多压力层系下固井液密度确定方法的研究

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

室内利用模拟试验装置进行了环空压差和层间压差与固井质量的关系的试验研究。结合现场调查和统计规律，建立了环空压差和层间压差与固井质量的关系图版。提出了高压层固井环空压差大于１ＭＰａ和低压层固井环空压差小于９ＭＰａ的情况下，用 Ａ级水泥原浆固井能够保证固井质量。建立了调整井小层孔隙流体压力的计算及调整方法，地层压力调整的临界系数为 １． ５５，从而优化了固井液（包括循环钻井液、隔离液和水泥浆）密度设计，使其更加合理，在大庆油田调整井中得到广泛应用，有效地提高了调整井的固井质量。

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.