New Way to Converting Gas Wells into Oil Wells to Exceeding the Life of Mature Oil Field: Case Study at Handil Field, Mahakam Block, East Kalimantan, Indonesia

Abstract

Handil field is a giant oil field in Indonesia which started discovery since 1975. Currently, Handil Field has production around 12,000 bopd and 44 MMSCFD of gas. Through new wells data in the Handil Field from 2018 to 2022, there are around 55% of tubingless completion wells that have a main focus on producing gas reservoirs in the Handil Main Zone and Deep Zone. During drilling operation, sometimes it was found several oil reservoirs based on open hole logging result on well which will be completed by tubingless completion. To switch the completion from tubingless completion into oil well completion will make the well completion will be delayed, therefore the well will be completed with tubingless completion. Over time, where the gas reservoirs begin to deplete, there are still others oil reservoir layers in this well that wait to be produced. Due to low reservoir pressure and no gas lift facility in the tubingless well completion, thus these oil reservoirs cannot be produced. The previous solution that has been implemented is to do heavy workover, by cutting upper completion and replacing it with a new completion that includes a side pocket mandrel; or do a light workover by installing a Gas Lift Macaroni inside the existing tubing. Both solutions have disadvantages, because of high operational cost and the second solution will reduce the flow area in the tubing. Annulus Oil Based Mud Circulation is the latest solution implemented in the Handil Field, which utilizes the existing annulus to perform gas injection and then followed by the installation of Gas Lift Pack Off (GLPO) or Siphon String. This work begins with tubing punch at a depth where the gas lift injection point will be used, then proceeds to circulate OBM from the annulus to the waste tank, then followed by installation of GLPO or siphon string. This method has advantages, there are no heavy workover is required, no additional spool is needed on the tubing hanger for gas injection, and has a faster work duration compared to the two previous methods. Through this method, out of a total of 11 tubing less wells, there is a remaining stake of 1200 kbbls in the oil reservoir which has been successfully unlocked and some have been produced through this method and lifts with gas lift deepening, and there is still a remaining stake of 746 kbbls as a future candidate to be generated through the application of the OBM Annulus circulation method. This method is particularly applicable to old oil fields where there is residual oil-based mud in the annulus of several depleted gas wells and there are still oil layers that need to be saved.