改进的重力归一化总梯度法及其在胜利油区油气藏探测中的应用效果
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摘要
提出处理并解释高精度重力数据的改进的重力归一化总梯度法 ,给出三维空间的重力归一化总梯度(GH)计算式。用非均匀密度情况的二维球冠模型近似表示背斜型油气藏 ,理论模型计算结果表明 :GH 场特征取决于计算所用的谐波数 (N) ,还与计算剖面长度 (L)或计算范围有关 ,L是背斜底部深度 1 0倍时的最佳N值为 1 0 ,L仅是目标深度的 2倍时不能反映深部的低密度体 ;相邻构造引起的重力异常叠加可能使存在低密度体的“两低夹一高”标志不再存在。在济阳坳陷胜海工区、大北工区高精度重力资料的多次处理过程中 ,以地震、钻井资料为约束 ,根据GH 三维分布探测油气藏 ,获得良好效果 ,应用探测结果部署的探井发现了高产气层。胜海工区和大北工区GH 极小值与钻井资料的符合程度约达 70 % ,证实GH 极小值水平分布图可以比较可靠地显示较厚且埋藏较浅的与油气藏有关的低密度体的存在及位置 ,为地震及其它物探工作的详细部署提供依据 ,在有利的条件下还可近似估计低密度体深度范围 ,为探井设计提供依据。图 6表 1参 1 1 (王孝陵摘 )
Modified normalized full gradient of gravity anomalies constrained by seismic and drilling data for high precision gravity data processing and interpretation to detect reservoirs is presented. Some hypothetical characteristics of normalized full gradient due to an anticline saturated with oil and gas and their relationship to the geometry and physical parameters of an inhomogeneous anticline are studied. Model computation from 2D spherical cap to simulate inhomogeneous anticline with reservoir shows that the normalized full gradient depends on the number of harmonic N to a considerable extent, and is related closely to the length of gravity profile or the size of the study area. Application of the method to the Shenghai area and Dabei area of Shengli oil field in the Jiyang depression shows that the method is considerable effective in detection of reservoirs from the 3D normalized full gradient of gravity anomalies. The coincidence of minima of normalized full gradient with the drilling data is up to about 70%. This method has been used for selecting well locations and some high production gas bearing strata was discovered in a well from the selection. The modal calculation and field data processing show that the closed minima of normalized full gradient of gravity anomalies on G H map can reflect occurrence and horizontal locations of mass centers of density deficiencies or oil reservoirs, and can be used to select well locations. The closed minima on cross section map can be used to estimated the depth of mass centers of possible reservoir. Seismic and other geophysical programs can be scheduled over the anomalies of normalized full gradient calculated in prospecting areas.
Modified normalized full gradient of gravity anomalies constrained by seismic and drilling data for high precision gravity data processing and interpretation to detect reservoirs is presented. Some hypothetical characteristics of normalized full gradient due to an anticline saturated with oil and gas and their relationship to the geometry and physical parameters of an inhomogeneous anticline are studied. Model computation from 2D spherical cap to simulate inhomogeneous anticline with reservoir shows that the normalized full gradient depends on the number of harmonic N to a considerable extent, and is related closely to the length of gravity profile or the size of the study area. Application of the method to the Shenghai area and Dabei area of Shengli oil field in the Jiyang depression shows that the method is considerable effective in detection of reservoirs from the 3D normalized full gradient of gravity anomalies. The coincidence of minima of normalized full gradient with the drilling data is up to about 70%. This method has been used for selecting well locations and some high production gas bearing strata was discovered in a well from the selection. The modal calculation and field data processing show that the closed minima of normalized full gradient of gravity anomalies on G H map can reflect occurrence and horizontal locations of mass centers of density deficiencies or oil reservoirs, and can be used to select well locations. The closed minima on cross section map can be used to estimated the depth of mass centers of possible reservoir. Seismic and other geophysical programs can be scheduled over the anomalies of normalized full gradient calculated in prospecting areas.
引文
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3 БерезкинВМ .Изпользованиеполноговертикальногоградиентасилатяжёстидляопределенияглубиныдоисточникагравитационныханомалий .РазведочнаяГеофизика,1967,Вып.18.
4 БерезкинВМ .Применениегравиразветкидляпоисков месторож денийнефтиигаза.Москва:Недра,1973 .
5 别列兹金ВМ (著 ) ,陆克 ,刘文锦 ,焦恩富 (译 ) .物探数据的总梯度解释法 .北京 :地质出版社 ,1994 .
6 肖一鸣 .重力归一化总梯度法 .石油地球物理勘探 ,1981,(3 ) :4 7～5 7.
7 肖一鸣 ,张林祥 .重力归一化总梯度法在寻找油气中的应用 .石油地球物理勘探 ,1984 ,(3 ) :2 4 7～ 2 5 4 .
8 侯重初 ,施志群 .实现重磁异常规格化总梯度的傅氏积分法 .石油物探 ,1986,2 5 (3 ) :75～ 86.
9 TalwaniM ,WorzelJLandLandismanMM .Rapidgravitycalculationfortwo dimensionalbodieswithapplicationtotheMendoeinosubmarinefracturezone.J.Geophy .Res.,195 9,64 :4 9～ 5 9.
10 李小孟 ,曾华霖 .高精度重力资料在胜利油区油气藏探测中的应用 .现代地质 ,1996,10 (2 ) :2 5 0～ 2 5 9.
11 曾华霖 .重力梯度测量的现状及复兴 .物探与化探 ,1999,2 3 (1) :1～6.
2 袁业培 ,金文丽 ,金红 .高精度重力探测油气藏的可能性 .石油地球物理勘探 ,1995 ,3 0 (1) :13 9～ 14 4.
3 БерезкинВМ .Изпользованиеполноговертикальногоградиентасилатяжёстидляопределенияглубиныдоисточникагравитационныханомалий .РазведочнаяГеофизика,1967,Вып.18.
4 БерезкинВМ .Применениегравиразветкидляпоисков месторож денийнефтиигаза.Москва:Недра,1973 .
5 别列兹金ВМ (著 ) ,陆克 ,刘文锦 ,焦恩富 (译 ) .物探数据的总梯度解释法 .北京 :地质出版社 ,1994 .
6 肖一鸣 .重力归一化总梯度法 .石油地球物理勘探 ,1981,(3 ) :4 7～5 7.
7 肖一鸣 ,张林祥 .重力归一化总梯度法在寻找油气中的应用 .石油地球物理勘探 ,1984 ,(3 ) :2 4 7～ 2 5 4 .
8 侯重初 ,施志群 .实现重磁异常规格化总梯度的傅氏积分法 .石油物探 ,1986,2 5 (3 ) :75～ 86.
9 TalwaniM ,WorzelJLandLandismanMM .Rapidgravitycalculationfortwo dimensionalbodieswithapplicationtotheMendoeinosubmarinefracturezone.J.Geophy .Res.,195 9,64 :4 9～ 5 9.
10 李小孟 ,曾华霖 .高精度重力资料在胜利油区油气藏探测中的应用 .现代地质 ,1996,10 (2 ) :2 5 0～ 2 5 9.
11 曾华霖 .重力梯度测量的现状及复兴 .物探与化探 ,1999,2 3 (1) :1～6.
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