ANALYSIS AND CLASSIFICATION OF CAUSES OF UNCERTAINTIES ARISING DURING GEOLOGICAL MODELING

摘要

In order to lower the risks in the processes of field development and waterflooding systems planning geologic and simulation models are built on the base of core material examinations, geophysical well logging (GWL) and seismic survey, flow well test (FWT), downhole samples. The crucial moment in simulation is the integration of all methods available of data obtaining that will allow constructing the best detailed and accurate geologic and simulation model, as the disadvantages of one method are compensated by the advantages of another and allow forming the notion of the object under study. The given article is devoted to studying causes of variety of uncertainties that arise during construction of geologic and simulation field model.Within the work the causes of arising uncertainties have been classified according to the type of measurement (direct or indirect), the scope of research by area, the vertical resolution capacity, and according to the nature of uncertainties causes. They, in turn, are subdivided into measurement problems (equipment error and non-compliance with measurement procedures) and problems of application in modeling (interpretation problems and problems of constructing the model).In order to reduce uncertainties we can define two possible ways. The first is minimisation of uncertainties in the frames of a separate method. The second way is the integration of all available information in a manner of reducing the uncertainty band by means of measurement’s mutual constraints, imposed on each other, i.e. the use of complex system approach to applying initial data obtained by different methods.Instant assessment of field-geologic information and taking it into consideration when correcting geologic and simulation model allow producer to acquire practical instrument for operating and, if necessary, adjusting field development process, which includes taking into account location of the zones of remaining oil reserves the possibility for developing scenarios of enhancing reservoirs’ recovery, performing justified calculations of forecasts of production and financial risks reduction.