Research and preparation of ultra-heavy slurry

In order to resolve the technical problem of cementing when drilling super high-pressure gas layers or saltwater layers of Guandu structure in Chishui region, Guizhou province, an ultra-heavy slurry was developed by optimizing weighting materials and designing particles, and applied to well Guanshen1 for liner cementing. According to the needs of preparing ultra-heavy slurry, the weighting additive MicroMAX in spherical particles was selected and combination of weight additives—reduced iron powder, iron powder, MicroMAX—was chosen for optimization. The particle size-distribution of the slurry was designed on the basis of the theory of tight packing, and the actual particle size-distribution is close to the ideal condition of tight packing. The ultra-heavy slurry with a density of 2.70-3.00 g/cm3 was designed, which is good in basic performance, flow ability and stability. In the simulated mixing test on the ground, a slurry with an average density of 2.71 g/cm3 was prepared by using conventional one-time cementing process. In the liner cementing of well Guanshen 1, the slurry with a density of 2.80 g/cm3 was used to successfully seal the super high-pressure saltwater layer: the average density of the slurry pumped into well was 2.78 g/cm3 and the maximum density was 2.82 g/cm3; amplitude log showed that the cementing quality was good; the well bore kept stable in follow-up drilling when the density of drilling fluid was reduced from 2.77 g/cm3 to 2.00 g/cm3.