Carbonate reservoirs are characterized by low production rates and low oil recovery factors. This may be due to imperfection of the conventional waterflooding system. To overcome the production challenges, we need to improve our knowledge of waterflooding mechanisms in dual porosity carbonate reservoirs. Dedicated flow-after-flow tests involved 36 injection wells in carbonate reservoirs of Ttaneft PJSC. On the resulting Inflow Performance Relationships (IPR) curves intersection points represent limited pressures. Any pressure increase above these values would result in a rapid water breakthrough. The limited pressure values were also determined from sharp increase of the permeability-thickness product evident from the interpretation of injection and fall-off curves at different liquid rates made possible through different-size chokes. Predictably, this is caused by closing of fractures and matrix at pressure drawdown; maximum permeability was recorded on the injection curve with maximum injectivity. The resultant bar graphs of limited bottomhole pressure, wellhead pressure, and differential pressure vary significantly and lack normal distribution. So, further attempt was made to obtain a relationship between a limited pressure and some influencing parameter. The reservoir pressure was found to be the influencing parameter. The obtained relationships are characterized by high correlation number (R2>0.88) and have a physical meaning. The paper offers equations to determine a limited bottomhole pressure as a function of reservoir pressure for different types of carbonate reservoirs with a calculation error of less than 10 %. Maintenance of limited pressures will allow to improve the performance of waterflooded development of carbonate reservoirs.
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