A Unique Cement Slurry Overcoming Low Temperature, Shallow Water/Gas Flows in Deepwater Cementing

Abstract The hydrocarbon resources in deepwater areas are very captivating. The trend of developing and utilizing the hydrocarbon resources is necessary. Unfortunately, severe challenges have been proposed on deepwater cementing, i.e., the low temperature, weak formations, shallow water/gas flow, environmental protection and highly day rate for deepwater rigs. Conventional cements and low density cement slurries usually take a long time to set and can't allow significant compressive strength development at these low temperatures. In addition, conventional cement additives are often environmentally unacceptable subject to more stringent environmental regulations. Therefore, it is stringent to design environmental friendly low density cement slurry to overcoming low temperature and shallow water/gas flow during deepwater cementing. As the low temperature and shallow water/gas flow is concerned in deepwater cementing, a unique deepwater cement system DWC, combining the sulfoaluminate cement and class-G oil well cement, was developed for the first time. And, various environmental friendly additives, including cement dispersant, fluid loss control agent and accelerator, were developed. Finally, a unique low density deepwater cement slurry was designed. Laboratory tests show that the unique deepwater cement slurry has exhibited low density, excellent fluid loss control, no free fluid, right-angle-set, short time of wait-on-time at low temperature, and a shortened transition time of static gel strength. Results presented in this paper should help resolving problems in deepwater cementing.