Du Dianfa, Zhang Yaozu, Liu Xin, Zhang Lina, Ren Lichuan, Liu Peng
College of Petroleum Engineering, China University of Petroleum, Qingdao, Shandong 266000, China.
Institute of Engineering Technology, East China Company, SINOPEC, Nanjing, Jiangsu 210000, China.
ACS Omega. 2021 Sep 15;6(38):24752-24764. doi: 10.1021/acsomega.1c03588. eCollection 2021 Sep 28.
Different from conventional oil and gas, the storage and seepage space of heavy oil reservoirs are extremely complicated, thereby making it difficult to describe reservoirs in detail over the heavy oil production process. Acquiring development results accurately in real time is still a demanding task, and it is also a challenge to predict the average remaining heavy oil saturation during the production process. Tracers are mostly used to monitor steam flooding to obtain the real-time dynamics during heavy oil production in fields. However, the flow pattern of gas tracers in heavy oil is still unclear, with very rare investigations. In this work, a new one-dimensional gas tracer convection-diffusion model that considered the retention and oil phase migration velocity was established using the percolation law of gas tracers. The reservoir description coefficient was introduced to describe the relationship between the migration velocities of the oil and gas phases in the heavy oil reservoir. Subsequently, a new gas tracer well pattern flow model was also constructed based on the gas tracer linear flow model and verified simultaneously. The results revealed that at a larger partition coefficient, more amounts of gas tracers were distributed in the crude oil, the duration of stagnation was extended, and the start time of tracer production was moved backward. The injection velocity had a very minor effect on the tracer production performance. As the fluid injection rate increased, the duration of gas tracer production was extended; however, after the injection rate reached a certain level, the difference in the arrival time of the peak become minor. The effects of crude oil viscosity on the tracer production were reflected by the breakthrough time, production time, peak concentration, and peak arrival time of the tracer. Compared with the production curve of the crude oil viscosity, the peak of the production curve with high crude oil viscosity has a faster peak time and a large peak value. The reservoir description coefficient mainly affects the peak concentration of tracer production and has very minor effects on the production time and other parameters. The outcomes of this work can be applied in the field of heavy oil development, in particular, for the heavy oil reservoir description and dynamic monitoring.
与常规油气不同，稠油储层的储存和渗流空间极其复杂，因此在稠油生产过程中难以详细描述储层。实时准确获取开发成果仍是一项艰巨任务，预测生产过程中的平均剩余稠油饱和度也是一项挑战。示踪剂大多用于监测蒸汽驱，以获取油田稠油生产过程中的实时动态。然而，气体示踪剂在稠油中的流动模式仍不明确，相关研究非常少见。在这项工作中，利用气体示踪剂的渗流规律建立了一个新的考虑滞留和油相迁移速度的一维气体示踪剂对流扩散模型。引入储层描述系数来描述稠油储层中油气相迁移速度之间的关系。随后，还基于气体示踪剂线性流动模型构建了一个新的气体示踪剂井网流动模型并进行了同步验证。结果表明，在分配系数较大时，更多的气体示踪剂分布在原油中，停滞持续时间延长，示踪剂产出开始时间后移。注入速度对示踪剂产出性能的影响非常小。随着流体注入速率增加，气体示踪剂产出持续时间延长；然而，注入速率达到一定水平后，峰值到达时间的差异变小。原油粘度对示踪剂产出的影响通过示踪剂的突破时间、产出时间、峰值浓度和峰值到达时间体现。与原油粘度的产出曲线相比，原油粘度高的产出曲线峰值时间更快且峰值更大。储层描述系数主要影响示踪剂产出的峰值浓度，对产出时间等参数影响非常小。这项工作的成果可应用于稠油开发领域，特别是用于稠油储层描述和动态监测。
