摘要
为了提高低渗透煤层增透效果,提出采用表面活性剂协同酸液的腐蚀煤体技术改进煤层传统水力压裂技术,利用腐蚀性压裂液增强压裂液在煤体中的破坏效果,揭示腐蚀煤体力学变化特性,并将基于压裂液腐蚀的煤体增透技术在煤矿现场进行工业化应用,考察煤层增透及瓦斯抽采效果。研究结果表明:经过压裂液腐蚀的煤样破坏过程分为4个阶段:裂隙闭合阶段、弹性变形阶段、裂隙稳定扩展阶段及裂纹加速扩展阶段,腐蚀压裂液深入煤岩内部的孔洞和裂隙中,与其中的黏土矿物和无机盐矿物等杂质矿物反应,造成煤岩孔洞和裂隙的破坏,导致煤样内部出现了不贯通裂隙,在经过腐蚀处理后,煤样破坏过程中进入裂隙稳定扩展阶段所受的应力变小,煤样强度降低,经过十二烷基磺酸钠(SDS)协同腐蚀处理后煤样强度最低,煤样产生裂隙所受的应力值最低,表明SDS对腐蚀效果破坏煤体结构具有积极作用。通过工业性试验可得,同普通水力压裂孔对比,酸化腐蚀压裂孔维持在高浓度、高流量的时间长,衰减得慢。压裂影响区域导向孔瓦斯抽采体积分数最高达到76%;与平均瓦斯浓度相比,水力压裂钻孔瓦斯抽采体积分数提高了8%,钻孔间距从6 m扩大到11 m,节约了煤矿瓦斯治理成本。
In order to improve the permeability enhancement effect of low permeability coal seams,the traditional hydraulic fracturing tech⁃nology of coal seam is improved by using surfactant and acid solution to corrode the coal,and the corrosive fracturing fluid is used to en⁃hance the damage effect of the fracturing fluid in the coal body,revealing the mechanical change characteristics of the corrosive coal.The anti-permeability technology of coal based on fracturing fluid corrosion is industrially applied in the coal mine site,and the effect of coal seam anti-permeability and gas drainage is investigated.The research results show that the failure process of coal samples corroded by fracturing fluid is divided into four stages:fracture closure stage,elastic deformation stage,stable fracture propagation stage and accelerated crack propagation stage,the corrosive fracturing fluid penetrates deep into the pores and fissures inside the coal rock,reacts with the clay minerals and inorganic salt minerals and other impurity minerals in it,causing the destruction of the coal rock cavities and fissures,resul⁃ting in the appearance of non-penetrating fissures in the coal sample.After the corrosion treatment,the stress value of the coal sample in the stable expansion stage of the crack during the failure process becomes smaller,and the strength of the coal sample decreases.The low⁃est,indicating that SDS has a positive effect on the corrosion effect destroying the coal structure.It can be seen through industrial tests that,compared with ordinary hydraulic fracturing holes,acid corrosion fracturing holes maintain a high concentration and high flow for a long time and decay slowly.The concentration of pilot holes in the fracturing-affected area is up to 76%;the average gas concentration is 8%higher than that of hydraulic fracturing holes,and the drilling spacing is expanded from 6 m to 11 m,saving coal mine gas control costs.
作者
王宁
李树刚
WANG Ning;LI Shugang(School of Safety Science and Engineering,Xi’an University of Science and Technology,Xi’an 710054,China;Shaanxi Coal and Chemical Industry Group Co.,Ltd.,Xi’an 710100,China;Shaanxi Coal Industry Co.,Ltd.,Xi’an 710077,China)
出处
《煤炭科学技术》
CAS
CSCD
北大核心
2022年第5期150-156,共7页
Coal Science and Technology
基金
国家自然科学基金面上资助项目(51774234,51874234)。
关键词
低渗透煤层
压裂液
腐蚀煤体
力学损伤
增透技术
low permeability coal seams
fracturing fluid
corroded coal
mechanical damage
anti-reflection technology
