Song Z.,Drilling and Production Technology Research Institute |
Song Z.,National Engineering Laboratory for Low permeability Oil and Gasfield Exploration and Development |
Su W.,Drilling and Production Technology Research Institute |
Su W.,National Engineering Laboratory for Low permeability Oil and Gasfield Exploration and Development |
And 14 more authors.
Natural Gas Industry | Year: 2014
The CO2/sand dry-frac process involves a waterless fracturing technology with CO2 replacing the conventional hydraulic fracturing fluid. The application of the technology in foreign countries (the USA and Canada) show its strong performance in low-pressure and low-permeability reservoirs with high fluid-block and strong water sensitivity. A series of experimental studies were conducted of stimulation mechanism, fracturing fluid system, pressurized closed-system sand blender, and fracturing process. The following achievements were made. First, the CO2 viscosity enhancement technology is successfully developed, increasing the CO2 viscosity by 240-490 times and improving the sand-carry and fracture-making capacity of CO2 fracturing fluid, so it is served as a key technology to achieve the CO2/sand dry-frac process. Second, the development of CO2 pressurized closed-system sand blender realizes the allocation of critical devices for the CO2/sand dry-frac process. Third, absolute automatic flowback is also realized. Fourth, CO2 is used to replace the water-based fracturing fluid, saving a great amount of water consumed in fracturing to make the recycling and low cost both realized. Fifth, the CO2/sand dry-frac process is feasible and will obviously improve the stimulation in low-pressure and low-permeability reservoirs with serious fluid block.