FACIES ANALYSIS AND CHARACTERIZING A RESERVOIR SANDSTONES LOWER TALANG AKAR FORMATION (TAF) TO HELP INCREASING THE EFFECTIVENESS OF OIL RECOVERY IN BROWN OIL FIELDS

• Main Author: Alam, Saepul
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/40463
• Institution: Institut Teknologi Bandung

Brown oild fields which located in the depositional environment transition zone and in the criss-cross compaction zone (~ 950-1100m) have the value of sandstone P wave propagation ( pwave ) that overlays with pwave values shale , so it's crossplot pwave against gamma ray does not have a regular pattern, pwave is not sensitive to changes in lithofacies. However, in the model rock dispered shally sand , the density profile has a good relationship with gamma ray so that the acoustic impedance which is the multiplication of the density with pwave still reflects lithology and can be used for pseudo gamma ray prediction in the framework of analysis distribution of lithofacies. Pseudo gamma ray prediction is performed with optimum wiener filter (OFW) . Optimum weiner filter (OFW) designed from three wells can be done in three scenarios, namely (1) the average optimum wiener fiter of each well, (2) the average of the input and desired output, and (3) the average cross-correlation and auto - correlation. Of the three scenarios, the third scenario gives the most optimum results. Pseudo gamma ray obtained by OFW used for prediction of gamma rays using a multi attribute analysis and probabilistic neural network to increase the level of correlation to actual data and increase the involvement of well data from three to 15 wells. Because the target is a thin layer, the lateral distribution is carried out using a colocated cokrigging geostatistical . The level of lateral correlation before geostatistics is 86% while after geostatistics a significant increase with a correlation level of 99%. There are three clusters of gamma ray distribution that stretch from north to south with shale volume levels (vshale) different. Difference in vshale content indicates a difference in the features of the developing transition zone. The first cluster in the north is a fluvial sand feature that is clean and well-grain with high porosity, developing in terrestrial environments . The second cluster is feature tidal flats which is very shally, while the third cluster is a sand bar feature which developed in a shallow marine that was washed over so it was quite clean . The boundary between the features of the terrestrial zone is the coastline that moves along the sea level.