racture Critical Length Estimative Using Percolation Theory and Well Logging Dat

Autor(es)

Kowalski, Andre C. G. ^[1] ; Mendonca, Carlos A. ^[1] ; Ofterdinger, Ulrich S. ^[2] ; Rocha, Humberto R. ^[3]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Geophys, Rua Matao 1226, BR-05508090 Sao Paulo - Brazil

^[2] Queens Univ Belfast, Sch Nat & Built Environm, David Keir Bldg, Stranmillis Rd, Belfast BT9 5AG, Antrim - North Ireland

^[3] Univ Sao Paulo, Dept Atmospher Sci, Rua Matao 1226, BR-05508090 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ENVIRONMENTAL AND ENGINEERING GEOPHYSICS; v. 26, n. 4, p. 279-286, DEC 2021.
• Citações Web of Science: 0

Resumo

Groundwater transport in crystalline rocks follows pathways along fractured zones because of low primary porosity and permeability in such formations. Fractured systems encompass an imbricated set of joints and fractures with different lengths, apertures and orientations resulting in complex permeable systems with heterogeneous groundwater transport properties. Geophysical well logging has proved effectiveness in detecting depth levels with denser fracture distributions as well as the apparent aperture of fractures contributing to groundwater flow. In many cases, the extension spanned by a fracture network cannot be directly inferred because it may extend beyond the radius of investigation of common well logging probes, thus preventing quantitative estimation of critical length for lateral extension a connected fractured system may have. Here we apply a percolation theory model to estimate the critical length as inferred from the linear density of fracture distribution observed at the borehole wall with an optical imaging probe. Our results are analyzed with electrical well logging data (normal resistivity and single-point resistance) cross borehole slug tests using a set of three boreholes. A critical length of 3.9 m was inferred with a percolation model which revealed consistency with the cross borehole slug tests from two wells situated 10 m and 30 m in the vicinity of the monitored borehole. Our results suggest the utility of inferring critical percolation lengths from fracture parameters obtained using standard well logging imaging techniques with potential applications to evaluate groundwater resources, characterize contaminated sites and provide geotechnical information for works in fractured formations. (AU)

• Processo FAPESP: 18/22533-4 - Integração de técnicas geofísicas de time-lapse inovadoras no nexo água-energia
• Beneficiário: Humberto Ribeiro da Rocha
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 17/50241-5 - Interações multi-escalas na zona crítica em secas extremas utilizando dados experimentais
• Beneficiário: Humberto Ribeiro da Rocha
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 19/23853-5 - Riscos e oportunidades regionais de mudanças do uso da terra e das mudanças climáticas aos serviços ecossistêmicos hídrico-climáticos: investigação para bacias na Caatinga e na Mata Atlântica do Sudeste
• Beneficiário: Humberto Ribeiro da Rocha
• Modalidade de apoio: Auxílio à Pesquisa - Regular