Summary

Water flooding of carbonate reservoirs with complex porosity, fracture system and high vugginess is complicated by water breakthrough and quick waterflooding of the producers. At that, reservoir pressure maintenance is essential means as due to reduced reservoir energy state resulting from formation and bottom hole pressure decrease at elasto-plastic drive, well production rate decreases. Analyses of well test study show that pressure drop fracture healing takes place and leads to production loss of the producers. High vertical permeability leads to technogenic formation of gas caps at reservoir pressure drawdown below bubble point pressure and to necessity of shutting off some producers drilled under the field arch.

To reduce water flooding in producers and involve non-draining uninvaded areas to injection high-elastic solutions are injected. This helps to distribute the fluid injected to uninvaded intervals. As a rule, fracture system and secondary porosity are less developed in these intervals. For that reason the reservoir are of less permeability.

Liduid injection to the wells is carried out at high pressures. According to transient well test results which were undertaken before and after injection of high-elastic solutions large – spontaneous growth of vertical fracture in injection wells are observed. Thus, according to log-log plot after the undertakings logarithmic derivative view (flow pattern for single vertical fractures) is fundamentally changed. Field research results show that after the injection of high-elastic solutions and further injection at high pressure rates in reservoirs with bad flow properties artificial hydrofracs are forming which helps to involve earlier non-draining intervals.

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