Cementing technology of adjustment wells in Area Duanliuba of Dagang Oilfield

The Duanliubo Block of Dagang Oilfield is characterized by deep burial depth and long well interval in reservoirs, so under the comprehensive influence of long-term water injection and edge-bottom water, the area appeared multi-pressure systems and complex water-oil relation, leading to difficulty in improving cementig quality. Based on the analysis of the early cementing data and combined with the actual situation, this paper presents the idea that adjusting rheological properties and pH value of silicate-based drilling fluids is key technology for removing the “virtual filter cake”. A new evaluation method was used to optimize the cement slurry formulation which has short liguid-solid transformation time and can be fast setting and early strong. In addition, a inverted pulp-column structure and over-balance pressure cementing technology was used with heavy spacer, high density lead slurry and conventional density tail slurry. These technologies were continuously applied to 12 wells, such as Duan38-30, the percent of pass was 100% and high-quality interval rate of cementing quality was improved from 23% to 72% in the area of Duanliubo. And the cementing technologies which were applicable to Dagang Oilfield adjustment wells were formed.