Shuwaihat Sour Gas and Condensate Field, Abu Dhabi, United Arab Emirates
Shuwaihat sour gas and condensate field is located approximately 25km from Ruwais in the western section of Abu Dhabi, UAE. The field lies partly on mainland and partly in the Persian Gulf. Abu Dhabi National Oil Company (ADNOC) has appointed Wintershall as the operator to appraise the field.
Upon successful completion of the appraisal, a development plan will be devised followed by the investment decision. A joint venture of Wintershall and ADNOC, with the latter being majority shareholder, will develop the field.
Shuwaihat field is expected to emerge as a key gas and condensate field for the UAE, as well as help the country meet the increasing domestic and export demand for gas.
Shuwaihat field development
The Shuwaihat field reservoir is located at a depth of roughly 4,000m both onshore and offshore. To develop the field, Wintershall is testing the reservoir by drilling three appraisal wells and conducting a 3D seismic survey.
Onshore drilling was completed in July 2015 with the spudding of the SH-5 well. The 3D seismic survey was also completed by the same month. Data from the seismic survey will help in understanding the reservoir geology and distribution of the hydrocarbon fill. The information will further help in optimal placing of the development wells.
Wintershall partnered with OMV for the initial drilling and technical assessment activities. Initial drilling has revealed the reservoir to contain more than 20% hydrogen sulphide, making further appraisal and exploration activities essential.
Based on the data received from the onshore well, SH-5, Wintershall drilled the first offshore well, SH-6, in November 2016. Drilling of the SH-6 well is expected to be completed by 2017.
The wells are being drilled to a depth of approximately 5,000m. The third appraisal well, SH-7, will also be drilled offshore to further appraise the field reservoir.
Construction and infrastructure
Wintershall has developed temporary facilities at the Mugharraq Port instead of building dedicated facilities, to support the offshore appraisal activities. A section of loading and berthing area has been leased to Wintershall for developing the facilities.
The leased area includes temporary tanks to store liquid bulk cargoes, and related facilities to support the appraisal activities. Wintershall was able to achieve significant cost savings by using the Mugharraq Port.
Safety at the Shuwaihat field
The sour gas contained in the Shuwaihat field has been found to have 23% hydrogen sulphide (H2S) and 7% carbon dioxide (CO2), which are known to be highly corrosive and can damage pipes and production equipment. H2S is especially highly toxic at concentrations of just 0.05%.
The production programme at the field will, therefore, need to take the same into account and ensure a high degree of safety and use state-of-the-art equipment.
During the appraisal stage itself, Wintershall will use both fixed and portable gas detection and alarm systems to identify any release. In addition, breathing air cascade systems on the rig and self-contained breathing apparatuses will be used to ensure worker safety.
Sour gas processing
To address the highly corrosive nature of hydrogen sulphide in the downstream production, Wintershall is planning to use techniques developed by parent company BASF.
The sour gas will be first processed by a cleaning plant to remove hydrogen sulphide using BASF's OASE gas treatment technology. The methane produced from the process can then be transported for domestic and industrial purposes.
The hydrogen sulphide recovered from the process is first converted into sulphur dioxide and then into pure sulphur, which can be sold to the chemical industry.