Using SP logs to estimate the water quality of borehole layers in the Duero basin (Iberian Peninsula)

ABSTRACT

This work presents a proposal for the use of spontaneous potential logs to estimate the water quality in permeable layers of a formation that are located below the water table in uncased boreholes. These estimates aim to obtain the values for conductivity and total dissolved solids, which would enable us to learn their distributions with depth and determine the optimal extraction levels prior to completing these boreholes. This proposal consists of a methodology to process and interpret spontaneous potential logs. Laboratory measurements have been necessary to obtain the water resistivities versus their equivalent resistivities and versus the total dissolved solids. In addition, continuous analytical relationships have been developed for the range of applications found, and specific algorithms have been developed to determine the baseline of the spontaneous potential log. This methodology has been applied to a group of 27 boreholes located in the southern Duero continental detrital basin.

KEYWORDS:

• well logging
• spontaneous potential
• baseline
• water resistivity
• total dissolved solids
• Duero basin

Editor A. FioriAssociate editor F. Tauro

Editor A. FioriAssociate editor F. Tauro

Acknowledgements

The authors thank the Consejería de Agricultura de la Comunidad de Castilla León (Spain) and the Empresa de Transformaciones Agrarias (TRAGSA) for providing part of the survey data.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was partly supported by the Regional Government of Madrid [Comunidad de Madrid] under the Consejería de Educación e Investigación [Grant number P2018/EMT-4317].