煤层气含量地面井密闭取心与快速测定技术研究.pdf

煤炭科学研究总院 博士学位论文 煤层气含量煤层气含量地面地面井井密闭密闭取心取心 与与快速测定技术研究快速测定技术研究 作者姓名 孙四清 学科专业 矿产普查与勘探 导师姓名 张群 研究员 完成时间 二○一八年六月十五日 万方数据 万方数据 China Coal Research Institute A dissertation for doctors degree Study on Surface Well Sealed Coring and Fast Measurement for Coal Seam Gas Content Author’s Name Siqing Sun SpecialityMineral Resource Prospecting and Exploration Supervisor Prof. Qun Zhang Finished Time June 15th 2018 万方数据 万方数据 煤炭科学研究总院学位论文原创声明 I 煤炭科学研究总院学位论文原创声明煤炭科学研究总院学位论文原创声明 本人郑重声明此处所提交的学位论文煤层气含量地面井密闭取心与快速 测定技术研究是本人在导师指导下，在煤炭科学研究总院攻读博士学位期间独 立进行研究工作所取得的成果。据本人所知，论文中除已注明部分外不包含他人 已发表或撰写过的研究成果。对本文的研究工作做出重要贡献的个人和集体，均 已在文中以明确方式注明。本声明的法律结果将完全由本人承担。 作者签名 日期 年 月 日 煤炭科学研究总院学位论文使用授权书煤炭科学研究总院学位论文使用授权书 煤层气含量地面井密闭取心与快速测定技术研究 系本人在煤炭科学研究 总院攻读学位期间在导师指导下完成的学位论文。 本论文的研究成果归煤炭科学 研究总院所有，本论文的研究内容不得以其他单位的名义发表。本人完全了解煤 炭科学研究总院关于保存、使用学位论文的规定，同意学校保留并向有关部门送 交论文的复印件和电子版本，允许论文被查阅和借阅，同意学校将论文加入中 国优秀博硕士学位论文全文数据库和编入中国知识资源总库 。本人授权煤 炭科学研究总院，可以采用影印、缩印或其他复制手段保存论文，可以公布论文 的全部或部分内容。 本学位论文属于（请在以下相应方框内打“√“; 保密□,在 年解密后适用本授权书 不保密□ 作者签名 日期 年 月 日 导师签名 日期 年 月 日 万方数据 煤炭科学研究总院学位论文原创声明 II 万方数据 摘 要 1 摘摘 要要 煤层气含量是表征煤储层特征的重要参数之一， 准确获取煤层气含量对于煤 层气资源勘探开发和煤矿瓦斯防治具有重要意义。 本文针对碎软煤层和低煤级煤 层按现有地面井取心测试方法获取的煤层气含量比煤炭开采中获取的煤层气含 量明显偏低，以及中-高煤级煤层的煤层气含量测试时间很长两大难题，依托国 家自然科学青年基金“钻孔绳索取芯煤层气损失量估算方法研究”项目 （4120212） 和“十三五”国家科技重大专项任务“地面钻井煤层密闭取心气含量测试技术及装 置” （2016ZX05045-002-002） ，运用煤田地质学、煤层气地质学、油气藏工程、 数学物理、机械设计和钻探工程学等理论、方法和手段，开展了不同粒径系列煤 样在变压或变温条件下煤层气解吸扩散规律的理论分析、 模拟试验与密闭取心设 备及工艺研究工作，并在典型矿区进行了现场工程试验应用，取得了如下主要研 究成果和认识。 （1）研究揭示了高压匀快速降压条件和常压条件下小粒径煤样的煤层气解 吸速率变化规律，建立了变压条件下煤样的煤层气扩散解吸模型。模拟地面井绳 索取心过程， 开展了系列煤级不同粒径煤样在吸附高压甲烷气体平衡后匀快速降 压解吸试验，试验结果表明模拟提心和地面暴露阶段的煤层气解吸速率分别为 解吸罐中的 9116 倍和 627 倍， 实测模拟损失气量是按美国 USBM 直接法估算 的 1.731.4 倍，并且煤样粒度越小彼此差异越大，说明按现有地面井取心测试方 法获取的煤层气含量偏低主要受损失气量估算不准影响。 （2）提出了适合于煤储层特征（与油藏相比，埋藏较浅、压力较低、温度较 低） 的煤层气井密闭取心技术方案， 首次研制出适用于煤层气井气含量测定的“三 筒单动、球阀关闭、取心筒与解吸罐一体化”的密闭取心器。其主要组成部件包 括取心外筒、取心内筒、液压推进筒、球阀、悬挂总成和辅助部件等；取心器长 2.15m，外筒直径 120mm，煤（岩）心直径可达 38mm，保压能力达 10MPa，适 用于煤层埋深 1000m 的地面井取样；具有几何尺寸小、结构简单、使用简便、经 济实用等特点。 （3）发明了适合于碎软煤层的前端小径钻心--后端大径钻井的双径 PDC 取 心钻头，减少了钻进取心过程中钻井液对碎软煤层的冲洗旋流作用，有效提高了 碎软煤层的煤心采取率。 （4）研发形成了地面井煤层气含量密闭取心技术工艺，得出的密闭取心钻进 最佳工艺参数是中硬煤层的钻压、转速、流量、泥浆密度分别为 1830kN、 70100r/min、90145L/min、1.01.1g/cm3；碎软煤层的钻压、转速、流量、泥浆 密度分别为 1216kN、5080r/min、4060L/min、1.01.05g/cm3。 万方数据 摘 要 2 （5）建立了煤样加温、自然解吸的煤层气含量快速测定方法。结果表明，温 度对煤层气的解吸速率有重要影响；将煤样在加温到 50℃进行自然解吸，煤层 气含量测定周期由常规储层温度下的几周～几个月缩短为几个小时～几天时间， 在不影响煤层气含量测定精度情况下，大大缩短了测试时间，显著提高了工作效 率。 （6）研究成果在我国典型矿区进行了地面井煤层气密闭取心工程试验，取 得了很好的应用效果。结果表明安徽省淮北矿区芦岭煤矿和淮南矿区潘三煤矿 的碎软煤层， 由密闭取心方法获得的煤层气含量比常规取心法获得的煤层气含量 高 21.4542.8， 均值为 31.90； 陕西省彬长矿区文家坡煤矿的低煤级中硬煤层， 由 密 闭心方法获得 的煤层气含量比常 规取心法获得的煤 层气含量高 16.6741.67，均值为 29.17。 我国华北、华南和西南地区石炭-二叠纪煤田碎软煤层分布广泛，西北地区 侏罗纪低煤级煤层非常发育， 煤层气资源非常丰富。 该论文研究成果的推广应用， 对于精准快速测定地面井煤层气含量、 提高煤层气资源勘探开发和煤矿瓦斯灾害 治理水平，具有重要意义和良好应用前景。 