STUDI TERINTEGRASI PERENCANAAN IN-SITU GAS LIFT

• Main Author: Victor Siahaan, Jhon
• Format: Final Project
• Language: Indonesia
• Subjects: Pertambangan dan operasi berkaitan
• Online Access: https://digilib.itb.ac.id/gdl/view/58865
• Institution: Institut Teknologi Bandung

Gas lift is the most used artificial lift method in oil fields because its suitablity for various reservoir condition. Gas lift can be applied in high Pwf wells with high or low productivity index (PI), or in low Pwf wells with high or low PI. Besides continuous and intermittent gas lift (conventional gas lift), there is in-situ gas lift or natural gas lift or auto gas lift. In-situ gas lift is an artificial lift system using gas from gas bearing formation/zone or gas cap as the injected gas. Both conventional and in-situ gas lift has the same principle to reduce fluid pressure gradient in well therefore increase fluid production. The main advantages from in-situ gas lift is lower investment cost compared to conventional gas lift because it does not need compressor unit to inject gas from surface to tubing through the annulus. Injected gas can be supplied by gas zone above or below the oil producing zon.Therefore, this artificial lift method is called in-situ gas lift. In this paper, in –situ gas lift system is designed in a well exist in a synthetic reservoir with low pressure. Reservoir model is built using PETREL RE. The reservoir has an oil zone and a gas zone overlaying the oil zone. The reservoir has 100 ft thickness with depth of top reservoir and bottom reservoir is 3000 ft and 3100 ft respectively. Reservoir pressure is 1000 psi with its productivity index equals 2.6 STB/psi. Before in-situ gas lift is applied, the optimum oil production rate through 2.441 inch inside diameter tubing will be determined. Using the software PROSPER IPM, this natural flow case give 406 STB/D of oil production rate with 830 psi bottomhole flowing pressure. The AOFP from the IPR Ais 1441 STB/D so that there is a possibility to increase the well production rate using the in-situ gas lift. An important parameter in optimizing a gas lift well is the GLR. Sensitivying the GLR value yields the optimum GLR as 600 SCF/STB which will increase the oil production rate to 983 STB/D with bottomhole flowing pressure as 518 psi. To reach the optimum GLR, 458 MSCF/D gas rate is needed to the tubing through the downhole SSD valve. The diameter of the valve is 1/16 inch to get the optimum GLR. By simulating integrated production from reservoir to the wellhead, in-situ gas lift case increase the oil significantly compared to natural flow case.