Publications

Offshore North West Java (ONWJ) Fields have been producing since 1971, typically with wells completed by commingling several zones. After several years producing it was found that many wells were watered out, even by structurally producing zones which should have been a still low water cut according to adjacent well performances. It is because one of the producing zones started producing water earlier than the others. The unwanted water would dominate production and increase pressure drops in tubing.Usually, mechanical shut off techniques using cement and re-perforation were implemented to shut off watered out zone and increase oil production. But referring to recent ONWJ statistics, the techniques have some operational problems during execution, which then reduced the success ratio. Some examples of problems are difficulties to clean out the excess cement or retrieve plugs, especially for aging and complex well completion, formation damage due to fluid invasion during cementing jobs, and cement placement for high angle wells.Chemical water shut off techniques offer an innovative solution to mitigate these problems. Two chemical functions were applied, which are relative permeability modified and polymer or total gel shut off to the water formation zone. Six jobs have been executed in ONWJ Field, and successfully solved water production problems and increased oil production.This paper will share the success of the chemical water shut-off pilot project of the ONWJ team, from the candidate selection process, operational aspects, lessons learned, and further implementation of the chemical WSO techniques in ONWJ field.