基于小波变换图像分割技术的电成像测井资料裂缝、孔洞面孔率提取方法

对于裂缝、溶蚀孔洞发育的碳酸盐岩缝洞储层,如何从测井资料中提取裂缝、溶蚀孔洞信息是评价储层有效性的关键问题.为了从电成像测井静态图像上准确地分割出清晰的裂缝、溶蚀孔洞子图像进而提取其参数信息,本文提出了一种基于小波变换模极大值图像分割技术的电成像测井资料缝洞面孔率提取方法.以钮扣电极电导率曲线为对象,先消除井壁凹凸不平导致的地层背景噪声的影响,利用小波变换模极大值图像分割方法得到包含裂缝和溶蚀孔洞目标的子图像,根据子图像提取裂缝-孔洞总面孔率、裂缝面孔率、孔洞面孔率等信息.本文利用塔里木盆地奥陶系碳酸盐岩地层的电成像测井数据提取了缝洞面孔率参数,还利用同井岩心CT扫描图像计算的平均缝洞面孔率、双侧向电阻率、常规测井资料三孔隙度模型计算的相对连通缝洞孔隙度进行了对比,并进行了试油验证.对比表明,电成像测井裂缝-孔洞总面孔率、裂缝面孔率、孔洞面孔率与岩心CT扫描图像平均缝洞面孔率、双侧向电阻率、相对连通缝洞孔隙度、试油结果均有较好的一致性.这一方面验证了采用本文方法提取的裂缝-孔洞总面孔率、裂缝面孔率、孔洞面孔率的合理性,另一方面表明所提取参数可用于指示缝洞型碳酸盐岩储层的渗透性和有效性.     

塔河油田碳酸盐岩缝洞型储层的测井识别与评价方法研究

塔河油田奥陶系以碳酸盐岩为主，油气的主要储渗空间为裂缝和溶蚀孔洞，具有很强的非均质性．本文利用常规及成像测井资料，对碳酸盐岩缝洞型储层的识别与评价方法进行研究．为了综合各种测井方法识别裂缝，建立了综合裂缝概率模型，计算综合裂缝概率指示裂缝的发育程度．利用地层微电阻率扫描成像测井资料进行裂缝和溶蚀孔洞的定性、定量解释．定量计算的裂缝参数为：裂缝密度、裂缝长度、裂缝平均宽度、平均水动力宽度、裂缝视孔隙度；定量计算的溶蚀孔洞参数有：面孔率、孔洞密度．根据缝洞型储层孔隙空间类型及其中子孔隙度、补偿密度、声波、双侧向电阻率的测井响应物性特征，建立缝洞型碳酸盐岩储层复杂孔隙介质解释模型，用于确定裂缝、溶蚀孔洞孔隙度和评价储层．     

电成像测井储层非均质性评价方法在川东北G地区FC段地层的应用

岩心、成像测井资料表明川东北G地区FC段碳酸盐岩储层溶孔、裂缝发育,非均质性较强.根据溶孔、裂缝的发育程度与分布特征,可划分为6种典型储层类型.因此,有效评价储层非均质、划分储层类型是该区油气勘探与开发工作的关键.电成像测井资料能通过定性识别孔洞与裂缝对储层非均质性进行定性评价,但是由于缺乏能综合表征溶孔、裂缝等特征的定量参数,使得电成像测井资料对储层非均质性的定量表征存在问题.为此,基于分形理论,提出一种电成像测井定量评价方法,即计算电成像测井图像的分形维数来定量描述储层非均质性.储层类型与分形维数相关分析表明,分析维数可综合表征储层溶孔、裂缝,评价储层非均质性.应用实例表明,基于电成像测井分形维数的非均质性表征与储层类型划分应用效果较好,推动了该区的油气勘探与开发工作.     

