Exploration and Hydrogeology

Exploration and Hydrogeology

Since 1996, COGEGOBI has been continuously carrying out geological reconnaissance and exploration work in the Dornogobi and Sukhbaatar aimags, in southeastern Mongolia. This work is being conducted in accordance with the law on minerals adopted by the Mongolian parliament, and in compliance with the strictest safety, security and environmental standards.

Major achievements to date include discovery of the Dulaan Uul deposit in 2007 and the world class Zuuvch Ovoo deposit in 2010, which significantly increased Mongolia’s overall uranium resources.

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From grassroots to advanced exploration

COGEGOBI is working simultaneously on several projects, all at different stages of investigation. The work carried out by the compagny's teams is dedicated to improving geological knowledge of the Gobi region and assessing the uranium potential of propective Mongolian sedimentary basins.

Today, COGEGOBI holds 14 exploration licenses covering a total of more than 400'782 ha in the vast sedimentary basin of the Dornogobi and Sukhbataar aimags:

  • 3 licenses in the Sainshand basin
  • 11 licenses in the Dariganga basin 

The most advanced projects are the studies of the Zuuvch Ovoo and Dulaan Uul deposits, but the exploration teams are still looking for new exploration targets within other areas possibly fertile in uranium.

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Geological exploration

Key steps of exploration

  • Prospection

The first step in discovering new geological resources is to use the available geological information to identify areas where there is a high chance of finding natural uranium concentrations. Common approaches include satellite or airborne surveys, ground geophysical measurement and geological prospecting.

Based on these data, the exploration team determines the best drilling targets to verify their geological hypothesis at depth.

  • Drilling operation

Drilling operations have 2 objectives:

  • collecting sample from the deep geological formation (core)
  • having a hole to run and record continuous geophysical parameter of the rock formations (well logging)

Exploration drilling use standard equipments with mud. The mud is constituted by water mixed with bentonite, natural clay and biodegradable polymer following international standards.
The average depth of the wells range from 150 to 450m in function of the area.
Each year drilling operations are conducted following the obtaining of authorizations.

  • Core drilling

From drill cores, the composition and the nature of the rocks, the concentration of various minerals at greater depths are determined.

  • Core samples

Core samples are transported to sheds where geologists do an initial inspection and note their observations concerning the samples, their color, the size of the grains and other characteristics. Selective samples are then put in tightly sealed plastic bags to preserve their quality and sent for precise geochemical analysis to independent laboratories.

  • Systematic well log

A well log is a recording describing where drilling is being done. It measures physical parameters all along the drill hole to assess the geological formations - if they are sand or clay, the natural gamma radiation - indicating the presence of uranium -, and the characteristics of the drilling operation itself.

The measures are done with an array of probes and sensors that are connected to an electrical wire and lowered into the borehole.

The new geological information collected via these drill holes provides a more accurate geological understanding of the prospecting area and may result in the discovery of new mineral deposits.

The work currently is being carried out in the Sukhbaatar aimag corresponds to this grassroots exploration phase.

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From advanced exploration to project development

Grassroots exploration conducted since 1997 in the Dornogobi aimag has resulted in the successful discovery of two new sandstone-hosted type uranium deposits (Roll-Fronts type deposits): Dulaan Uul, located in the Uneget basin, and Zuuvch Ovoo, located in the Zuunbayan basin.

Advanced exploration began in 2006 for Dulaan Uul and 2011 for Zuuvch Ovoo. This involves detailed delineation of the mineralization in order to measure the quantity, grade, and geometry of the uranium ore bodies, as well as hydro geological studies and geological environment.


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During advanced exploration works, hydrogeologists study and monitor the quality and the stability of the physical and chemical parameters of the groundwater at site and in the different aquifers of the basin.

  • Hydrogeological monitoring wells

Based on observation and data from hydrogeological drilling and installation of hydrogeological wells and piezometers, they identify groundwater that might be used as a source of potable or non potable therefore industrial water.

  • Pumping test

Pumping tests are conducted in hydrogeological wells to determine the hydrodynamic properties of the targeted aquifer being studied and then use the results to estimate groundwater resources. These estimates permit efficient management of the different aquifer.

  • Water sampling

Hydrogeologists analyze water samples and measure piezometric levels. Water samples are sent for analysis to independent laboratories and to the former Nuclear Energy Authority (now at the Authority of the Professional Inspection) to determine the quality and chemical composition of the water. Water levels in the wells in the piezometers are checked at the beginning of each month. This information is part of the process to assess the feasibility of future uranium mining.

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Drilling work remediation and environmental care

At the end of drilling operations, each borehole collar is cemented, the mud pits are emptied and backfilled with the original soil and the drilling platforms are cleaned and evened up by the subcontractor. The remediation work is then inspected and validated by COGEGOBI’s environment protection team before official environmental inspection and delivery of conformity certifications.

COGEGOBI and its drilling subcontractors have constantly sought to improve their practices over the years in order to minimize the environmental impact of drilling operations.

This work to improve practices includes:

  • optimizing transportation and trucking by using existing track networks and minimizing the creation of new tracks for access to the drilling pads,
  • optimizing the drilling pad setup to minimize its size and reduce the footprint on the ground,
  • exclusively using natural clay such as bentonite and biodegradable component such as polymer in the drilling mud,
  • protecting the ground with a liner from accidental oil spills.

A unique mud-recycling method to reduce water consumption.

Since 2013, a unique mud recycling method has been implemented to reduce water consumption by 30 to 60%, depending on the drilling depth. This new method reduces the impact of the drilling operations on the surface as well as the amount of trucking needed to supply water and mud, and the volume of mud waste. The method also makes it easier to carry out remediation work on the drilling pad.


Exploration activities and environment

Discover how natural materials are used during drilling to respect the environment.


Exploration activities and sacred sites

Discover how Mongolian traditions, including traditional sacred sites are respected.