The Reservoir Plane Heterogeneity Characteristics of the Number 2 of the Shanxi Formation in Changbei Gas Field, Ordos Basin, China

Abstract

Reservoir plane heterogeneity means the geometry，the scale，the continuity and the plan variation of physical properties of reservoirs, which is one of the main factors influencing the injection-production in oil reservoirs. Therefore, the study of the reservoir plane heterogeneity play a great role in guiding development wells deployment，gas reservoir well nets adjustment and residual oil & gas development. The reservoir heterogeneity of the sandstone size of gas and the border, and unbalanced formation pressure because of the degree of the development of each well is uneven prevent ChangBei gas field to develoment. They cause difficulty of evaluating the gas field comprehensive，level development wells deployment and well trajectory adjustment，and lead to certain geology risk. It is necessary to study the reservoir heterogeneity of the number 2 of shanxi Formation in this block for concerning the unfavourable extraction condition. The composite index of reservoir plane heterogeneity of the number 2 of shanxi Formation in ChangBei gas field have calculated by adopting entropy method considering influcing reservoir plane heterogeneity which is porosity, tight sandstone, mutation coefficient and variation coefficient of permeability, range of permeability and interlayer frequency. The distributive maps of reservoir's plane heterogeneity under the restriction of sedimentary facies have also been drawed. The entropy method can full use of the reduction and strengthen of entropy method,which means the characteristic of removing the similarities and depositing differences. The study indicate that reservoir plane heterogeneity of the number 2 of shanxi Formation in study area presents the medium to slightly strong characteristics in general.