Sandstone surface relaxivity determined by NMR T-2 distribution and digital rock simulation for permeability evaluation

Autor(es)

Lucas-Oliveira, Everton ^[1] ; Araujo-Ferreira, Arthur G. ^[1] ; Trevizan, Willian A. ^[2] ; Coutinho dos Santos, Bernardo C. ^[2] ; Bonagamba, Tito J. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sao Carlos Inst Phys, POB 369, BR-13560970 Sao Carlos, SP - Brazil

^[2] CENPES PETROBRAS, BR-21941915 Rio De Janeiro, RJ - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING; v. 193, OCT 2020.
• Citações Web of Science: 7

Resumo

Many of the world's oil reservoirs are sandstones and some equations have been widely explored to estimate their permeability from NMR measurements, especially those based on the Schlumberger Doll Research (SDR) and Timur-Coates models. In both cases, the permeability is assumed to be related to pore sizes. Brownstein and Tarr showed that, under fast diffusion regime, the NMR transverse relaxation time is proportional to the pore size and the proportionality constant is defined by the interaction fluid/surface and represented by the surface relaxivity rho. However, although there are several methods in the literature to estimate rho, no standard methods have been established so far, to our knowledge. In this work, we estimated surface relaxivity by combining experimental and simulated NMR data using a recently developed computational method to emulate the NMR signal of fluids within Digital Rocks. In addition, we analyzed the correlation between the pore radii and the experimentally measured gas permeability. Comparing Schlumberger and Timur-Coates models for permeability prediction, we propose that the macro and microporosity intensities identified in the T-2 distribution are correlated with characteristics of the sandstone surface. Thus, sandstone surface relaxivity can be estimated using the ratio of macro and microporosity intensities from NMR and, consequently, the pore size distribution can be obtained using only T-2 distribution data. (AU)

• Processo FAPESP: 12/00380-5 - Avaliação da resistência à fadiga cíclica de sistemas rotatórios e recíprocos
• Beneficiário: Idomeo Bonetti Filho
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 12/02208-5 - Processamento da informação quântica via ressonância magnética nuclear
• Beneficiário: Tito José Bonagamba
• Modalidade de apoio: Auxílio à Pesquisa - Regular