东营凹陷王庄--宁海地区馆陶组储层预测

在研究地质资料、测井资料的基础上,针对胜利油田王庄宁海地区馆陶组地层的变化特征规律,制定了新的储层预测技术方法.（1）精细构造技术研究：利用原始地震资料、地震道积分资料及小波分解资料,结合地质平面层序地层单元分析方法,划分出地质单元边界.（2）反演测井声波时差技术研究：利用地震小波变换属性、测井声波时差资料,采用稳健回归方法直接反演声波时差,进而计算孔隙度.该方法,可提高反演的分辨率,增加了反演结果的可靠性.结合研究区地质资料,把这种研究技术方法应用到王庄宁海地区馆陶组储层的预测研究,取得了良好的效果.     

委内瑞拉水平井资料在地质统计反演中的应用

M区块位于委内瑞拉奥里诺科重油带,其砂岩储层埋藏浅,厚度大,胶结疏松,内部泥岩隔夹层发育.该区块地震资料品质差,缺少声波测井资料,无法实现常规的地震反演,并且区块内大部分井是水平井,如何利用水平井资料难度大.针对以上问题,本文创新性地提出了综合应用直井和水平井资料进行地震反演,利用GR和电阻率曲线重构出拟声波曲线,在已有声波做速度趋势的约束下,利用倾角叠加技术对水平井进行层位标定,采用稀疏脉冲反演和地质统计模拟进行地震反演.研究表明,重构的拟声波波阻抗能够很好地区分岩性,水平井信息参与反演大大提高了储层和隔夹层的预测精度,从而实现了在缺少声波和密度资料的情况下的直井和水平井约束的地震反演.     

测井多尺度分析方法用于准层序自动划分研究

多尺度分析方法实现了信号分析的时频局部化,是测井数据时频分析与地质解释恰当的数学工具.测井资料作为地层岩性、物性的反映,其中必然蕴含了大量与沉积地层旋回变化有关的信息.以胜坨油田某井为例,采用db4最佳小波基分别对自然伽马、自然电位和声波等测井曲线进行了多尺度分析,将一维测井数据拓展为二维深度-尺度空间,提取小波变换系数的时频色谱信息和能量信息,从而确定出测井曲线识别准层序界面的最佳尺度.依据最佳尺度下的小波系数幅度振荡特征和时频色谱信息实现了对准层序界面的自动划分,与传统方法所划分的界面基本一致.这些探索为层序地层的定量划分提供了一种新的思路.     

测井约束与神经网络联合反演储层预测技术

目前地震反演方法广泛应用于储层预测,并已取得重要进展.常规反演技术以测井数据为约束,有效结合测井资料与地震资料的优势频段信息,根据反演结果波阻抗的差异区分储层.但在复杂地质条件下薄储层砂泥岩波阻抗信息较为接近,反演结果难以满足储层精细刻画要求,为此在已有波阻抗信息的基础上进行神经网络岩性反演,将波阻抗等地震属性转化为与岩性更密切的伽玛数据体,使地震反演的地质属性与测井标定的地质属性达到最大程度的相关,从而提高对簿储层的识别能力.实际资料的应用效果表明,该方法较为准确地实现了对簿储层的精细刻画,为非构造油气藏的勘探提供了重要依据.     

浊积岩储层孔隙结构分类及其测井响应特征——以鄂尔多斯盆地黄陵油田长6储层为例

为判定不同测井系列评价划分储层孔隙结构的能力强弱,进而利用测井资料划分储层孔隙结构类型,筛选储层"甜点"的目的,应用岩芯压汞、物性资料,将鄂尔多斯盆地黄陵油田长6浊积岩储层孔隙结构划分为4种类型.基于此,建立4种孔隙结构样品的岩性、孔隙度与电阻率测井系列响应交汇图,分析不同测井系列识别不同孔隙结构的能力强弱.结果表明,岩性测井系列中,针对Ⅰ、Ⅱ、Ⅲ、Ⅳ类孔隙结构储层,其对应自然伽马分布范围及变化幅度差异明显,反映其识别不同类型孔隙结构最为敏感;钍含量、钾含量及光电吸收截面指数对不同孔隙结构分辨力较强,能够识别四种孔隙结构类型;但铀含量测井对不同孔隙结构分辨力整体较差,自然电位测井识别Ⅱ、Ⅲ类孔隙结构能力较弱.孔隙度测井系列中,声波时差、密度、中子测井识别不同孔隙结构能力相当,鉴于经济实用角度评价,可加强声波时差资料的有效挖掘和应用.电阻率测井系列中,鉴于研究区长6储层致密、孔隙结构复杂及储层油水混储等因素影响,双感应和阵列感应测井难以解释不同孔隙结构储层流体性质及含油性判定.经黄陵油田145口井应用检验,自然伽马、钍含量、钾含量及声波时差等敏感测井系列不仅反映浊积岩储层岩性、物性及含油性特征,且有效提高优质储层识别精度和实用效果.     

