Analysis and Design Innovation on Underground Gasifier for Medium-Deep Coal Seam

Over the past 80 years,dozens of underground coal gasification(UCG)mine field tests have been carried out around the world.However,in the early days,only a small number of shallow UCG projects in the former Soviet Union achieved commercialised production.In this century,a few pilot projects in Australia also achieved short-term small-scale commercialised production using modern UCG technology.However,the commercialisation of UCG,especially medium-deep UCG projects with good development prospects but difficult underground engineering conditions,has not progressed smoothly around the world.Considering investment economy,a single gasifier must realise a high daily output and accumulated output,as well as hold a long gasification tunnel to control a large number of coal resources.However,a long gasification tunnel can easily be affected by blockages and failure,for which the remedial solutions are difficult and expensive,which greatly restricts the investment economy.The design of the underground gasifier determines the success or failure of UCG projects,and it also requires the related petroleum engineering technology.Combining the advantages of the linear horizontal well(L-CRIP)and parallel horizontal well(P-CRIP),this paper proposes a new design scheme for an“inclined ladder”underground gasifier.That is to say,the combination of the main shaft of paired P-CRIP and multiple branch horizontal well gasification tunnels is adopted to realise the control of a large number of coal resources in a single gasifier.The completion of the main shaft by well cementation is beneficial for maintaining the integrity of the main shaft and the stability of the main structure.The branch horizontal well is used as the gasification tunnel,but the length and number of retracting injection points are limited,effectively reducing the probability of blockage or failure.The branch horizontal well spacing can be adjusted flexibly to avoid minor faults and large cracks,which is conducive to increasing the resource utilisation rate.In addition,for multi-layer thin coal seams or ultra-thick coal seams,a multi-layer gasifier sharing vertical well sections can be deployed,thereby saving investment on the vertical well sections.Through preliminary analysis,this gasifier design scheme can be realised in engineering,making it suitable for largescale deployment where it can increase the resource utilisation rate and ensure stable and controllable operations.The new gasifier has outstanding advantages in investment economy,and good prospects for application in the commercial UCG projects of medium-deep coal seams.

基于地球物理电性特征的踏卡穹隆构造研究

这是一篇地球科学领域的论文。踏卡穹隆与江浪穹隆位于松潘—甘孜地块南缘,地质特征显示其物质组成、变质-变形特征较为相似。江浪穹隆发现有里伍、黑牛洞、中咀等铜锌矿床,但踏卡穹隆同层位还未发现相似矿床。为查明踏卡穹隆中深部构造特征及成矿的关系,本次开展了不同时代地层的地球物理电性参数测定和音频大地电磁测深剖面,以获得地下中、深部电性特征。结果表明,穹隆总体显示为两侧低、中阻,核部高阻为主夹杂低阻的特征,整体电性特征与穹隆结构的时空规律相吻合。深部电性剖面中出现3条主要低阻异常带,推断为低阻岩性、断层或构造破碎带的反映;3条主要高阻异常带,推断为踏卡穹隆内完整的中、高阻特征的中元古界里伍群上段(Pt2l3)岩体反映。上述认识为探索踏卡穹隆中、深部地质空间结构提供了地球物理学上的证据。

小秦岭金矿田中深部构造控矿规律及盲矿预测——以文峪矿区S505矿脉为例

在小秦岭金矿田内,断裂构造控制着金矿床的产出,断裂带产状形态的变化、展布规律控制了矿体的形态、产状和富集规律,总结出缓—中等倾斜的矿脉沿断裂带走向和倾向普遍存在矿化强弱相间分布的特点。通过S505号矿脉1500m中段以上断裂构造对金矿体的控制条件及控矿规律研究认为,S505号矿脉严格受构造控制,并成功地预测了深部第二矿化富集段应在1000m以下。

厚软弱夹层岩巷中深孔爆破试验研究

为了改善含有厚软弱夹层的岩巷掘进爆破效果,基于软弱夹层爆破理论分析得出的基本结论,探讨分析了软弱夹层的位置、数量、厚度以及走向等对巷道爆破的影响。采用改变炮眼布置方式、调整起爆顺序、减少装药量等方法,进行了现场中深孔爆破试验,取得了良好的爆破效果。结果表明:炮眼利用率均高于92%,循环进尺由原来的1.5 m提高到2.3 m;单位炸药消耗、单位雷管消耗、单位岩体炮眼长度比试验前均明显降低。

鄂尔多斯盆地南缘延安地区中深层地热能特征研究

近年来水热型、浅层地热能发展产生的缺点问题日益突出,以取热不取水为原则,中深层U型水平对接换热技术成为新的技术方向。通过对鄂尔多斯盆地南缘延安地区地层岩性、地温梯度特征、热储层特征等特征研究,分析了研究区中深层地热资源潜力,研究结果表明鄂尔多斯盆地南缘奥陶系马家沟组为良好的热传导型热储,深部地温梯度为3.05℃/100m。当马家沟组深度在3157m时,对应温度达到110.67℃。测井及注水试验结果表明,奥陶系马家沟组为极弱含水层,几乎没有流体,属于良好的干热岩型地热资源,具有较高的开采价值。充分确定了该区地热地质条件良好、地热资源潜力巨大。为合理、高效开发利用该区地热资源提供了科学依据,对进一步开发利用该区的地热能具有重要意义。

Mitigation of long-term heat extraction attenuation of U-type medium-deep borehole heat exchanger by climate change

U-type medium-deep borehole heat exchanger(U-MDBHE)is a sustainable building heating technology.Current studies assess the long-term thermal performance of U-MDBHE using typical meteorological year weather data.The conclusions indicate a discernible deterioration in the thermal performance of U-MDBHE attributed to heat extraction attenuation.The thermal performance deterioration leads to the oversize of U-MDBHE and hinders the widespread application of U-MDBHE.This study introduces a novel idea that the long-term thermal performance of U-MDBHE should be evaluated considering climate change(CC)and verifies that the favorable effects of CC on the thermal performance of U-MDBHE can effectively mitigate the adverse effect of heat extraction attenuation.The favorable effects of CC include reducing the heating demand(due to the reduced building heating load(BHL)caused by CC)and improving the heating supply capacity(due to the enhanced outlet temperature caused by CC).In addition,the reduced BHL under CC enhances the inlet temperature of U-MDBHE,thereby improving its operation safety.CC mitigates the heat extraction attenuation of U-MDBHE,with the strongest effect in the ascending well,followed by the descending well,and then the butted well.Case studies using experimentally validated simulations on the 30-year operation of U-MDBHE demonstrate that by mitigating the adverse effect of the heat extraction attenuation,CC reduces the accumulated energy consumption by 14.31%–26.59%and improves the operation safety by up to 100%in Harbin(severe cold region)and Beijing(cold region).This study significantly contributes to improving the long-term thermal performance of U-MDBHE.