【作者】 王红岩；

【导师】 万天丰；

【作者基本信息】 中国地质大学（北京） ， 构造地质学， 2005， 博士

【摘要】 中国的含煤盆地多具有复杂的演化史和构造变形史,煤的变质作用类型复杂且多经历过多阶段变质演化与多热源叠加变质作用,煤储层物性差异较大、且孔渗性与含气饱和度大多偏低,构成我国煤储层性质的主要缺陷。本文通过收集大量煤田地质、天然气地质和煤层气地质资料,采集煤岩、砂泥岩、灰岩、岩浆岩样品,选择山西省东南部沁水盆地典型地区(阳城、霍山、沁源)建立沁水盆地沉积埋藏史模型,确定了煤层气成藏关键时刻;开展大量测试分析与实验模拟,确定了构造热事件在煤层气富集成藏中扮演的作用;研究渗透性的控制因素,寻找有效的高渗区预测方法;开展高煤阶煤层气成藏综合模拟,确定高煤阶煤层气成藏特征及成藏优势。建立起来一套具有独立知识产权的煤层气成藏模拟实验装置,申请专利两项,其中发明专利一项(200420093572.0),实用新型一项(200410074732.1),开展大量物理模拟实验,形成了若干煤层气勘探开发中的部分机理上的新认识。如煤层气藏开采过程中的降压基质膨胀二元论、煤层气原地状态的突破参数、运聚压差、水对煤层气藏的溶解作用等等,在生产和科研中取得了很好的应用效果。提出煤层气成藏的“关键时刻“定义,即煤层最后一期生烃后上覆有效厚度在地史上埋藏最小的时刻。通过正演、反演和模拟实验明确提出演化程度最高的地质时期决定了煤层气的地化特征,是决定煤层气地球化学特征的关键地质时期。用正演和反演相结合的方式探讨“关键时刻”的温、压条件;结合聚气历史明确指出煤层的聚气量与煤层气藏演化的“关键时刻”有关。系统提出高煤阶由于受异常热事件的影响,一方面促进煤层气大量生成,同时改善了储层物性,形成煤层气高产富集区。提出物性变化二元论规律,高煤阶随着系统压力降低,割裂隙压力降低,上覆压力相对增大,裂隙闭合渗透率降低。低煤阶随着压力的降低,基质在卸压状态下不断膨胀,造成孔隙增大,基质渗透率增大,也就是说随着煤层气排采工作的进行,煤层物性不断变好。利用现代构造应力场主应力差值及应力方向与试井渗透率之间的耦合关系,开展高渗区域预测。总结了中国高变质无烟煤成藏特征及成藏优势。中国高变质无烟煤成藏特征主要集中在六个方面:(1)煤层气成因以原生和次生热成因煤层气为主;(2)煤阶高,煤层吸附量大,含气量高;(3)变质程度高,煤层基质致密,物性偏低;(4)构造热事件和构造应力场对煤层物性影响较大;(5)滞流水区域为富气区;(6)成藏过程复杂。成藏优势包括:(1)煤变质程度高,生气量大,煤吸附能力强,含气量大;(2)构造热事件和构造应力场对煤层物性影响较大;(3)滞流水和高矿化度区域煤层气保存条件好,利于煤层气保存和排水降压开采。更多还原

【Abstract】 Main limitations of reservoir property of coal-bed methane (CBM) in China include as following: Generally coal-bearing basins have complex history of evolution and tectonism; Type of coal metamorphism is complex and coal undergone through multi-periods metamorphic evolution and superimposed metamorphism of multi-thernal source; Physical property of different coal reservoir is diverse and the porosity, permeability and gas saturation are usually low. On the basis of collecting large amount of geological data of coal field, natural gas and CBM, samples of coal, sand-shale, limestone and magmatite, this paper selects typical districts (Yangcheng, Huoshan and Qinyuan) of Qinshui basin in the southeast of Shanxi province and sets up model of sedimentary and burial history, determined key period of CBM reservoir formation. The great deals of test analysis and experiment simulation have been carried out and function of tectono-thermal event in CBM reservoir formation has been determined, in which it also studies the control factors of permeability and looks for valid prediction method of high-permeability area. At the same time comprehensive simulation of reservoir formation of high rank CBM has been carried out to determine characteristic and predominance of reservoir formation. A set of simulation experiment device of CBM reservoir formation with absolute intellectual property right was established and two patents were applied including an invention patent and a practical patent. A lots of physical simulation experiments were carried out and several new understandings about mechanism of CBM exploration and development were obtained and won good application effect in production and scientific research, such as dualism of pressure-relief and matrix expansion in the process of CBM production, breakthrough parameter and pressure difference of migration and accumulation of CBM in place, dissolving function of water to CBM. Definition of “Key moment”was presented that is the moment when buried depth i.e. effective thickness of overlying strata is minimum in geological history after last time of hydrocarbon formation in coal bed. The forward, backward consequence and modeling experiments show that geologic time when evolution degree is highest determines geochemical feature of CBM. This paper discussed condition of temperature and pressure in “Key moment”in combination with forward and backward consequence, and pointed out definitely that quantity of gas accumulation is correlative to “Key moment”of CBM reservoir evolution combined with gas accumulation history. This study shows that high coal rank will accelerate the large amount of CBM generation and improve physical properties of reservoir and to form CBM enriched area, influenced by abnormal thermal event. Different variable laws of physical properties were proposed: For high rank coal, with the reduction of system pressure, fissure pressure will decrease; overlying pressure will increase comparatively; and closure of fissure leads to the decreasing of permeability. On the contrary, for low rank coal, with the reduction of system pressure, matrix will expanse continuously in the state of pressure-relief, which results to the increase of pore diameter and matrix permeability, that is, with the production of CBM, physical properties of coal reservoir will become better. Prediction of high permeability area was developed to use the coupling relationship between the orientation of maximum principal compression stress, differential stress magnitude of recent tectonic stress field and permeability in test hole. The characteristics and predominance of reservoir formation for high metamorphic anthracite in China were summarized. Predominances include following three parts: 1. If metamorphosis degree is high, then amount of generated gas is large, adsorption capacity of coal is strong and gas content is high; 2. The tectono-thermal event and stress field will greatly affect on physical properties of coal reservoir; 3. The preserved condition of CBM, existed occluded water and high salinity water in the area, will be good, in which is beneficial to the preservation and production of CBM with pressure-relief methods by water draining.更多还原