【作者】 张晓峰；

【导师】 潘保芝；

【作者基本信息】 吉林大学 ， 地球探测与信息技术， 2011， 博士

【摘要】 随着世界油气勘探的发展,裂缝性储层中发现了相当一批高产油气藏,已经成为国内外油气勘探关注的焦点。在裂缝性储层油气勘探当中,裂缝参数的求取和裂缝性储层的评价至关重要,也是裂缝性油气藏勘探研究中的一个难点。裂缝的发育使得碳酸盐岩、岩浆岩、变质岩和泥岩等几类重要的岩石都能成为储层,并且在深层的低渗透砂岩储层中起着重要的作用。据不完全统计,世界上已探明总储量的一半为裂缝性油藏。裂缝不但是重要的流体渗滤通道,也是流体的储集空间。裂缝在致密的砂岩油藏中可以大大改善低孔低渗透储层的生产能力,主要作为渗流通道存在；在碳酸盐岩地层中,裂缝还控制其溶孔、溶洞的发育,同时地层中原始流体的分布状况和泥浆侵入特性也会受到影响；在火成岩地层中,裂缝是地层产能的最重要、最直接的影响因素。裂缝参数的表征是研究裂缝以及裂缝性储层的基础。裂缝参数的表征包括岩石力学的裂缝参数表征、岩心描述的裂缝参数表征、成像测井的裂缝参数表征以及实验室的裂缝参数表征。岩石力学参数的表征是从岩石力学角度出发,对裂缝的体密度、面密度以及裂缝开度等参数进行研究。岩心描述的裂缝参数表征是以岩心观测的宏观裂缝和微观裂缝为基础进行裂缝参数表征研究的。成像测井的裂缝参数表征是以成像测井识别出的裂缝为基础进行裂缝参数表征研究的。实验室裂缝表征是通过实验的方式对岩心的裂缝进行表征研究的。裂缝性储层的储集空间类型的多样性和复杂性,使得对不同岩性裂缝性储层进行统一的裂缝识别和裂缝性储层的评价很难,必须开展系统的、全面的研究工作,建立适当的计算方法和评价理论,才能使得适用于多种岩性储层的裂缝参数求取与裂缝性储层评价工作有所突破。本文分为以下几个部分：1.裂缝参数的表征本文从裂缝信息来源的不同将裂缝参数分为了三类,分别为岩心裂缝参数表征、地质露头的裂缝参数表征和成像测井的裂缝参数表征。本次研究所表征的参数有裂缝密度、裂缝长度、裂缝开度、裂缝倾角,每类表征参数所采用的计算方法各不相同。2.裂缝性储层测井响应特征及其发育程度的评价指标首先参考国内外裂缝测井响应的文献,并对储层裂缝的测井响应特征加以总结,给出了一般储层裂缝发育层段的测井响应特征,其中包括裂缝发育层段的常规测井响应特征、核磁测井响应特征、偶极横波测井响应特征以及成像测井响应特征。其次对裂缝发育程度的评价指标进行了研究,本文中裂缝发育程度的评价指标主要有裂缝发育程度分维、裂缝发育概率。由于裂缝具有统计意义上的自相似性即自仿射性。所以可以将分形用于裂缝的研究之中。由于各种测井方法对裂缝的敏感程度并非完全相同,加之某些非裂缝因素也可能引起与裂缝相同的异常响应。所以,用一、二种测井方法判别裂缝往往很难作出确切的回答,在井眼条件较差时尤其如此,而多种测井方法综合反映裂缝的可能性明显增大,用多种测井方法综合判别裂缝更趋合理。利用测井特征判断裂缝发育的概率,多种测井方法加权计算,最后构成一条裂缝概率曲线,对裂缝进行综合判。3.储层裂缝的识别裂缝的存在对储层的电性、弹性、放射性等各种物理性质均有不同程度的影响,可在测井曲线上造成异常响应,因此出现了多种常规测井资裂料识别缝的方法,如双侧向幅度差、放射性铀峰、椭圆形井眼等依据单条或两条测井曲线识别裂缝的方法。小波变换方法是一种窗口大小即窗口面积固定、但窗口的形状可变、时间窗和频率窗都可改变的时频局部化分析方法,很适于探测正常信号中突变信号的成分。并且它具有多分辨特性,也叫多尺度特性,可以由粗到精地逐步观察信号。只要适当地选择基小波,就可以使小波变换在时域和频域都具有表征信号局部特征的能力。本文首先对测井曲线进行能量分析,由于裂缝在测井上的响应一般会出现在能量高的部分,所以能量分析的目的在于找出高能量所对应的频段；然后对测井曲线进行小波变换,通过常规测井曲线的小波变换与裂缝的对比研究,寻找到适合于裂缝的基小波,再将常规测井曲线在这个基小波下的小波变换与曲线变化率法相结合建立裂缝指示曲线来识别裂缝发育段和评价裂缝密度,而电成像测井的二维小波变换可以很好的增强图像上的裂缝信息,从而可以提高电成像测井识别裂缝的准确度。最后从图像处理角度,应用蚂蚁聚类算法对其裂缝进行增强和追踪处理,效果良好。4.裂缝参数的求取裂缝参数是评价裂缝性储层的基础。在“三孔隙结构”模型的基础上应用常规测井对裂缝孔隙度、次生孔隙度、裂缝密度和裂缝面积孔隙度进行研究,并对裂缝数据进行统计处理及分析。由于小波变换的优点和曲线变化率的优点可以进行互补,所以通过常规测井曲线中的密度曲线的小波变换与其曲线变化率对储层中的裂缝密度进行了相对准确的求取；并建立了裂缝指示曲线,进而研究了指示曲线与裂缝面积孔隙度之间的关系。其次利用全井眼地层微电阻率成像测井(FMI)连续性、方位性、直观性和高分辨率的优势,将电阻率数值转化为孔隙度,可获得孔隙度频率分布曲线进而求出基质及缝洞孔隙度。5.裂缝性储层分级综合评价由于不是每口井都存在成像测井资料,所以将裂缝发育程度的综合评价分为两个部分：①存在成像测井的研究区,以成像测井为基础对裂缝性储层进行分级,然后对研究区中的其他井进行处理,进而对裂缝性储层进行分级综合评价。②在没有成像测井的研究区中,以岩心描述中存在裂缝描述的资料为基础,对岩心描述的裂缝资料进行量化处理,在对裂缝性储层进行分级,最后对研究区中的其他井进行处理,进而对研究区的裂缝性储层进行分级综合评价。6.实际应用本次研究分别在松辽盆地南部的火山岩裂缝储层和川西的致密砂岩裂缝储层中进行了应用,取得了良好的效果。更多还原

【Abstract】 With the development of the oil and gas exploration in the world, a considerable number of high production oil and gas reservoirs were found in fractured reservoir. It has become the focus of oil and gas exploration at home and abroad. Calculation of fracture parameters and the evaluation of fractured reservoirs are essential in the exploration of fractured reservoirs, and difficult in the research of fractured reservoirs.It’s possible that some kind of rocks become reservoirs because of the development of fracture such as carbonate rock, magnetic rock, metamorphic rock and mud rock, and the development of fracture plays an important role in the deep low permeability sandstone reservoir. According to incomplete statistics, half of the world’s total proven reserves is the fractured reservoir. Fracture is not only important channel of fluid infiltration, but also the reservoir space of fluid. In the tight sandstone reservoirs, fracture can improve the production capacity of low permeable reservoir greatly, and exist primarily