Drilling fluid technology for the Wen-23 depleted sandstone gas storage

Abstract:

The Wen-23 gas storage reservoir is a depleted sandstone type gas reservoir with a massive salt rock cover and a maximum temperature of 120°C at the bottom. To address severe leakage and formation contamination during drilling in the Wen23 reservoir， a leak-proof low-density micro-foam drilling fluid system with a temperature resistance of 120°C was developed. Test showed that the micro-foam drilling fluid system had a density change of only 0.04g/cm³ after 72hrs aging at 120°C. Only 325mL was required to reach a pressure of 10MPa or more with the permeability recovery value of the formation up to 87.9%. The micro-foam drilling fluid has been applied to 66 wells in the Wen-23 gas storage reservoir with the incidence of leakage only 13.6%， and the well wall was stable during the drilling operations. The leak-proof low-density microfoam drilling fluid with 120°C resistance has demonstrated good leak prevention in the construction of the Wen-23 gas storage reservoir with effective protection of the well wall stability and reduction of the damage to the reservoir， providing a guarantee for the safe and efficient development of the Wen23 gas storage reservoir.