During the last years, drilling operations have increased into areas where water resources have been affected by different natural phenomena and where strikes and social conflicts have been generated by drilling activities. In addition, current government protocols are more limiting about fresh water abstraction and their use, and wastewater disposal methods. For those reasons, environmental sustainability has become in one of the oil and gas industry's main concerns.

For drilling operations a large volume of water is required, including domestic and industrial processes. Thus, taking into account several experiences in diverse Colombian oil drilling fields operated by Ecopetrol, show that the average of drilling water consumption per drilling rig is roughly 400 barrels of water per day and the wastewater volume to be disposed by different methods is coming from mud dewatering process followed by a physical and chemical treatment. That volume of wastewater contains dissolved salts such as chlorides and sulphates which make it impossible the re-use the water into the drilling mud process due to high content of salts that affects directly the polymers reactions of the drilling mud causing an inadequate fluid rheology.

To tackle that situation, a wastewater management was designed to create a closed loop minimizing the environmental impact in terms of fresh water abstraction and wastewater discharge. Therefore, reverse osmosis process was implemented in those fields located in areas where water resources or disposal methods have been restricted by the environmental licences. As consequence of this wastewater technology as post-treatment step has permitted to re-use, in some cases more than 90% of the wastewater for preparing new drilling mud, fluids dilution and industrial uses. On the other hand, an important decrease of water abstraction was achieved as result of the reverse osmosis implementation.

A discussion about reverse osmosis process as eco-friendly technology and cost-effective management of the drilling wastewater production has been provided, summarising some relevant results obtained in different oil drilling fields operated by Ecopetrol in Colombia. In addition, it is important to show how Ecopetrol is committed with environmental and sustainable development reducing the impact from the drilling operations.

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