Patent attributes
The present invention relates to a carbonate reservoir filtration-loss self-reducing acid fracturing method. The carbonate reservoir filtration-loss self-reducing acid fracturing method comprises the steps: (1) calculating a fracture pressure and a fracture extension pressure of a reconstructed reservoir; (2) injecting an agent A into a stratum under a pressure higher than the stratum fracture pressure, so that fractures are generated on the stratum; (3) injecting an agent B into the stratum under a pressure higher than the stratum fracture pressure, such that the agent B extends the fractures and communicates with a natural fracture net; (4) pumping an acid liquor system agent C with a high etching power into the stratum under a pressure higher than the extension pressure but lower than the fracture pressure to improve the conductivity of the fractures; (5) injecting a displacing liquid agent D under a pressure lower than the stratum fracture pressure to jack acid liquor in a well casing into the stratum; and (6) shutting down a well and performing flow-back. The agent A is a gel acid or VES acid, the agent B is a filtration-loss self-reducing gel acid or filtration-loss self-reducing VES acid, the agent C is closed acid, and the agent D is a displacing liquid. According to the method of the present invention, precipitation type solid filter cakes are formed on wall surfaces of the fractures by utilizing a filtration-loss self-reducing system, so as to perform temporary blocking to reduce the filtration loss. The technology is simple with easy injection, and the filtration-reducing agent is easy to disperse and flow back, and the method is safe and environment-friendly.
