Preliminaries Study of Pilot Project Carbon Capture Utilization and Storage in An East Java Oil and Gas Field

Abstract

A preliminary study for Carbon Capture Utilization and Storage (CCUS) pilot project in an East Java oil and gas field Indonesia has been conducted. CCUS projects have dual purposes: providing a means for increasing production in declined oil fields and reducing greenhouse gas emissions from oil and gas sector by injecting the separated CO2 into the declined oil and gas reservoir. CCUS will be attractive in Indonesia since it could offer additional income for the country from the incremental oil and gas productions and the implementation could use the existing regulations that valid for oil and gas sector. The study of a CCUS pilot project plan has been conducted in order to make sure that the reservoir is suitable for CO2 EOR storage. The CCUS pilot project plan is situated in an oil onshore field in East Java province, Indonesia, which was discovered in 2001. It is situated in the Tuban block, and has nearly 308 million STB of oil in place and more than 100 million barrels of oil in cumulative production. The chosen oil field for has been in production decline for several years and yet the efforts to increase recovery, such as water injection, have been ongoing. Suitability for a CO2-EOR operation is dependent on the petrophysical properties of the reservoir, such as porosity, permeability, and fluid saturation, as well as in-situ reservoir fluid properties such as oil density and viscosity. Reservoir depth is also a key parameter in making a decision as it will impact the miscibility and interaction between CO2 and oil phases. This CO2 EOR pilot project consists of a total of five wells – four production wells at the four corners of a square with an injection well in the middle. The preliminary design for a pilot scale is based on the available CO2 from the field itself, which currently produces 4.4 million SCF (240 tones) of CO2 per day. This pilot-scale test is aimed at examining the performance and viability of a gravity stable CO2 flood. The proposed CO2 injection volumes at the pilot scale are 5 million SCFD respectively, which are estimated to correspond to a production increase of 400 BOPD. For a gravity (gas cap) drive EOR system, the gas (in this case CO2) will be injected into the gas cap above the producing zone. This will help in driving the oil down to the production zones and into the production wells. When injecting into the gas cap, the wellbore integrity in the gas zone and just above the gas zone in the sealing layer must be evaluated. This is to ensure that the CO2 does not escape up the wellbore outside the casing and enter a higher layer. It is essential to include well integrity in the baseline monitoring program to evaluate periodic changes in the well integrity with injection. Monitoring is crucial for the success of a subsurface CO2 injection operation. CO2 injection monitoring is used to verify and compare the injection behaviour with reservoir simulation predictions as well as monitor for potential CO2 leakage through faults or wellbore and avoid any CO2 migration to and accumulation at the surface.