煤炭地下气化应力场及其诱导裂隙演化模拟——以准噶尔盆地百口泉地区西山窑组煤层为例  

Simulation of UCG stress field and its induced fracture evolution:A case study of Xishanyao Formation coal seams in the Baikouquan area,Junggar Basin

作　　者：屈怀林[1] 李道清[1] 姚新阳 李鑫 QU Huailin;LI Daoqing;YAO Xinyang;LI Xin(PetroChina Xinjiang Oilfield Company,Kalamay,Xinjiang 834099,China;Xinjiang University,Urumchi,Xinjiang 830046,China)

机构地区：[1]中国石油新疆油田公司 [2]新疆大学

出　　处：《天然气工业》2025年第3期179-188,共10页Natural Gas Industry

基　　金：新疆维吾尔自治区天山英才计划项目“新疆前陆冲断带深部煤系天然气形成机制与富集机理”(编号:2022TSYCCX0043);新疆维吾尔自治区科技重大专项“新疆难开采煤炭煤层气资源高效开发技术”(编号:2022A03015)。

摘　　要：煤炭地下气化(Underground Coal Gasification,简称UCG)成功运行的核心影响因素是气化炉能否安全平稳运行,研究气化炉上覆岩层的应力场分布及其诱导裂隙扩展演化规律,对于UCG技术的大规模推广应用具有重要意义。为此,以准噶尔盆地百口泉地区侏罗系西山窑组煤层为研究对象,基于ABAQUS有限元分析软件,建立了原位UCG地质模型,研究了在不同气化工作面推进速率和不同天然裂隙发育程度下,气化炉应力场及其诱导裂隙的分布演化规律。研究结果表明:(1) UCG会影响上覆岩层的应力分布,引起应力集中并产生诱导裂隙,使气化通道上覆岩层下沉;(2)气化通道200 m、气化工作面推进速率0.5 m/d时,温度场扩散半径最大可达15 m,顶板最大下沉位移量、底板最大上升位移量分别为3.880 m、0.097 m;(3)各工况条件下裂隙扩展高度最高达67.5 m,平均为57.5 m,上覆岩层最大下沉位移量为14.38 m;(4)过慢或过快的气化工作面推进速率均会导致上覆岩层应力过度集中,顶板岩石天然裂隙发育程度越高,虽削弱了上覆岩层整体强度,但邻近裂隙相互影响会制约裂隙的扩展。结论认为:(1)在UCG气化过程中,需要密切监测岩层的应力变化和裂隙发育情况,采取相应的预防措施来确保气化炉的安全运行;(2)为气化炉选址是UCG工程至关重要的一环,需确保顶板及上覆岩层具有一定强度以抵抗地层压力,并避免上方存在地下强含水层,导致地下水涌入气化通道,影响气化炉的安全平稳运行。Underground coal gasification(UCG)runs successfully under a core influential factor which is the safe and smooth operation of a gasifier.It is of great significance to study the distribution of stress field in the overlying strata of a gasifier and its induced fracture extension and evolution law for the large-scale popularization and application of UCG technology.In this study,with the coal seams of Xishanyao Formation in the Baikouquan area of the Junggar Basin as an example,an in-situ UCG geological model is established using the ABAQUS finite element analysis software.With this model,the distribution and evolution of the stress field of the gasifier and its induced fractures are investigated under different advancement rates of the gasification working face and different degrees of natural fracture development.The following results are obtained.First,UCG affects the stress distribution in the overlying rock layers,causing stress concentration and induced fractures,which allow the rock layers overlying the gasification channel to subside.Second,when the gasification channel is 200 m and the advancement rate of the gasification working face is 0.5 m/d,the temperature field diffusion radius is up to 15 m,the maximum subsidence displacement of the roof is about 3.880 m,and the maximum rise displacement of the floor is about 0.097 m.Third,under various working conditions,the maximum and average heights of fracture expansion are 67.5 m and 57.5 m respectively,and the maximum subsidence displacement of the overlying rock layer is 14.38 m.Fourth,too low or too high advancement rate of the gasification working face leads to excessive concentration of stress in the overlying rock layer and a higher degree of development of natural fractures in the roof rock.This weakens the overall strength of the overlying rock layer,but the interaction between neighboring fractures constrains the fracture extension.It is concluded that UCG requires careful monitoring on the stress changes and fracture development in rock layers and t

关 键 词：准噶尔盆地 煤炭地下气化 数值模拟 天然裂隙 裂隙扩展 应力场 温度场 位移场 

分 类 号：TQ546[化学工程—煤化学工程]