Abstract
Inspite of all efforts to obtain competent kick-off plugs in minimum attempts, plug failure is frequently encountered. It results in unproductive downtime and additional rig costs on repeat jobs. Failure of side track plug is typically due to contamination of slurries during plugging operations. Good operational practices somewhat controls the mud contamination. However, in conjunction with the best practices, implementing slurries least affected by mud contamination can substantially enhance plugging success rate. This paper presents strategies wherein atypical cement formulations (normal / light weight 11-12 ppg) have been engineered for the purpose by incorporating pozzolana materials like micro silica, metakaolin, ground blast furnace slag, either singly or in combination. These non-conventional cement slurries have excellent properties. Formulated slurries have low fluid-loss, nil free-fluid, high stability and excellent rheology for facilitating efficient mud removal compared to contemporary field slurries. Further, mud contamination studies performed showed that these slurries retained much higher residual compressive strengths compared to prevailing slurry designs under comparable conditions. Higher residual strength enhances success for plugging. This study while successfully addressing the industry concern provides solutions for achieving competent kick-off plug at minimal attempts with engineered slurries. The study is focused on practical field challenge and solutions elucidated here would effect substantial savings on expensive rig time as repeated plug jobs would be reduced / eliminated. Details of the novel slurries with conclusions and recommendations derived from this endeavor are presented in this paper.
