Flow-Based Determination of Hydraulic Units (SPE-107158)

摘要

It is common knowledge that the identification of hydraulic units is vital for the construction of reservoir simulation models that preserve dynamically relevant geological features from the underlying geological model. To date, both static-based and flow-based techniques were suggested for assessing hydraulic units. The static-based methods are used more commonly and are based on the minimization of a statistical measure of permeability heterogeneity or on establishing a relationship between log and core derived reservoir properties. The dynamic methods are based on single phase numerical simulation. This paper presents a new flow-based method to determine hydraulic units considering multiphase flow, gravitational phase separation and capillary forces. The underlying concept assumes that, for every geological block, it is possible to estimate the time that is necessary for a fluid particle to traverse it laterally. The best way for that is a three dimensional streamline simulation. A stack of blocks can be lumped vertically to a hydraulic unit, if the time, which is necessary to achieve the vertical saturation equilibrium, is within a defined fraction of the traverse time. A multiphase simulation will be performed considering the reservoir as isolated columns. Water will be placed on top and then it will be calculated how far the vertical equilibrium can be achieved within 10 to 20 % of the local traverse time. The blocks, for which the required equilibrium is achieved, can be members of the same hydraulic unit. This method takes both the lateral flux and the vertical heterogeneity into consideration. The paper presents a full field example to demonstrate the applicability of the suggested method.