基于卷积神经网络的电成像图像空白条带填充方法

全井眼微电阻率成像(Fullbore Formation Micro Imager,FMI)技术广泛应用于强非均质性的碳酸盐岩储层测并精细解释.然而,由于各极板间间隙的影响,FMI无法测量360°全井壁地层电阻率信息,这使得FMI图像出现空白条带,严重影响了图像视觉和测井解释进程.为获取全井壁的电阻率信息,必须有效的填充空白条带.本文在探讨现有的电成像图像空白条带填充方法基础上,提出了一种基于卷积神经网络的电成像图像空白条带填充方法.与常用的Criminisi插值法对比填充效果显示:该方法完全适用于各种特征的电成像图像空白条带填充,延续了所有待填充边缘的暗色条带和亮色背景,填充结果与原始图像的像素值频率占比相关性高达0.9581.Criminisi插值法在复杂区域电成像图像的填充结果连通性较差且存在干扰区域,填充结果与原始图像的像素值频率占比相关性仅为0.5924.本文提出的方法具有处理速度快、干扰区域少、连通性强、相关性高的特点,能够满足电成像空白条带成规模填充的实际应用需求,还可为测量极板间的测量缺失带信息处理提供参考手段.     

电成像测井资料变换为孔隙度分布图像的研究

FMI成像测井给出了由电阻率像素点阵构成的图像。将此电阻率点阵通过Archie公式转换为相应的孔隙度点阵;以一个地层为一个图像窗口单元,计算每一个点阵的孔隙度对用常规测井资料确定的该地层的总孔隙度的贡献份额,并做出它沿孔隙度值的统计分布图;计算出不同m值对应的m√a值,并绘出m√a-m曲线。孔隙度分布图因储层类型的不同而不同,地层的溶蚀程度是影响石m√a-m曲线形态的重要因素。这些现象给定量评价储层的缝洞孔隙发育带来了希望。     

利用微电阻率扫描成像测井计算岩性剖面

微电阻率扫描成像测井可以提供高分辨率的岩性图像,但目前对它的应用还仅仅限于定性分析。FMI静态图像数据是一组色标值阵列,其数值反映了电阻率的高低。碎屑岩地层按其粒度大小划分为泥质、粉砂质和砂质3种岩性,将图像色调信息通过他们的电阻率定量转换为岩性信息。建立了基于图像面积分割原理将FMI图像转换为3种岩性的相对含量的方法,实现了将FMI成像测井与常规测井联合处理解释以获得高分辨率的、定量的砂泥体积含量岩性剖面及半定量的钙质胶结强度等信息。实例表明,该方法可以定量计算碎屑岩的岩性粒度剖面,进而得到测井相剖面和辅助沉积微相解释。     

花岗岩储层测井解释方法研究及应用

针对花岗岩储层非均质性特点,采用了三重孔隙结构解释模型对其进行解释评价.该模型的储集空间包括基质、裂缝和孔洞三部分,随着储集空间的变化,可将该模型转化为孔隙型储层解释模型、孔洞型储层解释模型和裂缝型储层解释模型,这样就可适应多种储层性质的解释需要.由此利用常规测井资料计算了花岗岩储层的总孔隙度、基质孔隙度、孔洞孔隙度和裂缝孔隙度,利用岩心和电成像测井对裂缝孔隙度和孔洞孔隙度的计算结果进行标定和验证,并根据这些参数划分储层类型,计算含油气饱和度,划分油气水层.含油气饱和度的计算是采用反映储层孔隙结构变化的孔隙结构指数变m值,使阿尔奇公式适用于非均质花岗岩储层含油气饱和度的计算.应用上述测井解释方法,对目标井进行精细处理解释和综合评价,取得了很好的应用效果.     

松辽盆地营城组火山岩孔隙与裂缝的成像测井研究

岩心和薄片观测与成像测井图像对比研究发现,成像测井可识别的火山岩储集空间有4类裂缝和3类孔隙,即:冷凝收缩缝、炸裂缝、构造缝、溶蚀缝和原生气孔、粒间孔、溶蚀孔.火山岩孔缝的成像响应特征主要受孔缝类型、规模、充填特征和该孔缝与其它孔缝间相互关系等四个因素控制.孔缝的全井眼地层微电阻率成像测井(FMI)响应特征分别为,裂缝...     

