INVESTIGATION OF PERMEABILITY ANISOTROPY IMPACT ON DEVELOPMENT OF BLOCK OILFIELD OF TERREGINOUS OIL-SATURATED RESERVOIR DURING SIMULATION

Abstract

The relevance of the research lies in the problem of insufficient information in collection and analysis of geological and physical-chemical properties of the developed reservoirs. In particular, such problem concerns permeability anisotropy, the value of which can initially be realized only on the basis of cores obtained by core drilling. This is often costly and not beneficial for the subsurface user. However, during construction of geological model, the permeability anisotropy value is one of the key characteristics and significantly effects its behavior. The aim of this work is to determine the optimal value of vertical anisotropy based on the available data and to propose options to improve the existing development system during simulation of anisotropy model. The study object is one of oil fields of the Tomsk region, consisting of terrigenous sediments. A feature of the field is its location in the system of complex local lifted blocks of various orders. The main productive reservoir is represented by Jurassic sediments, created in a regressive-transgressive sedimentation series and have a complex distribution of poroperm properties. Methods: studying the flow characteristics of fluids in the porous medium, measuring and selecting the value of vertical permeability anisotropy, as well as carrying out simulations considering the proposed improvements of the development system. As a result, it has been learned that increasing the value of vertical anisotropy does not always lead to a growth in production of reserves in the well area. Thus, at a vertical anisotropy value of 0,5, the value of cumulative oil production was 1,968 MM m3, while for 0,86 this value was 1,913 MM m3. This result is related to the geological features of reservoir and emphasizes the importance of the permeability anisotropy effect. Simulations on isotropy and anisotropy models were performed, which allowed highlighting optimal options of optimization of the current development system. The oil recovery factor for the isotropy model was 23,4 % and for the anisotropy model 22,8 % relative to the size of the geological reserves to be extracted. Thus, the resulting 0,6 % difference again shows the importance of the permeability anisotropy phenomenon and the need for as much data as possible.

Keywords

• permeability anisotropy
• anisotropy scale
• vertical anisotropy
• hydrodynamic simulation
• development strategy