Analysis of Components of Gas Well Blocking Substances and Study on a Composite Block Removing System

Gas wells drilled in the Gaoshiti block of the Southern Sichuan Gas District have encountered serious formation blocking problem, resulting in significant decline in the gas production. To restore the gas production, blocking removing needs to be performed with blocking removing fluids in wells where reservoir formations are blocked. By analyzing the blockages taken from the wells with IR and XRD methods, the organic and inorganic components and their contents in the blockages were determined. Based on the blocking removing principles, a composite blocking removing system was formulated with xylene, 15% HCl and isopropnaol, and was then optimized for the material ratio. The effects of action time, solid/liquid ratio as well as temperature on the blocking removing performance of the blocking removing system were investigated. It was found that the blocking removing system formulated with m (xylene)∶m (15% HCl)∶m (isopropnaol) = 17.32∶25.99∶56.69 has the optimum blocking removing performance. At solid/liquid ratio of 1∶15 the efficiency of blocking removing is 90.25%, which is the highest efficiency. This composite blocking removing system can effectively dissolve the blockages found in the Gaoshiti block, and the residues after dissolution have smaller particle sizes, beneficial to discharging from where the formations are blocked. Wells operated with this blocking removing system have their gas production restored.