Evaluating the original gas in place (OGIP) is vital to the development and production of CBM reservoirs. However, most of the existing material balance equations (MBEs) perform well in some CBM reservoirs but have significant errors in the CBM reservoirs with a different coal rank. In addition, the MBEs for deep and ultra-deep coals with different coal ranks are still lacking. Therefore, this paper established a comprehensive MBE at the gas desorption stage for CBM reservoirs, which can be reliably used in different ranked coals and even deep and ultra-deep coals. Based on the validation and factor analysis results, some conclusions are drawn. (1) The cleat porosities calculated by the proposed model containing adsorption hysteresis well match the values from the numerical simulators. (2). The proposed MBE has been proven reliable and robust under validations by two medium-rank CMG models and a high-rank field case with errors of about 0.127%∼0.213%. (3). The adsorption hysteresis has been verified as an essential factor; it can help improve the accuracy of evaluating OGIP for the studied CBM reservoirs by 30%-50%. The improvement goes up with an increase in the adsorption hysteresis degree. (4). The free gas in the matrix and a matrix shrinkage effect have been proven to be necessarily considered in an MBE method to help decrease its relative errors. (5). The proposed comprehensive MBE method has been verified to have higher accuracy and advantages than other compared MBE methods in estimating gas reserves in CBM reservoirs. Overall, this study contributes to knowledge gaps in evaluating OGIP by MBE methods in CBM reservoirs with different coal ranks or depths. And it provides a relatively simple method for engineers to accurately estimate gas reserves, recoverable reserves, and recovery factors and correctly design development strategies to avoid unnecessary waste of resources in the post-adjustment stage.

评估原始天然气储层 (OGIP) 对煤层气储层的开发和生产至关重要。然而，大多数现有的物质平衡方程（MBE）在一些煤层气储层中表现良好，但在不同煤阶的煤层气储层中存在显着误差。此外，不同煤阶的深部和超深部煤的MBE仍然缺乏。因此，本文建立了煤层气储层瓦斯解吸阶段的综合 MBE，可可靠地应用于不同等级的煤种，甚至深部和超深部煤层。根据验证和因子分析结果，得​​出了一些结论。(1) 所提出的包含吸附滞后的模型计算的割理孔隙率与数值模拟器的值很好地匹配。(2)。所提出的 MBE 在两个中级 CMG 模型和一个高级场案例的验证下被证明是可靠和稳健的，误差约为 0.127%~0.213%。(3)。吸附滞后已被证实为重要因素；它可以帮助将研究的煤层气储层的OGIP评估精度提高30％-50％。该改善随着吸附滞后程度的增加而增加。(4)。已证明在 MBE 方法中必须考虑基质中的游离气体和基质收缩效应，以帮助减少其相对误差。(5)。所提出的综合 MBE 方法已被证实在估算煤层气储层中的气体储量时比其他 MBE 方法具有更高的准确性和优势。全面的，这项研究有助于在不同煤阶或深度的煤层气储层中通过 MBE 方法评估 OGIP 的知识差距。为工程师准确估算天然气储量、可采储量和采收率，正确设计开发策略，避免后期调整阶段不必要的资源浪费提供了一种相对简单的方法。