gravity data interpretation using the algorithm fourth horizontal derivatives and s- curves method

نویسندگان

فائزه بهرامی

دانشجوی کارشناسی ارشد، دانشگاه آزاد اسلامی واحد همدان، ایران وحید ابراهیم زاده اردستانی

استاد، گروه فیزیک زمین، موسسه ژئوفیزیک دانشگاه تهران، ایران

چکیده

the gravity method is one of the first geophysical techniques used in oil and gas exploration. an algorithm is developed for a fast quantitative interpretation of gravity data generated by geometrically simple but also the estimated depths and other model parameters of a buried structure. following abdelrahman et al (1989). the general gravity anomaly expression produced by a sphere, an infinite long horizontal cylinder and a semi- infinite vertical cylinder can be represented by the following equation (1) where and z is the depth of the body, xi is the horizontal position coordinate, σ is the density contrast, g is the universal gravitational constant and r is the radius and q is factor related to the shape of the buried structure and is equal to 0.5,1.0,and 1.5 for the semi- infinite vertical cylinder, horizontal cylinder and the sphere respectively. consider nine observation point (xi -4s), (xi -3s), (xi -2s), (xi -s), (xi ), (xi +s), (xi +2s), (xi +3s), (xi + 4s), along the anomaly profile where s=1,2,3,m spacing units and is called the window length. using equation (1) the simplest first numerical horizontal gravity gradient (dg/dx) (2) the second horizontal derivative gravity anomaly is obtainedfrom equation (2) as (3) the third horizontal gradient is(3) (4) similarly, the fourth horizontal gradient is (4) 5) which yields; where (7) equation (5) can also be solved using a simple iteration method. equations (5) can be used to determine the depth and the shape of a buried structure using the window curves method. the validity of the method is tested on synthetic data white and without random errors. the method was applied to a gravity anomaly from the abade of iran .the results shows that the s-curves intersect each other in a narrow region where 7.220

برای دانلود باید عضویت طلایی داشته باشید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

using relation figures of horizontal and vertical gradient in quantitative interpretation of gravity data

in this paper, it has been shown that there is a special relation between horizontal and vertical gradients of gravity data and the vertical and horizontal components of magnetic data for some of 2-d sources. it has been shown that the hilbert transform is useful in calculating the vertical gradient of gravity and magnetic anomalies from the horizontal gradient for transformation of gravity and...

متن کامل

An Algorithm for Modeling and Interpretation of Seismoelectric Data

Generally speaking, seismoelectric modeling is a prospecting method based on seismic and electromagnetic waves, in which waves generated by a seismic source at the boundary of the two environments generate a relative fluid-solid motion formed as a result of antagonism between the elastic properties of the environment with the saturated fluid. This research has as its objective, a study of the e...

متن کامل

Interpretation of Gravity Data Using Wavelet Transform

Various techniques have been developed to interpret potential field data which are broadly categorized as: Forward and Inverse modeling (Blakely, 1995). Ambiguity in identification and characterization of the sources from the potential field data makes formulation of initial model a critical step while analyzing the data. The second category of techniques (inversion) shows many constraints such...

متن کامل

buckling of viscoelastic composite plates using the finite strip method

در سال های اخیر، تقاضای استفاده از تئوری خطی ویسکوالاستیسیته بیشتر شده است. با افزایش استفاده از کامپوزیت های پیشرفته در صنایع هوایی و همچنین استفاده روزافزون از مواد پلیمری، اهمیت روش های دقیق طراحی و تحلیل چنین ساختارهایی بیشتر شده است. این مواد جدید از خودشان رفتارهای مکانیکی ارائه می دهند که با تئوری های الاستیسیته و ویسکوزیته، نمی توان آن ها را توصیف کرد. این مواد، خواص ویسکوالاستیک دارند....

New Improvement in Interpretation of Gravity Gradient Tensor Data Using Eigenvalues and Invariants: An Application to Blatchford Lake, Northern Canada

Recently, interpretation of causative sources using components of the gravity gradient tensor (GGT) has had a rapid progress. Assuming N as the structural index, components of the gravity vector and gravity gradient tensor have a homogeneity degree of -N and - (N+1), respectively. In this paper, it is shown that the eigenvalues, the first and the second rotational invariants of the GGT (I1 and ...

متن کامل

Modeling and Interpretation of Simultaneous Horizontal and Vertical Polarization Transmit Radar Data. Part 2: Microphysical interpretation of S-Pol data

In this second article in a two-part work, S-Pol polarimetric data collected during TiMREX (Terraininfluenced Monsoon Rainfall Experiment) is analyzed and used to infer the storm microphysics. Both simultaneous horizontal (H) and vertical (V) transmit polarization data and fast alternating H and V transmit polarization data are used in the analysis. Dual-Doppler synthesis and sounding data char...

