The challenge of meeting ever-pressing energy demand and reducing GHG emissions presents a significant challenge. One of the recent trends in the energy transition is hydrogen, which is experiencing unseen support from various stakeholders. Hydrogen roadmaps and net-zero strategies announced by governments and companies indicate that demand for low-carbon hydrogen will increase significantly. Therefore, it is essential to establish a reliable supply of low-carbon hydrogen. In our previous work, we have shown that Kazakhstan is located between the two largest hydrogen markets - China and Europe. Natural gas can be a feedstock material for low-carbon hydrogen, which is also known as blue hydrogen.
Kazakhstan holds the 16th largest natural gas reserves in the world. Nevertheless, finding feedstock natural gas for hydrogen in Kazakhstan can be challenging. In 2020, the gross natural gas production in Kazakhstan reached 55.1 bcm of natural gas of which 34.8 bcm and 20.3 bcm are commercial and reinjected volumes, respectively. Commercial volumes are tightly used for rising domestic market and export. Reinjection volumes are also tightly used to maintain the production of oil in the largest hydrogen reservoirs of the country - Tengiz, Kashagan and Karachaganak.
In our work, we propose an approach to use reinjected gas volumes for large-scale hydrogen production while keeping the oil production targets in the largest fields as before. CO2 emissions resulting from the hydrogen production would be used to replace currently reinjected natural gas in maintaining reservoir pressure. CO2 can decrease the viscosity of the reservoir fluid, thus enhancing oil recovery (EOR). This work presents the viability of the concept in the example of the Kashagan field by showing the material balance of both surface and subsurface processes. Several development scenarios were which also involved coproduction of elemental sulfur and methanol. Blue hydrogen production was modeled in Aspen Hysys v12.1.