孔径结构、水分对低阶煤煤层气赋存的影响——以新疆地区侏罗系西山窑组褐煤为例

通过对新疆伊犁盆地和准噶尔盆地侏罗系西山窑组主力煤层样品进行了压汞法及低温液氮法实验,分析了煤岩的孔隙结构特征;利用煤样的甲烷等温吸附实验,研究了孔隙结构、水分对吸附气赋存的影响。实验和综合分析结果表明:低煤阶煤以中孔、大孔为主的孔隙特征决定了煤层气主要以游离状态赋存其中,水分是影响吸附气的重要因素。     

应用高温甲烷吸附实验研究川东北地区五峰组页岩甲烷吸附能力

页岩甲烷吸附能力是决定页岩气井开采方案的重要参数,对评估页岩气藏潜力意义重大。干酪根类型、总有机碳含量、矿物组成、成熟度和孔径等是影响页岩吸附性能的因素,但针对高温高压下过剩吸附现象对页岩甲烷吸附能力影响的研究还需开展进一步的探索。为揭示四川盆地东北地区五峰组页岩甲烷吸附能力,本文通过场发射扫描电镜、低温氮气吸附和高压甲烷吸附实验,研究了高温高压下页岩的甲烷吸附能力,并分析了页岩孔隙结构等对页岩吸附能力的影响。结果表明:①五峰组页岩孔隙结构非均质性强,发育有机孔隙、粒(晶)间孔隙、粒(晶)内孔隙和粒(晶)间溶孔等多种孔隙;②比表面积平均为19.1282m^2/g;孔体积平均为0.0195cm^3/g;孔径平均为5.2226nm;③修正后的饱和吸附气量为2.56m^3/t;④五峰组页岩甲烷吸附性能受控于比表面积、孔体积;有机质含量越大、有机质热演化程度越低,其甲烷吸附性能越强;⑤孔隙结构是影响页岩甲烷吸附能力的重要内因。同时指出低压条件下的实验吸附曲线不适合直接评价页岩甲烷吸附能力。     

煤储层特征及其对吸附能力的影响——以鸡西盆地城子河组为例

采用扫描电镜、低温氮吸附法对鸡西盆地城子河组煤岩储集空间特征和孔隙结构进行研究,探讨煤岩吸附能力的主要影响因素。结果表明,煤岩常见孔隙类型包括残余组织孔、屑间孔、角砾孔和气孔,其中气孔的广泛发育既证实了煤岩大量生烃的过程,又为煤层气赋存富集提供优质储集空间。形式多样的张性裂隙组合,对改善渗透性具积极意义;煤岩低温氮吸附曲线呈现两种类型,反应不同特征的孔隙系统。鸡东坳陷相对梨树镇坳陷煤岩中微孔更为发育,使得比表面积和总孔体积值较高,平均孔径值降低,孔隙形态从开放性逐渐过渡为墨水瓶孔,微孔中墨水瓶孔的含量是导致滞后环形态发生变化的主要原因;煤岩的比表面积和总孔体积能够较好的反应煤岩的吸附能力。灰分、镜质组含量和成熟度通过控制鸡西盆地城子河组煤岩孔隙发育特征,从而影响煤岩的吸附能力。煤岩镜质组和演化程度升高会增强煤岩的吸附能力,而灰分含量高会减少煤岩对甲烷的吸附量。     

榆神府矿区富油煤多尺度孔隙结构特征

利用富油煤提油炼气是弥补我国油气供给不足的重要措施,而富油煤的孔隙发育特征及其渗透能力等方面的研究是开发利用富油煤的基础工作。以榆神府矿区富油煤为研究对象,采用低温液氮吸附法、压汞法、核磁共振法以及气渗透法等多元手段对富油煤多尺度孔隙结构进行分析,并开展富油煤全段孔隙表征研究。基于富油煤多尺度孔隙结构测试结果,开展富油煤孔隙特征与传统低阶煤样差异性讨论。结果发现:榆神府矿区富油煤微小孔隙极为发育,占比高达70%以上,大孔、中孔发育相对不足,仅占总孔隙的25%~30%;核磁共振结果与低温液氮吸附法、压汞法联合表征结果对比发现,联合低温液氮吸附法与压汞法可较好地表征煤样全段孔隙;相较于传统低阶煤,富油煤具有较大的孔比表面积与低温氮吸附量,分别为27.48 m2/g、40~50 cm3/g,具备富油煤提油炼气的良好物性条件。      