as a flow channel. In the carbonate reservoirs, fracture control the development of corroded hollow and limestone cave. At the same time, the distribution of fluid in the original formation and the characteristics of mud invasion will be affected. In igneous rock reservoirs, fracture is the most important and direct factor of formation capacity.The characterization of fracture parameters is the basis of fracture and fractured reservoir. Characterization of fracture parameters includes the characterization of fracture parameters of rock mechanics, core description, FMI and laboratory. The characterization of fracture parameters of rock mechanics is based on the perspective of rock mechanics for studying fracture density, surface density and fracture aperture. The characterization of fracture parameters of core description is based on micro-fractures and macro-fractures of core observation for studying fracture parameters. The characterization of fracture parameters of FMI is based on FMI for studying fracture parameters. The characterization of fracture parameters of laboratory is based on experiments to studying fracture parameters.As diverse and complex types of fractured reservoir of storage space, it is difficult to unified identification of fracture and unified evaluation of fractured reservoirs of different lithologv. we must carry out systematic and comprehensive research work, establish appropriate evaluation methods and theoretical calculations can allow for multiple fractures in the reservoir rock and fractured reservoirs parameters of evaluation of a breakthrough. This article is divided into the following sections:1. The characterization of fracture parametersThe fracture parameter is divided into three types in this paper according to different sources of fracture information, and they are the characterization of fracture parameters of core, geology outcrop and FMI. Several fracture parameters are studied in the paper, such as fracture density, fracture length, fracture aperture and fracture dip.2. Response characteristics of fractured reservoir and the development degree of fracture of evaluation indicatorsFirst, logging response characteristics of fractured reservoir are summarized by refering domestic and foreign literature. Such as conventional logging response characteristics of fractured interval, nuclear magnetic logging response characteristics of fractured interval dipole shear wave logging response characteristics of fractured interval and FMI response characteristics of fractured interval.Second, evaluation indicators of fracture development are studied in this paper. Including the fractal dimension of fracture development and fracture probability, fracture has self-similarity of statistical significance, so the fractal can be used for studying the fracture.A variety of logging methods are not identical to the sensitivity of fracture, and some non-fracture factors may also cause the same abnormal response with fracture. So it is difficult to distinguish fracture using one or two methods definitely, especially poor conditions exist in the borehole. However, it is reasonable to combin a variety of logging comprehensives to distinguish the fracture. We can use logging feature to determine the probability of fracture, a variety of logging methods constitute a fracture probability curve though weighting, and