Status and prospect of key drilling and completion technologies for the development of HTHP gasfield in South China Sea

The development of offshore HTHP gas fields is the large-scale offshore system engineering with high investment, high risk and high difficulty. In this paper, the basic characteristics of HTHP gas fields in western South China Sea were investigated, and then the corresponding technical difficulties during their development were analyzed from the aspects of wellbore safety, drilling and completion fluid, cementing, directional well and horizontal well drilling, composite drilling speed improvement and well completion. The key HTHP well drilling and completion technologies which had been developed were summarized systematically, including composite anti-corrosion of tubing and casing, “five-prevention” cementing slurry and self-repairing slurry, overpressure cap rock ROP improvement, fine reservoir protection, directional well trajectory control and safe well completion. As the HTHP exploration field is expanded further in the South China Sea, huge challenges emerge in HTHP and deepwater HTHP environments. Faced with these challenges, it is proposed that the drilling and completion technologies for offshore HTHP natural gas development shall focus on the research and development of new equipments, materials and technologies that are suitable for higher temperature and pressure and the completion of offshore emergency rescue system, so as to ensure the safety and efficiency of offshore HTHP well drilling.