基于Ono-Kondo格子模型的页岩气超临界吸附机理探讨

页岩气吸附机理的研究对于页岩气成藏和储量评价具有重要意义.甲烷在地层温度和压力条件下处于超临界状态,页岩气的吸附实际上为超临界吸附,但其机理目前尚不明确.在建立Ono-Kondo格子模型的基础上,结合低温氮气吸附和高压甲烷等温吸附实验,对龙马溪组页岩的微观孔隙结构和超临界吸附曲线进行了分析.结果表明,页岩中发育的孔隙尺度较小,比表面积较大,吸附气主要赋存于微孔和中孔中;页岩的等温吸附曲线在压力较大时,必然存在下降的趋势,这并非异常现象,而是超临界甲烷过剩吸附量的本质特征.Ono-Kondo格子模型对页岩高压等温吸附曲线的拟合效果很好,相关系数均在0.99以上,说明该模型可以表征页岩纳米孔隙中超临界甲烷的吸附特征.基于拟合得到的吸附相密度可将过剩吸附量转换为绝对吸附量,并直接计算地层温度和压力下甲烷的吸附分子层数,计算层数均小于1,表明甲烷分子并没有铺满整个孔隙壁面.因此受流体性质、吸附剂吸附能力和孔隙结构3个方面的影响,页岩气的吸附机理为单层吸附,不可能为双层甚至多层吸附.      

高压氮气置换甲烷对煤基质孔隙的影响

为探究高压气体吸附-解吸试验对煤基质中孔隙发育规模和结构的影响,选取安鹤矿区鹤壁六矿二1煤层煤样进行了高压氮气置换甲烷吸附-解吸试验,采用低温液氮吸附方法分别测定了高压氮气置换甲烷前后煤的低温液氮吸附解吸曲线,利用BET、BJH和QSDFT 3种分析模型,对煤基质中1.14~300 nm的孔隙规模、分布与结构特征进行了对比分析。分析结果显示煤样的孔容、比表面积和孔隙结构在高压气体置换过程中均发生了变化,孔隙BET比表面积从12.746 0 m2/g降低到7.227 0 m2/g,总孔容从0.009 0 cm3/g降低到0.006 6 cm3/g;孔隙发育规模与孔径分布均发生明显变化,但孔隙形态基本保持不变,孔径分布的变化主要表现为微孔孔容与比表面积的降低为主,而中孔和大孔基本保持不变。      

褐煤孔隙结构及比表面积特征

为揭示褐煤孔隙结构及比表面特征,选取全国主要褐煤产地样品,进行煤岩显微组分含量测定和低温氮吸附实验,从吸附曲线形态、比表面积、孔径结构分布刻画煤储层微孔隙特征,探讨孔径结构与比表面积的关系,分析BET比表面积与煤岩显微组分的相关性。结果表明:褐煤低温液氮曲线形态大致可以分为无吸附回线、有拐点的吸附回线和无拐点的吸附回线3类;BET比表面积随BJH总孔体积的增加呈线性增加趋势,在2~10 nm范围内的孔径和比表面积关系可以分为正相关、负相关和复合相关3种;显微组分组和比表面积的相关性较弱,但比表面积与细屑体含量具有较好的线性关系。      

