An extensive drilling campaign was done for the purpose of reservoir appraisal of an offshore Brazilian field that included complex deviated pilot wells. One of the objectives of this campaign was to provide detailed reservoir pressure information to determine fundamental reservoir properties. In order to optimize the data collection, it was necessary to acquire pressure measurements and also to transmit real time to validate test responses. Due to the complexity of well trajectories, the solution for executing pressure tests consisted of using Formation Pressure While Drilling technology.

The operation was carried out in five pilot wells providing critical results. The first result was the detection of non-linear reservoir depletions. Pressure tests also identified change of fluid phase in a black oil reservoir containing a gas cap. By comparing the fluid phase and gradient from early exploration wells, it was evident that the free gas was not originally present. This multiphase behavior reinforces the second result: confirmation of the dynamic process that reservoir fluids are undergoing. Moreover, different degrees of pressure depletions were observed in locations up to 1.5 km distant from producer well within same connected reservoir proving third outcome: the long lateral connectivity of reservoir sands. Another important outcome is that the actual bubble pressure is higher in magnitude and the current pressure depletion had fallen below it. The final outstanding result was the potential increase of oil reserves where pressure values identified unexpected sand channels with no drainage or very small depletions. The results of this pressure measurements analysis reinforced the need to optimize the potential capacity of oil recovery through acceleration of drilling injection wells for pressure maintenance.

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