Technical Committee Reservoir Engineering

Simulation of the production behaviour of fractured wells in low-permeability formations

Objective of the project is the prognosis and optimization of the production from Tight-Gas reservoirs and the identification of damaging mechanisms in the system well-fracture-reservoir. The productivity of fractured wells in Tight-Gas formations remains frequently behind the forecasts. Therefore, this research work focuses on the following: (i) the investigation of the potential and the deficits of conventional reservoir simulators, (ii) the simulation of fractured wells in low-permeability formations and (iii) the further development of available standard software with derivation of applicative modelling practices.
Two main issues emerge in the case of modeling hydraulically fractured wells: (i) the simulation of the Clean-Up period and (ii) the simulation of the long-term behaviour, the so called post-fracturing period. The Black-Oil simulator Eclipse E100 is used in the study with different discretisation schemes. To investigate the two periods, field data from two wells were supplied by the industry.
In the case of the well 1 the Clean-Up process was matched lasting several days. The match achieved an adequate approximation to the measured field values. The break-through time of gas as well as the gas- and water production rates showed a good agreement. The case of the well 2 simulated a 4 year production period. Again, the history match results were characterized by a good correspondence of measured and simulated well pressures. The conclusion of both case-studies is: Eclipse is suitable for the simulation of fractured wells in Tight-Gas
The conclusion of both case-studies is: Eclipse is suitable for the simulation of fractured wells in Tight-Gas Reservoirs. Within the framework of the investigations turned out, that (i) the geomechanical dependency on reservoir- and fracture-parameters on the effective stress as well as (ii) the initial saturation conditions and the gas-water functions for the tight sandstone are major factors of influence for fractured wells in low-permeability reservoirs.