低煤阶煤储层孔隙结构特征及其扩散方式

采用数值模拟、扫描电镜、低温氮吸附曲线对呼和湖凹陷不同构造位置煤岩储集空间类型和孔隙结构特征进行系统研究,分析构造作用对孔隙系统的控制作用,探讨不同压力下甲烷气体在纳米级孔隙中扩散方式。研究表明:1洼槽区以原生孔隙和内生裂缝为主;斜坡带构造相对活跃,以反映构造行迹的碎粒孔和张性、剪性裂缝为主,裂缝数量明显增多,规模扩大,对改善渗透性意义较大。2煤岩孔隙的比表面积与孔体积具有较好的正相关关系,与平均孔径呈负相关性,斜坡带孔隙遭到破坏,微孔数量增多,比表面积和孔体积较洼槽区成倍增长,煤岩对甲烷的吸附能力增强。利用吸附、脱附曲线特征对煤岩孔隙结构特征进行评价,斜坡带相对于洼槽区孔隙系统复杂,利于吸附,难于解吸。3斜坡带和洼槽区在采气初期甲烷以分子扩散为主,随着压力的降低,由于孔隙结构的差异性,开采后期洼槽区甲烷分子逐渐由过渡区流动取代分子扩散,斜坡区扩散方式则变化不大。综合分析认为,斜坡带是呼和湖凹陷煤层气勘探的有利区块。     

基于氮吸附法的页岩有机孔隙结构表征

页岩的微观孔隙结构对页岩气的赋存至关重要,气体吸附法可以较好对页岩的微观孔隙结构进行表征。通过测量丁页1井不同深度样品的矿物含量、RO值和TOC含量,结果表明丁页1井龙马溪组页岩样品的矿物含量比较稳定,有机质成熟度变化不大,均为过成熟。通过低温氮吸附法计算样品的比表面积和微、介孔容积和孔径分布,结果表明：（1）样品的平均孔径为2.8 ~ 4.9 nm,10 nm以下的孔隙提供了大部分的微、介孔容积。微、介孔容积为0.00136 ~ 0.0108 cm3/g,平均0.004 cm3/g,比表面积为2.54 ~ 13.69 m2/g,平均6.68 m2/g;（2）微、介孔容积、比表面积和TOC三者之间有很强的正相关性。通过计算TOC含量为0时的微、介孔容积和比表面积推算无机孔和有机孔之间的比例和其对比表面积的影响,发现有机孔提供了大部分的微、介孔容积,有机孔还是比表面积的主要贡献因素;（3）样品的吸附曲线符合IPUAC分类中的第IV型吸附曲线,样品的脱附曲线反映样品孔隙形态随TOC含量的增加,由楔形孔（不定型孔）变为连通的墨水瓶型孔（狭缝型孔）或墨水瓶型孔。     

鄂尔多斯盆地东部煤岩孔隙特征实验分析

煤层气储层孔隙结构特征决定着煤层的吸附能力。利用低温氮吸附法和汞侵入法对鄂尔多斯盆地东部地区煤样的孔隙特征进行测试,并分别对煤样的低温氮吸附孔隙特征和汞侵入孔隙特征进行分析。在此基础上,综合两种实验的测试结果,对煤样的孔隙类型进行分类。压汞实验表明:压汞曲线和退汞曲线相似性较好,两者之间的间距很小,退汞效率达65%~75%;液氮实验表明:低变质煤孔以一端封闭的孔为主,随着煤变质程度的增加,先是较大的孔变为两端开放的孔,接着较小孔变为两端开放的孔,到了无烟煤阶段微孔也变成以两端开放的孔为主。综合两种结果,认为煤样的孔隙中以微孔和过渡孔为主,并且微孔和过渡孔是构成煤样孔隙容积的主要贡献者,大孔和中孔的总孔容所占比例较小。鄂尔多斯盆地东部煤岩的孔隙特征有利于煤层中气体的吸附,是煤层气储层的良好场所。     

