Research and application of a plug removal technology through foam soaking in Bohai offshore oilfield

Blockage usually happens near the wellbore in heavy oil reservoirs due to unconsolidated cementation, high gum asphaltic content, especially when the sand-cont rolling strings were blocked by heavy constituents and fine silts as well as argillaceous sediments, which would reduce oil well productivity dramatically.It is very difficult to deal with this composite blockage by conventional organics plugging removal or acidization stimulation methods.A novel plugging removal technology has been developed by experiments and numerical simulation.The experiment sand numerical simulation results indicate that the viscosity reduct ion rate can reach 99.28% and oil sands-cleaning efficiency can reach 94.6% for the selected detergent Po-Ca at the concentration of 5%.The technology has been successfully used in a shutdown well of Bohai oilfield for the first time, and the average oil production increases to 28~30 m³/d. As a novel technology for improve the oil production of low efficient wells, this technology has a great application prospect in off shore heavy oil reservoirs.