Increasing Brown Oil Field Recovery Factor by Integrated Subsurface Review, Drilling & Workover Operation, and Surface Facility Reconfiguration – Case Study: Rama E Platform Reactivation

Abstract

Abstract Deal with brown oil field with runlife of the production more than 35 years has many challenges. Pressure depletion was one of the main concerns of maintaining survival of the field. From the geological aspect, reservoir which produced from limestone was also have many challenges, especially for heterogeneity of the reservoir. Both problems were faced in Rama field which impact the low recovery factor of this brown limestone field. Some approaches was held to increase oil recovery of this field, integrated sub surface review was done aggressively to bring some concept and followed up by some efforts from drilling, workover also surface facility. Rama field was developed in 1975 with the initial production was about 20,000 BOPD. As of June 2009, Rama field has been producing more than 137 MMBO with production ± 4,000 BOPD mainly from Upper Baturaja. A waterflood project was held in the field from 1982 until 1991 where a large amount of sea water had been injected into Baturaja formation. As the result, the reservoir pressure increased and maintained from 700 psi into 950 psi during the water flood period. However, early water breakthrough was occurred as well and got the water cut jumped into more than 90% from initially 60%. In some wells the water cut could be as high as 99%. Due to its bad impact on the oil production the water flood project was suspended in 1991. Ten years later an oil re-saturation phenomenon has been observed from some wells produce from Upper Baturaja with water cut in the range of 50–90%. The oil production rate from Upper Baturaja was 3,000 BOPD with 85% - 90% water cut. In early 2009 two infill well was drilled and one well was reactivated and gave good indication of decreasing water cut Rama E wells are among the wells that got bad impact from massive waterflood due to water cut increase, and one by one those wells are abandoned. The platform itself has been abandoned since 1999. Regarding good result of two infill and one reactivation wells, it was proposed to reactivate Rama E platform by modification of Rama-E platform include refurbishment of existing platform, installation of mezzanine deck, Power Control Room, iso-transformer, production process piping and equipment. Reactivation of the wells themselves would be done using jack up rig and snubbing unit. The objective of this project is to add oil reserves and production with sufficient cost by doing reactivation abandoned platform without drilling new wells.The recovery factor by June 2009 from Upper Baturaja is estimated 14% (OOIP ≈ 505 MMBO). By reactivation of five wells in Rama E, reserve increase up to 631 MBO (2011), it was increase recovery factor significantly.