This paper presents the thermal stimulation project for two horizontal wells, started from the completion design, cold production performance, preparation and the execution as well as well evaluation of the practical application of CSS are the main keys to understanding reservoir performance and identifying that opportunities of steam stimulation will improve the ultimate recovery.

Horizontal wells typically yield a higher primary recovery than vertical wells due to their larger contact area with the reservoir. The original expectation for primary production performance of these wells has not been achieved for three reasons: high oil viscosity, formation damage and sand accumulation around the liner during the early production. Following performance during period of primary production, it was decided that these wells should be stimulated using cyclic steam, with the use of steam as both heating and lifting agent; additional recovery is expected to be achieved. The well completion designs utilized thermal compliance equipment with cost effective considered and to focus the efforts on the new stimulation processes with the use of thermal completions.

Based on the screening result and taking into account the reservoir characteristic and preliminary calculation of oil recovery and requirement, thermal method is considered as the appropriate EOR method for B field. The viability of thermal recovery in B field was tested with Cyclic Steam Stimulation (CSS) in K sand.

The wells selected for the pilot are B1 and B2, both are horizontal well and thermal compliance well. They are around 400 m of horizontal length. A portable steam generator was utilized to produce steam with steam quality of 87 %

The total cumulative steam injected in well B1 was 5000 tons and estimated energy injected at reservoir was 2.9 BBtu. The effective day of soaking period was 10 days which included hoist and hook-up activity. The initial oil gain was 124% gain and it is as per reservoir model prediction. The temporary steam-to-oil-ratio (SOR) as of 2013 is 4.2 ton/m3.

On the other hand, the plan for CSS in B2 was cancelled due to well problem. The plan for steam injection was shifted to 2014.

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