Building a Computational Model of the Cementation Exponent for Complex Porous Reservoirs Based on the Maxwell Equations

作者：Li, X. Y.^*; Qin, R. B.; Mao, Z. Q.; Liu, C. C.

来源：Petrophysics, 2013, 54(4): 341-348.

In complex porous reservoirs the cementation exponent m is no longer a fixed constant. The accuracy of m is critical to the Archie-derived calculation of saturation. Using a range of lithologies (including loose sand, medium sand, tight sand, conglomerate, tuff, breccia, basalt, andesite, dacite and rhyolite) this paper analyzes the average error in saturation caused by the change in 711, which ranges from 5 to 30%. For sandstone and conglomerate the average error in saturation of <10%, and for tuff, breccia, basalt, andesite, dacite and rhyolite the average error in saturation is >10%. Using Maxwell's equations we have found a strong linear correlation between m and the difference between the effective porosity and conductive porosity. The functional relationship between the conductive porosity and the effective porosity is not static and can be shown as linear, exponential, power and polynomial functions. We derive the general expression of m and the effective porosity, and develop a computational model of m for reservoirs with complex porosity. Lastly, we apply the method to processing dolomite and limestone reservoirs in a well from a field in Iraq, and the results compared with core-analysis data. We find that the computational model for m can be used for quantitative saturation evaluation in carbonate reservoirs. The feasibility and operability of the method is verified, and provides a theoretical and practical foundation for the quantitative saturation evaluation of reservoirs with complex porosity.

• 出版日期2013-8
• 单位中国石油大学（北京）