Threshold pressure gradient of fluid flow through multi-porous media in low and extra-low permeability reservoirs  

作　　者：DOU HongEn MA ShiYing ZOU CunYou YAO ShangLin 

机构地区：[1]Research Institute of Petroleum Exploration & Development,PetroChina

出　　处：《Science China Earth Sciences》2014年第11期2808-2818,共11页中国科学（地球科学英文版）

基　　金：sponsored by National Key Project of Science and Technology of the Ministry of Science and Technology(MOST)(Grant No.2011ZX05043-002)

摘　　要：After analyzing many studies of fluid flow theory of multi-porous media in low and extra-low permeability reservoirs and the numerical simulation of non-Darcy flow, we found that a negative flow rate occurs in the existing non-Darcy flow equation, which is unreasonable. We believe that the existing equation can only be considered as a discriminant to judging Darcy flow or non-Darcy flow, and cannot be taken as a fluid flow governing equation of multi-porous media. Our analysis of the experimental results shows that the threshold pressure gradient(TPG) of low and extra-low permeability reservoirs is excessively high, and does not conform to fluid flow through multi-porous media in the actual reservoir situation. Therefore, we present a reasonable TPG ranging from 0.006 to 0.04 MPa/m at the well depth of 1500 m and oil drainage distance of 500 m. The results of our study also indicate that the non-Darcy flow phenomenon will disappear when the TPG reaches a certain value. In addition, the TPG or non-Darcy flow in low and extra-low permeability reservoirs does not need to be considered in the productivity prediction and reservoir numerical simulation. At present, the black oil model or dual-porous media is suitable for simulating low and extra-low permeability reservoirs.After analyzing many studies of fluid flow theory of multi-porous media in low and extra-low permeability reservoirs and the numerical simulation of non-Darcy flow, we found that a negative flow rate occurs in the existing non-Darcy flow equation, which is unreasonable. We believe that the existing equation can only be considered as a discriminant to judging Darcy flow or non-Darcy flow, and cannot be taken as a fluid flow governing equation of multi-porous media. Our analysis of the experi- mental results shows that the threshold pressure gradient （TPG） of low and extra-low permeability reservoirs is excessively high, and does not conform to fluid flow through multi-porous media in the actual reservoir situation. Therefore, we present a reasonable TPG ranging from 0.006 to 0.04 MPa/m at the well depth of 1500 m and oil drainage distance of 500 m. The results of our study also indicate that the non-Darcy flow phenomenon will disappear when the TPG reaches a certain value. In addi- tion, the TPG or non-Darcy flow in low and extra-low permeability reservoirs does not need to be considered in the productiv- ity prediction and reservoir numerical simulation. At present, the black oil model or dual-porous media is suitable for simulat- ing low and extra-low permeability reservoirs.

关 键 词：low permeability extra-low permeability non-Darcy flow threshold pressure gradient MATRIX FRACTURE dual-porositymedia 

分 类 号：P618.13[天文地球—矿床学]