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Application of iTilt-Euler deconvolution in gravity data processing and fault system interpretation |
CHEN Qing1,2( ), SUN Shuai1, DING Cheng-Yi1, HUANG Xiao-Yu1, CHEN Hao3, SHEN Peng1, LUO Gang1, WEI Yao-Cong1 |
1. Department of Earth Science, School of Petroleum and Natural Gas Engineering, Chongqing University of Science and Technology, Chongqing 401331, China 2. Chongqing Key Laboratory of Complex Oil and Gas Exploration and Development, Chongqing 401331, China 3. Chongqing 208 Geoenvironmental Engineering Survey and Design Institute Co., Ltd., Chongqing 400700, China |
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Abstract In order to improve the convergence and stability of Euler inverted results, the iTilt-Euler method, which do not depend on the structure index, is used for the calculation. Furthermore, the data points are constrained by the peak values of tilt angle of the total horizontal derivative (TAHG) to optimize the solutions. The method has been demonstrated with synthetic and real data. For synthetic data, the convergence of iTilt-Euler inversion results constrained by the TAHG method is improved effectively to detect the fault structures with deeper depth. Application to gravity data for the ANZA basin in Kenya shows that the iTilt-Euler inversion results constrained by peak values of TAHG have good continuity. The results distribute generally along NW direction, followed by NE direction, and these characteristics are consistent with the identifying features of fault in the second-order vertical derivative and total horizontal derivative anomaly maps. Furthermore, the inversion depth results show that the solutions along NW direction are extend to large scale and with higher values, which is reflected as a basement fault that controls the boundary of the main tectonic units in the study area and usually cut by the superficial faults with NE extension. It is worth noting that a large deep fault with NNE extension is developed in the southeast of the study area, which cuts the north-west direction and the north-east direction fault. It is speculated that it may control the southeast boundary of the regional tectonic unit. We can conclude that the iTilt-Euler deconvolution combined with the peak constraint method can provide a reliable method for fault system interpretation, and has good practicability.
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Received: 18 May 2021
Published: 21 December 2021
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Gravity anomaly forward modeling of conbined model (the black dotted lines represent the actual edges of the models) a—sketch representation of combined model;b—gravity anomaly of combined model;c—random noise with amplitude equal to 2% of maimum data amplitude was added to the gravity anomaly of combined model
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模型体 | 中心点坐标/km | 长度/km | 宽度/km | 顶面埋深/km | 厚度/km | 旋转角度/(°) | 1 | (-18,-34) | 52 | 20 | 1 | 2 | -45 | 2 | (-18,34) | 52 | 20 | 2 | 2 | 45 | 3 | (36,0) | 120 | 16 | 3 | 3 | 0 |
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Combined model parameters
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Results of Euler deconvolution based on the combined model without noise a—tilt angle;b—estimated results from the Tilt-Euler; c—improved tilt angle; d—estimated results from the iTilt-Euler; e—total horizontal derivative of tilt angle; f—estimated results from the iTilt-Euler under the peak constraint of total horizontal derivative of tilt angle
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Results of Euler deconvolution based on the combined model with 2% Gaussian noise a—tilt angle; b—estimated results from the Tilt-Euler; c—improved tilt angle; d—estimated results from the iTilt-Euler; e—total horizontal derivative of tilt angle; f—estimatedresults fromthe iTilt-Euler under the peak constraint of total horizontal derivative of tilt angle
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The map of the Bouguer gravity anomaly in study area
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Euler deconvolution results of gravity anomalies in the study area a—second order derivative; b—total horizontal derivative; c—estimated results from conventional Euler deconvolution(N=0.5); d—estimated results fromTilt-Euler method; e—estimated results from iTilt-Euler method; f—estimated results from iTilt-Euler method under the peak constraint
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The distribution of fault structure in study area
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