关键词关键词碎软煤层；低煤级煤层；地面井；煤层气含量；密闭取心；快速测定 万方数据 摘 要 3 ABSTRACT Coal seam gas content is one of important parameters to characterize coal reservoir characteristics, it is of great significance in coal seam gas exploration and development as well as gas control and management. In this paper, aiming at two challenges coal seam gas content obtained by the existing surface well coring test is clearly lower than obtained by coal mining in broken, soft and low rank coal seams, and coal seam gas content testing time in meddle-high rank coal seams is quite long; relying on the project “Study on Estimation of Coal seam Gas Loss Quantity by Wireline Coring in Borehole”4120212 supported by National Science Youth Fund and the “13th Five- Year” National Science and Technology Major Project “Technology and Device for Sealed Coring Gas Content Measurement in Surface Drilling Coal Seams”2016ZX05045-002-002; applying theories and s of coal geology, coal seam gas geology, reservoir engineering, mathematical physics, mechanical design and drilling engineering. This study was pered using theoretical analysis, simulation test, sealed coring equipment and process research of coal seam gas desorption and diffusion for coal samples with different particle sizes under variable pressure or temperature conditions, and field engineering test application was pered in typical mining areas. The results and findings of this study are summarized as follows. 1 The study reveals the change law of coal seam gas desorption rate under variable pressure and atmospheric pressure. A coal seam gas diffusion-desorption model of coal samples under variable pressure has been established. simulates the process of wireline coring of surface wells, and a serious of coal rank samples with different particle sizes is tested for even and fast desorption after adsorbing high pressure methane gas. The Results show that the desorption rate of coal seam gas in simulated coring and exposed surface stage is respectively 9116 times and 627 times in the desorption tank. The measured simulation loss volume is 1.731.4 times that of US USBM direct , and the smaller the size of coal samples, the greater the difference between them. This indicates that lower coal seam gas content obtained by the existing surface well core tests is mainly affected by inaccurate loss of gas estimation. （2）A technical solution of coal seam gas well sealed coring suitable for coal reservoir characteristicscompared with reservoirs, shallower burial, lower pressure and lower temperature is proposed. For the first time, a sealed coring device which “outer barrel rotates with two inner barrels holds still, closed ball valve and integrated core 万方数据 摘 要 4 barrels-desorption tank” is developed that is suitable for the measurement of gas content in coal seam gas wells. The main components include outer barrel, inner barrel, hydraulic drive barrel, ball valve, suspension assembly and accessories, etc; The length of sealed coring device is 2.15m,diameter of Outer cylinder is 120mm,diameter of coal rock core can be up to 38mm,the pressure-holding capacity is up to 10 MPa, and it is suitable for sampling of surface wells with a depth of 1 000 m in coal seams; in addition, it is featured by small geometry, simple structure, easy to use, economical and practical. 3 A dual-diameter PDC core drill bit for front small diameter drilled core-back large diameter drilling in broken and soft coal seams is invented. The drill bit reduces the ing effect of drilling fluid on broken and soft coal seams during core drilling, and effectively improves the recovery of coal core in broken and soft coal seams. 