Matrix Stimulation of Thick Carbonate Formation:High Rate Acid and CT Acid Treatments-A Case History

摘要

Most of oil and gas wells in Indonesia are developed in Sumatra and Java.Central Sulawesi is one area in Indonesia that previously didn't really have high activity in oil and gas because of its location that drives the logistics to become an issue.Central Sulawesi now is showing more activities on oil and gas exploration and production with the presence of Tiaka field that produced about 2,981 BOPD (Dec-07).This paper covers several stimulation works performed in Tiaka field,Central Sulawesi.The produced oil is being temporaryly stored in an FSO facility and then transported to refinery in Indonesia or exported.Tiaka wells are drilled at some angles into Tomori formation,a thick carbonate formation which ranges from 70'-131' in thickness containing 28 API oil.Porosity varies from 10%-15%.Four wells (Tiaka #5,6,7,8) were completed with cemented casing and perforated across the target zone.Two wells (Tiaka #9,10) were completed with uncemented pre- perforated liner across the target zone.Length of perforation for stimulation work ranges from 170'-840'.Combinations of hydrochloric acid and acetic acid were used and the composition was held constant for all acid stimulated Tiaka wells.However several acid volume loadings (in gal per ft of interval treated) were tried to optimize the treatment.Several acid placement methods were tried:high rate acid treatment with gelled acid and acid through CT.All stimulated wells showed significant production increase compared to their production rates prior to stimulation.Discussion is made on which methods gives the best production result for the existing wells and the preferred method of stimulation for the future Tiaka development wells.This paper details the application of acid stimulation works in 5 Tiaka wells,post treatment well performance,best practices,and lessons learned.