高地应力、高瓦斯压力和低煤层透气性等因素严重制约着我国深部煤炭开采，且随着深部煤层开采条件逐步恶化，本煤层瓦斯治理难度凸显，通过保护层卸压开采的方式治理瓦斯和消除煤与瓦斯突出可达到事半功倍的效果。为了满足实际工程的需求，综述近年来我国在保护层开采技术、被保护层应力特性变化规律、裂隙系统演化规律、渗透率演化规律及被保护层卸压瓦斯抽采技术等方面的研究工作，总结并探讨了保护层卸压开采研究的不足，发现对处于弯曲下沉带内的超远距离上被保护层煤体卸压效果的关注较少，未能满足实际工程需求，根据保护层卸压开采期间超远距离上被保护层煤体变形特征及其横向裂隙开启和闭合特征，提出了保护层卸压开采的“时间窗口期”这一概念，同时指出，建立保护层开采与被保护层瓦斯流动特性演化的时空关系，构建瓦斯抽采“时间窗口期”判识模型，建立保护层卸压开采和超远距离上被保护层瓦斯治理时空协同模式是今后治理超远距离被保护层卸压瓦斯的重要方向。最后提出采用定向长距离钻孔抽采上被保护层卸压瓦斯的方法，并在河南平顶山矿区实践验证了其抽采效果。

Deep coal mining in China is seriously restricted by factors including high stress, high gas pressure, and low coal seam permeability. Moreover, with the gradual deterioration of the mining conditions of deep coal seams, it is increasingly difficult to control the gas in these coal seams. Fortunately, the pressure-relief mining of protective layers serves as an efficient way to control gas and eliminate coal and gas outbursts. To meet the demand of practical projects, this paper reviews the studies on the mining technology for protective layers, the law of change in the stress of protected layers, the evolutionary law of the fracture system, the evolutionary law of permeability, and pressure-relief gas extraction technology of protected layers conducted in China in recent years. After summarizing and exploring the shortcomings in studies on the pressure-relief mining of protective layers, it is discovered out that small attention is paid to the pressure-relief effect of coals in the upper protected layers at an ultra-long distance within a bending subsidence zone, failing to meet the demand of practical projects. Based on the deformation characteristics of coals in the upper protected layers at an ultra-long distance during the pressure-relief mining of protective layers, as well as the opening and closing of transverse fractures in the coals, this study proposes the concept "time window" for pressure-relief mining of protective layers. Meanwhile, it points out that the important directions for the control of pressure-relief gas in the protected layers at an ultralong distance in the future include establishing the spatial-temporal relationships between the mining of protective layers and the evolution of the gas flow in protected layers, constructing the identification model for the "time window " of gas extraction, and building a spatial-temporal coordination pattern for the pressure-relief mining of protective layers and the control of gas in the upper protected layers at and ultralong distance. Finally, this study develops a method of pressure relief gas extraction from the upper protected layers using directional long-distance drilling and verifies the performance of the method in the Pingdingshan mining area, Henan Province.