流体动力场演化与地层流体低压成因

在松辽盆地北部东区的扶杨油层和在东南缘的十屋断陷中,发育了三个地层流体低压区,压力系数分别为0.93～1.0,0.65～0.96和0.96～0.55,都是松辽盆地主要的天然气聚集区。低压的成因机理是由于天然气的漏失减小的能量大于天然气和地下水运移补给增加的能量。在盆地北部东区的扶杨油层中,由于在天然气流动方向上储层厚度、孔渗都明显增加,流体补给增加的能量与流体散失减小的能量之间的差值在天然气的运移方向上增加,导致在天然气运移方向上压力系数减小。十屋断陷的地层压力剖面可以划分为明显的三个带,它们分别对应于三个水文地质分带,即自由交替带,交替阻滞带和交替停滞带。在自由交替带地下水供排平衡,保持正常的地层压力。在交替阻滞带和交替停滞带,由于天然气漏失损失的能量大于天然气、地下水下渗补给增加的能量,形成低压,且往下地下水的补给量迅速减小、消失,而天然气的漏失量随着埋深的增加而增加,从而使得天然气运移方向上压力系数增加。     

渤海沙垒田凸起带地层流体特征及其形成机制

盆地流体动力学研究是当前油气勘探的焦点问题,针对沙垒田凸起带流体化学特征及压力系统特征认识不清等问题,通过对沙垒田凸起及其周缘地区上百个地层流体化学数据和实测地层压力数据的系统分析,查明了研究区平面上和垂向上的地层流体特征,进而讨论了水-岩相互作用过程。研究结果表明,沙垒田凸起及其周缘地区新生界分为3个水化学作用带,包括地层水交替自由带、地层水交替阻滞带和地层水交替停滞带;地层水蒸发浓缩作用和泥岩压实排水作用在1300m以浅的交替自由带,而黏土矿物淡化作用主要是在2300m以深的地层水交替停滞带,地层压力系统也与之有一定联系;地层水矿化度呈现出随地层埋深而增大的趋势,在3000m处出现峰值;膏盐溶解是交替自由带和交替阻滞带Na⁺富集的主要因素,碳酸盐胶结物的形成、斜长石的钠长石化、钠长石的高岭石化是研究区地层水交替停滞带的主要水-岩相互作用。通过地层水化学和压力特征以及两者之间耦合关系的研究,揭示了地层流体的形成机制,可指示油气赋存的层位,对于沙垒田凸起带的油气勘探有一定借鉴作用。     

中扬子地区地层水特征及与油气保存的关系

地层水是与油气共存的地下水,它与油气的生成、运移、聚集和成藏有着十分重要的联系。在整理分析中扬子地区地层水化学资料的基础上,统计分析了各储层地层水的矿化度,计算了水化学特征系数,包括变质系数、脱硫系数等。认为中扬子区纵向上下组合地层水属于交替阻滞和交替停滞带,油气保存较好;上组合地层水大多属于自由交替带和交替阻滞带,油气保存较差。该区块中鄂西渝东区有利于油气保存,其次是江汉平原区,湘鄂西区最差,总的来说鄂西渝东是最有利的勘探区域。     

中国南方海相地层水文地质地球化学特征与油气保存条件

地下水水文地质地球化学性质与油气运移、聚集和保存存在密切关系。地下水在纵向上可划分为3个不同区带,即自由交替带、交替阻滞带和交替停止带。交替停滞带是不受地表水影响的水文地质带,有利于油气保存;自由交替带受地表水强烈影响,长期冲刷、氧化,不利于油气保存。中国南方海相地层的油气藏被构造运动改造的强度大,油气保存条件破坏严重。在详细地分析了南方几个主要油气勘探区块的地下水水文地质地球化学特点及其与油气保存条件的关系后,提出了封存大气水的概念,论述了封存大气水的形成过程及其地球化学的基本特点。不整合面附近的封存大气水应该可以认为是油气藏被破坏和保存条件差的标志。在此基础上,针对中国南方海相地层初步总结了一套比较系统的油气保存条件的水文地球化学综合判别指标体系。     

