Septoratno Siregar

An Investigation on Gas Lift Performance Curve in an Oil-Producing Well

The main objective in oil production system using gas lift technique is to obtain the optimum gas injection rate which yields the maximum oil production rate. Relationship between gas injection rate and oil production rate is described by a continuous gas lift performance curve (GLPC). Obtaining the optimum gas injection rate is important because excessive gas injection will reduce production rate, and also increase the operation cost. In this paper, we discuss a mathematical model for gas lift technique and the characteristics of the GLPC for a production well, for which one phase (liquid) is flowing in the reservoir, and two phases (liquid and gas) in the tubing. It is shown that in certain physical condition the GLPC exists and is unique. Numerical computations indicate unimodal properties of the GLPC. It is also constructed here a numerical scheme based on genetic algorithm to compute the optimum oil production.

Laboratory study: The development of a sodium lignosulfonate (SLS) surfactant formulation for light oil reservoir to improve oil recovery

Sodium lignosulfonate is an anionic surfactant that has good potential for enhanced oil recovery (EOR). Surfactants based on sodium lignosulfonate (SLS) are selected because they can be synthesized from renewable materials, available raw materials, relatively cheaper than other surfactants, and are environmentally friendly. Previous studies on SLS for the EOR show SLS performance not yet optimum, so it needs to be formulated to improve its performance. The formulations applied in this study were the addition of sodium oleate as cosurfactant and ethylene glycol butyl ether (EGBE) as dispersants, with a ratio of 80% of SLS surfactants: 16% sodium oleate: 4% EGBE. Tests conducted in this study included the SLS surfactant compatibility test in the laboratory scale and continued to the coreflooding test. The compatibility test consisted of aqueous stability test, phase behavior test, and interfacial tension test (IFT) with three test concentrations. All testing was done for light oil reservoir. The SLS surfactant solution before formulation showed the two phases in aqueous stability test and high IFT in 10-1mN/ m while after formulation the IFT reached 10-3mN/ m. The phase behavior before and after formulation showed the same performance, in low concentration had lower phase and in high concentration had middle phase. The incremental recovery from coreflood test using 0.5 % and 1 % concentration of SLS formulation were 34.09 % and 37.5 % respectively. The results showed that SLS surfactant can be good candidate for chemical EOR.Sodium lignosulfonate is an anionic surfactant that has good potential for enhanced oil recovery (EOR). Surfactants based on sodium lignosulfonate (SLS) are selected because they can be synthesized from renewable materials, available raw materials, relatively cheaper than other surfactants, and are environmentally friendly. Previous studies on SLS for the EOR show SLS performance not yet optimum, so it needs to be formulated to improve its performance. The formulations applied in this study were the addition of sodium oleate as cosurfactant and ethylene glycol butyl ether (EGBE) as dispersants, with a ratio of 80% of SLS surfactants: 16% sodium oleate: 4% EGBE. Tests conducted in this study included the SLS surfactant compatibility test in the laboratory scale and continued to the coreflooding test. The compatibility test consisted of aqueous stability test, phase behavior test, and interfacial tension test (IFT) with three test concentrations. All testing was done for light oil reservoir. The SLS surfact...