深水稀井区天然气藏储盖组合定量预测方法研究:以琼东南盆地陵水凹陷为例

南海北部油气勘探表明天然气是本地区主要的资源类型。与石油相比,天然气藏的形成对盖层要求更为严格,因此开展天然气藏储盖组合研究对油气勘探具有重要意义。通过统计和调研的方法,将砂岩储层孔隙度12%定义为琼东南盆地天然气有效储层评价的下限参数,将泥岩排替压力1 MPa定义为天然气有效泥岩盖层评价的下限参数。利用测井资料开展了单井天然气藏储盖组合窗口定量预测,得出陵水凹陷W22-1井发育单个天然气藏储盖组合窗口。在此基础上,针对稀井或无井区,提出了基于地震反演速度剖面的天然气藏储盖组合定量预测方法,以琼东南盆地陵水凹陷主洼过井测线为例,开展了天然气藏储盖组合窗口地震预测,确定出该凹陷主洼发育单个天然气藏储盖组合窗口,大体上包括陵水组-莺歌海组上部多套地层,拓宽了陵水凹陷天然气勘探层系。这种方法对其它深水区和低勘探新区均有借鉴意义。     

Theoretical aspects of cap-rock and fault seals for single- and two-phase hydrocarbon columns

Cap-rock seals can be divided genetically into those that fail by capillary leakage (membrane seals) and those whose capillary entry pressures are so high that seal failure preferentially occurs by fracturing and/or wedging open of faults (hydraulic seals). A given membrane seal can trap a larger oil column than gas column at shallow depths, but below a critical depth (interval), gas is more easily sealed than oil. This critical depth increases with lower API gravity, lower oil GOR and overpressured conditions (for the gas phase). These observations arise from a series of modelling studies of membrane sealing and can be conveniently represented using pressure/ depth (P/D) profiles through sealed hydrocarbon columns. P/D diagrams have been applied to the more complex situation of the membrane sealing of a gas cap underlain by an oil rim; at seal capacity, such a two-phase column will be always greater than if only oil or gas occurs below the seal.These conclusions contrast with those for hydraulic seals where the seal capacity to oil always exceeds that for gas. Moreover, a trapped two-phase column, at hydraulic seal capacity will be less than the maximum-allowed oil-only column, but more than the maximum gas-only column. Unlike membrane seals, hydraulic seal capacity should be directly related to cap-rock thickness, in addition to the magnitude of the minimum effective stress in the sealing layer and the degree of overpressure development in the sequence as a whole.Fault-related seals are effectively analogous to membrane cap-rocks which have been tilted to the angle of the fault plane. Consequently, all of the above conclusions derived for membrane cap-rocks apply to both sealing faults sensu stricto (fault plane itself seals) and juxtaposition faults (hydrocarbon trapped laterally against a juxtaposed sealing unit). The maximum-allowed two-phase column trapped by a sealing fault is greater than for equivalent oil-only and gas-only columns, but less than that predicted for a horizontal membrane cap-rock under similar conditions. Where a two-phase column is present on both sides of a sealing fault (which is at two-phase seal capacity), a deeper oil/water contact (OWC) in one fault block is associated with a deeper gas/oil contact (GOC) compared with the adjacent fault block. If the fault seal is discontinuous in the gas leg, however, the deeper OWC is accompanied by a shallower GOC, whereas a break in the fault seal in the oil leg results in a common OWC in both fault blocks, even though separate GOC's exist. Schematic P/D profiles are provided for each of the above situations from which a series of fundamental equations governing single- and two-phase cap-rock and fault seal capacities can be derived. These relationships may have significant implications for exploration prospect appraisal exercises where more meaningful estimates of differential seal capacities can be made.The membrane sealing theory developed herein assumes that all reservoirs and seals are water-wet and no hydrodynamic flow exists. The conclusions on membrane seal capacity place constraints on the migration efficiency of gas along low-permeabiligy paths at depth where fracturing, wedging open of faults and/or diffusion process may be more important. Contrary to previous assertions, it is speculated that leakage of hydrocarbons through membrane seals occurs in distinct pulses such that the seal is at or near the theoretically calculated seal capacity, once this has been initially attained.Finally, the developed seal theory and P/D profile concepts are applied to a series of development geological problems including the effects of differential depletion, and degree of aquifer support, on sealing fault leakage, and the evaluation of barriers to vertical cross-flow using RFT profiles through depleted reservoirs. It is shown that imbibition processes and dynamic effects related to active cross-flow across such barriers often preclude quantitative analysis and solution of these problems for which simulation studies are usually required.     

Improved understanding of petroleum migration history in the Hongche fault zone,northwestern Junggar Basin (northwest China): Constrained by vein-calcite fluid inclusions and trace elements

Calcite veins and cements occur widely in Carboniferous and Permian reservoirs of the Hongche fault zone, northwestern Junggar Basin in northwest China. The calcites were investigated by fluid inclusion and trace-element analyses, providing an improved understanding of the petroleum migration history. It is indicated that the Hongche fault behaved as a migration pathway before the Early Cretaceous, allowing two oil charges to migrate into the hanging-wall, fault-core and footwall reservoirs across the fault. Since the Late Cretaceous, the Hongche fault has been sealed. As a consequence, meteoric water flowed down only into the hanging-wall and fault-core reservoirs. The meteoric-water incursion is likely an important cause for degradation of reservoir oils. In contrast, the footwall reservoirs received gas charge (the third hydrocarbon event) following the Late Cretaceous. This helps explain the distribution of petroleum across the fault. This study provides an example of how a fault may evolve as pathway and seal over time, and how reservoir diagenetic minerals can provide clues to complex petroleum migration histories.     

