Connectivity Modelling of Heterogeneous Systems: Analysis and Field Study

A statistical approach is proposed and validated against a realistic field dataset to model connectivity of heterogeneous systems such as low to intermediate net-to- gross reservoirs. An object based technique is used to model the spatial distribution of aligned isotropic and anisotropic facies bodies. The connectivity of the model is estimated using percolation theory. First account is made to evaluate the effect of the aspect ratio of the facies. The outcome is two universal curves for the connectivity and its associated uncertainty which can be used to estimate the connectivity of all sorts of body sizes and aspect ratios very quickly. The approach is then developed to be applicable for variable body sizes as well as a system with oriented bodies. An effective size based on the square root of the average area of bodies is used to represent the distribution of body sizes. For systems with oriented bodies, a new aspect ratio is defined and the reduced percolation thresholds of the system are determined. The results show that with above changes the universal curves are still applicable for both orientated and variable size systems. Finally, a conventional facies modelling of a carbonate layered reservoir is used to be compared with the results of the proposed method. The comparisons were in good agreement. It is found that the new method gave reliable and broad estimate of connectivity of the system in compare with exact and uncertain results from modelling of real data, while the first one is so fast, the latter is so costly and time consuming. This framework can be further extended to evaluate recovery factor and sweep efficiency of a reservoir. The technique can also be used for preliminary evaluation of a reservoir as a quick method which offers fast estimates of important parameters of a reservoir based on its simple basic data.