The article considers the problem of correct organization of the system of reservoir pressure maintenance by water injection into the reservoir PK1-3 of Vostochno-Messoyakhskoye oilfield that has a complex geological structure. According to the results of wells drilling and testing in the oilfield it was determined that what was previously thought about reservoir properties of PK1-3 to be a relatively homogeneous is a set of three cyclites: A(PK1), B (PK2), C (PK3), that have different filtration properties and vertical connectivity and lateral heterogeneity due to different conditions of sedimentation. It was determined that the approach to development and flooding of each cyclite should be different.
Cyclite with the best reservoir properties and with the most reservoir continuity is the underlying cyclite C which has a contact with the underlying waters. It was selected as the primary object for drilling. On the one hand, the good properties of cyclite C and the changed economic macro parameters of the company determined the usage of denser oilfield exploitation system. It led to the change in the distance between wells from 300 meters to 150 meters. On the other hand, it has led to considerable uncertainty for selecting correct flooding system. Firstly, the question appeared of the lateral risk of water breakthrough in conditions of high viscosity difference of the displacement front (the viscosity of the oil - 111 μPa·c, the viscosity of water - 1 μPa·c), and secondly, in conditions of the contact with the underlying waters the question appeared about the geometry of the streamlines of the flooding of the reservoir (lateral displacement or displacement through the aquifer) and the activity of bottom waters, which can change the flooding system decisions.
To remove these uncertainties it was offered the pilot well program of flooding system and detailed proposals for data diagnosis obtained during this program that will help to determine the most correct approach to the flooding system for this type of reservoir.
References
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