Transition Zone Characterization for Simulation Models of Gas Bearing Carbonate Reservoir

Nowadays demand makes gas one of the desirable hydrocarbon sources of energy. However reservoirs size and quality of new discoveries or old preserved one are poor. This fact set the task for simulation of accurate prediction in order to evaluate economic reasonability of production. This study concerns the question of changes gas production profile at the gas-bearing carbonate formation due to presence of transition zone. The different ways of simulation models initialization are implemented. Then the changes of the total output are compared and analyzed. In addition the advantages of initialization by means of J-function over capillary pressure curve assignment for the carbonate formation with highly heterogeneous flowing properties are explained. All results are coupled to vertical flow performance of wells which were matched at the tests. The study shows that transition zone should be taken into account in simulation modeling of the gas-bearing no less than for the oil-bearing formations. Also the total gas production compared with and without the transition zone implementation due to its production is sensitive to presence any liquid. Accurate J-function matching at the core data provide better result for water breakthrough thus the performance of wells and finally the total production profile. The vertical flow performance curves adjustment and subsequent use for the simulation is the additional need which considered because in the case of the surface equipment restriction, such as the tubing head pressure limits, the pressure loss in the presence of gas and water mixture could be huge which cause early shutdown of the wells. It is shown that gas bearing is not the reason to neglect the importance of the capillary force and the presence of the transition zone which has essential impact on the total formation performance.