天然气充注导致储层增压的定量研究

超压对于油气勘探具有重要的意义。以天然气为载体的压力传递是储层超压的重要成因机制。由于地层水和原油对于天然气的溶解性和压缩性存在明显差异,造成了含水地层和油层在天然气充注过程中具有不同压力演化路径。本研究模拟计算不同原始孔隙流体的地层在受到甲烷充注时的压力演化,建立了甲烷充注量与超压的定量关系,进而探讨天然气充注增压的影响因素。结果表明：天然气充注在一定条件下可以造成地层压力的增大;不同原始孔隙流体的储层压力演化路径不同。原始孔隙流体为天然气的地层最先出现超压,但增压缓慢;含水层比含油层增压迅速,更易形成超压;同等封闭条件下,浅部地层比深部地层更易形成超压,高温盆地比低温盆地更易形成超压。     

库车坳陷东部吐格尔明地区天然气地球化学特征及油气充注史

库车坳陷东部油气地质条件复杂,天然气成因与油气充注时间存在争议,油气充注史不明,制约其油气勘探进程。利用天然气组分、碳同位素组成、流体包裹体岩相学与均一温度等分析测试数据,结合沉积埋藏史及构造演化史,研究了库车坳陷东部吐格尔明地区天然气地球化学特征、天然气成因类型及油气充注时间,分析了油气充注成藏过程。结果表明：吐格尔明地区天然气组分以甲烷为主,甲烷含量为75.56%～90.11%,干燥系数为0.79～0.93;δ¹³C₁和δ¹³C₂值为-35.73‰～-33.80‰和-26.41‰～-25.30‰,天然气成因类型属于成熟阶段的煤成气。吐格尔明地区侏罗系砂岩储层发育两类流体包裹体,分别为黄色液态烃包裹体和蓝白色荧光的气液烃包裹体、灰色的气烃包裹体,表明该区存在两期油气充注,第一期为13～7 Ma的原油充注,第二期为2.6 Ma以来的天然气充注。康村组早中期,吐格尔明地区烃源岩形成的原油充注至宽缓背斜圈闭中保存;库车组晚期,侏罗系克孜勒努尔组与阳霞组发育良好的源储组合,天然气近距离充注成藏。     

应用流体包裹体研究致密砂岩储层多期油气充注历史——以鄂尔多斯盆地镇泾地区延长组长8段砂岩为例

本文以鄂尔多斯盆地西南缘镇泾地区延长组长8段致密砂岩储层为例,利用流体包裹体岩相学、微束荧光光谱及显微测温等分析方法, 厘定油气充注期次和时间,同时结合储层成岩演化,探讨储层致密化与油气成藏过程。研究表明,储层孔隙沥青呈黄色和蓝白色荧光, 并以蓝白色为主;石油包裹体呈黄色、黄绿色及蓝白色荧光,并以后两者居多。与黄色荧光石油包裹体同期的盐水包裹体均一温度主峰为 80℃～90℃; 而与黄绿色和蓝白色荧光石油包裹体同期的盐水包裹体均一温度主峰分别为105℃～115℃和110℃～120℃。研究区储层主要经历了3期烃类充注：第一期发生在早白垩世早期（138～130Ma）,表现为少量的低熟油充注;第二期发生在早白垩世晚期（124～105Ma）,为关键成藏期,与大规模成熟油充注相关; 第三期发生在晚白垩世（85～73Ma）,古油藏发生调整,再次成藏。储层早成岩阶段以机械压实、薄膜状绿泥石、高岭石及微晶方解石胶结为主,在中高孔渗条件下发生了早期石油充注;随着继续压实,石英加大、孔隙填充绿泥石、高岭石及亮晶方解石胶结发育,储层逐渐致密化 晚期石油在低渗致密储层内的运聚成藏主要受早期烃类充注路径控制。     

An experiment to study and control the Langmuir sheath around INTERBALL-2

The satellite INTERBALL-2 has an orbit with high inclination (62.8°), covering the altitude range between a few hundred and about 20000 km. The ambient plasma conditions along this orbit are highly variable, and the interactions of this plasma with the spacecraft body as well as the photo-electron sheath around it are considered to be interesting topics for detailed studies. The electric potential of the spacecraft with respect to the ambient plasma that develops as a result of the current equilibrium reacts sensitively to variations of the boundary conditions. The measurement and eventual control of this potential is a prerequisite for accurate measurements of the thermal plasma. We describe the purpose and technical implementation of an ion emitter instrument on-board INTERBALL-2 utilising ion beams at energies of several thousand electron volts in order to reduce and stabilise the positive spacecraft potential. First results of the active ion beam experiments, and other measures taken on INTERBALL-2 to reduce charging are presented. Furthermore, the approach and initial steps of modelling efforts of the sheath in the vicinity of the INTERBALL-2 spacecraft are described together with some estimates on the resulting spacecraft potential, and effects on thermal ion measurements. It is concluded that even moderate spacecraft potentials as are commonly observed on-board INTERBALL-2 can significantly distort the measurements of ion distribution functions, especially in the presence of strongly aniso-tropic distributions.     

