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A Modified Approach for Volumetric Evaluation of Shaly Sand Formations from Conventional Well Logs: A Case Study from the Talhar Shale, Pakistan

  • Muhsan Ehsan
  • Hanming Gu
  • Zulfiqar Ahmad
  • Malik Muhammad Akhtar
  • Saiq Shakeel Abbasi
Research Article - Earth Sciences
  • 12 Downloads

Abstract

In potential shale-gas basins, due to limited data availability, volumetric evaluation of shaly sand formations is a challenging task for researchers, as well as for exploration and production companies, with the use of conventional well logs. This paper is intended to provide a better understanding of volumetric evaluation in unconventional shaly sand formations. Petrophysical parameters derived from conventional well logs play a significant role in the volumetric estimation of shale. The assessment was performed using numerical equations, well log indexes, and cross-plot analysis. Deep and shallow resistivity logs overlap with each other; this phenomenon indicates that the Talhar Shale in Pakistan can be considered to be an unconventional formation. The average values of shale volume, total porosity, effective porosity, and matrix volume are 29, 16, 12, and 59%, respectively. The Talhar Shale is dominantly characterized by intergranular porosity. It has been observed that at low shale volumes (10–20%), porosities (total and effective), and resistivity measurements (deep, shallow, and microlaterolog), well log signatures have close contents with the shale volume. In contrast, for the remainder of the shale volume, there is significant separation of log signatures. Well log indexes indicate significant responses in 10–20% shale volume zones.

Keywords

Shaly sand formations Volumetric shaly sand evaluation Gamma ray logs Porosity logs Resistivity logs Well log indexes 

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Notes

Acknowledgements

I thank Directorate General Petroleum Concession (DGPC), Pakistan, for providing data for this research. I would like to pay my regards to my elder brother Mr. Mohsin Raza from University of East London, UK, and my friend Mr. Ahsan Shafi from China University of Geosciences, Wuhan, for their moral support and their help to complete this work.

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Copyright information

© King Fahd University of Petroleum & Minerals 2018

Authors and Affiliations

  1. 1.Institute of Geophysics and GeomaticsChina University of GeosciencesWuhanPeople’s Republic of China
  2. 2.Department of Earth and Environmental SciencesBahria UniversityIslamabadPakistan
  3. 3.Office of Research Innovation and Commercialization (ORIC)University of WahWah CanttPakistan
  4. 4.Department of Environmental SciencesFLSI, Balochistan University of Information Technology, Engineering and Management Sciences (BUITEMS)QuettaPakistan

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