متن کامل

منابع من

با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

ذخیره در منابع من قبلا به منابع من ذحیره شده

{@ msg_add @}

عنوان ژورنال:

فیزیک زمین و فضا

جلد ۳۹، شماره ۴، صفحات ۷۳-۸۲

کلمات کلیدی

[ ' t h e g r a v i t y m e t h o d i s o n e o f t h e f i r s t g e o p h y s i c a l t e c h n i q u e s u s e d i n o i l a n d g a s e x p l o r a t i o n . a n a l g o r i t h m i s d e v e l o p e d f o r a f a s t q u a n t i t a t i v e i n t e r p r e t a t i o n o f g r a v i t y d a t a g e n e r a t e d b y g e o m e t r i c a l l y s i m p l e b u t a l s o t h e e s t i m a t e d d e p t h s a n d o t h e r m o d e l p a r a m e t e r s o f a b u r i e d s t r u c t u r e . r n f o l l o w i n g a b d e l r a h m a n e t a l ( 1 9 8 9 ) . t h e g e n e r a l g r a v i t y a n o m a l y e x p r e s s i o n p r o d u c e d b y a s p h e r e ' , ' a n i n f i n i t e l o n g h o r i z o n t a l c y l i n d e r a n d a s e m i ' , ' i n f i n i t e v e r t i c a l c y l i n d e r c a n b e r e p r e s e n t e d b y t h e f o l l o w i n g e q u a t i o n r n x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 ( 1 ) r n w h e r e r n x a 0 r n a n d z i s t h e d e p t h o f t h e b o d y ' , ' x i i s t h e h o r i z o n t a l p o s i t i o n c o o r d i n a t e ' , ' σ i s t h e d e n s i t y c o n t r a s t ' , ' g i s t h e u n i v e r s a l g r a v i t a t i o n a l c o n s t a n t a n d r i s t h e r a d i u s a n d q i s f a c t o r r e l a t e d t o t h e s h a p e o f t h e b u r i e d s t r u c t u r e a n d i s e q u a l t o 0 . 5 ' , ' 1 . 0 ' , ' a n d 1 . 5 f o r t h e s e m i ' , ' i n f i n i t e v e r t i c a l c y l i n d e r ' , ' h o r i z o n t a l c y l i n d e r a n d t h e s p h e r e r e s p e c t i v e l y . r n c o n s i d e r n i n e o b s e r v a t i o n p o i n t ( x i ' , ' 4 s ) ' , ' ( x i ' , ' 3 s ) ' , ' ( x i ' , ' 2 s ) ' , ' ( x i ' , ' s ) ' , ' ( x i x a 0 ) ' , ' ( x i x a 0 + s ) ' , ' ( x i x a 0 + 2 s ) ' , ' ( x i x a 0 + 3 s ) ' , ' ( x i x a 0 + 4 s ) ' , ' a l o n g t h e a n o m a l y p r o f i l e w h e r e s = 1 ' , 2 , 3 , ' m s p a c i n g u n i t s a n d i s c a l l e d t h e w i n d o w l e n g t h . r n u s i n g e q u a t i o n ( 1 ) t h e s i m p l e s t f i r s t n u m e r i c a l h o r i z o n t a l g r a v i t y g r a d i e n t ( d g / d x ) r n x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 ( 2 ) r n t h e s e c o n d h o r i z o n t a l d e r i v a t i v e g r a v i t y a n o m a l y i s o b t a i n e d f r o m e q u a t i o n ( 2 ) a s r n x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 ( 3 ) r n t h e t h i r d h o r i z o n t a l g r a d i e n t i s ( 3 ) r n x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 ( 4 ) r n s i m i l a r l y ' , ' t h e f o u r t h h o r i z o n t a l g r a d i e n t i s ( 4 ) r n 5 ) r n w h i c h y i e l d s ; r n x a 0 r n x a 0 r n w h e r e r n x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 x a 0 ( 7 ) r n e q u a t i o n ( 5 ) c a n a l s o b e s o l v e d u s i n g a s i m p l e i t e r a t i o n m e t h o d . r n e q u a t i o n s ( 5 ) c a n b e u s e d t o d e t e r m i n e t h e d e p t h a n d t h e s h a p e o f a b u r i e d s t r u c t u r e u s i n g t h e w i n d o w c u r v e s m e t h o d . t h e v a l i d i t y o f t h e m e t h o d i s t e s t e d o n s y n t h e t i c d a t a w h i t e a n d w i t h o u t r a n d o m e r r o r s . r n t h e m e t h o d w a s a p p l i e d t o a g r a v i t y a n o m a l y f r o m t h e a b a d e o f i r a n . t h e r e s u l t s s h o w s t h a t t h e s ' , ' c u r v e s i n t e r s e c t e a c h o t h e r i n a n a r r o w r e g i o n w h e r e x a 0 7 . 2 2 0 ' ]

میزبانی شده توسط پلتفرم ابری doprax.com