两步相控反演火山岩及围岩储层预测——以南堡2号构造为例

南堡凹陷下第三系火山岩及与火山活动相关的碎屑岩围岩储层单井产量高、稳产能力强,具有良好的勘探开发潜力,但该类储层纵向上与火山岩多呈现上覆直接接触关系特征,厚度具有不均匀性,横向变化大．受地震资料分辨率及火山岩强反射等影响,储层预测困难,制约了该领域下步勘探开发部署．本文以南堡凹陷2号构造研究为例,首先通过测井岩石物理分析和叠前地震资料的对比分析发现,纵波阻抗是识别火山岩与围岩储层的敏感参数,入射角CRP道集近角优势叠加地震能够提升火山岩反演分辨率,基于此,第一步运用迭代低频模型确定性反演技术实现规模性火山岩单体概率预测,第二步将火山岩单体三维岩性概率作为先验信息进行相控地质统计学反演,实现火山岩与沉积岩地震反射信号分离,有效消除火山岩强反射对围岩储层预测的影响,提高了围岩薄储层预测精度;预测效果显示,本次研究建立的迭代低频确定性反演和相控地质统计学反演两步法串联工作流程兼具预测性与描述性,能够解决多期火山岩与储层互层沉积模式下隐蔽性油藏岩性识别问题,在类似资料及地质条件研究区具有借鉴应用价值．     

测井、井间地震与地面地震数据联合约束下的地质统计学随机建模方法研究

利用能够整合测井信息与井间地震信息的地质统计学随机模拟方法,结合传统的地质统计学反演思路,得到了一种能够同时整合测井、井间地震与地面地震三种先验信息的地质统计学反演与储层建模方法.由于井间射线信息、测井信息与地面地震数据在随机反演与建模过程当中都得到了尊重,因此与传统地质统计学反演仅利用了测井与地面地震数据相比,本文的地质统计学反演与建模方法更充分地利用了先验信息,有效提高了反演的精度,降低了随机建模中的多解性.基于理论数据的测试证实了上述观点.     

基于集成聚类均质度与储层地质边界度联合的测井曲线自动分层

现有的储层分层方法主要对焦于地质边缘奇异点的理解,而忽略了储层相应曲线集隐含的均质性信息.为此,开展了基于集成聚类的均质度与储层地质边界度联合测井曲线自动分层方法研究.具体地,通过利用集成聚类联合共生关联矩阵进行均质地层信息的编码,提取曲线均质度特征,并利用简单的阈值分割实现对均质地质区域的初始分割;同时,为对区域信息形成补充,提出了一种相关差特征获取曲线集各点的地质边界度.通过联合应用测井曲线集蕴含的均质区域信息与异构(奇异)地质边缘信息实现了一种灵活利用测井曲线集进行自动分层的方法.取用自然伽马、井径等7条常规测井曲线,对大庆油田陆相坳陷盆地齐家凹陷工区多口井进行实验与应用,研究结果表明,相对于传统分层方法更加准确高效,精度更高,特别在工区内的薄层和薄互层上取得较好的应用效果,不仅能高效稳定的实现单砂体级别的储层目标自动精细分层,还在一定程度上增加了对人工解译结果的补充,具有一定的实用性,可为提高测井储层解释的准确性提供较可靠的分层依据.     

叠后MCMC法岩性反演算法研究

叠后MCMC(马尔科夫链蒙特卡罗)反演是一种地质统计学反演方法,该方法能够利用地震、测井等多尺度信息综合预测储层砂体,并使反演结果忠实于地震数据.算法的重点是在贝叶斯框架下,对样本点构建能够反映空间相关性的马尔科夫链,基于蒙特卡罗迭代算法实现对复杂后验分布空间进行有效搜索.文章以一维垂向视角阐述基于MCMC算法预测储层砂体的统计学原理,将反演过程所运用的统计学符号赋予地质含义,较为形象地将随机算法的数学意义与储层反演的地质意义联系起来.并在此基础上,以朝阳沟油田扶余油层未开发区朝65井所在剖面的砂体预测为例,验证叠后MCMC法岩性反演的可靠性.     

SG地区叠前地震弹性参数交会定量解释技术预测有效储层的方法

鄂尔多斯盆地SG气田是我国典型的低孔,低渗,致密砂岩气藏的代表.该区地震勘探开发面临着两大难题:一是含气砂岩和围岩的声波阻抗存在较大范围叠置,利用声波阻抗预测储层存在明显的多解性;二是SG气田局部地区气、水关系复杂,地质上不存在统一的气、水层分界面,产水井严重影响产能建设,流体类型的识别是面临的又一难题.为了降低声波阻抗预测砂岩储层的多解性,提高有效储层预测精度,定量识别储层中流体的类型,本文提出了叠前地震弹性参数交会定量解释技术,从横波测井资料不同岩性、流体的岩石物理参数分析入手,优选了能够区分岩性和流体的最佳敏感弹性参数,制作了敏感弹性参数交会模板,通过地震叠前反演获得反映储层物性和含气性的地震弹性参数体,最后进行地震弹性参数交会定量解释预测有效储层和识别流体.勘探实例证实了该技术方法在SG地区对有效储层的预测是有效的,能够为井位优选提供可信的依据.地震弹性参数交会技术将纵向分辨率较高的测井岩石物理分析和横向分辨率较高的地震叠前反演结合在一起,使用了多个弹性参数交会,减少了以往单一弹性参数预测储层的多解性,最终获得比较可靠、更量化的反映储层物性和含气性的地震弹性参数交会体,为有效储层预测和流体识别探索出了新的途径,这一技术的应用和推广可以降低地震解释的风险,提高储层预测精度.     

SCIENCE CHINA Earth Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Distribution of throughfall and stemflow in multi‐strata agroforestry,perennial monoculture,fallow and primary forest in central Amazonia,Brazil

The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi‐strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuaçu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open‐area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuaçu monoculture and 3·1% in the fallow. With more than 20% of the open‐area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd.     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Anthropogenic Eutrophication and Red Tide Outbreak in Lacustrine Systems of the Kashmir Himalaya

Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate.