管道中天然气水合物的形成对"西气东输"的影响   总被引：1，自引：0，他引：1  

刘怀山  赵月霞 《中国海洋大学学报(自然科学版)》2003,33(2):275-280

"西气东输"是我国距离最长、口径最大的输气管线,将成为贯穿我国腹地的大动脉.管线位处北纬的寒冷环境,温度低、压力大,形成的天然气水合物对管线的堵塞及其分解引起的危害是不容忽视的问题.本文从天然气水合物的结构出发,对它产生条件和分解方法进行了研究,给出了管线中天然气水合物的抑制方法,并提出了实施过程中可能出现的环境问题.  相似文献   

Thermodynamics of gas and steam-blast eruptions   总被引：1，自引：1，他引：0  

L. G. Mastin 《Bulletin of Volcanology》1995,57(2):85-98

Eruptions of gas or steam and non-juvenile debris are common in volcanic and hydrothermal areas. From reports of non-juvenile eruptions or eruptive sequences world-wide, at least three types (or end-members) can be identified: (1) those involving rock and liquid water initially at boiling-point temperatures (boiling-point eruptions); (2) those powered by gas (primarily water vapor) at initial temperatures approaching magmatic (gas eruptions); and (3) those caused by rapid mixing of hot rock and ground- or surface water (mixing eruptions). For these eruption types, the mechanical energy released, final temperatures, liquid water contents and maximum theoretical velocities are compared by assuming that the erupting mixtures of rock and fluid thermally equilibrate, then decompress isentropically from initial, near-surface pressure (10 MPa) to atmospheric pressure. Maximum mechanical energy release is by far greatest for gas eruptions (1.3 MJ/kg of fluid-rock mixture)-about one-half that of an equivalent mass of gunpowder and one-fourth that of TNT. It is somewhat less for mixing eruptions (0.4 MJ/kg), and least for boiling-point eruptions (0.25 MJ/kg). The final water contents of crupted boiling-point mixtures are usually high, producing wet, sloppy deposits. Final erupted mixtures from gas eruptions are nearly always dry, whereas those from mixing eruptions vary from wet to dry. If all the enthalpy released in the eruptions were converted to kinetic energy, the final velocity (v _max) of these mixtures could range up to 670 m/s for boiling-point eruptions and 1820 m/s for gas eruptions (highest for high initial pressure and mass fractions of rock (m _r) near zero). For mixing eruptions, v _max ranges up to 1150 m/s. All observed eruption velocities are less than 400 m/s, largely because (1) most solid material is expelled when m _r is high, hence v _max is low; (2) observations are made of large blocks the velocities of which may be less than the average for the mixture; (3) heat from solid particles is not efficiently transferred to the fluid during the eruptions; and (4) maximum velocities are reduced by choked flow or friction in the conduit.  相似文献   

天然气水合物与全球变化研究   总被引：24，自引：4，他引：24  

陈汉宗  周蒂 《地球科学进展》1997,12(1):37-42

天然气水合物含碳量超过全球所有其他来源有机碳的总和,是地圈浅部的极重要碳库。自然界中温压条件的微小变化都会引起天然气水合物的形成或分解,从而吸收或释放甲烷,对全球碳循环和温室效应产生重要影响。天然气水合物对全球气候变化、冰期和间冰期的交替的反馈在极地和中低纬度不同,在中低纬度
也有两种相反的过程,因而对其总效应的方向和强度尚需详细研究和估计。我国许多海区有天然气水合物存在的条件,在南海已有报道;可通过地震剖面的重新判读及数值模拟估计天然气水合物的储藏量和它对海平面变化的反馈,以提供边缘海这类研究的范例。  相似文献   

Palaeoenvironments associated with caddisfly-dominated microbial-carbonate mounds from the Tipton Shale Member of the Green River Formation: Eocene Lake Gosiute     

V. LEROY LEGGITT  ROBERTO E. BIAGGI†  H. PAUL BUCHHEIM 《Sedimentology》2007,54(3):661-699

Caddisfly‐dominated microbial‐carbonate mounds and avian eggshell fragments are common in a nearshore, oolite facies of the Tipton Shale Member of the Eocene Green River Formation. The fossils occur in a 9 m thick carbonate sequence exposed on the south‐west flank of Essex Mountain, Sweetwater County, Wyoming. The eggshell was determined to be of avian origin by examination of the radial eggshell microstructure by scanning electron microscopy and polarized light microscopy. Common allochems in the limestone include: ooids, pisoids, oncoids, ostracods, gastropods, intraclasts, caddisfly larval/pupal cases, fish bones, avian bones and avian eggshell fragments. Carbonate mineralogy varies between 95% calcite and 95% dolomite. Oxygen stable isotopes vary between −10·1 and −1·3‰ (V‐PDB). Carbon and oxygen stable isotopes co‐vary. Co‐variance of oxygen and carbon stable isotopes indicates that Lake Gosiute was hydrologically closed during the formation of this oolite sequence. Positive excursions of oxygen stable isotope values are correlated with dolomite, caddisfly cases and avian eggshell fragments. These factors are probably associated with lake regression and more saline conditions. Negative excursions of oxygen stable isotope values are correlated with calcite, gastropods and intraclasts. These factors are probably associated with lake transgression and lake freshening. In the 9 m oolite sequence studied there are at least two inferred transgressions, three regressions and two storm events. The caddisfly cases and avian eggshell fragments occur in sediments formed only during low‐stands of the lake as determined by other lake level proxies (dolomites and more positive oxygen stable isotope values). As avian eggshell fragments were formed under subaerial conditions, the avian eggshell fragments independently confirm lake regression. In addition, the occurrence of avian eggshell fragments during saline phases of the lake may indicate that the birds which produced the eggshell preferred saline conditions (or that their food preferred saline lake water).  相似文献   

A theoretical model for gas adsorption-induced coal swelling   总被引：6，自引：2，他引：6  

Zhejun Pan  Luke D. Connell 《International Journal of Coal Geology》2007,69(4):243-252

Swelling and shrinkage (volumetric change) of coal during adsorption and desorption of gas is a well-known phenomenon. For coalbed methane recovery and carbon sequestration in deep, unminable coal beds, adsorption-induced coal volumetric change may cause significant reservoir permeability change. In this work, a theoretical model is derived to describe adsorption-induced coal swelling at adsorption and strain equilibrium. This model applies an energy balance approach, which assumes that the surface energy change caused by adsorption is equal to the elastic energy change of the coal solid. The elastic modulus of the coal, gas adsorption isotherm, and other measurable parameters, including coal density and porosity, are required in this model. Results from the model agree well with experimental observations of swelling. It is shown that the model is able to describe the differences in swelling behaviour with respect to gas species and at very high gas pressures, where the coal swelling ratio reaches a maximum then decreases. Furthermore, this model can be used to describe mixed-gas adsorption induced-coal swelling, and can thus be applied to CO₂-enhanced coalbed methane recovery.  相似文献   

新10号泉溶解气的变化特征及与地震的对应关系     

朱成英  李新勇  李艳萍 《内陆地震》2007,21(4):334-341

对新疆新10号泉溶解气的变化特征进行了研究。通过对13组MS≥4.6地震的分析可以看出:(1)深、浅源气体的异常形态和异常时间有所差别;(2)不同气体各有其异常特点,同源气体的同步性很好。在所统计的13组15次地震中,来自深源的CH4、He震前发生异常次数分别是11次和10次,两者同步的有9次,它们异常起始时间接近,异常形态都表现为趋势性中短期异常;来自浅源的Ar、N2映震率接近,15次地震前Ar异常有4次,N2异常为3次,两者同步性好,以高值异常为主,短临异常明显;来自深、浅源的混合气体CO2多表现为趋势性高值中短期异常,在恢复背景值的过程中发震。  相似文献   

气层在纵波和转换波谱分解中的特征     

黄中玉  王于静  孙显义  王桂水 《应用地球物理》2007,4(1)

