Publications

As a part of the 2010-2012 heavy oil exploration program in IH Field, 2 shallow wells at TB (TD max. 580 ft) and 3 ultra-shallow wells (TD max. 378 ft) at TL prospects were proposed, firstly to ensure the presence and the variation of heavy oils on the crest-structure, and secondly to evaluate the reproducibility of heavy oil by using appropriate enhanced oil recovery methods. To ensure the highest quality of 4” sample core recovery in the pre-determined objective oil loose sand, full closure coring technology was implemented for the continuous coring job in both TB and TL wells (total core cut min. 194.8 ft, max. 480 ft). The lessons learned from the TB-1 well construction were implemented in the remaining wells and excellent results were achieved, such as more than 93% core recovery for each well). All the TB-TL wells were designed taking into account the high temperature, including aspects such as thermal cement, high temperature wellhead, and high grade casing, since cyclic steam stimulation (CSS) method was chosen to evaluate the producibility of heavy oil in these wells. After a completion job, each well was tested by conventional pumping method (for a period of between 2 weeks and 1 month). Next, CSS operation was applied, with a maximum injection temperature of 455o F and pressure of 420 psi (2 weeks to 1 month). The results were a continuous influx rate of 52-550 blpd (100% WC) at TB wells and an intermittent influx rate of 1.0-6.3 blpd (12-100% WC) at TL wells. The main risk of CSS method is the integrity of top seal and avoiding steam eruption in the prospect area. This was investigated by using the coring result and a topography study. No eruption was identified during the CSS operation. Although producibility of heavy oil is challenging, the implementation of CSS well design in TB-TL wells has proven to meet the aforementioned technical objectives.