MODELING OF NON-THERMAL RECOVERY OF HEAVY OIL BY CYCLIC SOLVENT INJECTION

使用低绿色家用气体（GHG，非蒸汽）工艺开发重油具有相当大的推动力。这可以使用溶剂来实现，这在之前已经经历了含砂冷采重油（CHOPS）的阿尔伯塔和萨斯喀彻温省的重油油田中可能特别相关。这些储层的初级生产导致原始石油储量（OOIP）的5 - 10%的采收率，因此仍然存在大量的石油，并且在CHOPS后的油田中没有注入蒸汽的能力，这使得它们成为开发非热溶剂采收工艺的优秀候选者。循环溶剂注入（CSI）是一种单井工艺，通过注入气相溶剂对储层加压。在升高的压力下，溶剂溶解到重油中并降低其粘度。然后，油井开始生产，因此油井压力下降，并为溶剂稀释的石油提供流动的驱动力。关于这一进程的几项实地试点研究已经在进行中。CSI面临的挑战是，随着生产井压力下降，溶剂从溶液中出来，石油粘度将再次增加。生产是实现流动和保持气体溶解之间的平衡行为。直觉表明，石油产量有可能大幅增加，但尚未确定的是，这一过程是否可以商业化。 通过了解CSI的物理特性（即控制石油生产的因素），并能够正确建模该过程，这有助于深入了解该过程在大规模上的未来可行性。 ** 根据我们过去在实验室规模岩心驱替方面的经验，初次生产后CSI恢复率较低，并且在每个连续周期中需要增加压力下降率。在现场，压降速率比实验室中慢得多，因此存在实验室研究中尚未捕获的物理现象。这项工作的目的是确定这些物理是什么，以及是否有可以控制的操作参数，以改善CSI的恢复。该计划的第一部分侧重于了解什么机制是重要的石油回收从重复CSI周期。CSI的实验室测试通常在比现场看到的高得多的初级生产之后开始。 此外，堆芯泛洪一般不考虑重力对CSI性能的影响。 最后，油-溶剂系统的PVT试验不能正确地代表溶剂离开油中溶液的非平衡响应作为压力和时间的函数。 不同的溶剂也可能具有不同的非平衡效应，因此它们在减压（生产）循环期间可能会有不同的反应。 该程序将运行实验来研究所有这些参数，并对CSI生产进行建模，以捕获适当的恢复机制。

There is a considerable push to develop heavy oil using low Green House Gases (GHG, non-steam) processes. This can be achieved using solvent, which may be particularly relevant in the heavy oil fields in Alberta and Saskatchewan that have previously undergone Cold Heavy Oil Production with Sand (CHOPS). Primary production from these reservoirs leads to recovery of 5 – 10% of Original Oil in Place (OOIP) so there are significant volumes of oil still present, and without the ability to inject steam in post-CHOPS fields this makes them excellent candidates to develop non-thermal solvent recovery processes.******Cyclic Solvent Injection (CSI) is a single well process, whereby a vapour phase solvent is injected to pressurize the reservoir. At elevated pressures solvent dissolves into the heavy oil and reduces its viscosity. The well is then placed on production, so well pressure drops and provides a driving force for solvent-diluted oil to flow. Several field pilot studies of this process are already underway. The challenge to CSI is that as the production well pressure drops, solvent comes out of solution and oil viscosity will increase again. Production is a balancing act between achieving flow and keeping gas in solution. Intuition suggests the potential for significant incremental oil production, but what is not defined is whether this process can be commercial. By understanding the physics of CSI (i.e. what controls oil production), and being able to model the process properly, this can help to provide insights into the future viability of this process on a large scale. ******In our past experience in lab-scale core floods, CSI recovery is low after primary production and the pressure decline rate needs to be increased in each successive cycle. In the field, pressure drawdown rates are much slower than in the laboratory, so there are physics present that are not being captured yet in lab studies. The objective of this work is to determine what those physics are, and if there are operational parameters that can be controlled to improve recovery from CSI.******The first part of this program focuses on understanding what mechanisms are important for oil recovery from repeated CSI cycles. Lab tests of CSI generally start after a much higher primary production than what is seen in the field. In addition, core floods generally do not consider the effects of gravity on CSI performance. Finally, PVT tests on oil-solvent systems do not properly represent the non-equilibrium response of solvents leaving solution in oil as a function of pressure and time. Different solvents may also have different non-equilibrium effects, so they may respond differently during depressurization (production) cycles. This program will run experiments to study all of these parameters, and model CSI production capturing the proper recovery mechanisms.