Cairn’s reputation for responsible exploration is underpinned by a rigorous approach to well design and well control.
All our wells are engineered to the highest industry standards and are designed to comply fully with the requirements of the Cairn Well Engineering and Construction (WEC) standards and Corporate Risk Management System. Safe drilling is dependent on the development and implementation of multiple safety barriers, which are designed into our drilling programmes and verified by a series of rigorous internal and external WEC assurance processes.
Design – our wells are designed and assured to a level that exceeds requirements for the expected characteristics of the geological formations to be encountered. We apply our well design standards to ensure the appropriate materials are used and installation methods conform to recognised good industry standards. We also select drilling fluids to maintain well integrity and minimise impact on the environment.
Primary well control – we apply a dual barrier approach during drilling activities. This involves control measures designed to maintain fluids in the wellbore, including drilling-hole pressure evaluation and management, kick detection, kick tolerance management, fluid management, cementing practices, blow-out preventer (BOP) system testing and assurance. Testing of a BOP system is rigorous and conducted routinely on a defined schedule to ensure it remains functional. In the event of unsuccessful tests, we make safe the well and cease drilling until the problem is found and resolved, which can result in substantial lost time and cost. Despite this, we do not recommence drilling until completion of any required remedial work and, if necessary, specialist support to assure the BOP system is fully functional.
Secondary well control – this includes measures to prevent wellbore fluids escaping from the well, using a BOP. The BOP, which is usually installed on the wellhead at the seabed, is made up of a series of hydraulically operated rams and can be operated in an emergency from the rig or via the backup remotely operated vehicle (ROV) onboard a standby vessel that remains with the rig. The BOP is rated for pressures significantly in excess of those expected to be encountered in the exploration well.
Tertiary well control – these measures provide a third line of defence when formations cannot be controlled by primary and secondary measures, and cover well control options such as drilling of a relief well and use of a capping device
Well engineering and construction – internal and external assurance processes
|Cairn Project Delivery Process (PDP) gate reviews||Major hazard assessment|
|Project risk register|
|Corporate risk management review|
|Well Engineering and Construction Team competency assessment||Regulator and partner review|
|Inspection, testing, acceptance and induction of drilling rigs and vessels||Independent expert review of critical equipment and systems|
|Daily operational reviews|
Project Delivery Process
Our Project Delivery Process (PDP) is the well-established method by which we can ensure we understand and can control risks at key stages in our projects. During the oil and gas lifecycle, the PDP helps us maintain focus on what is important to the Company and apply good practice through the application of local and international standards.
We use the Cairn PDP to manage Corporate Responsibility (CR) issues and apply these standards to all operated projects under our control. Specific project types (e.g. seismic, drilling) must meet defined criteria at designated ‘stage gates’. Each stage gate has defined actions and deliverables, which must be available and signed off by a ‘gatekeeper’ who is independent of the project. In this way, project integrity and performance are reviewed throughout the process and, where they deviate from standards, corrective actions are identified and implemented.