Experimental Study on Plugging Fracturing Technology for Water-Flooded Well in Low-Permeability Reservoir

In order to restore or improve the production of single water flooded well,different plugging fracturing technologies were developed for such wells depending on types of water breakthrough.For pore-breakthrough well,the selective plugging fracturing technology was defined;the selective water plugging agent was highly capable of selective plugging,with rate 3.3 times that of the oil plugging rate.For fracture-breakthrough well,the technology of plugging old fractures and directional perforating to create new fractures was proposed;the fracture volume changed by less than 5% after solidifying of the agent,with breakthrough pressure up to 9.8 MPa;according to the residual oil distribution of old well,the azimuth of directional perforation was selected to control the extension direction of fractures.By field test in 2 wells,it was found that the average daily oil increment is 0.81 t and 0.76 t respectively after water plugging and fracturing,indicating better stimulation effects.Therefore,these technologies provide effective solutions to improve the production of single water-flooded well in low-permeability reservoir of Changqing Oilfield.