ارايه مدل به منظور مطالعه اثر مقياس بر پارامتر تخلخل مخازن نفتي (مطالعه موردي)

Studying the scale effect on reservoir porosity parameter (Case Study)

One of the most important characteristics in the reservoir studies is the determination of porosity. The amount of reservoir porosity represents the in-situ hydrocarbon whereas production rate is related to connectivity between pores. Porosity determination is done by different methods such as experiment on small samples in laboratory or in-situ determination using well logs. The difference between these ways is due to scale effect. Changing in sample volume has different results. So studying the scale effect is very important and was done by different methods. In this paper, we studied scale effect on porosity variable from an oil reservoir by geostatistic that is powerful in determine of anisotropy and data spatial variation. Also the anisotropy determined by semivariogram function that is representative dispersal of variables. Specifically, the behavior of the variance of the mean is used to investigate the definition of a representative elementary volume. To describe porosity, (or any other aquifer or reservoir parameter) it is useful to first define the concept of representative elementary volume. The representative elementary volume is a volume of reservoir over which the porosity, for example, is describable by a single value. This concept is necessary because a volume smaller than the volume that fits the definition of a representative elementary volume will yield different reservoir parameters depending upon where one places the representative elementary volume on the sample. According to this research the representative elementary volume for porosity was calculated for a gas reservoir. Also according to varigraphy results the reservoir is anisotropic.