Long Column Cementing of Light Slim Hole Wells, Mahakam Delta, Indonesia Case History

摘要

Gas fields in the Mahakam Delta are the most prolific in Indonesia. TOTAL E&P Indonesia operates Tunu, Tambora, Handil, Peciko, Bekapai and Sisi Nubi fields. To meet the increased production requirements while enhancing economic development, the operator is reducing drilling costs as much as possible. Slim hole well is the optimal gas well configuration being applied in Tunu and Tambora fields. The slim hole design diminishes the size and number of casing strings to produce the low pressure gas reserves economically. The latest well design, known as the light slim hole well, reduces the number of casing strings from previously four, to become three strings: conductor, surface, and production tubingless. In light slim hole well, the 24-in. conductor casing is hammered to 130 m depth, similar to the previous design. The 9 5/8-in. surface casing is set at 1,300 m TVD. The well then is completed with 4 1/2-in. production tubing, which is set at around 4,000 m TVD. Like all gas wells, light slimhole requires adequate zonal isolation along the production section. Cement sheath failure will result in sustained casing pressure and, in the worst case, loss of the well. A long open hole section has to be cemented from bottom across the production zones to 300 m above surface casing shoe. Placing a nearly 3,000 meters column of cement slurry along production casing is therefore one of the most challenging operations done on the well. The long cement column translates into large temperature differences between the bottom hole and the top of cement and high circulating pressure during slurry placement. In this case, the temperature difference can reach 90 degC [162 degF]. Design and selection of the cement slurry requires specific and tailored approach to ensure the cement sets uniformly along the long column, ensuring proper zonal isolation. By using advance software resources, the temperature of the cement particle is analyzed precisely during the cement placement. This paper outlines cement design approach for this long section hole, describes the overall cementing process, and shows field results of light slim hole wells in the Mahakam Delta.