Numerical simulation investigations of the applicability of THAI in situ combustion process in heavy oil reservoirs underlain by bottom water

Q1 Earth and Planetary Sciences
Muhammad Rabiu Ado , Malcolm Greaves , Sean P. Rigby
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引用次数: 3

Abstract

The presence of a bottom water (BW) layer in heavy oil reservoirs can present substantial problems for efficient oil recovery for all recovery techniques. Hence, it is necessary to know how particular production processes are affected by different BW layer thicknesses, and how standard production procedures can be adapted to handle such reservoirs. Toe-to-heel air injection (THAI) is a thermally efficient process, generating in situ energy in the reservoir by burning a fraction of the oil-in-place as coke and has the potential to economically and environmentally friendly work in reservoirs with BW layer. However, to ascertain that, studies are needed first. These are conducted via numerical simulations using commercial reservoir thermal simulator, CMG STARS. This work has shown that the shape of the combustion zone in THAI remains forward-leaning even in the presence of a BW layer, indicating that the process is stable, and that there is no oxygen bypassing of the combustion front. However, the oil recovery rate is highly negatively affected by how large the thickness of the BW zone is, and the severity of such effect is determined to be proportional to the thickness of the BW layer. This study also shows that there is a period of low oil production rate which corresponds to mobilised oil displacement into the BW zone which in turn causes a surge in water production rate. The practical implication of this is that prolonged period of low oil production rates will expose companies and/or investors to higher risk due to the oil market volatility. In this study, it is also revealed that the height of the mobilised oil that is displaced into the BW zone equates to that of the displaced and replaced water thereby implying that when the BW layer thickness is 50% that of the oil layer (OL), less than 50% of the mobilised oil will be recovered when the entire reservoir is swept by the combustion front. Therefore, conclusively, applying the THAI process in its conventional form in reservoirs containing bottom water is not recommended, and as a result, a new strategy is needed to enhance process economics by improving the oil production and hence recovery rates.

THAI原位燃烧过程在底水下覆稠油油藏适用性的数值模拟研究
稠油油藏中底层(BW)的存在可能会给所有采油技术的有效采油带来实质性问题。因此,有必要了解不同BW层厚度对特定生产工艺的影响,以及如何调整标准生产程序来处理此类储层。从头到脚空气注入(THAI)是一种热效率高的工艺,通过将一部分石油作为焦炭燃烧在储层中原位产生能量,并有可能在具有BW层的储层中进行经济和环境友好的工作。然而,要确定这一点,首先需要进行研究。这些都是通过使用商业油藏热模拟器CMG STARS的数值模拟进行的。这项工作表明,即使在存在BW层的情况下,THAI中燃烧区的形状仍然向前倾斜,这表明该过程是稳定的,并且没有氧气绕过燃烧前沿。然而,BW区的厚度有多大对采油率有很大的负面影响,并且这种影响的严重程度被确定为与BW层的厚度成比例。这项研究还表明,存在一段低采油率时期,这段时期对应于将石油驱替到BW区,这反过来又会导致水生产率的飙升。这一点的实际含义是,由于石油市场的波动,长期的低石油生产率将使公司和/或投资者面临更高的风险。在这项研究中,还揭示了被驱入BW区的动员油的高度等于被驱替和置换的水的高度,从而意味着当BW层厚度为油层(OL)厚度的50%时,当整个储层被燃烧锋扫掠时,将回收不到50%的动员油。因此,最终不建议在含有底水的储层中应用传统形式的THAI工艺,因此,需要一种新的策略来通过提高石油产量和采收率来提高工艺经济性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Petroleum Research
Petroleum Research Earth and Planetary Sciences-Geology
CiteScore
7.10
自引率
0.00%
发文量
90
审稿时长
35 weeks
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