用核磁共振测井资料评价碳酸盐岩等复杂岩性储集层

对于碳酸盐岩等复杂岩性油气藏,由于其储集空间复杂、非均质性强等因素,用常规测井技术难以进行准确描述.核磁共振测井测量的对象是储层空间中的流体,因而可以直接用来划分储集层,而且能提供几乎不受岩性影响的孔隙度和渗透率等参数;同时,由于其T2分布表征了岩石的孔隙结构,所以可以根据T2分布形态判断有效裂缝和溶蚀孔洞.通过多口井的岩心对比和成像测井对比,研究出了一套用MRIL和CMR 的T2分布形态评价储集空间的方法;此外,在特定条件下,根据核磁计算的有效孔隙度和可动流体体积给出了一个计算含油饱和度的公式.利用这些核磁测井技术及其分析方法对车古20古潜山碳酸盐岩储集层裂缝及溶蚀孔洞发育特征进行准确描述,还计算了埕北潜山复杂复杂岩性油气藏的饱和度,对于储量计算具有重要意义.     

基于图像分割的成像测井资料目标拾取与计算

为了从FMI资料中提取定量信息,一个很重要的步骤就是要对FMI图像数据进行分割.即从实际FMI资料中分离出反映孔洞、裂缝的子图像,然后用相应的方法对分割后的子图像进行分析处理,提取相应参数.本文通过研究大量图像分割算法,认为奇异点多阈值分割算法、基于过度区的分割算法、Hopfield网络方法、基于图像间模糊散度的阈值化算法是FMI图像分割的有效方法,实现了从FMI图像中将地层中有用目标,从背景中分离出来.同时,为了得到孔洞及裂缝的形状参数,本文还研究了轮廓跟踪标识边缘的方法以及根据标识的边缘进行填充的算法.在此基础上,也研究了根据目标边缘坐标计算目标的长度、宽度、圆度、裂缝密度、孔洞密度等参数的方法.上述所有方法在SUN工作站GeoFrame平台上开发成功,通过对LX45等八口井的处理结果与岩心分析数据对比表明,效果较好.     

碳酸盐岩洞穴型储层双侧向测井数值模拟和响应特征(英文)

洞穴型碳酸盐岩地层具有显著的非均质性和测井预测难度大的特点,如何利用双侧向测井对识洞穴进行准确识别与定量评价,是当前的一个研究难点与热点。利用数值模拟方法计算电测井响应,可为洞穴识别与评价提供理论依据。本文根据双侧向测井原理,采用有限元素法,研究了球状洞穴模型的测井响应特征,并考察了不同尺寸的洞穴对电测井响应的影响;然后,系统研究了不同充填程度的洞穴模型的测井响应,得出了电阻率与充填程度之间的关系;最后,研究了洞穴中充填泥质、灰质、砾岩和砂泥岩薄互层等多种充填物的测井响应特征。研究结果对碳酸盐岩洞穴型储层的识别与评价具有较高的应用价值和研究意义。     

基于二维小波变换的FMI图象分割

为了从FMI资料中定量提取参数，一个重要的步骤是从实际FMI资料中分离出反映溶孔、溶洞、裂缝的子图像。本文给出的方法，考虑图像像元邻域的特征，应用二维小波变换求出目标与背景边缘的点集，按这个边缘点集的坐标点所对应的原图像像素灰度值的平均值作为分割阈值进行图像分割。实际资料处理表明，应用这种方法可以从实际的FMI资料中准确地分割出孔洞、裂缝的子图像并且可以按深度段连续自动处理，为后续定量计算参数奠定了良好基础。     

Quantitative geophysical pore‐type characterization and its geological implication in carbonate reservoirs

