Lessons Learned from the First Chemical Sand Consolidation in Zawtika Field

Abstract

Abstract The conventional gravel pack sand control completion (High Rate Water Pack / Extension Pack) was the primary sand control method for PTTEPI, Myanmar Zawtika field since 2014 for more than 80 wells. Although the completion cost of gravel pack sand control was dramatically reduced around 75 percent due to the operation performance improvement along 5 years, the further cost reduction still mandatory to make the future development phase feasible. In order to tackle the well economy challenge, several alternative sand control completion designs were reviewed with the existing Zawtika subsurface information. The Chemical Sand Consolidation (CSC) or resin which is cost-effective method to control the sand production with injected chemicals is selected to be tested in 3 candidate wells. Therefore, the first trial campaign of CSC was performed with the Coiled Tubing Unit (CTU) in March to May 2019 with positive campaign results. The operation program and lesson learned were captured in this paper for future improvement in term of well candidate selection, operation planning and execution. The three monobore completion wells were treated with the CSC. The results positively showed that the higher sand-free rates can be achieved. The operation steps consist of 1) Perform sand cleanout to existing perforation interval or perforate the new formation interval. 2) Pumping pre-flush chemical to conditioning the formation to accept the resin 3) Pumping resin to coating on formation grain sand 4) Pumping the post-flush chemical to remove an excess resin from sand 5) Shut in the well to wait for resin curing before open back to production. However, throughout the campaign, there were several lessons learned, which will be required for future cost and time optimization. In operational view, the proper candidate selection shall avoid operational difficulties e.g. available rathole. As well, detailed operation plan and job design will result in effective CSC jobs. For instance, the coil tubing packer is suggested for better resin placement in the formation. Moreover, accommodation arrangement (either barge or additional vessel) and logistics management still have room for improvement. These 3 wells are the evidences of the successful applications in Zawtika field. With good planning, lesson learned and further optimization, this CSC method can be beneficial for existing monobore wells, which required sand control and also will be the alternative sand control method for upcoming development phases. This CSC will be able to increase project economic and also unlock the marginal reservoirs those will not justify the higher cost of conventional gravel pack.