UTILIZING ACIDIZED NH2 FOR MITIGATING FORMATION DAMAGE AND IMPROVING OIL RECOVERY: CASE STUDY OF PENARA FIELD, MALAYSIA

Deposition of solid hydrocarbons such as asphaltene and wax near the wellbore and in the tubing is known to cause decline in the well production performance. Various mitigation methods such as chemical wax inhibition, thermal insulation, and coiled tubing clearance are repetitive and exhaustive. These methods could temporarily remove deposits but not prevent them from reoccurance. On the other hand, the thermo-chemical method utilizing acid-base reactions seems to be offering the most effective and simple solution to the problem. Reaction products and heat from the acid-base reactions could be utilized to dissolve and disperse wax or asphaltene deposition in addition to changing the wettability profile. The present study is to evaluate the performance of acidized amines for mitigating formation damage and improve oil recovery in the Penara Field, offshore Peninsular Malaysia. Wells in the field have been recording massive production decline of more than 5000 stb/d despite continuous treatment of pour point depressant, wax dispersant, de-emulsifier and frequent tubing clearance activities.

Physical observation and interfacial tension measurement were carried out to qualitatively and quantitatively measure the performance of the acidized amines. Improvement in the oil recovery was measured through coreflooding test. The study found that acidized amines by-products dispersed the suspended wax solid and prevented it from re-depositing after 48 hours. Thus, oil recovery increased to 51.3 % for non waxy-liquid crude and 13.0 % for waxy-gelled crude. These findings from the laboratory were further validated by production optimization using Wellflo.

The thermochemical method utilizing acidized amines is simple and yet experimentally proved to be effective in solving the wax related problem. Considering the reserve potential in the Penara Field and supported by sufficient well data, the incremental production of 22 % could be predicted.