This paper discusses and addresses two questions in carbonate reservoir characterization: how to characterize pore‐type distribution quantitatively from well observations and seismic data based on geologic understanding of the reservoir and what geological implications stand behind the pore‐type distribution in carbonate reservoirs. To answer these questions, three geophysical pore types (reference pores, stiff pores and cracks) are defined to represent the average elastic effective properties of complex pore structures. The variability of elastic properties in carbonates can be quantified using a rock physics scheme associated with different volume fractions of geophysical pore types. We also explore the likely geological processes in carbonates based on the proposed rock physics template. The pore‐type inversion result from well log data fits well with the pore geometry revealed by a FMI log and core information. Furthermore, the S‐wave prediction based on the pore‐type inversion result also shows better agreement than the Greensberg‐Castagna relationship, suggesting the potential of this rock physics scheme to characterize the porosity heterogeneity in carbonate reservoirs. We also apply an inversion technique to quantitatively map the geophysical pore‐type distribution from a 2D seismic data set in a carbonate reservoir offshore Brazil. The spatial distributions of the geophysical pore type contain clues about the geological history that overprinted these rocks. Therefore, we analyse how the likely geological processes redistribute pore space of the reservoir rock from the initial depositional porosity and in turn how they impact the reservoir quality.     

基于3D-FEM的洞穴型地层双侧向测井数值模拟及响应特征研究

洞穴型碳酸盐岩储层非均质性强、电测井响应复杂、测井识别和表征难度大,利用数值模拟方法明确该类储层的电测井响应特征,可为洞穴识别与评价提供理论依据.本文基于三维有限元素法(3D-FEM),引入边界局部加密技术,实现对复杂球形洞穴的精细刻画与响应精确计算;对比分析井眼钻穿型洞穴和井旁洞穴的双侧向测井响应特征和敏感性,进而考察双侧向测井对两者敏感范围的差异.结果表明:洞穴的存在导致双侧向测井响应明显降低,受洞穴边界及仪器探测深度等影响,井眼钻穿型洞穴双侧向测井曲线复杂,而井旁洞穴曲线呈"抛物线"型;双侧向测井对井眼钻穿型洞穴的敏感性远大于对井旁洞穴的敏感性,深侧向和浅侧向测井最大可对洞穴边界距井壁0.5 m和0.3 m的井旁洞穴敏感.     

利用成像测井自动判别礁滩储层沉积相和岩性

礁滩储层是我国海相碳酸盐岩油气勘探的重要目标,也是我国油气产能的重要接替领域之一。由于礁滩储层储集空间类型多样,非均质性极强,依靠常规测井判别其沉积相和岩性非常困难。成像测井能够清晰地反映礁滩储层的结构组分和沉积构造,为沉积相和岩性的判别提供了可靠的依据。在对大量礁滩储层的成像和岩心对比观察的基础上,我们提出了9种典型的成像解释模式,建立了利用成像解释模式自动判别礁滩储层沉积相和岩性的方法并研制了相应的处理软件。该方法在塔中和川东北地区礁滩储层的实际应用中取得了良好的效果。     

Characterizing moldic and vuggy pore space in karst aquifers using borehole-wall,slabbed-core and thin-section images

Carbonate aquifers are prolific and important sources of potable water in many parts of the world owing to enlarged dissolution features that enhance porosity and interconnectivity. To better understand the variations of pore space in different karst aquifers, image and geospatial analyses are used to analyze pore attributes (i.e., pore area and perimeter) in images of vuggy aquifers. Pore geometry and 2D porosity derived from images of the moldic Castle Hayne and vuggy Biscayne aquifers are analyzed at three scales of observation: borehole televiewer, core and thin-section. The Castle Hayne and Biscayne aquifers are the foci of this study because the pore spaces that control the hydrologic properties in each of these aquifers are markedly different even though both of these carbonate reservoirs are prolific aquifers. Assessments of pore area, perimeter and shape index (a measure of shape complexity) indicate that pore geometries and pore complexities vary as a function pore type and scale of observation. For each aquifer type, the areas, perimeters and complexities of pores are higher at the larger scale of observation (e.g., borehole) than the smaller scale of observation (e.g., thin section). When the complexity of the moldic pores is compared to the complexity of vuggy pores, the results indicate that moldic pores are generally more complex than vuggy pores at the same scale of observation. Whereas estimates of 2D porosity from the borehole televiewer image of the vuggy aquifer are higher than those derived from the moldic aquifer, the range of 2D porosities is larger in core and thin section images for the vuggy aquifer than the moldic aquifer. A model for the development of pores is presented that suggests that the coalescence of small pores with simple shapes leads to the growth of larger pores with more complex shapes. The model suggests that the younger Biscayne aquifer is a more mature karst than the Castle Hayne aquifer.     

