 20 FIT results from actual downhole memory data andyields a close match.
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