3D finite volume modeling of steel casings in controlled source electromagnetic surveys using the concept of edge conductivity

Hu，Ying1; Yang，Dikun2

10.1190/segam2021-3587537.1

2021

1052-3812

1949-4645

SEG Technical Program Expanded Abstracts

2021-September

533-537

High conductivity fluid injected during the fracturing provides a distinguishable physical property for the electric or electromagnetic (EM) methods to track its distribution and flow. There are also steel well casings existing at the fracturing sites and casings are also non-negligible conductivity anomalies given their conductivity many orders of magnitude higher than that of the surrounding geologic units. High-resolution monitoring of the fracturing requires quantitative understanding of the casings' EM responses, but the numerical modeling is non-trivial because of the extreme conductivity and geometry of casings. In this study, we propose a novel equivalent-property approach to rapidly simulate the EM effect of steel casings without any mesh refinement. Our approach is based on the idea of assigning edge-conductivity, an area-integrated conductivity, to mesh edges for the simulation of thin and conductive objects. Using a fine-mesh modeling, we show that the edge-conductivity is an adequate approximation at some typical frequencies. Then our modeling approach is applied to the simulation of two EM monitoring configurations - the long-offset and near-well excitations. In both configurations, the data anomaly due to the injected fluid concentrates around the well heads. This phenomena emphasizes the importance of steel casings in EM surveys, and also provides a reference for the optimal deployment of EM receivers.

第一 ; 通讯

英语

EI

20215011325267

Fracture ; Surveys

Computer Applications:723.5 ; Combinatorial Mathematics, Includes Graph Theory, Set Theory:921.4 ; Materials Science:951

2-s2.0-85121012096

Scopus

1.Department of Earth and Space Sciences,Southern University of Science and Technology,China
2.Shenzhen Key Laboratory of Deep Offshore Oil and Gas Exploration Technology,Southern University of Science and Technology,China

Hu，Ying,Yang，Dikun. 3D finite volume modeling of steel casings in controlled source electromagnetic surveys using the concept of edge conductivity[C],2021:533-537.