OPTIMUM SALT CONCENTRATION DESIGN OF LOW SALINITY WATER INJECTION IN T STRUCTURE AT S FIELD USING TNAVIGATORTM SIMULATOR

• Main Author: Vincent Bungaran Parded, George
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/40056
• Institution: Institut Teknologi Bandung

In Indonesia, most of the oil fields have been entered as a mature field. Reservoir fluids in those fields overall are categorized as medium to light oil. According to the condition of the fields, it needs to be produced with secondary recovery method and further with tertiary recovery, or usually called Enhanced Oil Recovery (EOR), in the future. For over the years ago, waterflood has been the most successful method to increase oil recovery in secondary recovery method. The waterflood is preferable over other fluid injection methods due to its available source, simple for operation, and relatively low cost. However, a waterflood is often designed without looking at the chemistry role of the injection water. Low Salinity Water Injection, which involves tuning the salt concentration and ionic composition of the injection water, has been given great attention as a new EOR method which has gained its popularity in the past decade. Some laboratory tests have indicated that injecting low salinity water can improve conventional waterflood performance by 5 – 20%. Hence, it introduces a promising idea that Low Salinity Water Injection should be implemented to mature fields in Indonesia for EOR activity. This paper will focus on determining the optimum salt concentration of injection water for low salinity water injection. Low salinity water injection in this study will be acted as a secondary recovery method. The production performance as a result of low salinity water injection was acquired by numerical simulation using tNavigatorTM Simulator. This simulation will be conducted in “T” Structure at “S” Field, one of an oil field in Indonesia, through a reservoir simulation study. The field has two producer wells and one injection well, which will be produced about seven years with ten months of injection, according to the development plan from the company. The simulation is done with the constraint injection rate of 1,000 STBD. The low salinity water is designed by dilution of salt concentration from formation water with 18,000 ppm of concentration. In this case, the designed low salinity water will be used in the simulation such as 2x diluted (LSW 1), 5x diluted (LSW 2), and 10x diluted (LSW 3). The result of this study concluded that Low Salinity Water Injection achieved more oil recovery than conventional waterflood did, especially from TGI-3 producer well. This incremental is caused by alteration of salt concentration at clay surface in formation, which is described from Salting-in Effect mechanism. This mechanism causes increased of solubility in injection water that will lead the oil particles easier to be released from the clay surfaces. The simulation result shows that injection water with 5x diluted (3,600 ppm), or LSW 2, is chosen as an optimum salt concentration design, which gives the best result with a recovery factor about 57.41%.