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

使用低温室气体(温室气体，非蒸汽)工艺开发重油是一种相当大的推动。这可以使用溶剂来实现，这在艾伯塔省和萨斯喀彻温省的重油油田中可能特别相关，这些油田以前曾用砂岩(CHOPS)进行过冷稠油开采。这些油藏的一次开采可回收原始原地石油(OOIP)的5%-10%，因此仍有大量的石油存在，而且无法在碎屑后油田注入蒸汽，这使它们成为开发非热溶剂回收工艺的极佳候选者。*循环溶剂注入(CSI)是一种单井工艺，通过注入汽相溶剂来给油藏加压。在高压下，溶剂溶解于重油中，降低其粘度。然后，油井投入生产，因此油井压力下降，并为溶剂稀释的石油提供流动的动力。对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，原油粘度将再次增加。生产是在实现流量和将天然气保持在溶液中之间的平衡行为。直觉表明，石油产量有大幅增加的潜力，但没有确定的是，这一过程是否可以商业化。通过了解CSI的物理原理(即控制石油生产的因素)，并能够正确地对该过程进行建模，这有助于深入了解该过程未来的大规模可行性。*根据我们过去的实验室岩心驱经验，在一次采油后，CSI采收率较低，在每个后续周期中都需要增加压力递减率。在现场，压力下降的速度比实验室慢得多，所以存在着实验室研究中尚未捕捉到的物理现象。这项工作的目标是确定这些物理是什么，以及是否有可以控制的操作参数来提高CSI的采收率。*本计划的第一部分侧重于了解哪些机制对于从重复的CSI周期中回收石油是重要的。CSI的实验室测试通常在初级产量比现场看到的高得多之后开始。此外，岩心泛洪一般不考虑重力对CSI性能的影响。最后，对油-溶剂体系的PVT测试不能正确地表示出溶剂离开油中的溶液作为压力和时间的函数的非平衡响应。不同的溶剂也可能有不同的非平衡效应，因此它们在降压(生产)周期中的反应可能不同。该计划将运行实验来研究所有这些参数，并模拟CSI生产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.