塔河缝洞型碳酸盐岩油藏注气提高采收率物理模拟研究

鉴于塔河缝洞油藏单井注气吞吐试验取得了较好采油效果,为将注气技术从单井吞吐向单元区块进行推广,有必要优化缝洞型油藏单元注气方式。本文首先通过岩板刻蚀缝洞模型来研究不同气驱方式的产液特征、产液规律,在此基础通过具有类似缝洞结构的玻璃刻蚀模型开展可视化物理模拟研究来定性解释上述规律产生的机制。板状模型物理模拟研究发现,缝洞模型水驱后以不同方式注气,第一阶段皆表现为产水、不出油；不同注气方式产油速度、采收率增值差别较大。从采油速度看,转单纯注气效果优于气水同注、气水交替和注泡沫；从采收率增值看,泡沫驱 >气水同注> 纯氮气驱 >气水交替。研究表明,水、气体、泡沫在缝洞介质中流动特征可概括为：气往高处去,水往低处流,泡沫高低都能走,上述驱替介质在缝洞模型中特定的行进方式决定了其对水驱剩余油的作用机制和产液特征。

Physical simulation study of gas enhanced oil recovery for fractured-vuggy carbonate reservoirs in Tahe oilfield

Gas huff and puff in single well has achieved perfect oil recovery in Tahe fractured-vuggy reservoirs. In order to apply gas injection from single well to reservoir block, it is essential to optimize gas injection method. First, liquid production properties and patterns were studied by fractured-vuggy plate model. Based on that, the liquid production mechanism was studied by the glass etching model, which had similar structures of fractures and cave as the plate model. Results of plate model show that after water flooding, the first production stage is water production despite of gas injection methods; oil production rate and oil recovery varies significantly under different gas injection methods. Among gas injection alone, simultaneous injection of water and gas, alternative injection of water and gas and foam flooding, gas injection alone has the highest oil production rate. As to oil recovery, foam flooding is better than the others and alternative injection of water and gas recovers the least oil. From visualized simulation, flow characteristics of water, gas and foam can be generalized as follows: gas flows to the higher and water flows to the lower; foam can sweep the both. Above flow characteristics of displacement media determine the remaining oil pattern and liquid production.