Surface and Borehole Geophysical Methods in Ground Water Investigations

Ground water flow in karst terranes generally occurs in the solution channels of carbonate aquifers. A hydrogeologist may utilize borehole geophysical methods to identify these solution channels in aquifers. Two specific methods that are applicable in karst terrains are:
1. Natural gamma ray logging
2. Borehole caliper logging.
Gamma ray logging can detect the presence of inter-bedded strata in the main limestone unit, such as shale, which emit high levels of gamma radiation. Gamma ray logging can also detect clay deposits in solution channels that may act to restrict the flow of ground water. The areal extent of these rock strata or clay-filled solution channels can be determined when gamma ray logs are conducted at several borehole locations across the site of investigation.
Borehole caliper logging can be employed to determine the presences of solution channels within the aquifer when penetrated by a borehole. In addition, since shale layers and clay filling are less resistant than the surrounding limestone, the caliper log may detect both the presence and the thickness of shale or clay layers in the aquifer.
Gamma ray logs can be used in conjunction with caliper logs to provide data on the stratigraphic location and thickness of solution channels and clay and shale layers within a limestone aquifer. This information is valuable to the hydrogeologist performing investigations at sites located in limestone terranes because ground water flow preferentially occurs along solution channels.     

碳酸盐岩孔洞型储集体地震反射特征分析

定量分析碳酸盐岩孔洞型储集体的地震响应特征,对孔洞储集体的预测和刻画研究有着重要意义.基于声波方程,在忽略多次散射的情况下,导出了深层小尺度孤立洞体的地震响应近似解析式,该解析表达式给出了孔洞尺度、充填程度与地震振幅属性之间的关系.分析表明:(1)当孔洞异常体尺度小于地震波长的1/8时,反射波振幅与异常体体积呈近似正比关系;(2)异常体横向上的尺度对反射波振幅的影响主要由菲涅耳半径控制,同时振幅随横向尺度的变化规律受到纵向尺度的影响;(3)异常体纵向上的尺度对反射振幅的影响主要表现为调谐效应,当纵向上的尺度等于调谐厚度(地震波长的1/4)时,反射振幅最强.不同尺度溶洞的数值模拟研究结果以及不同填充物的单洞物理模型试验和溶洞群物理模型试验验证了以上结论的正确性.     

Paleoflood events recorded by speleothems in caves

Speleothems are usually composed of thin layers of calcite (or aragonite). However, cemented detrital materials interlayered between laminae of speleothemic carbonate have been also observed in many caves. Flowstones comprising discontinuous carbonate layers form due to flowing water films, while flood events introduce fluviokarstic sediments in caves that, on occasion, are recorded as clayey layers inside flowstones and stalagmites. This record provides a potential means of understanding the frequency of palaeofloods using cave records. In this work, we investigate the origin of this type of detrital deposit in El Soplao Cave (Northern Spain). The age of the lowest aragonite layer of a flowstone reveals that the earliest flood period occurred before 500 ka, though most of the flowstone formed between 422 +69/‐43 ka and 400 +66/‐42 ka. This suggests that the cave was periodically affected by palaeoflood events that introduced detrital sediments from the surface as a result of occasional extreme rainfall events, especially at around 400 ka. The mineralogical data enable an evolutionary model for this flowstone to be generated based on the alternation of flood events with laminar flows and carbonate layers precipitation that can be extrapolated to other caves in which detrital sediments inside speleothems have been found. Copyright © 2014 John Wiley & Sons, Ltd.