Investigation of Factors Influencing HPHT Well Integrity in Deepwater
Muhammad, Nursyahidatul, A
Engineering Honours Degree 2008
University of Adelaide
This research outlines the issues affecting HPHT well integrity in deepwater. With the global increase in demand for energy as well as revenues for oil and gas, the drive to exploit more difficult reserves becomes greater. However, unlocking these reserves relies on sophisticated methodologies, and there are still many challenges that need to be understood and addressed. The industry trend to move into deeper drilling has produced significant challenges which arise from various areas including technical, economic as well as from the environment itself. The major challenges appear from the technical side which include cement fatigue, CO2 and H2S corrosion and completion design in HPHT environment. All of these factors play major roles in affecting the HPHT well integrity. Cement fatigue can trigger premature water breakthrough, initiate a path for fluid influx and create a chance of building up barite plug. CO2 and H2S corrosion will cause pitting and metal loss as well as initiate blisters. In designing the completion for HPHT environment, lots of aspects need to be taken into consideration. This includes corrosion, metallurgy, sand control and many more. Implementation of rapid set cements, gas block additives and reverse-circulated cement on casing string can assist in cementing problems. Corrosion due to CO2 and H2S can be mitigated by using corrosion resistant alloy for completion equipment and injecting corrosion inhibitor. Implementing packerless completion and mono-bore completion can help to overcome the completion design challenges. Even though, there are a large number of solutions that can be implemented to overcome the difficulties, the technology of the existing equipment is no longer adequate for this hi-tech frontier. Existing technologies can be improved to accommodate the need of deepwater. Longer term research and development efforts are required for the resolution of the causes affecting HPHT well integrity in deepwater operation particularly related to the technical side.