Study Of Reservoir Energy Evaluation For Carbonate Reservoirs Fractured-Vuggy Unit

The reservoir energy is the power to push petroleum and gas flow from far stratum to the bottom of the well during the exploitation process, which is the foundation for setting exploitation policy and well working regulations. The availability of the energy consumption is calculated by pressure drop, however, the unitary evaluation index is not adapted to various exploitation methods in different types of reservoirs. The Tahe Oilfield is a typical fractured-vuggy reservoir with high heterogeneity. With complex geological condition and variable pore structure it is neither the same as the normal sandy reservoir nor the fractured carbonate one. Therefore, it is very difficult to make exploitation plans as well as adjustments. The cognition and evaluation to the reservoir energy are one of the most important reasons that cause the present situation. With the production dynamic data and reservoir geological research, the paper has verified the connectivity between fractured vuggy units by using the dynamic method on the basis of fractured vuggy unit compartition in carbonate reservoir in DistrictⅥTahe oilfield. Taking fractured vuggy unit as research object, aiming to obtain reservoir pressure, direct calculation, optimization method and neural network method are comprehensively applied to the calculation method and the prediction method of reservoir pressure. As a result, it is formed a mixed module to calculate the pressure on the bottom of the well with dynamic data and static data and comparison verification has been processed. Regarding the actual exploitation situation of carbonate reservoir fractured vuggy unit, the evaluation system on the energy of carbonate reservoir has been established with Mass Balance Principle after systematical study on dynamic production data of typical fractured vuggy units category by category, which can accurately appraise the relationship between strong/weak reservoir energy and production in the stage of elastic energy development. Under the circumstance of lack of measurable pressure data, the fuzzy evaluation system has been set up with some optimized index by fully considering the traits of dynamic production. Comparing to the precisely calculated system, some parameter will be modified so as to be adapted to real production situation. Based on the evaluation system, the production characteristics of different reservoir energy fractured vuggy unit has been analyzed, the patterns of energy variation have been processed, Also, the internal relationship that the change of liquid production or water content will cause the variation of production has been worked out. After systematically studying on the regulations of exploitation techniques of all kinds of units, the exploitation principles for DistrictⅥTahe Oilfield have been proposed. The creation includes that the carbonate reservoir fractured vuggy unit has been regarded as a research object, integrating multiple methods to study the ways of reservoir pressure acquisition, combining several index while focus on the movement of pressure, setting up a evaluation system for fractured vuggy unit energy and investigating the dynamic features of fractured vuggy unit exploitation incorporation with different levels of reservoir energy. The research improves on the means, methods and applications of reservoir energy evaluation, which can be used for reference to exploitation of other similar reservoirs in Tahe Oilfield, whereas the research technique can be applied into other twin oilfields.