This paper presents two different and simple methods of tracking water rise in a gas reservoir. From the case study of a complex multi-layered sand reservoir of Indonesia, it shows how the two independent approaches were validated, and generalised to other similar reservoirs. The objective is to control the water production, thus extending the life of reservoirs with an active aquifer.

The first method is based on material balance coupled with 3D mapping. The paper shows how water influx which is initially calculated from history match of the material balance, can then be converted into water rise. This approach can be easily implemented on a spreadsheet with some basic input from the geological maps of the reservoir, without the need for any heavy 3D reservoir simulation. Once water rise is calculated, the paper goes on to describe how it can simply be predicted.

The second method is based on reservoir saturation logging. The paper details step by step, the procedure that was elaborated to get direct in situ measurement that could be exploitable despite a complex environment in an ageing field. It describes how the combination of different recorded parameters can reduce the uncertainty from the raw measurement. It also highlights recommendation that were drawn from initial unsuccessful attempts to log through two strings of pipe.

This paper shows how these two methods were validated on the same reservoir when a new well was drilled and tagged the new water contact at the predicted depth.

You can access this article if you purchase or spend a download.