Publications

Stupa is a gas condensate field in Mahakam PSC operated by Pertamina Hulu Mahakam (PHM) and located offshore at east of Kalimantan. Due to sedimentation on deltaic environment, the field has more than 50 layers containing hydrocarbon which increase the field complexity. Initially, core data is used as reference to estimate permeability in forecasting well performance. However, permeability derived from core data is too low compared to actual well performance. This leads to long process for history match and low accuracy in production prediction. The aim of this study is to improve permeability estimation by incorporating production logging data, which is frequently performed to have split of commingle production as the main objective. Based on Darcy law, productivity is related to various parameters in which each parameter has several degree of uncertainty depend on the available data and field operational condition. For Stupa field, pre-study has shown that reservoir skin will have the highest uncertainty. However, skin uncertainty could be minimized by focusing evaluation at reservoirs perforated in virgin condition. Reservoir permeability is then calculated from measured gas rate on production logging, and new Phi-k correlation can statistically be generated once sufficient data is available. As validation, new permeability correlation is applied to existing material balance model and history matching is re-performed. The method actually suggests correction of permeability correlation as soon as the first Production Logging (PL) campaign is performed. Permeability correlation generated from APERM is obviously accurate; hence shorter time to perform history match and higher confidence in delivering production forecast. Furthermore, the method could be used to calibrate porosity-permeability correlation on producing field, or to generate one for the field with no core data.