How to Survive Brown Oil Field Production - Re-route Venting System to Derrick Mast Rig to Anticipate Oil Production Losses

Abstract

Abstract SBU (South Bussiness Unit) fields was found in 1970 and has been produced more than 40 years. There are nine fields produced from this area, they are Cinta, Rama, East Rama, Wanda, North Wanda, South West Wanda, Kittty, Nora, Gita, Selatan, Lita and Suratmi. Reservoir pressure in the main reservoir Rama Cinta Wanda was originally more than 1700 psi, and by the time it was decreasing to 300 – 500 psi, with low reservoir pressure so many wells in SBU could not be produced due to gas problem and low influx. In year 2008–2009, venting system to scrubber was introduced to reduce the casing pressure of the well to anticipate back pressure in each wellbore. In the well which had reservoir pressure below bubble point, in every drawdown of ESP (create delta pressure), the gas would release in fill the column of annulus in the wellbore. If the casing pressure is close or flow to the system riser pressure of the platform, the column of gas would push the fluid level in the wellbore and make problem of the pump (gas lock, pump off, slug flow, etc). By venting the casing pressure to the scrubber and vented to the atmosphere, that problem was solved. That is way almost all platform in SBU was installed venting system to scrubber to maintain the oil production. In addition, SBU field also had H2S concern in the gas vented from the scrubber, this H2S concentration was very dangerous for human to work in the area. This had been a big concern from management to have a safety workplace for all manpower. ESP (Electrical Submersible Pump) was installed in all SBU wells as arlificial lift system. These ESP had runlife with average one year life time. Since SBU have almost 140 wells running with some reactivation and workover job per year, so well intervention job need to be done in whole year to maintain the production of SBU. Since the oil and gas block was located in offshore, workover rig was used to do well intervention, and barge as accomodation place. In May 2013, there was a small fire incident in one platform with venting system while well intervention which direcltly to be extingushed. It caused management give regulation to shut in venting system while well intervention. SBU production was decreased dramatically since the implementation of this policy since a number of wells in the platform need to be shut off while well intervention in the same platform. Re-routing venting sytem to derrick mast is a new technique in South East Sumatra block which can accomodate well intervention using workover rig in the platform which has continues running venting system. Some studies has been done to ensure this job was accepted in the technical, safety, and Indonesian goverment's regulation. This job lead SBU inceeasing oil production since all wells in the vented platform were still running while workover rig coming to replace ESP of DHP (down hole problem) well.