A METHOD TO DETERMINE CEMENTING SLURRY DENSITY IN MULTI-PRESSURE STRATA

The experimental study on the relationship between annulus pressure differential, interlayer differential and cementing quality is carried out on the lab simulation test unit. Based on field investigation and statistical data, the relation plate of annulus pressure differential, interlayer differential and cementing quality is plotted. When annulus differential in high pressure formation is larger than IMPa, and/or when the differential in low pressure formation is smaller than 9MPa, the cementing quality would be guaranteed using Grade A cement slurry. The calculation and correction method of the pore fluid pressure in substratum for adjustment well. The critical coefficient of formation pressure correction is 1.55. Thus, the density design of cementing slurry, including recycle drilling fluid, spacer fluid and cement slurry, is well optimized. The method is widely used for adjustment wells in Daqing Oilfield with high cementing quality.