中扬子区海相地层水化学特征与油气保存

根据对中扬子区86口海相探井地层水测试成果的总结与分析,辅以盖层、水动力条件以及地表热液、热水(泉)、油气苗等流体的分布规律,系统研究了中扬子区海相地层水化学特征,认为中扬子区地层水具有垂直分带性(自由交替带、交替阻滞带、交替停滞带)和横向分区性(开启区、次封存区、封存区);阐述了地层水化学性质与油气保存的相关性,建立了中扬子区地层水化学特征与油气保存评价标准;认为中扬子区纵向上下组合地层水属交替阻滞-交替停滞带,地层开启程度低,油气保存好,上组合地层水大多属自由交替带-交替阻滞带,地层开启程度较大,油气保存逊色;横向上以石柱复向斜(石柱)、当阳复向斜中部(江陵)、沉湖-土地堂复向斜中南部(仙桃)为封存区,油气保存好.提出下组合地层以及石柱、江陵、仙桃地区是中扬子区油气勘探的重点.     

桂中坳陷及周缘海相地层油气保存条件

桂中坳陷及周缘原始生油条件优越,但经历多期构造运动,油气保存条件受到严重破坏,因此油气保存条件成为制约本区勘探决策的关键因素之一。笔者从动态演化角度对盖层、构造作用以及盆地构造演化过程中油气保存条件演变的地下水化学-动力学行为响应特征等与油气保存条件有关的几个方面进行了综合研究。桂中坳陷及周缘主要发育下、中、上泥盆统和下石炭统4套泥质岩盖层,盖层封闭性属中等-好,且坳陷东部泥质岩更发育。燕山运动与喜马拉雅运动使得桂中坳陷东部、东南部遭受强烈抬升和剥蚀,断裂发育,大气水下渗强烈且范围广、持续时间长,而对坳陷中西部影响较弱。现今坳陷中西部地层埋深小于800m的浅部地层,大气水下渗作用强烈,地层水普遍为低矿化度水,属于自由交替带;800m以下地层进入交替阻滞带,油气保存条件逐渐变好,推测交替停滞带在2000m以下。坳陷东部和东南部大气水下渗深度更大。总体上,桂中坳陷及周缘现今油气保存条件整体已受到了一定的破坏,坳陷中西部相对较好。     

渤海湾盆地廊固凹陷地层水化学纵向分带性与油气富集

渤海湾盆地廊固凹陷地层水纵向上特征复杂,地层水化学动力带的分布具有明显分带性。通过对廊固凹陷固安-旧州、柳泉-曹家务和河西务构造带上地层水化学动力带纵向特征及其与流体封存箱、油气分布关系探讨认为,地层水化学动力带主要划分为地层水交替流畅带、地层水交替阻滞带、地层水交替迟缓带及3者频繁交替带。地层水交替阻滞带与流体封存箱相吻合,该带也是油气纵向上开始富集的层段;地层水交替迟缓带一般位于流体封存箱之下,是油气富集的区域;水化学动力带频繁交替部位,是地层水矿化度低值背景上的相对高值区域,有利于油气富集。      

上扬子地块黔北坳陷及周缘水文地质-地球化学特征与油气保存

从地下水化学-动力学角度对上扬子地块黔北坳陷及周缘油气保存条件进行了研究。结果表明：黔北坳陷及周缘自震旦纪以来共经历了3次重要的水文地质旋回,即加里东期、海西期-印支期和燕山期-喜马拉雅期。黔北坳陷及周缘在加里东期和海西期-印支期是两次主要的油气成藏期,但加里东末期和燕山期-喜马拉雅期运动使得区内原已形成的油气藏几乎被破坏殆尽。多次构造运动和多期大气水下渗作用使得现今黔中隆起埋深小于2 500 m、黔北坳陷埋深小于3 000 m的地层水矿化度低,处于自由交替带且底界尚不清楚,油气保存条件较差;川南坳陷在埋深800 m的浅部地层已进入交替阻滞带,油气保存条件相对较好。     