应用拟合追逐分解MPD(Matching pursuit decomposition)法对地震数据进行谱分解能够提供更好的分辨率,在时间分辨率和频率分辨率上到达一致,避免付氏变换方法中时窗大小选择和分析时间点不准确的问题。含气地层对纵波资料产生较大的频率衰减,在储层下方可能见到低频强振幅的低频阴影现象。而转换波资料受气藏影响小,在转换波剖面中不会出现同纵波类似的低频阴影区。因此,综合两种资料在分频剖面上的表现,可以进行含气性异常的预测。对已知气藏的实际多波地震资料,进行MPD分频处理,在不同波场的分频剖面上,分析气层响应特征。  相似文献   

大牛地气田上古生界压力封存箱与储层孔隙演化   总被引：1，自引：3，他引：1  

李仲东  张哨楠  周文  惠宽洋  李良  过敏  范世龙  袁京素 《矿物岩石》2007,27(3):73-80

针对大牛地气田二叠系和石炭系泥岩发育高压封存箱,与之相对应层段的砂岩具异常高孔隙这一现象,通过对砂岩高孔隙段的发育现状、成岩作用特征和不同阶段压力封存箱形成与储层孔隙演化关系进行研究后认为:①砂岩高孔隙发育段主要分布在上、下石盒子组、山西组,层位性强,具可对比性,与相应层段泥岩"欠压实"密切相关;②该区压力封存箱开始发育于砂岩正常压实之前,压力封存箱的形成,极大限制了层内的流体流动,阻碍了砂岩的进一步压实和胶结作用,从而对下石盒子组砂岩原生孔隙的保护有积极作用;③箱内山西-太原组烃源岩有机质成烃的有机酸性水溶蚀对形成次生孔隙最为有利;④晚成岩作用期砂岩内部异常高孔隙压力抑制了成岩作用的发生,使孔隙空间得到了有效保护;⑤烃源岩生烃过程中产生的超高压,引起砂岩破裂形成裂缝,不但增加了储层渗透性,也成为天然气运移的主要通道和成藏动力;⑥由于压力封存箱的封闭,溶蚀的物质不能有效带出系统,溶蚀与充填的消长影响,在盒3、盒2段成藏过程中,气水重力分异,对上部盒3、盒2段成藏有利,但对下部盒1、山1、山2段次生孔隙保存不利,同时对其成藏也有消极影响。  相似文献   

塔里木盆地柯克亚地区天然气和凝析油的地球化学特征与成因   总被引：1，自引：0，他引：1  

唐友军  侯读杰  徐佑德 《海相油气地质》2007,12(1):33-36

柯克亚气田的油气成因复杂,对原油和可能烃源岩的分子标志物特征进行了剖析,在凝析油中检测到3-甲基甾烷,不含4-甲基甾烷,富含重排藿烷和C30-未知萜烷,表明油源主要来自于二叠系源岩。柯克亚的天然气重烃含量高,属湿气,乙烷碳同位素偏重;天然气氩同位素和成熟度特征均指示混源气特征,通过气源判识天然气主要来源于石炭系—二叠系源岩,部分来源于侏罗系源岩。天然气的乙烷δ13C值明显重于凝析油全油δ13C值,揭示柯克亚地区凝析油和天然气分属不同来源。  相似文献   

The gas reservoir response in PP- and PS-wave frequency sections     

黄中玉王于静  孙显义王桂水 《应用地球物理》2007,4(1):51-57

Spectral decomposition using the method of Matching Pursuit Decomposition （MPD） for PP- and PS-wave data has higher resolution and higher consistency over the entire time-frequency plane. The MPD algorithm avoids the problems of inaccurate analytic time point and the time window size choice that may occur during a Fourier transform. The PP-wave attenuation is greater than the PS-wave attenuation while propagating through gas reservoirs. There are some stronger amplitude low-frequency shadows on the PP-wave single frequency sections beneath gas reservoirs which are not seen on corresponding PS- wave single frequency sections. Therefore, hydrocarbons are predicted from comparing the behavior on both frequency sections. The time-frequency analysis for multi-component data is decomposed by MPD for data from northeast China containing rich gas reservoirs. The gas response character is analyzed on different wave mode single frequency sections. We describe the MPD algorithm, compare it to other spectral decomposition methods, and show some examples of detecting low-frequency shadows beneath gas reservoirs.  相似文献