Well test mathematical model for fractures network in tight oil reservoirs

International Conference on Energy Engineering and Environmental Protection 2017

能源学;生态环境科学

Diwu, Pengxiang^1,2 ; Liu, Tongjing^1,2 ; Jiang, Baoyi^3 ; Wang, Rui^4 ; Yang, Peidie^5 ; Yang, Jiping^6 ; Wang, Zhaoming^7

Enhanced Oil Recovery Institute, China University of Petroleum, Beijing, China^1

Basic Theory Laboratory of Improving Oil Recovery in Low Permeability Oilfields, Tertiary Oil Recovery Key Laboratory, CNPC, Beijing, China^2

China Huadian Institute of Science and Technology, Beijing, China^3

Oiland Gas Survey, China Geological Survey, Beijing, China^4

SINOPEC International Petroleum Exploration and Production Corporation, Beijing, China^5

Research Institute of Engineering, CNPC Bohai Drilling Engineering Company Limited, Tianjin, China^6

Research Institute of Petroleum Engineering, SINOPEC, Beijing, China^7

关键词: Composite modeling;    Finite-conductivity fractures;    Fracturing wells;    Natural fracture;    Random distribution;    Semi-analytical solution;    Solution approach;    Threshold pressure gradient;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/121/5/052008/pdf
DOI  :  10.1088/1755-1315/121/5/052008

学科分类：环境科学（综合）

来源: IOP

【 摘 要 】

Well test, especially build-up test, has been applied widely in the development of tight oil reservoirs, since it is the only available low cost way to directly quantify flow ability and formation heterogeneity parameters. However, because of the fractures network near wellbore, generated from artificial fracturing linking up natural factures, traditional infinite and finite conductivity fracture models usually result in significantly deviation in field application. In this work, considering the random distribution of natural fractures, physical model of fractures network is proposed, and it shows a composite model feature in the large scale. Consequently, a nonhomogeneous composite mathematical model is established with threshold pressure gradient. To solve this model semi-analytically, we proposed a solution approach including Laplace transform and virtual argument Bessel function, and this method is verified by comparing with existing analytical solution. The matching data of typical type curves generated from semi-analytical solution indicates that the proposed physical and mathematical model can describe the type curves characteristic in typical tight oil reservoirs, which have up warping in late-term rather than parallel lines with slope 1/2 or 1/4. It means the composite model could be used into pressure interpretation of artificial fracturing wells in tight oil reservoir.