Abstract

Loss of fluid during workovers to formations that are underpressured has been experienced in wells in the Badak field of East Kalimantan. The formations are underpressured because of production of the respective reservoirs. Difficulties were experienced in returning some wells to production after workovers due to skin damage caused by water blockage or perforation plugging. Additionally, when work was being performed on a dually completed well with two formations having different pressure gradients, there was a possibility of one zone taking fluid while the other zone was attempting to produce, thereby creating a hazardous situation.

A method of preventing fluid from entering a particular zone was investigated. As well as preventing fluid invasion, the solution used has to be non-damaging to the formation.

A high-viscosity gelled fluid (hi-vis gel) was chosen to be used as a fluid loss prevention agent. The hi-vis gel was used in various types of completions and downhole conditions. A pill of hi-vis gel material was pumped to the particular zone of underpressure where it was allowed to set up in the casing or in the formation. When the workover was completed the gel was allowed to break over a period of time. In the event that the gel did not break over a period of time, a small amount of acid could have been used to cause the breaking action.