地震属性剖面在天然气水合物识别中的应用

在天然气水合物的地震资料解释过程中，常规（叠加和偏移）地震剖面上难以识别BSR、水合物成矿带以及游离气带的位置。通过多年的实践，笔者认为AVO（Amplitude Versus Offset）反演、波阻抗反演、地震瞬时属性和能量半衰时剖面，能够较好地揭示水合物的地球物理异常特征，从而给识别水合物和划分水合物的存在区域提供了有力的证据。     

同时反演泥浆与环空介质声阻抗的超声脉冲回波固井质量评价方法

固井质量评价是石油勘探开发过程中极为重要的一个环节, 对油气资源勘探开发效益以及油气资源安全生产和环境保护都有十分重要的意义.超声脉冲回波技术可以计算套管和地层间环空介质(水泥)声阻抗, 从而判断环空材料的种类以评价固井质量.传统的水泥声阻抗计算方法将井筒内的泥浆声阻抗看作是在环向上和轴向上均匀不变的值, 会导致计算的水泥声阻抗不准.为了解决这一问题, 本文利用多层介质模型的模拟数据研究了水泥声阻抗、泥浆声阻抗与脉冲回波波形在时域共振波区间内变换后的拟合直线的特征斜率与特征截距的变化规律, 提出了同时反演水泥声阻抗和泥浆声阻抗的方案.通过比较模拟数据、刻度井测量数据中的特征斜率和截距, 并构造迭代公式不断迭代水泥声阻抗、泥浆声阻抗, 形成了同时得到水泥声阻抗和泥浆声阻抗值的数据处理流程.数据处理流程经过等比刻度井数据测试, 反演结果与模型井实际情况一致, 证明了本文提出的数据处理流程的正确性.最后将本文的数据处理方法应用在某油田实测数据中, 并与传统数据处理结果进行了对比.

     

利用地球物理信息描述太古宇潜山有效储集体

基于新采集处理的高精度叠前深度偏移资料,综合地震、地质、油藏信息细化描述潜山内幕构造,有效提高潜山界面和内幕断层解析的精度和可靠性。东胜堡潜山形态表现为北西南东向展布的背斜特征,发育北东向、北西向、近东西向三组断层,其中北东向断层为主干断层,断层间切割关系比较合理。依据变质岩潜山多种类型岩性的测井响应差异和微观储集空间特征,综合3700系列测井资料定性识别6大类岩性,建立优势岩性和有利储层测井识别综合图版,进一步完善太古宇变质岩孔隙-裂缝型储层测井评价技术。通过有机结合井眼的"硬数据"与地震的"软数据",从骨架岩石特征、储层流体等方面分析影响内幕反射特征的关键因素,针对性提取38种井旁地震属性,解析地震反射特征,寻找岩性-裂缝-地震反射-产能之间的匹配关系,优选能量属性,实现内幕有利储集体预测。结果表明,有利储集体发育具有一定的分段性,在潜山顶面以下50~300 m范围内最为发育,局部表现出不规则透镜体状,是东胜堡潜山油藏开发的有利潜力区。     

Prediction of Overpressure Contributed Mainly by Structural Compression Using Impedance Inversion in Kuqa Depression, Tarim Basin

The origin and distribution of formation overpressure have effect not only on hydrocarbon migration and accumulation, but also on technique of drilling well. The study and prediction of overpressure are very important in basin analysis. At present, overpressure is mostly predicted by stack velocity.The process in calculating inter-velocity from stack velocity is very complex and inevitably leads to errors. Especially, this method is not available in the case that structural compression contribution to overpressure occurred. This paper introduces a new method, impedance inversion, to predict overpressure,and the principle is discussed. This method is used to predict the overpressure in Kuqa depression, Tarim basin and as a result, the absolute errors are less than 0.1, and relative errors are less than 5％ for predicted fluid pressure coefficients to the drill stem test (DST) measurements. It suggests that this method can be widely used to predict overpressure in foreland basins.     

