【作者】 肖鹏飞；

【导师】 孟令顺； 徐世浙；

【作者基本信息】 吉林大学 ， 固体地球物理， 2007， 博士

【摘要】 潮汐重力方法是利用时间域高精度重力勘探研究油气藏内流体(油气)储集情况的一种全新地球物理勘探方法。本文在参考俄罗斯学者提出的油气藏潮汐重力勘探思想下,把地下水的潮汐现象特征引入课题,建立了潮汐重力理论数值模型。并提出差值密度模型概念,以系统分析模型与潮汐重力数值之间的相互关系。本文在理论模型分析基础上,研究了潮汐重力的野外观测、数据处理及误差评价方法。获得实际数据并经过相应的处理后,结合巴楚地区资料,对结果曲线进行了初步的评价解释。从直观上分析得到了潮汐重力剖面,分析出地下构造内储油的可能性。文章最后提出了一种改进的高精度视密度反演方法,该方法利用徐世浙先生开发的迭代向下延拓代替原有方法中的延拓算子,使方法的精度和稳定性都得到极大的提高,满足了现阶段对高精度重力勘探的要求。利用该方法对实际潮汐重力数据反演了油气藏的差值密度分布情况。更多还原

【Abstract】 The studying on tidal gravity of oil and gas reservoir is a completely new issue inland. The river, ocean and ground water bring tidal phenomenon at the effect of universal gravitation, which brought some Russian scholars considered that the liquid in oil and gas reservoir would also arose tidal phenomenon. By some reasons, there is little research of the model mechanism, observation method, data processing, datum interpretation of the idea inland. Based on the information of oil-geology and geophysics, we put forward a numeric oil and gas reservoir model firstly, and calculate tidal gravity accordingly. Diff-density model has been advanced in the paper to better discuss the relationship which is between the tidal gravity and the numeric model. And then we analyze the course of observation and processing of the practical data. Combining with the oil-geology information of the work area, the results have been interpreted simply. At the end of this paper, an improved high precision apparent density inversion method is advanced to meet the order of work of high precision in the gravitational prospecting, the downwards continuation operator in the method was substituted by iterative-downwards continuation technique, which was exploited by Xu Shizhe. The method was used to inverse diff-density of an oil and gas reservoir.1. Anticline, which is the basic of the paper, is one of the most familiar types in the family of oil and gas reservoirs. At first we import tidal mechanism of ground water, and put forward a model, which is comparatively accorded to the fact, by analyzing the characteristics of oil and gas reservoir know from ground water(such as great deepness, good enclosing, nonuniform density in the reservoir etc)in order to study tidal gravity of oil and gas reservoir. We consider that the high density component of nonuniform liquid in the reservoir will assemble in the east effected by universal gravitation when the heavenly bodies (Sun or Moon) set up.2. We used the Parker method to forward gravity abnormity from numeric oil and gas model in this paper; with this understanding we calculate the model’s tidal gravity. And then we analyze the relationship between the model parameters and the tidal gravity. The relationship is complex correspondingly: The more model interface rise, the more maximum (minimum) of tidal gravity become bigger, also they are linear. The tidal gravity curve will smooth down with the depth increasing of model, the distance between the maximum and minimum of it will augment with the depth increasing of model, but the relationship of the anticline depth and maximum (or minimum) is not line variation yet. All of the results above obtain from model forward. To obtain better explaining purpose, we advance a diff-density model, which is the virtual source that arouses the tidal gravity on the ground.3. Before tidal gravity surveying, studying geological structure is the most important work in the schedule. Based on the known geological structure, corresponding to those models were work out to judge that whether it is possible to tidal gravity surveying in the area. Then we should design several east-west lines on the structure boundary. There are two sixty-four-dollar questions to which should be paid more attention after all the preparations done: confirm the survey manner and time. After analyzing the up and down of the heavenly bodies and the changing with time of the tide-generating force, we consider that two rules should be observed: one is that the survey time should be in the several hours fore-and-aft the time heavenly bodies up or down, another is that the survey time should be after the time when tide-generating force reach maximum (or minimum). The first rule assures that the cutting force reach maximum, and the second rule is adopted because of the lag relationship between hydrocarbon migration and tide-generating force. In order to obtain optimal datum, two manners could be adopted: fixed point manner and line manner. The former is a more accurate, but it is more expansive either. The later is a cheaper manner oppositely, and its precision improved by adopting a back and forth synchronous manner. We should adopt the later manner in practice.4. On one hand, tidal gravity belongs to high precision gravity surveying; some corrections used in high precision gravity surveying are the same with tidal gravity, such as solid tidal correction, zero correction etc. On the other hand, because we obtain the temporal change component of the gravity abnormity, some corrections in high precision, which contact with space change, are invalid, such as topographic-correction, spherical external correction, free-air correction, normal field correction etc. The course of calculating tidal gravity is lattice-valued change->tidal gravity correction->calculating the change of data from each instrument->calculating the difference of data from two time of each instrument->smoothing->averaging. And then we estimate the correction level of the results.5. Frequency apparent density inversion is a fast method, because that the core operation is an unstable downwards continuation operator, the method could not meet the order of high precision gravity measure now. An iterative-downwards continuation technique, which was exploited by Xu Shizhe, was used to substitute the downwards continuation operator in the method to improve the precision and stability of the method. We have forward two numeric models in the paper: one is a 2D density-layer model whose top plane and bottom plane are horizontal. The other is a 3D density-layer model whose top plane is up-and-down. Contacting the inverse density and the model density, we know that the precision will below 5% if the change of density continuous, even if the change of density breaks, the precision will below 10%.6. There are two sections in the tidal gravity interpretation: primary qualitative interpretation and inversion interpretation. Analyzing the four tidal gravity curves, we consider that the third of them reaction oil or gas, and the curves are high Signal-to-Noise. The No. 1 and No.4 curves lay on the west boundary of the construct, putting up positive abnormity. The No.3 curve lay on the east boundary of the construct, putting up negative abnormity. Because of some reasons, the No.2 curve could not present oil or gas. After the primary qualitative interpretation, we inverse the No.4 curve to gain the diff-density distributing of oil and gas reservoir,更多还原