A new type of low density cement slurry suitable for sandstone formation

Abstract

Unconsolidated sandstone reservoir is an important unconventional oil and gas resource with the characteristics of porosity, low permeability, strong heterogeneity and many interlayer. The main challenge of unconsolidated sandstone formation is sand production of oil wells, and the more serious situation is high-pressure oil and gas escaping, blowout accidents, environmental pollution and the safety of operators. In order to solve the sensitivity problem of loose sandstone, a low density admixture was developed: 10.5% artificial floating bead + 4.5% power plant floating bead + 35% micro silicon + 30% fly ash + 20% slag. The particle size distribution of single lightweight material is narrow, and the effect of reducing density is not significant. The developed low-density mixing material has wide and uniform particle size distribution, and can reduce the density of cement slurry to the maximum within the minimum dosage. The new low density admixture cement slurry with adjustable density in the range of 1.4 ∼ 1.7 g / cm3 has good rheological property, short thickening time, water loss less than 50 ml, 24 h compressive strength more than 12 MPa, which can meet the needs of site construction. The temperature and pressure test results show that the system has a wide range of temperature and pressure applications and stable performance. Compared with the similar low density cement slurry, it is about 40% lower than the market price and suitable for commercial application.