RESEARCH AND APPLICATION OF LOW DAMAGE FRAC TECHNOLOGY FOR LOW PERMEABILITY AND TIGHT GAS FIELD IN WESTERN SICHUAN

Low success rate of fracturing and low-efficiency measures caused by inappropriate fracturing technology have seriously affected the effective development of Penglaizhen and Suiningzu gas reservoir. The research results of fracturing damage mechanism showed that major damage was the damage of fracturing fluid and propping agent to fracture in the fracturing process. The paper put forward the methods of reduce formation damage,i.e. development low-damage fracturing fluid,optimization fracturing design and flowback technology. The concentration of low viscosifying fracturing fluid decreased 20 percent,the damage to reservoir decreased 11.7 percent and residue dropped down 16 percent. The optimal fracturing operation project suited for low permeability and tight gas field in western Sichuan has been determined based on simulation and optimization of a typical well. And some matching low damage fracturing techniques were formed,such as linear sanding technology,low proppant concentration fracturing technique,multiple fracturing technique etc. The application of low damage fracturing technology showed that the natural gas production was increased form 1.90×104m3/d to 8.5137×104m3/d in the Penglaizhen gas reservoir of field A,and gas-bearing area was high up to 129.07km2,the explored gas reserves have exceeded 100.78×108m3 in Suiningzu gas reservoir of field B in 2005. Low damage fracturing technology has been applied in other gas field of Western Sichuan,and it provided an important and valuable experience for the exploration and development of natural gas reservoir in Similar reservoir.