Fluid identification is an important objective to resolve key uncertainties of a complex reservoir prior to perforation in the developed fields of Eastern Kalimantan. This paper explains how using a formation tester equipped with two downhole fluid analyzer modules helped understand reservoir fluid characteristics, identify production zones and optimize perforation zone selection. Relying only on open hole log data and performing correlations among nearby wells may be inconclusive since the channel sands under study have limited lateral extent and hard to correlate. Several layers are potential pay zones and may contain oil or gas. However, water zones and secondary gas cap formation in a few layers are also common. Nonetheless, unexpected fluid production, such as water or excessive gas is an undesirable outcome. A formation tester equipped with an extra large diameter probe and two downhole fluid analyzer modules was used to identify reservoir fluids in newly drilled wells. Two fluid analyzers were placed above and below the downhole pump module. The fluid analyzers monitored downhole oil based mud filtrate contamination, free gas presence, water or oil flow at selected depths. The surveys identified the downhole fluids and clarified oil, gas and water bearing zones. Some zones were identified to have gas and possible oil presence. Few stations, which were clearly identified as oil were perforated and produced oil/dry oil with natural flow. The survey helped optimize perforation zone selection, avoided unwanted fluid production and helped the operator to find and produce oil in a complex setup.
Author : Andry Halim, Cosan Ayan, Elin Haryanto, Nicolas Orban