松辽盆地十屋断陷流体-岩石相互作用

根据松辽盆地十屋断陷199个水化学分析测试数据，探讨该区地层水化学特征所反映的成岩作用过程，以揭示水化学特征的分布以及沉化过程，示路流体-岩石相互作用过程。水化学的空间分布特征受流体动力场控制；大气降水沿盆地的边缘及断层复杂的中央隆起带下渗，导致该地区盐度降低（小于4.5g/L)，向盆地中心盐度逐渐增加到7～10g/L；垂向明显分为3个带：自由交替带（0～1250m)深度为NaHCO3型流体，交替阻滞带（1250～1650m深度1为NaSO4型流体，交替停滞带（深于1650m)为CaCl2型流体，水化学的时间演化过程受流体，岩石相互作用的控制，地层水中Cl^-与HCO3^-和Na^ K^ 与Ca^2 的关系表明，地层水早期为富含HCO3的低盐度流体，含钠矿物与碳酸盐矿物的深解导致了流体中各种离子及盐度的增高，随后的纳长石化作用导致流体中富集Ca^2 而Na亏损，形成CaCl2型流体。十屋断陷水化学特征所反映的流体-岩石相互作用过程得到了其它地质观察的佐证。图6参14     

玛湖-盆1井西复合含油气系统低压特征与成因

随着油气勘探的不断深入，已在越来越多的沉积盆地中发现了低压现象，但对低压成因及其与油气运聚分布关系的研究则显得不足。玛湖-盆1井西复合含油气系统是准噶尔盆地油气分布最集中的地质单元，研究表明该系统地层中高压和低压均存在，侏罗系及以上地层中多低压，且在气藏分布区低压更突出，形成较开放性的压力系统。随着盆地的形成演化，异常地层压力亦有产生、发展和消亡的过程。玛湖-盆1井西复合含油气系统中低压的形成与油气运移过程中轻烃组分的漏失量大于油气和地下水的运移补给量，同时盆地抬升剥蚀和地温的持续下降，进而造成地层中能量亏损有关，而低压的形成时间则应该在古近纪。     

Characteristics and origin of abnormally high porosity zones in buried Paleogene clastic reservoirs in the Shengtuo area, Dongying Sag, East China

There are three abnormally high porosity zones developed in buried Paleogene nearshore subaqueous fan and sublacustrine fan clastic＇reservoirs at 2,800-3,200 m, 3,250-3,700 m and 3,900- 4,400 m, respectively, within the Shengtuo area of the Dongying Sag. Here the porosity of reservoirs buried deeper than 4,000 m can still be greater than 20%. Investigation of these three abnormally high porosity （AHP） zones in the 3rd to 4th member of the Paleogene Shahejie Formation in the Shengtuo area was carried out with utilization of core observation, thin section identification, SEM observation, image analysis, core physical property testing and other technical methods. The results show that, the AHP zones in 2,800-3,200 m and 3,250-3,700 m are visible pores primary AHP zones dominated by significant primary intergranular pores （more than 50% of the total porosity）, while secondary pores and micropores in authigenic clays may develop in some reservoirs. AHP reservoirs in the AHP zone of 3,900-4,400 m are dominated by micropores in matrix, visible pores are mainly grain dissolution pores but with low absolute content （〈 1%）, so this zone belongs to the micropores primary AHP zone. The genesis of the three AHP zones was studied to distinguish between porosity enhancement and porosity preservation. Our research shows that, in deeply buried clastic reservoirs in the Shengtuo area, mineral dissolution occurred in a relatively closed diagenetic system with high temperature and high salinity. Reservoir rocks underwent extensive feldspar dissolution, while detrital carbonate grains and carbonate cements show no evidence of extensive dissolution. Although significant feldspar dissolution pores developed, feldspar dissolution enhanced porosity only a little due to the precipitation of almost isovolumetric dissolution products in the nearby primary intergranular pores in forms of authigenic clays and quartz cements. Net enhanced porosity originating from feldspar dissolution is generally less than 0.25%. Thus, the sub     

