IMPROVING PERFORMANCE IN A MATURE FIELD: INTEGRATED ANALYSIS FOR IDENTIFICATION AND OPTIMIZATION OF LOW-RESISTIVITY HYDROCARBON-BEARING SAND RESERVOIRS IN SEMBERAH FIELD, MAHAKAM DELTA, KUTAI BASIN

摘要

Semberah field is deposited in a fluvio-deltaic environment in the prolific Kutai Basin, East Kalimantan. For more than 30 years, the majority of the production comes from large reservoirs with high-permeability intervals, characterized by standard and near-ideal well log shapes. However, a number of potential pay zones with non-ideal log shapes, including low resistivity reservoirs, were initially bypassed, leaving significant reserves on the ground. This paper discusses the low resistivity zones in the Semberah field, which is possible to have hydrocarbon potential, which conventional analysis has missed before. The paper includes integrated analysis of logs, core, thin sections, XRD (clay minerals identification), fluid analysis (MDT), and dipmeter data that have been carried out to reveal the occurrence of low resistivity zones in Semberah field. Analysis from cores which show the presence of dispersed clay illite/smectite and conductive minerals such as pyrite and siderite are included as one of the main factors. The paper also includes several examples of some wells that were perforated using the recommendations from the integrated analysis above. The analysis has proved that these low resistivity zones are hydrocarbon bearing pay zones. Currently, some of these zones have produced more than 123 MMCF of gas and are still flowing. Others zones reveal presence of oil and condensate, but those have not yet been put on production because oil and condensate can’t flow naturally. Gas lift installations would be applied to put these wells on production. Currently, the impact to the production is 10% increase of daily production from Semberah.The results so far will increase level of confidence to continue developing these types of reservoirs.