4 The research develops a technology of sealed coring for coal seam gas content in surface wells, and the optimum parameters are the drilling pressure, rotary speed, flow rate and mud density of middle-hard coal seams are 1830 kN, 70100 r/min, 90145 L/min, 1.01.1 g/cm3 respectively; the drilling pressure, rotary speed, flow rate and mud density in broken and soft coal seams are 1216 kN, 5080 r/min, 4060 L/min, 1.01.05 g/cm3 respectively. 5 A fast measurement of coal seam gas content with warming and natural desorption of coal samples is established. The results show that temperature has an important influence on desorption rate; coal samples is desorbed naturally when heated to 50℃, and coal seam gas content measurement cycle is shortened from several weeks/months under conventional reservoirs temperature to several hours/days without affecting the accuracy of measurement of coal seam gas content. In the meantime, the test time is greatly shortened, and the work efficiency is significantly improved. 6 The results of this study were pered in a typical mining area in China, and achieved a great application effect. The results indicate that coal seam gas content obtained by sealed coring is 21.4542.8 higher than obtained by conventional coring in broken and soft coal seams in Luling coal mine of Huaibei mining area and Pansan coal mine of Huainan mining area in Anhui Province, and the average is 31.90; coal seam gas content obtained by sealed coring is 16.6741.67 higher than obtained by conventional coring in middle-hard coal seams in Wen Jiapo coal mine of Binchang mining area in Shaanxi Province, and the average is 29.17. The broken and soft coal seams in the Carboniferous-Permian coalfields in North China, South China and Southwest China are widely distributed, and the northwest 万方数据 摘 要 5 Jurassic low rank coal seams is developed with rich coal seam gas resources. The popularization and application of research results of this paper is of great significance and has good application prospect for accurate and fast measurement for coal seam gas content in surface wells, improvement of coal seam gas resources exploration and development and coal mine gas disaster control. Keywords Broken and soft coal seam; Low rank coal seam; Surface well; Coal seam gas content; Sealed coring; Fast measurement. 万方数据 摘 要 6 万方数据 目 录 I 目目 录录 第 1 章 绪 论 1 1.1 研究背景及意义 1 1.2 煤层气瓦斯解吸研究现状 3 1.2.1 煤孔隙结构及煤层气瓦斯赋存状态 3 1.2.2 煤层气瓦斯扩散解吸规律 5 1.2.3 煤层气瓦斯解吸主要影响因素 8 1.2.4 煤层气瓦斯含量测定方法 9 1.3 地面钻井密闭取心研究现状 10 1.3.1 国外密闭取心研究现状 11 1.3.2 国内密闭取心研究现状 14 1.4 存在主要问题 19 1.5 论文研究目标及研究内容 20 1.5.1 研究目标 20 1.5.2 主要研究内容 21 1.6 研究方法及技术路线 21 第 2 章 地面井取心过程煤层气含量逸散机理分析和实验模拟 24 2.1 煤层气解吸机理分析 24 2.1.1 煤层气赋存状态 24 2.1.2 煤层气解吸机理 25 2.2 取心过程变压条件下煤层气解吸扩散机理和模型 27 2.2.1 煤层气解吸扩散地质模型 27 2.2.2 煤层气扩散方程的建立 27 2.2.3 煤层气解吸-扩散数学模型的建立及求解 29 2.2.4 解析解讨论 33 2.3 地面井取心过程煤层气解吸-扩散模拟实验 34 2.3.1 实验方案及装置 34 2.3.2 实验样品采集及制备 37 2.3.3 高压条件下溶解气实验 38 万方数据 目 录 II 2.3.4 实验数据分析 39 2.4 地面井取心过程煤层气解吸-扩散规律 47 本章小结 48 第 3 章 地面井煤层气密闭取心器设计与研制 49 3.1 煤层气密闭取心技术方案 49 3.1.1 密闭取心器设计思想 49 3.1.2 密闭取心器工作原理 49 3.1.3 密闭取心器工作流程 50 3.1.4 三筒单动密闭取心器部件组成 52 3.2 密闭取心器关键部件设计 55