开平—涧河地区煤层气成藏条件评价

开平－涧河地区位于河北省唐山市境内,是一个由古生界、中生界及新生界叠合而成的构造盆地。盆内古生界含煤２０余层,可采及局部可采９层,由东南向西北累积厚度逐渐增大。全区煤层有机碳含量均较高,显微组分以镜质组为主,演化程度适中,多为气煤和肥煤,具有较强的生气能力。开平向斜由东南向西北,埋深逐渐增加,煤层含气量增大,变质程度加深,吸附量也随之变大,显示该盆地西北地区具有较好的勘探前景。盆内煤层气具有较好的     

合肥盆地重磁场的解析延拓对深部构造分析的意义

深部地质情况的探查已日益为人们所重视.本文应用重磁解析延拓的成果,参考其他资料,对隐伏断裂的力学性质和纵深延展的变化进行了探讨.根据主要隐伏断裂的构造格架及其所处深度,全区可依次划分为东西向构造带,南北向构造带和北北东向郯庐断裂带.全区地质体最主要的运动方式,表现为郯庐断裂带两侧地体的左行平错扭动,东西向构造地体层在南北向构造地体层之上发生挤压推复作用     

海拉尔盆地贝尔断陷苏德尔特变质岩潜山油藏特征

海拉尔盆地贝尔断陷中的变质岩潜山油藏规模大,产量高。变质岩储层在纵向上可分为:风化破碎带,裂缝、溶孔、溶洞发育带和致密带。前两个带储层均具有裂缝和孔洞储油的特点,它们是在长期剧烈的断裂构造活动、风化、淋滤、湖水侵蚀等作用下形成的。变质岩潜山油藏可分为侵蚀残丘块状潜山油藏、反向断块块状潜山油藏、顺向断块层状不规则潜山油藏3种类型,均具有储集物性优越、油质好、产能高的特点。尤其是在反向屋脊高部位,因裂缝、溶孔、溶洞发育而使其油气富集高产。另外,这些潜山的储集特点不受埋深的控制。     

OIL POLYMERISATION AND FLUID EXPULSION FROM LOW TEMPERATURE, LOW MATURITY, OVERPRESSURED SEDIMENTS

A mechanism for hydrocarbon expulsion from low temperature (T = <20 – 150° C), low maturity (R_o=<0.6), overpressured sediments (clays, shales and enclosed sands) with active hydrocarbon concentration and/or generation is outlined. Low temperature polymerisation of light hydrocarbons (e.g. biogenic methane) is considered to be a potential source for some oils found in association with hydrates (resulting from fluidisation discharges from overpressured zones), and some oils found in shales displaying suppression of vitrinite reflectance. It is observed that low temperature polymerisation will increase the potential pressure load retained within an overpressured zone and increase the overall volume of gas/fluids discharged on pressure release.
Field observations, including measured recharge volumes and the fluid discharge volumes through a chimney from an overpressured zone, have been used to produce a triple porosity, poroelastic fluidisation expulsion model which links the discharge volume to pressure loading. The model predicts that expulsion from an active pressure mound will be cyclic and episodic.
Published geochemical results from seismic chimneys in the Lower Congo Basin have been reinterpreted using the model to demonstrate that expulsion through a chimney is episodic, and to identify overpressured zones where the dominant fluid is oil and others where the overpressured zone contains both oil and gas. It is suggested that some of the oil in these overpressured zones, currently interpreted as thermogenic, may be derived from the polymerisation of biogenic gas.     

