Citing technical challenges and costs, Shell has decided to exit the Bab sour gas reservoirs project being jointly developed with the Abu Dhabi National Oil Co. (ADNOC), Shell said in a news release.

The decision follows a project evaluation, which concluded that developing the project does not fit with the company’s strategy given today’s economic climate in the energy industry, Shell said.

The company signed an agreement in 2013 with ADNOC to develop the onshore sour gas field. The project, challenged by the reservoirs’ high concentration of hydrogen sulfide and CO2, is estimated to cost about $11 billion.