海底电磁探测仪器的承压密封舱

在海底进行电磁场探测必须解决仪器的承压密封问题。密封舱的体重对海上投放作业的难易程度有直接影响。为协调设备安全与海上施工效率的一致性,对所研制的承压密封舱需进行合理设计,以较小的体积和重量实现所规定的承压指标。论述了海底电磁探测仪器的承压密封舱的可靠性设计方法、舱体内部的器件安装结构及海底测量过程,压力模拟试验表明所研制的承压密封舱已达到设计要求。     

中国石油战略选区重点目标油气地质条件分析及勘探建议

首先,分析了中国石油天然气股份有限公司优选出的3个战略选区重点目标,即河套盆地、塔里木东南坳陷和羌塘盆地的油气资源条件,认为这3个目标都具有资源量大、资源丰度较高的特点,具有开展战略选区的油气资源基础.其次,论述了3个目标的储盖组合和油气显示情况,指出每个地区虽然具有不同的特点,但都具有基本的油气成藏条件和较好的勘探前景.最后,在分析3个目标存在的主要问题的基础上,提出了相应的勘探工作建议.     

20世纪南极菲尔德斯半岛毛皮海豹食谱比例变化的同位素混合模型比较分析

稳定同位素比值分析已成功用于示踪动物的食物来源研究,近年来已发展了多个同位素混合模型用于计算混合物中多来源物质的组成比例。本文以过去百年来南极菲尔德斯半岛南极毛皮海豹(Arctocephalus gazella)毛发的C、N同位素数据为基础,运用同位素混合模型中的欧几里得距离法、线性模型和贝叶斯模型进行计算、分析和比较,得到毛皮海豹食谱中南极磷虾(Euphausia superb)、南极电灯鱼(Electrona antarctica)和尼氏裸灯鱼(Gymnoscopelus nicholsi)所占比例随时间的变化趋势。各模型计算得出的结果可分为两组,分别是欧几里得距离法公式(1)和(2)的结果,表现为近百年来毛皮海豹食谱中Euphausia superb比例与其毛发稳定N同位素比值呈同步上升的趋势;第二组为欧几里得距离法公式(3)、线性模型和贝叶斯模型的结果,Euphausia superb比例与毛皮海豹毛稳定N同位素比值呈反相关关系。综合对比研究区域气候、海冰环境变化背景和已有的南极磷虾种群密度调查资料分析,第二组模型结果与实际情况较为相符,可用于讨论食物比例的时间变化趋势。近百年来,菲尔德斯半岛毛皮海豹食谱中Euphausia superb的比例显著下降,很可能是由于区域气候快速变暖和海冰的消退造成的。本文的计算结果指示西南极半岛气候变暖已显著影响到区域海洋食物链变化。     

南极海豹类生态学

描述了南极海豹的种类组成、资源量和种类状况等一般性生态学问题,着重讲述了这些海豹在研究全球变化中所起的作用等科学前沿问题;同时,就海豹研究在各国际组织中的地位阐述了意见。     

基于流固耦合的围岩后注浆对大型水封石油洞库水封性影响分析

基于多孔弹性连续介质流固耦合理论,通过合理选取围岩主要物理力学参数,建立了大型石油储备地下水封洞库全断面开挖后洞室涌水量计算模型,利用大型商业软件Comsol对黄岛国家石油储备地下水封洞库地下水渗流场和位移场进行数值模拟分析。通过不同注浆方案及不同注浆厚度情况下地下水渗流量的比较分析发现,并不是注浆圈的厚度越大对洞室渗水量的控制效果越好,而是存在相对经济合理的阈值。研究表明,最佳的注浆方式是形成全断面闭合注浆圈,最佳注浆厚度为5 m。     

From Vagrant to Resident: occurrence,residency and births of leopard seals (Hydrurga leptonyx) in New Zealand waters

ABSTRACT

In contrast to previous reports that leopard seals (Hydrurga leptonyx) are rare vagrants to New Zealand, we show that this species is a regular member of the marine fauna of this region. We present a first analysis from the New Zealand Leopard Seal Database – an extensive collation of 2,711 records of leopard seals within New Zealand between 1200 and 2018. Of these records, 51.2% (n?=?1,408) were photographic. Leopard seal sightings have increased over time and been reported in all seasons and regions of New Zealand. Sightings are predominantly of adult individuals of good or excellent body condition, which differs to previous hypotheses suggesting that leopard seals visiting New Zealand shores are primarily juvenile animals in poor health condition. A total of 176 unique individuals have been identified in the New Zealand Leopard Seal Catalogue between 2014 and 2018 and preliminary results indicate that numbers per annum have continued to increase over time. Three leopard seal births and a number of juvenile animals (34% of the NZ records) have been documented. Considering the information presented here and the current definitions in the New Zealand Threat Classification System, the threat status of leopard seals within New Zealand waters should be reclassified from Vagrant to Resident.     

澳大利亚西北陆架深水盆地油气分布规律

澳大利亚西北陆架边缘海型被动大陆边缘是目前全球深水区油气勘探的热点地区之一,近年来的一系列深水(＞500m)油气重大发现使其备受关注.澳大利亚西北陆架油气分布总体上具有显著的不均一性.平面上呈“内油外气”的分布特征,油气主要分布于富烃凹陷的凹边隆和凹中隆.远岸带深水区发育大型、超大型气田且成群成带分布,近岸带浅水区以发育中、小型油田为主,亦成群成带分布.纵向上呈“上油下气”的分布特征,天然气和凝析油主要富集于上三叠统和中-下侏罗统,石油主要富集于上侏罗统和下白垩统.