title: Rapid determination of fluid viscosity using low-field two-dimensional NMR.
abstract: The rapid prediction of fluid viscosity, especially the fluid in heavy-oil petroleum reservoirs, is of great importance for oil exploration and transportation. We suggest a new method for rapid prediction of fluid viscosity using two-dimensional (2D) NMR relaxation time distributions. DEFIR, Driven-Equilibrium Fast-Inversion Recovery, a new pulse sequence for rapid measurement of 2D relaxation times, is proposed. The 2D relation between the ratio of transverse relaxation time to longitudinal relaxation time (T1/T2) and T1 distribution of fluid are obtained by means of DEFIR with only two one-dimensional measurements. The measurement speed of DEFIR pulse sequence over 2 times as fast as that of the traditional 2D method. Using Bloembergen theory, the relation between the distributions and fluid viscosity is found. Precise method for viscosity prediction is then established. Finally, we apply this method to a down-hole NMR fluid analysis system and realized on-site and on-line prediction of viscosity for formation fluids. The results demonstrated that the new method for viscosity prediction is efficient and accurate.
authors.affiliation: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China. Electronic address: xiaolizhi@cup.edu.cn.
authors.forename: Lizhi
authors.initials: L
authors.lastname: Xiao
authors.affiliation: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
authors.forename: Weiliang
authors.initials: W
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
authors.forename: Huabing
authors.initials: H
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
authors.forename: Guangzhi
authors.initials: G
authors.lastname: Liao
authors.affiliation: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
authors.forename: Mengying
authors.initials: M
authors.lastname: Wang
authors.affiliation: Key Laboratory of Shale Gas Exploration, Ministry of Land and Resources, Chongqing Institute of Geology and Mineral Resources, Chongqing 400042, China.
authors.forename: Qingming
authors.initials: Q
authors.lastname: Xie
keywords: Crude oil; Down-hole NMR system; Fluid viscosity; Nuclear Magnetic Resonance (NMR); Two-dimensional measurements