Publications

Fluids from producing wells in Duri Field typically contain high concentrations of calcium and asphaltene. High calcium concentration in the formation water increases scaling probability when heated by steam. Consequently, all wells that produce water are at high risk of calcite scaling because of increased tendency due to pressure drop and large temperature variations. In order to remove scale in the wellbore, workover jobs such as Revised Liner (RL) and Simple Acidizing (SA) are technically applicable. However, the RL cost is more than twice that of SA cost. For this reason, acidizing is the common well stimulation method used in Duri Field when scaling is indicated. In wells with temperature > 2500 F (121.10 C), simple acid jobs are performed to treat scaling with selective intervals layered over the commingled production zones. The procedurestimulates only the higher potential zones based oncorrelation with maturity of reservoir sand. This isaccomplished via pressurized down-hole treatmentand jetting effect through Coil Tubing Unit (CTU) to clean scale from perforations and liner. Acidizing selective intervals reduces the chemical volumes and also potentially prevents steam breakthrough from high temperature zones. The acid treatment effects only the scale adhering to liner in relatively colder reservoir zones still having oil potential. By reducing chemical volumes, the selective treatment method also reduces cost and is an effective method to improve well productivity in the high temperature wells in Duri Field.