泥页岩吸附天然气量主控因素及定量表征研究

发布时间：2018-02-28 18:23

本文关键词： 页岩气吸附主控因素吸附实验吸附模型　出处：《东北石油大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着世界油气能源供给的日趋紧张和常规油气勘探开发形势的日趋严峻,非常规油气资源,包括页岩油气、煤层气、致密砂岩油气等已引起人们的高度重视。北美勘探实践表明非常规油气中,目前发展势头最快、潜力最大的当属页岩气。页岩气的赋存方式分为游离气、吸附气和溶解气。对于页岩气中吸附气的比例构成,前人研究成果表明,不同页岩气产层有很大不同,但普遍占有较高比例,一般介于40%~85%之间。此外,吸附态的存在还将提高页岩气的保存能力。基于上述认识,吸附态的赋存方式被认为是页岩气能够被成功勘探开发的重要因素。为此,有必要对影响泥页岩吸附气量的主控因素进行研究。以往对于吸附气量主控因素的研究往往是多因素的复合,如有机质丰度与页岩吸附能力的关系可能同时包含了有机质成熟度、温度、湿度等其它因素的影响,毫无疑问对单一因素的逐一揭示更具说服力,为此本次设计开展了系列平行实验,以求最大限度地揭示各因素的影响力。通过系列平行实验和数值模拟揭示了有机碳含量、有机质成熟度、天然气组成、温压和湿度等对泥页岩吸附能力的影响,结果表明:(1)微小孔隙(3nm)是泥页岩比表面积的主要贡献者,其贡献比例占80%左右,有机质热演化过程中会产生大量的微孔(2nm),比表面积大量增加,吸附气量显著增大;(2)泥页岩对CO2、N2吸附能力高于CH4,暗示在进行页岩气开采时可注入CO2和N2提高CH4采收率;(3)兰格缪尔模型的拟合程度较好说明泥页岩对天然气的吸附为单分子层吸附。吸附势模型的地质外推说明了地质条件下温压共同作用下泥页岩吸附能力随埋深增加呈先增大后减小的趋势,而孔隙度一定情况下泥页岩储存游离气能力随深度增加则呈逐渐增大的趋势,泥页岩吸附能力与储存游离气能力变化趋势的不一致会造成一定地质条件下吸附气量与游离气的转化,有利于页岩气的保存;(4)泥页岩有机质热演化过程中亲水NSO官能团会逐渐降解,润湿性随之变小,吸附气量随之增大,成岩作用是温度、压力和水介质条件共同作用的结果,单纯温度的升高不会造成粘土矿物的转化;(5)泥页岩有机质的成熟度、天然气组分和地质环境(包括温度、压力和湿度)均会影响泥页岩的吸附能力,其中湿度影响较小,其影响往往会被有机质丰度等因素的影响掩盖。
[Abstract]:With the increasing shortage of oil and gas energy supply in the world and the increasingly severe situation of conventional oil and gas exploration and development, unconventional oil and gas resources, including shale oil and gas, coal bed methane, The exploration practice in North America shows that among the unconventional oil and gas, shale gas has the fastest development momentum and the most potential is shale gas. The occurrence of shale gas is divided into free gas. For the proportion of adsorbed gas in shale gas, the former research results show that different shale gas production layers are very different, but generally occupy a high proportion, generally between 40% and 85%. The existence of adsorbed state will also improve the ability to preserve shale gas. Based on the above understanding, the mode of occurrence of adsorption state is considered to be an important factor for the successful exploration and development of shale gas. It is necessary to study the main factors that influence the amount of gas adsorbed by shale. For example, the relationship between organic matter abundance and shale adsorption capacity may include the influence of organic matter maturity, temperature, humidity and other factors, so it is undoubtedly more convincing to reveal a single factor one by one. Therefore, a series of parallel experiments were carried out to maximize the influence of various factors. The organic carbon content, maturity of organic matter and composition of natural gas were revealed through a series of parallel experiments and numerical simulations. The effects of temperature, pressure and humidity on the adsorption capacity of shale show that: 1) small pore size 3nm) is the main contributor of shale specific surface area, and its contribution ratio is about 80%. During the thermal evolution of organic matter, a large number of micropores can be produced, and the specific surface area increases greatly. Adsorption capacity of shale to CO _ 2N _ 2 is higher than that of Ch _ 4, suggesting that CO2 and N _ 2 can be injected into shale gas to increase CH4 recovery. The fitting degree of Langmuir model shows that shale adsorbs natural gas better. The geo-extrapolation of the adsorption potential model shows that the adsorption capacity of shale increases first and then decreases with the increase of buried depth under the combined action of temperature and pressure. Under the condition of constant porosity, the storage capacity of free gas of shale increases with the depth of shale, and increases gradually with the increase of porosity. The inconsistency between shale adsorption capacity and storage free gas capacity will result in the transformation of adsorption gas and free gas under certain geological conditions. During the thermal evolution of shale organic matter, the hydrophilic NSO functional group will gradually degrade, the wettability will become smaller, and the amount of adsorbed gas will increase. The diagenesis is the result of the combined action of temperature, pressure and water medium condition. The increase of temperature will not result in the maturation of organic matter in shale. The composition of natural gas and geological environment (including temperature, pressure and humidity) will affect the adsorption ability of shale. Its influence will often be masked by factors such as the abundance of organic matter.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

【共引文献】