The studied object is a part of a large field of the Uvat region (Western Siberia). The development process of the oil formation is conducted applying the waterflooding system. It is complicated by naturally fractured carbonate member and generation of auto-fractures at injection wells. The advancing rated of watercut and premature water breakthrough toward the production wells are observed. The studied reservoir has a complex geology, lithological intersection consists of clastic and carbonate members. Waterflooding system is not optimized: reservoir pressure falls and auto-fracs occur due to high repressions, that causes increase of watercut at production wells. Great amount of oil reserves is not withdrawn according to prevailing proceses. In this case, it was necessary to determine the reasons of noneffective development strategy and to optimize waterflooding system. The algorithm for searching of a decision for optimization of reservoir development in case of auto- fracs generation is formed in this paper. The sequence of analysis and valid analytical methods for reasons determination of advancing watercut are defined during the work. Complex analysis of geology, reservoir engineering, well testing and reservoir simulation forms the basis of the applied algorithm: Analytical methods of advancing watercut determination are used during reservoir development analysis. As a result, the reasons of premature water breakthrough toward the production wells and volume of undrained oil reserves became obvious. During the geology analysis main facies and features of the occurrence and spread are defined; created a distribution map of "superpermeable" facies. As a result, the map of wells interference is generated, in which zones of noneffective waterflooding and degree of reserves involvement in production are determined. The presence of auto-fracs at injection wells is identified according to the well test analysis. As a result, dependency of auto-fracture generation pressure from injection rates and reservoir pressure is determine. Understanding of this dependency allowed to optimize technological regims of injection wells. Also, dual- porosity parameters of naturally fractured member are determined from these tests, after that simulation reservoir model was adjusted. Because of the comprehensive analysis and understanding of all processes the large number of scenarios for reservoir development optimization appeared. To reduce the labor-intensive calculations and culling options the analytical model and the algorithm for choosing the best solution was formed. According to the algorithm several options were selected for more detailed calculation with reservoir simulation model.
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