Improving reservoir souring treatments for chalk formations

Mohammad Reza Alizadeh Kiapi: Tiny bacteria deep down in the ground, friends or foes? Can we find a way to live together!

Deep down in the ground, in particular places all around the world, there exist very large amounts of hot water, oil and gas trapped within the porous rocks. These rocks look like sponge whose pore space is fully occupied by different fluids. These natural reserves have formed roughly 70% of our energy resources (Petroleum, Natural Gas and Geothermal) and therefore have been intensively deployed for production during the last century. For production of these fluids, wellbores (called producing wells) are drilled and the desired fluid can be produced spontaneously in the first place, however, after a while (few years), the production rate decreases. In order to help the production, several new wells (called injection wells) are drilled at farther distances from the producing wells and water can be injected through these injection wells. The injected water pushes the reservoir fluid towards the producing wells and helps the production.

The unfortunate thing is that, these fluids are not alone down there. There are hundreds types of microorganisms (bacteria) living in these fluids, not very active though. The injected water - if contains sulfate - stimulates a particular type of microorganisms called sulfate reducing bacteria (SRB) which convert the available sulfate (SO42-) in the injected water into hydrogen sulfide (H2S) which will be produced along with the reservoir fluid. This process is called “reservoir souring” in the literature. H2S is a toxic and corrosive material and exposure to it can cause severe long-term health and environmental problems. Some of the issues H2S generation can cause are: decreasing the life expectancy of facilities, health problem for people exposed to it and polluting the underground water if it finds its way to groundwater resources.

On the other hand, there are some other microbial processes in the reservoir that are beneficial as some products (e.g. bio-surfactant) of these microbial activities can facilitate reservoir fluid movement towards producing wells through various mechanisms and consequently decrease the amount of energy required for the production of reservoir fluid.

Hence, the necessity of a detailed and complete look into reservoir souring is transparent and having a comprehensive understanding of the processes, available solutions and devising possible new alternative solutions are highly demanding.

In this project, we aim to develop thorough numerical models which take all possible governing physics into account in order to further investigate realistically the reservoir souring processes from smallest scale (few micro-meters) to largest scale (few kilo-meters), evaluate and compare different treatment methods and eventually come up with the best treatment scenario in which H2S production reaches the least possible (or possibly zero). Having said that the developed model and simulator will be a general toolbox which can be widely used in different subsurface areas with similar concept such as petroleum, environmental, and geothermal engineering.

We hope this project and its outcomes will take part in our common mission towards building a more sustainable world as well as promoting a greener universe for ourselves and the generations to come.

PhD project

By: Mohammad Reza Alizadeh Kiapi

Section: Centre for Oil and Gas

Principal supervisor: Hamid Nick

Co-supervisor: Mohammad R. Hajiabadi

Project title: Improving reservoir souring treatments for chalk formations

Term: 01/07/2020 → 30/11/2023


Hamid Nick
Senior Researcher
DTU Offshore
+45 93 51 14 97


Mohammad Reza Hajiabadi
DTU Offshore