Abstract

Rantau is an oil field locating at Northern Sumatera with more than 500 wells have been drilled since 1918. From this figure, currently only less than 100 wells are producing by means of artificial lifting method.

From the well histories, there were a lot of wells producing below it's predicted capacity and some of their cummulative production were much below it's calculated reserves. These problems had been observed intensively and highlighted that some of these wells stopped producing immediately, jump off it's natural decline line. These phenomenon were occured due to the migrating clays that flows together from the matrix up to the surface. The production fluid becomes a "mud-like", cloudy and increase in viscosity. Most of the poor cement bond on the old wells that created a poor zonal isolation were accelerating the occurance process of clays production.

This paper is outlining the technical efforts to maintain the well producing life time and it's productivity in order to be in track on it's decline rate line. To achieve this goal, a series of clay stabilizing treatments were studied, and come up with the best specific fluid that is suited for a certain type of formation. The success ratio of this treatment depends on the dispersed clays content in the producing fluid. For wells having less than 20 % of dispersed clays content are the best well candidates for clays stabilization. More than 20 % of dispersed clays, the possibility of success are relatively small.