Study of Cyclic Steam Stimulation (CSS) Fuel Using Compressed Natural Gas (CNG) As Conversion From Marine Fuel Oil (MFO) to Enhance Energy Efficiency and to Reduce CO2 Emissions

Abstract

Batang is a marginal oil field in Indonesia with heavy oil and high pour point oil characteristics. When the well temperature drops during production, usually the water cut increases due to the lower mobility of oil. Hence, cyclic steam stimulation (CSS) is routinely needed to increase the well temperature and reduce the viscosity of oil, which improves flow assurance from the wells to the gathering station. Currently, marine fuel oil (MFO) is used as the fuel for the steam generator unit. However, the cost of MFO is even higher than the steam generator’s daily operation cost and the urge to reduce CO2 emissions is contrary to the utilization of this fuel. So a trial of compressed natural gas (CNG) has been introduced to tackle the problems from using MFO, and this trial has successfully lowered both the fuel price and the impact on the environment. MFO is simpler to use than using CNG, because MFO can easily be transported using tanker trucks without the need to maintain the tank within specific parameters. Also, MFO can be offloaded easily to the storage tank of the steam generator unit. CNG utilization is more complicated because firstly gas from the source needs to be compressed, which needs investment in a gas compression station to be built near the gas sales point based on an agreement between the buyer and the seller. Then, the CNG needs to be transported using a gas transportation module (GTM) to maintain the CNG’s parameters until reaching the location. After arriving, the gas needs to be decompressed to suit the steam generator’s operating parameters by using a pressure regulating system (PRS), and then the gas will be delivered to the steam generator to be used as fuel for CSS. A trial of CNG utilization has been performed in Batang and the results are promising. Using CNG reduces costs by 60% whilst also reducing CO2 emissions, which supports the company’s goal to achieve net zero emission. Beside the benefit of this conversion, deep risk mitigation was performed due to the additional hazards from CNG usage such as high pressure and temperature. This paper will discuss the detail of the technical execution, a comparison of parameters achieved, risk analysis, environmental impact, and an economic evaluation. This CNG fuel conversion for CSS activity can be a benchmark for the energy industry to significantly reduce both operational costs and environmental impact while maintaining the stimulation to increase oil production.

Key findings

• ▸CNG utilization is more complicated than MFO due to transportation and storage requirements.
• ▸The use of CNG has successfully lowered both fuel price and environmental impact.
• ▸MFO is simpler to use than CNG, but is costly and increases CO2 emissions.

Keywords

Identifiers

DOI

10.29118/ipa22-e-169

Journal

Proceedings of Indonesian Petroleum Association, 46th Annual Convention & Exhibition, 2022

Year

2022