CHARACTERIZATION OF GENESIS OF THE DECREASE OF FORMATION WATER SALINITY IN THE MAIN ZONE OF TUNU FIELD, KUTAI BASIN

• Main Author: KURNIAWAN SAID, DWI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/21833
• Institution: Institut Teknologi Bandung

The Tunu Field is the biggest gas and condensate field in Indonesia. One of the obstacle in developing this field is the uncertainty in resource or reserve calculation because of the uncertainty in water salinity parameter in this field. The purpose of this study is to know the genesis of water salinity in this field. <br /> <br /> <br /> <br /> The data used in this study are wireline log (gamma ray, density, neutron, and spectral gamma ray), core (scanning electron microscope and x-ray diffraction), and water chemistry data (salinity, formation water ion content, and isotopes (&#948;18O, &#948;D, dan &#948;87Sr/86Sr). The result of this study shows that there is a decrease in water salinity through depth in the Tunu Main Zone. The result of the data analysis shows that this decrease is caused by the contribution of compaction water from shale entering the reservoirs in the Main Zone. <br /> <br /> <br /> <br /> The process controlling this water expulsion from shale is interpreted to be reverse osmotic. In this process, water flows through semi permeable membrane to the region with lower salinity. In the study area, the shale acts as the semi permeable membrane. During the water expulsion from the shale, salts dissolved in the water cannot penetrate the shale beacue its molecular size is relatively bigger, so that only water molecul that can expell from the shale. Therefore, the expelled water has a very low salinity, and then, this water is mixed with reservoir water. This circumstance causes water salinity in the reservoir to be decreased. <br /> <br />