Determination of Residual Oil Distribution during Waterflooding in Tight Oil Formations with NMR Relaxometry Measurements
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- 作者：Ping Yang ; Hekun Guo ; Daoyong Yang
- 刊名：Energy & Fuels
- 出版年：2013
- 出版时间：October 17, 2013
- 年：2013
- 卷：27
- 期：10
- 页码：5750-5756
- 全文大小：318K
- 年卷期：v.27,no.10(October 17, 2013)
- ISSN：1520-5029
文摘
The NMR relaxometry measurements have been designed and applied to quantitatively determine residual oil distribution during waterflooding in tight oil formations. A tight core sample is first saturated with water to measure its NMR transverse relaxation time (T2) spectrum. NMR T2 spectrum is then measured for the core sample after it has been displaced with the fluorinated oil. Subsequently, the core sample is displaced with water until residual oil saturation is achieved, and the NMR T2 spectrum is measured again at the end of the displacement. Subsequently, the constant-rate mercury injection method is used to experimentally measure the size of the pore and throat in the core sample. The residual oil saturation is determined as a function of pore size by comparing the difference between the first and last NMR T2 spectrum. It is found from four core samples with permeability of 0.04鈥?.70 mD that the average pore size is in a range of 129鈥?45 渭m, and the pore throat has a radius of 0.17鈥?.89 渭m. The original oil saturation is found to be 76鈥?3%, whereas the oil recovery factor is 36鈥?2%; 4鈥?7% of the original oil is distributed in pores larger than 100 渭m, 50鈥?4% in pores from 10 to 100 渭m, and 21鈥?6% in pores and throats smaller than 10 渭m. Residual oil saturation is 1鈥?% in pores larger than 100 渭m, 29鈥?4% in pores from 10 to 100 渭m, and 34鈥?9% in pores and throats smaller than 10 渭m.