comprehensively distinguish the fracture.3. Identification of reservoir fractureFracture has different effects on various physical properties of the reservoir, such as electrical reservoir, flexible, radioactive, etc., and there is abnormal response in well -logging response. Therefore, there are a variety of conventional logging methods for fracture identification, such as amplitude difference of dual later log. peak U of radioactivity, oval hole. etc.Wavelet transform is a kind of time-frequency localization analytical method with fixed size and variable shape of window, variable time window and frequency window. It is suitable for detecting abrupt signal in the normal signal. Wavelet transform has the characteristic of multiresolution (multiscale). and could observe the signal from roughly to fine. The wavelet transform will have the ability of characterizing local feature of signal in both time domain and frequency domain with choosing mother wavelet appropriatelyFirst, this paper analyzes the energy of well logging curve. In well logging the response of fracture will appear in the part of the high energy, so the purpose of energy analysis is to find frequency band which correspond to high-energy.Second, the paper does wavelet transform of logging well curve by establishing fracture indicator curve through combining the method of wavelet transform and the differential curves of convention log, such as acoustic, neutron and density, the fracture interval has been further identified more accurately. At the end of the paper, an indicator function which could be used to precisely evaluate the fracture density is thus established by linearly combining the wavelet decomposed signal and the differential curve.Finally, this paper enhances the fracture information of FMI using ant clustering algorithm, and achieve good results.4. Calculation of fracture parametersFracture parameters are the basis of evaluation of fractured reservoir. The paper is aim to study fracture porosity, secondary porosity, fracture density and area of porosity of fracture using "three-pore structure" model, and statistical processing and analyze on fracture parameter data. Advantages of wavelet transform and advantages of curve ratio can be complementary. Therefore, fracture density can be relatively accurate calculated though wavelet transform of convention well logging and curve ratio. We establish a fracture indicative curve to study the relationship between the indicative curve and area of porosity of fracture. FMI image log has the advantage of continuity, azimuthally, intuitive and high resolution, so we can convert the resistivity values into porosity frequency distribution curves and figure out the matrix and fracture-vug porosity. 5. Comprehensive evaluation of fractured reservoirsComprehensive evaluation of fractured reservoirs is divided into two parts according to the existence of imaging logging data.1)In the presence of imaging logging of study area. Comprehensive evaluation of fractured reservoirs is based on imaging logging using grading. method2)In the non-presence of imaging logging of study area. Comprehensive evaluation of fractured reservoirs is based on fracture description of core using grading method.This study was applied in volcanic reservoir of Songnan basin and tight sandstone reservoir of Sichuan basin, and achieved good results.更多还原