Publications

Open hole log evaluation has been traditionally used for formation evaluation purposes and is commonly used for reservoir characterization. Adverse hole conditions can precluded use of these services, and under these circumstances, it becomes necessary to acquire the necessary log data after the well is cased for reservoir evaluation. Open hole logs provide answers with acceptable uncertainty in characterized formations. However, in cased wells, which are not well characterized, the results tend to have a higher uncertainty.During the drilling of well PTB-47 in Paluh Tabuhan Barat field, the open hole logging could not be carried out because of adverse hole conditions. High quality cased hole resistivity , density and neutron data were acquired over the zone of interest through casing, even though difficult borehole condition existed ( large wash outs filled with cement). Since no open hole data was available in the drilled section the measurements were compared with the nearby wells, with good results. The normalization factor for the cased hole resistivity tool was estimated using the open hole resistivity data of the nearby wells. Good quality of compensated densityand compensated neutron data was obtained in the cased section in spite of large washouts filled with cement, and the porosity matched well with the nearby well porosity.Evaluation of the logged section indicated the presence of hydrocarbons and based on this evaluation, the well was perforated and produced hydrocarbon. The ability to provide cased hole measurements helped the operator make a cost effective decision, as well as saving rig time and avoiding any further risk of stuck pipe, or even of losing the well.