Non-steady-state Productivity Prediction Model for Multi-layer Fractured Directional Wells in Tight Oil Reservoirs

Dai-gang WANG , Yu-zhe SHI , Guo-yong LI , Wen-juan NIU , Yao ZHAO , Zhe HU , Wen-shuang GENG , Kao-ping SONG

Science Technology and Engineering ›› 2025, Vol. 25 ›› Issue (9) : 3646 -3656.

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Science Technology and Engineering ›› 2025, Vol. 25 ›› Issue (9) : 3646-3656 DOI: 10.12404/j.issn.1671-1815.2403165
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Non-steady-state Productivity Prediction Model for Multi-layer Fractured Directional Wells in Tight Oil Reservoirs
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Abstract

China's tight oil reservoirs have distinctive characteristics, including thin interbedded layers with alternate distribution in the longitudinal direction and strong reservoir heterogeneity. In order to maximize productivity and economic benefits, a development approach was commonly employed, involving a well network with layered fracturing for the simultaneous development of multiple layers. However, existing productivity models for fractured directional wells are only applicable to single-layer development and do not consider inter-layer interference, making them unsuitable for predicting well productivity of multi-layer development. In order to improve the accuracy of productivity prediction, the flow field nearby the fractured directional well is divided into the main fracture region, the stimulated reservoir volume region, and the un-stimulated reservoir volume region. Considering the effects of flow patterns in different regions and stress sensitivity, and introducing a disturbance coefficient, a non-steady-state productivity prediction model for multi-layer fractured directional well in tight oil reservoirs was established. After validating the model accuracy, the influence of fracture half-length, fracture conductivity, threshold pressure gradient, stress sensitivity and reservoir heterogeneity on the productivity of fractured directional well was further investigated. The results indicate that the threshold pressure gradient, stress sensitivity and longitudinal heterogeneity significantly affect the productivity of fractured directional well. The larger the threshold pressure gradient, and the more significant the stress sensitivity and longitudinal heterogeneity, the lower the productivity of fractured directional wells. With the gradual increase in fracture half-length, fracture conductivity, and matrix permeability, the productivity of fractured directional wells increases, but each factor has its optimal range. The ranking of factors affecting productivity is as follows: matrix permeability, fracture conductivity, fracture half-length, threshold pressure gradient, longitudinal heterogeneity, stress sensitivity.

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tight oil / fractured directional well / productivity prediction / disturbance coefficient / non-steady state / sensitive factor

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Dai-gang WANG, Yu-zhe SHI, Guo-yong LI, Wen-juan NIU, Yao ZHAO, Zhe HU, Wen-shuang GENG, Kao-ping SONG. Non-steady-state Productivity Prediction Model for Multi-layer Fractured Directional Wells in Tight Oil Reservoirs. Science Technology and Engineering, 2025, 25(9): 3646-3656 DOI:10.12404/j.issn.1671-1815.2403165

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