利用SAXS表征不同变质程度煤纳米孔隙特征

文章通过小角X 射线散射（SAXS） 的方法研究了自然演化系列不同煤级煤的纳米孔隙结构和分布特征。结果表明, 随着煤级的增高,孔隙表面分形呈多阶段变化： Ro＜0.89%,壳质组开始逐渐液化,发育大量孔隙,分形维数不断增大; Ro 为0.9%~1.5%,因挥发分生油充填孔隙和原油沥青的芳构化等作用,而使微孔表面平整光滑,分形维数减小;Ro 为1.5% ~3.5%,镜质组裂解生气发育了大量纳米孔隙,分形维数再次增大;随后逐渐石墨化,表面分形再次降低。煤中纳米级孔 隙主要集中在50~100 nm 范围内。其中细介孔（2~10 nm） 体积百分比占0.21%~3.12%,中介孔（10~25 nm） 体积百分比占 5.06%~11.28%,粗介孔（25~50 nm） 体积百分比占21.06%~26.36%,大孔（50~100 nm） 所占体积百分比最大,高达 64.63%~68.36%。随着煤级升高,煤样的最可几孔径不断减小,最可几孔径由80 nm 减小到10 nm,减小的速度由缓到快; 中介孔和细介孔体积百分比不断增大,与成熟度分别呈对数和线性关系;粗介孔和大孔百分比不断减少,与成熟度呈对数 关系。最可几孔径变化也十分明显,在低煤化烟煤阶段时,随煤化程度增高最可几孔径略有下降（峰值处的孔径范围在 75~71 nm 内）,中高煤化烟煤阶段时,随煤化程度的增高最可几孔径呈较明显的下降趋势（峰值处的孔径范围在78~53 nm 内）,到无烟煤阶段时,其孔径则快速下降（峰值处的孔径范围在72~9 nm）。     

华北南部构造煤纳米级孔隙结构演化特征及作用机理

构造煤是在构造应力作用下,煤体发生变形或破坏的一类煤,在世界主要产煤国家皆有分布。构造变形不同程度的改变着煤的大分子结构和化学成分,而且也影响到构造煤的纳米级孔隙结构(<10 0 nm ) ,它是煤层气的主要吸附空间。通过构造煤显微组分和镜质组油浸最大反射率的测定,采用液氮吸附法对不同变质变形环境、不同变形系列构造煤的纳米级孔隙分类、孔隙结构特征进行了深入系统的研究,并结合高分辨透射电子显微镜和X射线衍射对大分子结构和孔隙结构的分析,结果表明:不同类型构造煤纳米级孔径结构自然分类,可将孔径结构划分为过渡孔(15～10 0 nm )、微孔(5～15 nm )、亚微孔(2 .5～5 nm )和极微孔(<2 .5 nm ) 4类。低煤级变形变质环境中随着构造变形的增强,不同类型构造煤过渡孔孔容明显降低,微孔及其下孔径段孔容明显增多,可见亚微孔和极微孔,过渡孔的比表面积大幅度降低,而亚微孔的却增加得较快。从脆韧性变形煤至韧性变形煤,总孔体积、累积比表面积、N2 吸附量随着构造变形的增强,这些结构参数均迅速增加,但中值半径进一步下降。非均质结构煤孔隙参数与弱脆性变形煤相当。中、高煤级变形变质环境形成的各种类型构造煤与低煤级变质变形环境相比,孔隙参数的变化基本一致。但不同类型构造煤的变化又有所区别     

