Analyzing Dynamic Reservoir Behavior and Connectivity by Means ofFormation Pressure While Drilling Technology

摘要

An extensive drilling campaign was done for the purpose of reservoir appraisal of an offshore Brazilian field thatincluded complex deviated pilot wells. One of the objectives of this campaign was to provide detailed reservoir pressureinformation to determine fundamental reservoir properties. In order to optimize the data collection, it was necessary toacquire pressure measurements and also to transmit real time to validate test responses. Due to the complexity of welltrajectories, 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-linearreservoir depletions. Pressure tests also identified change of fluid phase in a black oil reservoir containing a gas cap. Bycomparing the fluid phase and gradient from early exploration wells, it was evident that the free gas was not originallypresent. This multiphase behavior reinforces the second result: confirmation of the dynamic process that reservoir fluids areundergoing. Moreover, different degrees of pressure depletions were observed in locations up to 1.5 km distant fromproducer 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 hadfallen below it. The final outstanding result was the potential increase of oil reserves where pressure values identifiedunexpected sand channels with no drainage or very small depletions. The results of this pressure measurements analysisreinforced the need to optimize the potential capacity of oil recovery through acceleration of drilling injection wells forpressure maintenance.