Multi-combination exploiting technique of ultra-heavy oil reservoirs with deep and thin layers in Shengli Oilfield

Abstract

There isn't any mature technique to develop ultra-heavy oil reservoirs in the Shengli Oilfield because of large oil viscosity, deep and thin layer, high rate of resin and asphaltene. The multi-combination exploiting technique is developed which combines the techniques of under-pressure foam flow-back, efficient oil-soluble viscosity reducer, CO2 immiscible and steam huff and puff. The following experiments were conducted about the recovery mechanism of the technique: (1) measuring foam viscosity, sands suspension property and sands washing capacity; (2) comparing the capacities of viscosity breaking and emulsion breaking of oil-soluble viscosity reducer with the conventional viscosity reducer; (3) measuring emulsion breaking of CO2. The experimental results show: Foam has the advantages of greater viscosity, remarkable capacities of suspending and washing sands; the combination viscosity reducer has greater advantage on viscosity breaking over xylene. The emulsion breaking capacity of the combination viscosity reducer and CO2 is excellent, and the higher the W/O emulsion, the greater the capacity of emulsion breaking. Field tests show that the multi-combination exploiting technique is good in improving production of ultra-heavy oil reservoirs. ： 胜利油田超稠油埋藏深、储集层薄、原油黏度大、胶质和沥青质含量高，采用目前成熟的稠油开发方式无法有效动用。结合超负压泡沫混排技术、高效油溶性降黏剂降黏技术、CO2非混相驱油技术和蒸汽吞吐技术，提出深薄层超稠油多元复合开采技术。针对多元复合开采技术的开采机理，进行相关实验：①测定泡沫黏度以及泡沫悬砂、冲砂性能；②油溶性复合降黏剂与常规降黏剂降黏效果对比实验和破乳实验；③CO2破乳能力实验。实验表明：泡沫具有良好的悬砂、冲砂性能；复合降黏剂的降黏效果远好于二甲苯，复合降黏剂和CO2均具有很好的破乳效果，原油乳化程度越高，破乳效果越好。现场试验显示多元复合开采技术开发深薄层超稠油具有良好效果。图5表4参14