不同变质变形煤储层孔隙特征与煤层气可采性

煤储层孔隙是煤层气的主要聚集场所和运移通道,煤储层孔隙结构不仅制约着煤层气的含气量,而且对其可采性也有重要影响。文中选取淮北煤田和沁水盆地不同矿区有代表性的煤样,通过对研究区不同变质与变形煤样的宏微观构造观测、镜质组反射率与孔隙度测试以及压汞实验分析,研究了不同变质变形煤储层孔隙结构特征及其对煤层气可采性的制约。研究结果表明,按照不同的变质变形特征将研究区煤储层主要划分为5类,即:高变质较强至强变形程度煤储层(Ⅰ类)、高变质较弱变形程度煤储层(Ⅱ类)、中变质较强变形程度煤储层(Ⅲ类)、中变质较弱变形程度煤储层(Ⅳ类)及低变质强变形程度煤储层(Ⅴ类)。不同变质变形煤储层的孔隙结构具有以下特征:Ⅰ类和Ⅱ类煤储层吸附孔占主导,Ⅰ类煤储层孔隙连通性差,Ⅱ类煤储层因后期叠加了构造裂隙,孔隙连通性变好;Ⅲ类煤储层中孔、大孔增多,但有效孔隙少,孔隙连通性变差;Ⅳ类煤储层吸附孔较多,中孔、大孔中等,且煤储层内生裂隙发育,孔隙具有较好的连通性,渗透性明显变好;Ⅴ类煤储层吸附孔含量较低,中孔较发育,大孔不太发育,有效孔隙少,孔隙连通性差。由此,变质程度高且叠加了一定构造变形的煤储层(Ⅱ类)以及中等变质程度变形较弱且内生裂隙发育的煤储层(Ⅳ类),其煤层气有较好的渗透性,可采性较好。     

Adsorption Mechanism and Kinetic Characterization of Bituminous Coal under High Temperatures and Pressures in the Linxing‐Shenfu Area

The majority of coalbed methane(CBM) in coal reservoirs is in adsorption states in coal matrix pores. To reveal the adsorption behavior of bituminous coal under high-temperature and high-pressure conditions and to discuss the microscopic control mechanism affecting the adsorption characteristics, isothermal adsorption experiments under hightemperature and high-pressure conditions, low-temperature liquid nitrogen adsorption-desorption experiments and CO2 adsorption experiments were performed on coal samples. Results show that the adsorption capacity of coal is comprehensively controlled by the maximum vitrinite reflectance(Ro, max), as well as temperature and pressure conditions. As the vitrinite reflectance increases, the adsorption capacity of coal increases. At low pressures, the pressure has a significant effect on the positive effect of adsorption, but the effect of temperature is relatively weak. As the pressure increases, the effect of temperature on the negative effect of adsorption gradually becomes apparent, and the influence of pressure gradually decreases. Considering pore volumes of pores with diameters of 1.7-100 nm, the peak volume of pores with diameters 10-100 nm is higher than that from pores with diameters 1.7-10 nm, especially for pores with diameters of 40-60 nm, indicating that pores with diameters of 10-100 nm are the main contributors to the pore volume. The pore specific surface area shows multiple peaks, and the peak value appears for pore diameters of 2-3 nm, indicating that this pore diameter is the main contributor to the specific surface area. For pore diameters of 0.489-1.083 nm, the pore size distribution is bimodal, with peak values at 0.56-0.62 nm and 0.82-0.88 nm. The adsorption capability of the coal reservoir depends on the development degree of the supermicroporous specific surface area, because the supermicroporous pores are the main contributors to the specific pore area. Additionally, the adsorption space increases as the adsorption equilibrium pressure increases. Under the same pressure, as the maximum vitrinite reflectance increases, the adsorption space increases. In addition, the cumulative reduction in the surface free energy increases as the maximum vitrinite reflectance increases. Furthermore, as the pressure increases, the surface free energy of each pressure point gradually decreases, indicating that as the pressure increases, it is increasingly difficult to adsorb methane molecules.     

An Experimental Study on the Conductivity Changes in Coal during Methane Adsorption-Desorption and their Influencing Factors

During the processes of methane adsorption and desorption, the internal structure of coal changes, accordingly leading to changes in electrical conductivity. In this paper, using low rank coal seams of the Yan’an Formation in the Dafosi field as the research subject, the relationship between coal resistivity, methane adsorption quantity, and equilibrium pressure is analyzed through proximate analysis, mercury injection tests, low temperature liquid nitrogen adsorption tests, and coal resistivity measurements during methane adsorption and desorption. The results show that during the process of pressure rise and methane adsorption, the conductivity of coal increases, resulting from heat release from methane adsorption, coal matrix swelling and adsorbed water molecules replaced by methane, but the resistivity reduction gradually decreases. The relationship between coal resistivity and methane adsorption quantity and equilibrium pressure can be described by a quadratic function. During the processes of depressurization and desorption, the resistivity of coal rebounds slightly, due to decalescence of methane desorption, coal matrix shrinkage and water-gas displacement, and the relationship coincides with a linear function. Methane adsorption leads to irreversible changes in coal internal structure and enhances the coal conductivity, and resistivity cannot be restored to the initial level even after methane desorption. The resistivity and reduction rate of durain are higher than those of vitrain, with relatively greater homogeneous pore throat structure and fewer charged particles in the double electric layer. In addition, moisture can enhance the conductivity of coal and makes it change more complexly during methane adsorption and desorption.     

