Acid-Soluble Temporary Plugging Technology for Ultra-Deep Fractured Carbonate Reservoirs in Block 1 of the Shunbei Area

Ultra-deep fractured carbonate reservoir in Block 1 of the Shunbei Oil and Gas Field can be characterized by high temperatures, high pressure and developed natural fractures that is easy to cause mud loss in drilling. In order to solve the problem of circulation loss and formation damage after drilling fluid leakage, a high temperature resistant acid-soluble temporary plugging technology was developed. The technology mainly consists of high acid-soluble fiber, acid-soluble filling materials with different size and elastic graphite. Through the research on rock mineral composition, microstructure characteristics and damage factors, the reservoir protection strategy of “mud property control + acid-soluble temporary plugging” in Shunbei was put forward. The application results show that the temporary plugging system has a fairly good performance with temperature rating of 180℃, acid dissolution rate over 85.0% and permeability recovery rate over 87.0%, which is suitable for fractured reservoirs with fracture widths less than 1.0 mm. It is shown from field pilot of targeted formations in Well SHB1-10H that reservoir protection are apparently improved after the application of acid-soluble temporary plugging technology, and the oil production rate has been dramatically increased compared with offset wells, with oil production reaching 90.0 m³/d. It has achieved either plugging or breaking-down, which provides a new temporary plugging technique for efficient drilling in fractured reservoirs.