鄂尔多斯盆地中部延长组下组合流体包裹体特征和油气充注期次

通过对储层成岩作用、流体包裹体岩相学和孔隙沥青特征的分析,在烃包裹体期次划分的基础上,结合流体包裹体均一温度特征、烃源岩热演化史、地层埋藏史和储层成岩史,确定了鄂尔多斯盆地中部延长组下组合油气充注期次。结果表明:鄂尔多斯盆地中部延长组长8段和长9段致密储层主要发育压实、胶结、交代和溶解4种成岩作用,自生矿物主要为绿泥石、石英胶结物、长石胶结物和方解石胶结物。根据包裹体宿主矿物形成序列,识别出3期烃包裹体。第一期烃包裹体分布在石英愈合缝、石英次生加大边和充填孔隙的石英胶结物中,少数低成熟的黄色荧光烃包裹体及黑色荧光沥青包裹体代表了烃源岩进入生烃门限后排出的少量烃类充注,多数成熟度较高的蓝色、蓝白色荧光烃包裹体代表了生烃高峰期大量烃类充注;第二期烃包裹体分布在长石胶结物中,数量较少,显示蓝色和蓝白色荧光,在溶蚀孔隙周围或沿解理分布,呈短柱状,边界平直;第三期烃包裹体分布在方解石胶结物中,呈孤立或零星分布,形状近六边形;后两期烃包裹体均是在烃类充注结束后捕获孔隙中烃类形成的。研究区延长组长8段和长9段经历了晚侏罗世末期至早白垩世末期的一期烃类持续充注。     

苏里格低渗砂岩大气田天然气充注运移及成藏特征

苏里格气田位于鄂尔多斯盆地伊陕斜坡西北部,属于典型的低渗砂岩大气田.苏里格气田上古生界天然气组分和碳同位素组成特征变化较小,反映其来源和成藏过程的一致性.基于对成藏地质背景、储层物性、天然气地球化学特征、烃源岩成熟度、甲烷碳同位素动力学的综合分析,认为苏里格气田天然气主要为近源充注、近距离运移和聚集,为石炭系一二叠系煤系烃源岩生成的累积聚气.天然气运移输导体系主要包括砂体一孔隙、微裂缝及小断层等,由孔隙和裂缝构成的网状输导体系在成藏过程中起了重要作用,表现为动力圈闭成藏.苏里格气田形成过程经历了早侏罗世末期、晚侏罗世至早白垩世末期、早白垩世末期至今3个演化阶段,存在下生上储和自生自储两种成藏方式.     

白音查干银多金属矿床电性特征研究

通过在白音查干银多金属矿区开展中梯装置时间域激发极化法、偶极-偶极装置相位激电测深和可控源音频大地电磁测深的勘查试验,研究了典型热液银多金属矿床的电性特征,验证了综合电法在寻找银多金属矿床中的应用效果,对矿区外围找矿及其深部找矿具有借鉴意义。     

Effect of charging of aerosols in the lower atmosphere of Mars during the dust storm of 2001

Aerosols are very important in the Martian climate system. Aerosols get charged by the attachment of ions in the atmosphere. Charging of aerosols reduces the conductivity of the atmosphere as the very mobile ions are lost during the ion-aerosol attachment. During a dust storm the dust opacity increases and more ion-aerosol attachment process occurs and consequently conductivity reduces further. It was found that with the background aerosols (dust opacity ∼0.2), the conductivity close to the surface of Mars was reduced by a factor of 5, but during the dust storm (opacity ∼5) of 2001 the conductivity decreased by about 2 orders of magnitude.     

A modelling study of the effect of ice particle sizes and relative velocity on ice crystal/graupel collisional charge transfer

The effect of ice particle sizes and relative velocity on the sign of charge transfer during graupel/ice crystal interactions in thunderstorms is considered based on the concept of the Relative Growth Rate Hypothesis that the ice surface growing faster by water vapour diffusion charges positively. Diffusional growth rates of ice crystals and riming graupel particles are calculated for various particle sizes and velocities, and the sign of charging during crystal/graupel collisions is determined. The study reveals that larger graupel charges more negatively, while larger ice crystals, or higher relative velocity, lead to increased positive graupel charging.