阿尔金山前中、下侏罗统页岩气成藏地质条件

柴西阿尔金山前经历了早期断陷、中期拗陷和晚期隆升的多期改造叠合,其中早、侏罗世断陷期发育陆相湖盆泥页岩。地堑半地堑同沉积断裂控制沉积格局,断陷湖盆长轴为北东向,在小梁山凹陷、七个泉断鼻带和铁木里克凸起构造带沉积半深湖深湖相的泥页岩夹薄层砂岩、粉砂岩。泥页岩空间展布受沉积相控制,因此呈北东向带状连续稳定分布,由阿尔金山前七个泉-红沟子-小梁山构造带向盆地内部厚度逐渐减薄,累积厚度超过300 m,有效厚度在50～70 m,是阿尔金山前中、下侏罗统工业性页岩气聚集成藏必备的物质保障。研究证实,阿尔金山前中、下侏罗统泥页岩干酪根显微组分腐泥组、镜质组、惰性组的平均含量分别为60.7％、33.1%和6.2%,依据Tissot和Welte分类标准,有机质干酪根类型以Ⅱ型为主。 对25个野外样品进行岩石热解测试,TOC含量稳定分布在1%～4%,Ro在0.8%～2.5%,泥页岩有机质含量高,处于成熟过成熟阶段,生气条件优越。与北美和四川盆地海相页岩相比,阿尔金山前中、下侏罗统陆相泥页岩的黏土矿物含量相对较高,平均含量为52.51%;含硅质脆性矿物含量相对较低,平均含量为37.42%。泥页岩中发育大量裂缝、微裂缝、粒间孔、粒内孔和有机质孔,有利于页岩气富集和吸附。泥页岩比表面积在9.13～18.14 m2/g,平均值为13.43 m2/g;孔体积在0.026 6～0.088 7 cm3/g,平均值0.065 41cm3/g,平均孔径在25.76～72.48 nm,平均值为47.87 nm。比表面积和孔径呈负相关,孔体积和孔径呈正相关;孔径越小,泥页岩的比表面积越大。TOC和Ro与泥页岩表面积呈正相关,表明随着有机质成熟生烃形成的有机质孔对比表面有重大影响,比表面越大为页岩气吸附提供的吸附位越多,储集性能优越。上覆灰泥岩、泥灰岩和膏盐岩盖层区域广泛分布,早期浅埋-中期深埋、多次排烃-晚期抬升有利于页岩气藏的保存。综合页岩气成藏实际地质参数,优选出小梁山凹陷、七个泉断鼻带、洪水沟断鼻带和铁木里克凸起4个有利区带。     

