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Petroleum Science >2020,??Issue 4:??1-20 DOI: https://doi.org/10.1007/s12182-019-00410-3

Methods for simultaneously evaluating reserve and permeability of undersaturated coalbed methane reservoirs using production data during the dewatering stage Open?Access

文章信息

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作者：Jun-Tai Shi, Jia-Yi Wu, Zheng Sun, Zhi-Hua Xiao, Cheng Liu, Kamy Sepehrnoori
作者單位：

State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum Beijing, No. 18, Fuxue Road, Changping District, Beijing, 102249, China; MOE Key Laboratory of Petroleum Engineering, China University of Petroleum Beijing, No. 18, Fuxue Road, Changping District, Beijing, 102249, China; PetroChina Coalbed Methane Company Limited, Beijing, 100028, China; PetroChina Zhejiang Oil Field Company Limited, Hangzhou, 310023, China; The University of Texas, Austin, TX, 78712, USA;

投稿時(shí)間：2019-07-31
引用方式：Shi, J., Wu, J., Sun, Z. et al. Methods for simultaneously evaluating reserve and permeability of undersaturated coalbed methane reservoirs using production data during the dewatering stage. Pet. Sci. (2020). https://doi.org/10.1007/s12182-019-00410-3

文章摘要

In this work, a flowing material balance equation (FMBE) is established for undersaturated coalbed methane (CBM) reservoirs, which considers immobile free gas expansion effect at the dewatering stage. Based on the established FMBE, five straight-line methods are proposed to determine the control area, initial water reserve, initial free gas reserve, initial adsorbed gas reserve, original gas in place, as well as permeability at the same time. Subsequently, the proposed FMBE methods for undersaturated CBM reservoirs are validated against a reservoir simulation software with and without considering free gas expansion. Finally, the proposed methods are applied in a field case when considering free gas expansion effect. Validation cases show that the straight-line relationships for the proposed five FMBE methods are excellent, and good agreements are obtained among the actual reserves and permeabilities and those evaluated by the proposed five FMBE methods, indicating the proposed five FMBE methods are effective and rational for CBM reservoirs. Results show that a small amount of free gas will result in a great deviation in reserve evaluation; hence, the immobile free gas expansion effect should be considered when establishing the material balance equation of undersaturated CBM reservoirs at the dewatering stage.

關(guān)鍵詞

    Coalbed methane, OGIP, Permeability evaluation, Flowing material balance equation, Gas expansion