title: A fast forward algorithm for real-time geosteering of azimuthal gamma-ray logging.
abstract: Geosteering is an effective method to increase the reservoir drilling rate in horizontal wells. Based on the features of an azimuthal gamma-ray logging tool and strata spatial location, a fast forward calculation method of azimuthal gamma-ray logging is deduced by using the natural gamma ray distribution equation in formation. The response characteristics of azimuthal gamma-ray logging while drilling in the layered formation models with different thickness and position are simulated and summarized by using the method. The result indicates that the method calculates quickly, and when the tool nears a boundary, the method can be used to identify the boundary and determine the distance from the logging tool to the boundary in time. Additionally, the formation parameters of the algorithm in the field can be determined after a simple method is proposed based on the information of an offset well. Therefore, the forward method can be used for geosteering in the field. A field example validates that the forward method can be used to determine the distance from the azimuthal gamma-ray logging tool to the boundary for geosteering in real-time.
authors.affiliation: Institute of Geophysics & Geomatics, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Qin
authors.affiliation: Institute of Geophysics & Geomatics, China University of Geosciences, 430074 Wuhan, China. Electronic address: panpinge@163.com.
authors.forename: Heping
authors.initials: H
authors.lastname: Pan
authors.affiliation: Geophysics and oil resource institute, Yangtze University, 430100 Wuhan, China. Electronic address: wang1966@yangtzeu.edu.cn.
authors.forename: Zhonghao
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Well Logging Company, Daqing Drilling and Exploration Corporation, 163412 Daqing, China.
authors.forename: Bintao
authors.initials: B
authors.lastname: Wang
authors.affiliation: Reservoirs Evaluation Center, China Petroleum Logging Co. Ltd., 710077 Xi'an, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Huang
authors.affiliation: College of Earth Science, Yangtze University, 430100 Wuhan, China.
authors.forename: Shaohua
authors.initials: S
authors.lastname: Liu
authors.affiliation: Institute of Geophysics & Geomatics, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: Institute of Geophysics & Geomatics, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Amara Konaté
authors.affiliation: Institute of Geophysics & Geomatics, China University of Geosciences, 430074 Wuhan, China.
authors.forename: Sinan
authors.initials: S
authors.lastname: Fang
keywords: Azimuthal gamma-ray logging; Fast forward calculation; Geosteering; Logging while drilling; Real-time data