A new permeability predictive model based on NMR data for sandstone reservoirs
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ORIGINAL PAPER
A new permeability predictive model based on NMR data for sandstone reservoirs Hongjun Xu 1,2 & Changxi Li 2 & Yiren Fan 1,3 & Falong Hu 2 & Jun Yu 2 & Jinyu Zhou 4 & Changxue Wang 2 & Chunmei Yang 2 Received: 15 February 2019 / Accepted: 22 September 2020 # Saudi Society for Geosciences 2020
Abstract Predicting permeability from nuclear magnetic resonance (NMR) logging data using SDR model and Coates model provides a quick and relatively reasonable value for reservoir permeability estimate. Critical to these two models is to find contributions of different level of pore structure to permeability, but pore structure in them is only divided into two levels. In this study, T2 distribution is divided into several segments corresponding to different level of pore structure, and every segment has its weighted characteristic value. By this way, we have considered contributions of more different level of pore structure to permeability and established a new permeability model. It has been tested in dozens of core samples. Compared with results of Coates model and SDR model, the new NMR model result is more consistent with the air permeability. So, we provide an improved permeability estimate for low permeability and tight sandstone reservoir. Keywords NMR . Permeability . T2 distribution . Pore size distribution . MICP
Introduction Permeability is one of the most important parameters in reservoir evaluation. Engineers and petrophysicists usually use it to illustrate the capacity of reservoir rocks to transmit fluids in pore bodies. It can be predicted from experimental data or well-site logs based on many different models. Philip (1994) deeply analyzed these literatures on permeability, and classified permeability models into the five major model categories, which are as follows:
Responsible Editor: Liang Xiao * Hongjun Xu [email protected] 1
School of Geosciences, China University of Petroleum, Qingdao 266580, Shandong, People’s Republic of China
2
PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083, People’s Republic of China
3
Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266580, Shandong, People’s Republic of China
4
Exploration and Development Research Institute, Changqing Oilfield Company, Xi’an 710018, Shanxi, People’s Republic of China
1 2 3 4 5
Petrophysical models Models based on grain size and mineralogy Models based on surface area and water saturation Well log models Models based on basic rock pore dimensions
Although there are five major model categories above, every category is not independent, and their physical basis is the same, the Kozeny-Carman equation. The Kozeny-Carman equation (Carman 1956; Amyx et al. 1960; Timur 1968; Hearst and Nelson 1985; Nelson 2005) based on the capillary tube model is very famous in permeability estimation, and ideas concerning the dependence of permeability on porosity, pore throat size, and surface area stem from it, which is the intrins
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