地球电磁响应函数的旋转不变量特征

论述了不变量为整体或全局所共有的约束关系与旋转不变量的地球电性结构研究中的重要性,根据电磁响应函数的旋转特性,提出了几个基本的旋转不变量,也由此导出了其它一些旋转为变量,并指出这些不变量与电性分布的关系,最后,简单给出了大是电磁阻抗张量旋转不变量的Ｍｏｈｒ圆应用。     

地震勘探技术在煤系非常规气富集区预测中的应用

为了预测鄂尔多斯盆地东缘某勘探区煤系非常规气的资源富集区,采用地震勘探方法在这一新领域进行预测。首先,利用叠后波阻抗反演技术对储层进行岩性预测,通过波阻抗阈值得到样点个数,再与采样率计算出时间厚度,然后乘以岩层速度得到岩层厚度;其次,采用叠前AVO反演技术对储层进行含气性预测,经过分析含气饱和度与AVO相关属性参数之间的关系,得出与有利含气区敏感性最高的属性特征。最后,把储层厚度较厚和呈低拟泊松比属性特征的区域划定为各层含气有利区,并对勘探区下石盒子组八段、山西组和本溪组的砂岩气和页岩气进行了富集区预测,钻井验证效果较好。资源富集区的预测结果表明,地震勘探技术在该区域对煤系非常规气这一新领域的预测是可行的,此方法对其他区域煤系非常规气资源富集区的预测有借鉴意义。     

Active sensing using impedance‐based ARX models and extreme value statistics for damage detection

In this paper, the applicability of an auto‐regressive model with exogenous inputs (ARX) in the frequency domain to structural health monitoring (SHM) is established. Damage sensitive features that explicitly consider non‐linear system input/output relationships are extracted from the ARX model. Furthermore, because of the non‐Gaussian nature of the extracted features, Extreme Value Statistics (EVS) is employed to develop a robust damage classifier. EVS provides superior performance to standard statistical methods because the data of interest are in the tails (extremes) of the damage sensitive feature distribution. The suitability of the ARX model, combined with EVS, to non‐linear damage detection is demonstrated using vibration data obtained from a laboratory experiment of a three‐story building model. It is found that the vibration‐based method, while able to discern when damage is present in the structure, is unable to localize the damage to a particular joint. An impedance‐based active sensing method using piezoelectric (PZT) material as both an actuator and a sensor is then investigated as an alternative solution to the problem of damage localization. Copyright © 2005 John Wiley & Sons, Ltd.     

Transient Hydroelastic Response of VLFS by FEM with Impedance Boundary Conditions in Time Domain

A time-dependent finite element method (FEM) is developed to analyze the transient hydroelastie responses of very large floating structures (VLFS) subjected to dynamic loads. The hydrodynamic problem is formulated based on the linear theory of fluid and the structural response is analyzed based on the thin plate theory. The FEM truncates the unbounded fluid domain by introducing an artificial boundary surface, thus defining a finite computational domain. At this boundary surface an impedance boundary conditions are applied so that no wave reflections occur. In the proposed scheme, all of the procedures are processed directly in time domain, which is efficient for nonlinear analyses of structure floating on unbounded fluid. Numerical results indicate acceptable accuracy of the proposed method.     

The nature of horizontal anomalies and magnetotelluric impedance over southern India

The nature of horizontal anomalies and anomalous current systems in the region of the southern Indian peninsula is theoretically calculated with the aid of a thin sheet algorithm for northward and westward polarizations of a uniform inducing magnetic Held of period 20 min. The numerical model of the geoelectric structure is the one devised by Agarwal and Weaver (1989). The model results indicate the correspondence between the general features of the computed horizontal anomalies and the observed anomalies both at temporary array stations and at two permanent magnetic observatories (ANN and TRD). On the basis of model estimates of apparent resistivity and phase it is suggested that a one-dimensional interpretation of the sub-surface conductivity structure is valid near two of the array stations, whereas at all other coastal and inland stations, two-or three-dimensional interpretations of magnetotelluric (MT) data are required.     

Geological, geophysical and seismological criteria for local response evaluation in Bucharest urban area

Vrancea major intermediate-depth earthquakes produced extreme damage in Bucharest city, located at about 165 km epicenter distance. Our purpose is to investigate the influence of local geological conditions upon the seismic motion in Bucharest in case of large (M>7) Vrancea earthquakes. Two input data sets are used: (a) geological, geotechnical and geophysical information, including in situ measurements, and (b) acceleration recordings of Vrancea earthquakes. Local response evaluation based on first dataset is confirmed by the spectral analysis of the earthquake records. Two main features are outlined: non-stationarity of ground motion dynamic amplification from one event to other and inadequacy of limiting the investigation depth to uppermost 30 m to evaluate ground dynamic characteristics. Consequently (1) we cannot extrapolate the ground motion response determined for moderate and small earthquakes to anticipate the effects of the large Vrancea shocks and (2) the local response is controlled by the entire package of Quaternary deposits which are significantly deeper than 30 m depth beneath Bucharest Area.