Using Reservoir Engineering Data to Solve Geological Ambiguities: A Case Study of One of the Iranian Carbonate Reservoirs

In this work one of the Iranian fractured carbonate reservoirs has been studied. This reservoir is located in south west of Iran with 40 km long and 4 km wide and consists of two culminations with crest depths of 3780 and 3749 mss respectively. Eastern part is smaller and productive compared to the western part which is larger but with high water saturation causing no production from this part. Two parts are separated by a saddle like region. Economic production from this reservoir has been started in 1977 and the cumulative production has reached 12.064 MMSTB in 2004.The main ambiguity of this reservoir is whether two parts are sealed or not. Geologists couldn’t answer this question because of the lack of data. This question has been addressed in this study from reservoir engineering point of view. Therefore, after data gathering and calculating reservoir engineering parameters, oil in place and reserve are estimated in two parts. Then the reservoir is analyzed by material balance calculations, after which the reservoir has been simulated. By evaluating the results, the problem of communication between two parts is resolved in 7 sections: core description and analysis, core experiments and rock type, fluid characterization and PVT analysis, pressure analysis, water-oil contacts, production history and petrophysical evaluations. Finally considering all aspects of evaluations, it is concluded that there is no communication between two parts of the reservoir.

Keywords:

Petroleum Reservoir , culmination , material balance , reserve