OCEANIC METHANE HYDRATE: THE CHARACTER OF THE BLAKE RIDGE HYDRATE STABILITY ZONE, AND THE POTENTIAL FOR METHANE EXTRACTION

Oceanic methane hydrates are mineral deposits formed from a crystalline "ice" of methane and water in sea-floor sediments (buried to less than about 1 km) in water depths greater than about 500 m; economic hydrate deposits are probably restricted to water depths of between 1.5 km and 4 km. Gas hydrates increase a sediment's strength both by "freezing" the sediment and by filling the pore spaces in a manner similar to water-ice in permafrost. Concentrated hydrate deposits may be underlain by significant volumes of methane gas, and these localities are the most favourable sites for methane gas extraction operations. Seismic reflection records indicate that trapped gas may blow-out naturally, causing large-scale seafloor collapse.
In this paper, we consider both the physical properties and the structural integrity of the hydrate stability zone and the associated free gas deposits, with special reference to the Blake Ridge area, SE US offshore, in order to help establish a suitable framework for the safe, efficient, and economic recovery of methane from oceanic gas hydrates. We also consider the potential effects of the extraction of methane from hydrate (such as induced sea-floor faulting, gas venting, and gas-pocket collapse). We assess the ambient pressure effect on the production of methane by hydrate dissociation, and attempt to predict the likelihood of spontaneous gas flow in a production situation.     

东濮凹陷致密砂岩气藏特征的研究

致密砂岩气藏的储层,除岩性致密外,与渗透性储层相比较,含水饱和度对其影响更大,孔隙度与渗透率不具线性关系,封闭压力的影响远大于渗透层的影响。致密砂岩气藏的储层分类评价,主要以地下渗透率,再辅以孔隙度等参数为分类指标。其地质特征,主要表现在分布位置——沉积盆地洼陷中,或正向构造过渡的斜坡带上;圈闭类型——属岩性圈闭;并具有含气井段长、含气高度大、地层压力高异常等特点。应以大型三角洲砂体为主要勘探目标,目的层不宜超过4000m,含水饱和度为勘探中的重要参数。     

准噶尔盆地煤层气资源潜力及勘探选区

对准噶尔盆地侏罗系煤层宏观和微观特征的研究指出,盆地煤层气资源量十分丰富,但有效勘探深度范围内的资源量相对有限。优选出沙南-沙帐、梧桐窝子地区作为煤层气重点勘探区块,主要目的层系均为侏罗系西山窑组,沙南-沙帐区块目的层可加深到八道湾组。其煤层气成藏条件好,含气性较高,且埋深适中,地下构造和地表条件较简单,适宜进行勘探和开发。     

INDICATIONS FOR AN ACTIVE PETROLEUM SYSTEM IN THE LAPTEV SEA, NE SIBERIA

The shallow shelf of the Laptev Sea offshore NE Siberia is characterized by a number of rift basins more than 10 km deep. These basins are filled with sedimentary rocks of predominantly Cenozoic age and are likely sites for petroleum generation and accumulation. One objective of the BGR97 Arctic cruise to the Laptev Sea was to explore for near-surface indications of petroleum, and for this purpose water samples and near-surface sediments were collected for geochemical analysis. Gaseous hydrocarbons adsorbed in near-surface sediments include thermally-generated gas which has probably migrated upwards from deeper sedimentary strata. The hydrocarbons'compositions together with stable carbon isotope ratios indicate an origin from a marine source rock at a maturity of between 0.9 and 1.3% vitrinite reflectance. On reflection seismic profiles, zones of poor reflectivity were observed locally, also suggesting the presence of ascending gas. These geophysical indications for gas occur most frequently in the northern part of the Laptev Sea; here, seepages of thermogenic methane were detected in the sea water at two locations. Refraction seismic and multichannel data indicate the existence of sub-sea permafrost down to a depth of 500m, which probably prevents gas from escaping into the water column in most areas. The greater water depths at the northern edge of the shelf may have prevented the formation of the permafrost layer, allowing the upward migration of hydrocarbons to occur.