【作者】 王敬华；

【导师】 贺振华； 黄德济；

【作者基本信息】 成都理工大学 ， 地球探测与信息技术， 2010， 硕士

【摘要】 地震波衰减参数是识别油气储层的重要指标之一。对衰减参数的提取方法、影响因素分析、不同条件下的变化规律与应用条件及效果分析的深入研究与实践,从中找出对油、气储层识别和预测的最敏感参数。这些方法技术的研究成果,将对提高油气储层预测的可信度具有重要意义和实用价值。地震波的吸收衰减理论引自声波,经典的声波吸收衰减理论指出,波在介质中传播,会因质点振动的内摩擦和热传导而耗损波的能量,这种耗损就是波的吸收衰减,可用吸收系数表示,而吸收系数a(v,s,f)是传播速度、距离和频率的函数,表明对吸收系数的影响因素较多,解的唯一性相对较差。为此,经典声波理论假设波在均质介质中传播,用一个周期或一个波长的耗损来表征介质的吸收衰减特性。这一个周期或一个波长的耗损程度(一个应力循环所消耗的能量Δw与岩石应变为极大时储存的能量w之比)就定义为品质因数,它与频率和传播距离及传播速度无关,只与介质本身的物性有关,这就减少了解的多解性。除了Q和a之外还有很多地震时频属性参数也与储层结构具有不同程度的相关性。本文在消化吸收前人研究成果的基础上,通过数值模拟和批量的实测数据的计算分析,对用以求取波吸收的脉冲透射法(与谱比法等价)和地震波属性参数分析法进行了深入研究,研究了这两种方法的适用条件、影响因素和应用效果。经理论研究、实际岩样测试分析和两个地区8口井储层段子波属性提取分析,取得了批量研究成果。对这些成果进行综合提炼,得出如下几点认识:(1)波的吸收衰减参数与岩样或储层物性间的变化规律的认识:饱含水岩样Q值比饱气的大,饱油和饱水岩样Q值基本相等,表明用Q值大小很难进行识别油水。岩样Q值随温度的减小、压力的增大而增大,反之则减小。在地震波时频属性分析中,频率衰减梯度K,频带宽度中高频段宽度与低频段宽度之比ΔW、Q值等都随储层结构和含流体程度、储层有效厚度、孔隙度的变化而变化。(2)由8口井储层段井震合成记录提取的子波,对其进行属性参数提取与分析,认识到:LG三口气井的变化规律:有效储层厚度大、孔隙度高、产能高的井Q值小,ΔW值大、K值大。ZJ五口井的变化规律:含油储层的Q值小于水层,含油越多,Q值越小;含油储层的ΔW大于含水层的ΔW ,含油越多,ΔW越大,含水越多ΔW越小。(3)不同方法对均匀介质假设条件适应性的认识:脉冲透射法:在实验室,利用超声波测试的很小的岩石样品(高50mm或100mm),才有可能较为接近均质介质的假设。但在实际计算过程中,发现利用脉冲透射法在求取Q的过程中,标准的铝样与岩样振幅比的对数与自变量f有些情况下不是线性关系,表明测试系统或其他因素使测试过程不能满足均质介质的假设条件。在地震勘探中,因油气储层单层厚度很薄,地震波的分辨率与油、气储层单层厚度相比是很低的,根本无法接收到单层储层顶底的非调谐波。在一个地震反射波或子波的延续时间内,会对应多个储层和非储层互层的地层段。因此,在地震勘探的储层预测中一般不采用脉冲透射法(与谱比法等价)。时频特征参数提取分析法:地震反射波波形是对应储层段储层结构反射信息综合的具体体现,当储层段储层结构(包括流体)发生变化时,波形也会发生相应的变化,而描述波形或其频谱特征的参数也会随着变化。所以在时、频参数中寻找对储层物性,特别是流体变化的敏感参数是很重要的。还认识到只用单波求出的参数比用多波求出的参数多解性强,所以必须利用测井、钻井、开发等资料进行综合解释才可降低多解性。强迫振动法:这种方法要求的条件较高,在理论计算中多数的反射界面能够满足其要求,但实际地震资料,甚至实验室岩样测试资料都比较复杂,难以满足条件,因而用该方法求出的Q值不稳定。本文通过大量岩样测试和测井与钻井、开发资料的验证,表明指示地震波的吸收衰减参数Q、K、ΔW均可用作油气储层预测,其中最敏感参数是K。同时也证明了上述正演方法对油气储层预测亦是有效的。更多还原

