无井式煤炭地下气化岩层及地表移动与控制

煤炭地下气化是我国先进能源领域重要的研究方向之一,也是我国煤炭资源"流态化"开采技术体系的重要组成部分。目前已完成的煤炭地下气化工业性实验由于实验规模较小没有引起显著的裂隙发育和明显的地表沉降发生。但随着煤炭地下气化实验规模的扩大及推广应用,如何面向不同地质条件进行地下气化生产设计控制裂隙发育及地表沉降是目前亟待解决的瓶颈问题,极大的限制了煤炭地下气化的选址及规模化生产。为了解决这个难题,利用数值模拟方法研究了无井式煤炭地下气化岩层与地表移动规律以及导水裂隙发育高度与气化炉参数的关系,同时利用理论方法提出了"双曲线"型焦化隔离煤柱稳定性评价方法。研究得出:①无井式煤炭地下气化岩层和地表移动曲线与常规条带开采岩层和地表移动曲线形态相似,可参考条带开采地表沉陷预测方法进行无井式煤炭地下气化岩层和地表沉陷计算,但预测参数需修正;②"双曲线"型煤柱评价可分为弯曲和矩形两部分进行,并在此基础上建立了"双曲线"型煤柱稳定性评价方法,可为不同地质条件下地下气化生产设计提供技术支撑;③无井式煤炭地下气化引起的导水裂隙发育高度与气化炉参数直接相关。当气化炉高度一定且隔离煤柱稳定时,气化炉宽度与导水裂隙发育高度呈线性正相关;当气化炉宽度和隔离煤柱宽度一定时,气化炉高度与导水裂隙发育高度也呈线性正相关,故在覆岩含水层下进行地下气化生产时,要兼顾导水裂隙与气化炉参数的关系。

Movement and control of strata and surface during UCG without shaft

Underground coal gasification (UCG) is one of the important research directions in advanced energy field,and is also an important part of the fluidized mining technical system of coal resources.At present,the completed small scale UCG industrial experiments haven’t caused significant fractures and surface subsidence.However,with the application and large scale production of UCG,how to carry out UCG production design for controlling fracture development and surface subsidence under different geological conditions is the bottleneck problem that greatly hinders the site selection and large scale production of UCG and urgently needs to be solved.To overcome the problem,the numerical simulation method was adopted in this paper to study the strata and surface movement characteristic of UCG without shaft and the relationships between development height of water flowing fractures and gasifier parameters.At the same time,the stability evaluation method of hyperbolic coking coal pillar was proposed by the theoretical method.The results indicate that:① The curve shapes of strata and surface movement under UCG without shaft are similar with those under conventional strip mining.Therefore,the strata and surface subsidence calculation of UCG without shaft can refer to that in strip mining,but the prediction parameters need to be revised.② The stability evaluation of hyperbolic coal pillar can be divided into bending part and rectangular part.On which basis,the stability evaluation method of hyperbolic coal pillar was proposed,which could provide a technical support for UCG design and production under various geological conditions.③ The development height of water flowing fractures due to UCG without shaft is directly related with the gasifier parameters.When the gasifier height has a certain value and the isolated coal pillars are stable,the gasifier width has a linear positive correlation with the development height of water flowing fracture.When the gasifier and the isolated coal pillar has certain width,a linear positive correlation also exists in the gasifier height and the development height of water flowing fracture.Therefore,the implementation of UCG under overburden aquifer needs to consider the relationships between the development height of water flowing fracture and gasifier parameters.The research results could provide a scientific basis for large scale UCG production and site selection.