History matching of enhanced coal bed methane laboratory core flood tests

Enhanced coalbed methane (ECBM) involves the injection of a gas, such as nitrogen or carbon dioxide, into the coal reservoir to displace the methane present. Potentially this strategy can offer greater recovery of the coal seam methane and higher rates of recovery due to pressure maintenance of the reservoir. While reservoir simulation forms an important part of the planning and assessment of ECBM, a key question is the accuracy of existing approaches to characterising and representing the gas migration process. Laboratory core flooding allows the gas displacement process to be investigated on intact coal core samples under conditions analogous to those in the reservoir. In this paper a series of enhanced drainage core floods are presented and history matched using an established coal seam gas reservoir simulator, SIMED II. The core floods were performed at two pore pressures, 2 MPa and 10 MPa, and involve either nitrogen or flue gas (90% nitrogen and 10% CO₂) flooding of core samples initially saturated with methane. At the end of the nitrogen floods the core flood was reversed by flooding with methane to investigate the potential for hysteresis in the gas displacement process. Prior to the core flooding an independent characterisation programme was performed on the core sample where the adsorption isotherm, swelling with gas adsorption, cleat compressibility and geomechanical properties were measured. This information was used in the history matching of the core floods; the properties adjusted in the history matching were related to the affect of sorption strain on coal permeability and the transfer of gas between cleat and matrix. Excellent agreement was obtained between simulated and observed gas rates, breakthrough times and total mass balances for the nitrogen/methane floods. It was found that a triple porosity model improved the agreement with observed gas migration over the standard dual porosity Warren-Root model. The Connell, Lu and Pan hydrostatic permeability model was used in the simulations and improved history match results by representing the contrast between pore and bulk sorption strains for the 10 MPa cases but this effect was not apparent for the 2 MPa cases. There were significant differences between the simulations and observations for CO₂ flow rates and mass balances for the flue gas core floods. A possible explanation for these results could be that there may be inaccuracy in the representation of mixed gas adsorption using the extended Langmuir adsorption model.     

煤层气吸附量动态变化模型研究

基于吸附势理论、气体状态方程,建立了煤储层压力与煤体吸附半径、孔隙半径与煤体吸附量、储层压力与煤体吸附量之间的关系模型,得出储层压力、吸附量、孔隙半径等多参数耦合的煤层气吸附量动态变化模型,利用潘庄区块煤体结构测试数据以及等温吸附试验结果对模型进行了验证。结果表明:潘庄区块以孔径小于7.7 nm的微孔为主,以孔径7.7 nm为临界点孔容呈先减小后增大趋势;模型计算的吸附量动态变化结果与煤体空气干燥基等温吸附变化结果在趋势上具有较高的一致性,模型的起始点为枯竭压力以及枯竭吸附量,得出潘庄区块枯竭吸附量为3 m3/t。模型不仅能够计算地层条件下不同温度和压力共同作用下煤体对甲烷气体的吸附量,且能够预测煤层气排采过程煤层气吸附量的动态变化,有助于确定煤层气排采工作制度以及提高煤层气采收率。      

阳泉新景矿高煤级煤的孔隙结构分形特征

分形理论是宏观上定量评价储层非均质性的有效手段。以阳泉新景矿高煤级煤样品压汞数据为基础,建立分形几何模型,定量描述了孔隙结构。实验结果表明:样品孔隙以纳米孔为主,孔径、比表面积及孔容也集中分布在纳米孔段。煤样孔径65 nm以上的孔隙具有显著的分形特征,分维值分布范围为2.89~2.99,体积增量呈现阶段式的变化,孔隙结构复杂;孔径65 nm以下孔隙几乎无分形特征,比表面积增量与孔径在对数坐标中呈线性关系;基于分形特征及分子运动规律,将储层孔隙以孔径65 nm为界划分为扩散孔和渗透孔2个大类6个小类。分维值与体积孔隙中值半径、总孔隙体积呈负相关,与孔径65 nm以上的孔隙体积、比表面积呈正相关,与孔隙度无相关性。分形分维值对储层结构具有较全面的表征能力,可以作为综合指标在煤储层孔隙研究中加以应用。      

煤变质作用对煤层气赋存和富集的控制--以沁水盆地为例

通过对国内外有关煤变质作用与煤层气形成、赋存和富集关系研究成果的系统总结，阐述了煤变质作用类型及煤变质作用程度与煤层气的生成、吸附量、煤储层孔隙—裂隙系统形成发育及煤层特性的相互关系，认为煤变质作用对煤层气赋存富集的影响集中体现在它对煤储层孔隙一裂隙系统形成发育过程的控制上。并以沁水盆地为例，探讨了高阶煤煤变质作用对煤层气赋存富集的控制作用，提出了对沁水盆地高阶煤煤层气勘探开发研究的几点思考和建议。