【Abstract】 Seismic wave attenuation parameter is to identify an important indicator of oil and gas reservoirs. Attenuation parameters on the extraction method of influencing factors, the variation under different conditions with the application conditions and results of the in-depth research and practice, to find the oil, gas reservoirs to identify and predict the most sensitive parameters. These methods and techniques of research results, of great significance and practical value, will improve the reliability of oil and gas reservoir prediction In this paper,Attenuation of seismic wave theory cited in the classical theory of acoustic attenuation that the wave propagation in the medium, because of particle vibration of the internal friction and heat conduction and wave energy loss, such loss is the wave attenuation, the absorption coefficient can be used that the absorption coefficient a (v, s, f) is the propagation speed, distance and frequency of function, suggesting that the absorption of many factors, uniqueness of solution is relatively poor. To this end, the classical theory of acoustic wave propagation in homogeneous medium assumed to spread, with a cycle or a loss to characterize the medium wavelength absorption attenuation characteristics. This is a cycle or a wavelength of depletion levels (a stress cycle of the energy consumedΔw for the great time and rock strain energy stored in the ratio of w) is defined as the quality factor on its frequency and the dissemination and propagation distance and propagation velocity has nothing to do, only and physical properties of the media itself, which reduces the understanding of multiple solutions.Apart from Q, and a lot other than the earthquake, the frequency attribute parameters and reservoir structure with different degrees of relevance. In this paper, absorbing the results of previous studies based on numerical simulations and the calculation of quantities of measured data analysis, to obtain wave absorbing the pulse transmission method (with the spectral ratio equivalent) and the parameters of seismic attribute analysis method in-depth study of these two methods of application conditions, factors and application of results. The theoretical study, the actual testing of rock samples and two 8 wells in the reservoir region attribute extraction scripts wave analysis, the bulk of research results obtained. Fruitful results of this integrated refining, come to understand the following points:(1) wave absorption coefficient and reservoir properties of rock samples or variation between the understanding of:Q values of rock samples saturated by water saturated air than a large, full oil and saturated rock sample Q values are almost equal, with Q values that are difficult to identify the size of oil and water.rock Q value decreases with temperature, the increase of pressure, and vice versa.Time-frequency properties in the seismic wave analysis, the frequency attenuation gradient of K, the high frequency band width of the low frequency band width ratioΔw , Q value and so the structure and containing fluid with the reservoir, reservoir effective thickness, porosity and change .(2) From 8 wells in the reservoir section of synthetic seismograms calculated wavelet analysis, recognized that:Three wells in Sichuan, the variation: the effective thickness of a large reservoir, porosity, high-capacity wells is small andΔw large value, K value is large.changes in the South China Sea five well pattern: the Q value is less than oil reservoir water level, the more oil content, Q value is smaller; Oil reservoirΔw is larger than the aquiferΔw , the more oil, the greaterΔw , the more water , the lessΔw .(3) Different methods for constant velocity assumption understanding of adaptation:Pulse transmission method: In the laboratory, using ultrasonic testing of small rock samples (high 50mm or100mm), possible closer homogeneous medium assumption. But in the actual calculation, we found that the pulse transmission method to obtain Q in the process, the standard aluminum sample and the rock and the amplitude ratio of the number of independent variables in some cases f is not a linear relationship between the test system or other factors that the testing process does not meet the assumption of homogeneous media. In seismic exploration, oil and gas reservoirs due to the thickness of thin layer, the resolution of seismic and oil and gas reservoirs is very low compared to single-layer thickness, could not receive a single reservoir top and bottom of the non-harmonic tone. In a sub-wave seismic reflection or extension of time, would correspond to a number of reservoir and non-reservoir section of interbedded strata. Therefore, seismic reservoir prediction in the spectral ratio is generally not used (with the pulse transmission method equivalent).Time-frequency feature parameters extraction method: Seismic waveform is the reflection corresponding to the reservoir of reservoir structure information integrated embodiment, when the reservoir of reservoir structure (including the fluid) change, the wave will change accordingly, and describe the characteristics of the waveform or its spectrum With the change of parameters will be. Therefore, the frequency parameters to find on the reservoir properties, particularly sensitive to changes in parameters of fluid is important. Also recognized that only a single wave parameters obtained more waves than the parameters obtained multiple solutions is strong, it must make use of well logging, drilling, development of a comprehensive interpretation of such information can reduce the multiple solutions.Forced vibration method: This approach requires a high condition, the majority in the theoretical reflection interface to meet their requirements, but the actual seismic data, or laboratory test data of rock samples are complex, it’s difficult to meet the conditions, so use this method to find the Q value of instability.This had a lot of rock with the testing and logging and drilling, development of information, it proves the direct absorption of seismic wave attenuation parameter Q, K,Δw can be used for reservoir prediction, the most sensitive parameter is the K. It also shows the way forward on reservoir prediction is valid.更多还原